My 60 Seconds Binary Options Trading Style

OBLIGATORY FILLER MATERIAL – ESCAPE FROM STALAG SULTANATE, Part 1

That reminds me of a story.
“HELLFIRE AND DALMATIANS!” I shouted to no one in particular.
“What’s the problem, dear?” Esme asks in that way she has of telling me to calm down without having to say it directly.
“This bloody fucking country. A day late and several dollars short.” I fume. “Can’t get a new liquor license because of the bloody COVID. Can’t go to a hotel bar and have a snort because of the bloody COVID. Can’t even slip across the border to Dubai and soak up some room service and buckets of complimentary cocktails because of the bloody COVID.”
Yes, the Sultanate of Oman, in its infinitesimal wisdom, has traditionally followed other GCC countries by at least three months in making any sort of proclamations regarding this latest bugaboo: the hideous, deadly, itchy, loathsome, and possibly serially bent, noxious, pandemical COVID-19; aka, this pandemic’s entry for flu.
Their response is one of immense knee-jerk without first having thought of the consequences.
“Bloody lockdown, 2100 to 0700. What is this, the whole fucking country’s been bad and now being sent to bed without any supper?” I wondered aloud. “Idiot benchodes.”
Even Esme couldn’t come up with a rejoinder to that.
“Plus they close all the bars. And all the hotels. And the fucking bottle shops. It’s not enough that these fucking Muppets jack the ‘sin tax’ on booze and cigars by 100%, now they’re not even legally available.” I swore.
Of course, once you’ve spent even a small portion of the time that I have in the Middle East, you have your connections. Your system. Your access to the seedy underbelly of any society; the venerable Black Market.
Jesus Q. Christ on toast with baked beans, fried tomatoes, black pudding, and mushrooms, I could get most anything in the Middle East, be it legal, shady, or just plain illegal. However, before you all recoil in horror that the venerable Dr. Rocknocker dabbles in the prohibited, just remember: the ends always dojustify the means.
“I'm telling you, Esme dear; this Gulf story is getting too complicated. The weasels have started closing in.” I complain to Es as she hands me a fresh drink.
“Do you think…?” Esme asks expectantly.
Esme is more than ready to go. I’ve used this place as a base of operations for years whilst I wear out the Omani legal system suing those asswipes that think just because they’re local and I’m a kafir, they’re immune to the law.
I’ve spent a long, profitable and time-consuming period of the last few years proving them wrong.
But, time was marching onwards. I agreed with Esme, we’ve milked this particular cash cow dry. It was time to hitch up our bootstraps, call it a day, and get the hell out of Dodge.
But not before I took care of a few loose ends.
Now, the country had recently lost its venerable Sultan, who croaked back in January of this year.
Sultan Qaboos was a good egg, friend to expat and local alike. Did a shitload of good for this benighted Middle East sandpit. Dragged it kicking and screaming out of the 12th century into, well, not exactly the 21st, but a whole hell of a lot closer.
He realized that he needed revolutionary, not evolutionary change in the country. By revolutionary, he needed American, British, Canadian, and the like Western Expats here to do the heavy thinking and lifting and Eastern Expats like Indians, Bangladeshis and Nepalese to do all the scut work.
Yeah, I know. That sounds racist as fuck, but sometimes that’s the way the ball bounced.
Simple evolution of society where Omanis graduated the local equivalent of grade school, through high school, into University, and finally into Entry level jobs in the oil and gas industry wasn’t going to cut it. Took too long and the country needed a serious cash flow now.
So, that’s what he did. And it worked a treat.
Then he died.
And his chosen took over.
Except his chosen was pretty much antithetical to everything the previous and very revered and successful, Sultan wanted.
Soon, there are 100% ‘sin taxes’ aimed directly at the western expats. Tourists included.
Then there’s quotas and ‘Letters of No Objection’, which are impossible to get so that the Eastern Expats can’t switch jobs.
Then, there are Sultanic proclamations of new taxes on tourists, new taxes on fast food, new taxes on this, that and the other. Then there’s, in his own words, “Oman is for Omanis”, blatantly ridiculous and xenophobic Omanization, and the general swipe at all expats.
“GET OUT.”
This was the clear message of the new sultan.
He wanted to take over and possibly nationalize all the oil workings in the country.
Ask Venezuela, Iran, and Myanmar how well that worked out for them.
Then he wants all expats out on their asses. He wants Omanis to take over all the jobs, even though they’re nowhere near educated nor experienced enough for the positions. Then take up the massive GDP slack in lower oil production and oil prices with tourism.
Given everything else, that last line should be enough to get him off the throne.
He’s fucking nuts if he thinks people are going to want to cruise or overland anywhere near a place where foreigners are seen only as a cash supply, are despised, and would welcome these all new 100% tax levies.
Be that as it may, Esme and I decided that we have had enough of 135O F summer temperatures, virtual house arrest under the guise of a COVID lockdown, and idiots who were the only ones stupid or twisted enough not to vamoose when the great, big bloody letters were clearly written on the wall.
But, there was the physical act of getting out of the country.
Now, I had plenty of strings which I could pull, but I decided I’d start low and save those until we really needed them.
So low, in fact, we went to the US Embassy in Muscat.
“How low can you go?” reverberated through my head.
What a haven of sad-sacks, flubadubs, and third rate hobbyists.
Was either Esme or I surprised that when we finally secured an invitation to the embassy, that required a bit of string-pulling with the ex-Ambassador to Oman, now in Kabul; that besides the peach-fuzz faced Marine guarding the place, we were the only Americans in the joint?
“This is American soil!” I laughed, as I pulled out a huge Cuban cigar and was immediately told to extinguish it. “We’re as American as apple pie and napalm! We file our fucking 1040s every April; I pay my fucking long-distance taxes and demand US assistance to vacate this gloomy place of sandy, sweaty, sultry Sturm und Drang!”
“Shut up, Rock”, Esme chided me, “They don’t understand English. Much less, the florid English the way you trowel it on.”
“Fuckbuckets”, I remonstrated. “Here I had memorized the whole Patrick Henry speech he made to the Second Virginia Convention on March 23, 1775, at St. John's Church in Richmond, Virginia. Troglodytes. No admiration for the classics.”
“Rock, dear?” Esme noted, “It’s almost 1100 hours. Best to get to our appointment.”
True, our appointment was slated for 1100 hours. But around here, anything starting within three hours of the stated time was considered close enough.
We dragged ourselves, none too cheerfully, to the waiting room. Once we pried open the door, there was the usual “If you hear a high pitched wail, hit the deck” signs, and other things one could do while kissing one’s ass goodbye if there was a terrorist attack, we had a whole new slew of bullshit with which to deal.
“Social distancing. 6 feet. Or if you’re from Baja Canada, 1 cow’s length.”
“Must wear a mask. Bandanna, bandoliers, and large-caliber weapons or sombrero optional.”
“No sitting. Faux Naugahyde seats are too difficult to sterilize. You must stand at attention, do not talk amongst yourselves, and remain patient until your number is called.”
“Well, fuck!”, I snorted quietly, as I raised my first secret flask in rapt attention to our old glory of red, white, and blue.
“Good thing they didn’t say nothin’ about getting a load on. If I’m going to be treated like cattle, I’m going to at least have something to chew on in the process.”
“Oh, lord”, Esme grumbled, “You didn’t bring that Japanese Rye Whiskey with you, did you?”
“ルハイム”, I said, which is Japanese for “L’chaim”!
“Oh, hell”, Esme grinned as she borrowed my flask, “This is going to be a long day.”
I began to protest but remembered that I was wearing my Agency-issued field vest. I must have had at least 5 or 6 more flasks lurking around in those pockets somewhere.
Funny aside: they don’t bother with my going through an X-ray machine nor do they confiscate my phone, radio, knives, nor other field equipment when I go to the US Embassy.
It took them almost two solid hours last time, and by the time they got to my Brunton Compass, emergency flasks, a few spare blasting cap boosters, and saw the label sewn into the back of my vest, they decided they’d just send Rack and Ruin some evil Emails and let me pass unmolested.
“I’ll drink to that”, I say as I raise a flask as the locals raise an eyebrow. “Courtesy of Atheists International. We’re here for your children…”
The collective gasps and growls indicate they weren’t happy with me or my betrothed.
“Don’t care, Buckwheat”, I smiled, “Never did, never will. We’re out of here for good. You can curse my name all you want then. But, then again, why you standing in the American Embassy trying to get a visa to visit the land of the great evil empire?”
All the locals and most of the Eastern Expats crowded into a corner as far away from us as they physically could.
“BOO!” I snickered over a shot of Wild Turkey 101 Rye.
“Now serving number 58! Number 58!” came the call over the tannoy.
“Look at that”, I remarked to Es as I stashed both our flasks, “It’s only 12:35. Record time.”
We both shimmy into the glass-fronted and presumably bullet- but not C-4 resistant- glass.
We pick up the telephones there and acknowledge that we are who we said we were.
The East Indian fella, one Harsh Talavalakar, behind the multiple layers of glass asked us why we were here.
“Didn’t you read the appointment card?” I asked, “We’re here to have Uncle Sam get us passage out of this sordid and sultry place.”
“You are American citizens?” he asked, vacantly.
“That’s what it says on appointment cards and these here blue passports,” I replied.
“Well, how was I to know?” he scoffed, returning to his half-consumed powdered sugar doughnut.
“Maybe read the appointment card and see that we are US Citizens here on the behest of Ambassador Bethesda Orun?” I replied.
“Like I have time to read everything that comes across my desk”, he scoffed again.
I tapped on the glass to make certain I had his full attention.
“Look here, Herr Harsh. I’m not sure how you got this job at the American Consulate but want to be very clear with you. My wife and I are residents of this place for the last 20 years. We’re American citizens of very high standing and have more high powered connections than an Arduino in a nuclear power station. We have direct connections with Langley, Virginia and if you want to retain your cushy job, you’ll put down that fucking doughnut and pay very rapt attention to the two Americans standing here who are getting more and more irritated with some Indian benchode that doesn’t think he has to really do his job. You savvy? You diggin’ me, Beaumont
I guess the benchode got his attention. The two scowls he received from Esme and myself sort of cemented the idea that we’re not too pleased and not with to be trifled.
“Yes, sir?” he said, “And ma’am”, as Harsh quickly corrected himself as the doughnut disappeared.
“We want out. Gone. Vamoose. Outta here. AMF. You got me?” he nods behind the shatterprone glass.
“Now I know the borders are sealed and the airport’s closed, but fuck that. We want out and we want gone for good. I can’t make that much simpler or clearer. Get after it, son.” I said, as seriously as I could.
“Well, sir”, he began, “ The airport’s closed…”
“Are you deaf or born stupid and been losing ground ever since?” I asked, rhetorically. “I know that. We all know that. My HAT knows that. So, what devious little plan does the US Embassy have in store in just such an unsavory situation?”
“Well”, he chokes a bit, “There’s this unofficial lottery where America citizens are issued random numbers and if their number comes up, there are seats made available on special clandestine charter flights.”
Considering that Es and I are some of the last American citizens left in the country, I thought our chances might be pretty good.
“OK”, I said, “Let us have two of your finest numbers.”
“Yes, sir”, he said, “That will be US$500 total.”
“Excuse me?” I said.
“Oh, yes”, he smirked, “US$250 per number. Chances are you’ll never be called, but with these numbers, at least you stand a chance.”
“OK”, I said, “Forget the numbers. I want your name and operating number. I’ve got a report to file that’s due in Virginia before breakfast.”
“Oh, sir”, he smirked more, “I cannot release that information. Thanking you. Now be having a good day.” And he slammed the supposedly bulletproof shield between himself and Es and me.
“Bulletproof? Maybe. Nitro proof? No fucking way.” I groused as I fished out a couple of blasting cap superfast boosters.
“Calm down, dear”, Esme smiled to me as we walked out, “When he wasn’t looking, I took his picture, got his operating number, and full name. In fact, I think I got some information on where he lives…”
In the cab on the way back to our villa, I reviewed and confirmed Es’s subterfuge. Flasks number 6 and 8 needed serious replenishment by the time we arrived home.
“That’s fucking right, Ruin.” I yelled over the phone, “We need extraction. And now. Along with our personal effects and a few hundredweight of ‘don’t ask, don’t tell’ boxes of stuff we need to be transported.”
“Well, Rock”, Agent Ruin replied, “That’s a tall order. Usually, extraction is for one person and the stuff they’re wearing. Tell you what. Let Rack and I work on it for a week or so. We’ll arrange transport of your personal effects, then we’ll see about getting you and Esme to Dubai. At least there, you can order a plane. Hell, knowing you, you’ll get Tony Stark to fly in and provide door to door service. Sit tight. We’ll be back in touch.”
“Good!” I say as I slam the phone down. With these newfangled cellphone telephone instruments, they lack the same sort of satisfying “KER FUCKING CLANG” the old landlines used to have.
“Es!”, I yelled, “Start packing. We’re due out of here within a week.”
That meant we needed to do some packing triage:
• Things going home with us.
• Things being shipped.
• Things being sold.
• Things being left behind.
• Things no one was about to get their furry little mitts on.
“Oh, fuck!”, I startled. I had just remembered the John Wick-ian stash of various explosives, and adjunct materials I had buried in the basement. Obviously, I couldn’t take it home with me, I couldn’t sell it, and I sure as festering frothing fuck wasn’t going to leave it here.
I needed to call one of my more shifty and swarthy friends and arrange for passage out to the deep, dark desert. Around the area where the new sultan had opened a couple of brand new landfills.
Looks like I was going to expand them a few meters once we disposed of the few hundred kilos of accumulation I attained over the last few years.
See, I’m a packrat. I never leave nor toss anything that might be convenient. Might have a benefit. Might prove to be useful sometime down the line.
So, I’ve accumulated a bit of kit.
Like…well…a few hundred sticks of Du Pont 60% Extra Fast Dynamite. A couple dozen spools of Z-4 Primacord, in various degrees of fullness. A shitload of C-4; enough bricks for a Floydian wall. A couple, well, a dozen, well, two dozen cases of binary liquid explosives. Hey, this stuff is hard to come by…
Continuing, several thousand blasting caps and superfast flash blasting cap boosters. Some mercury fulminate. Some nitrogen triiodide. A couple tens of pounds of PETN. An equal amount of RDX. A few Erlenmeyer flasks full of shit even I’m not certain of what it is…
Oh.
And a few kilos of freshly decanted, raw nitroglycerin; packed in sturdy wooden boxes lined with new fuzzy lamb’s wool.
Not that much. Just 10 or 12 kilos.
Yeah. I can’t leave that here. Even a small accident with this stuff would lay waste to not only our villa; but my landlord’s villa with whom we share a common wall.
Besides, as Omanis go, my landlord was the only dishdasha dressed denizen for which I had any respect or admiration. He was a good guy. I needed to return his villa at least in some semblance of what I received when we first rented from him.
So, I had to dispose of many, many billions of kilojoules of potential energy. I needed to do this out in a distant and far away from prying ears and eyes regions and I needed a truck to haul this stuff out to the range.
To be continued…
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The Shoulders of Orion- Ch. 1: First Contact

Space-time rippled as the Horns of Glory snapped into real space. The normally smooth transition from FTL subspace travel back to the laws of relativity was instead dangerously jarring, as the inertial dampeners struggled to hold the innards of the massive warship in their proper places. After straining mightily for the briefest of moments, they failed, throwing Admiral Halon Va and the rest of his bridge crew violently into their restraining harnesses. The ship shuddered under the immense stress, then settled, drifting silently through space on minimal power.
“Tactical, get me a status report for the fleet on screen now. I want updates the instant ships jump in.” The Admiral’s voice was still firm and authoritative; it was taking every last shred of resolve he had to keep it that way. “Lieutenant Roshin, put a detail together and work with medical. I’m sure that re-entry caused more than a few extra injuries. Get as many of the crew patched up and ready for emergency action as fast as you can. I want a full casualty report as soon as possible. And if you find Science Officer Lentith and he’s still alive, send him to the bridge immediately.”
Admiral Va settled back into his command chair, drawing creaking sounds from the over-stressed frame as it absorbed the weight of his massive form. The bridge was completely silent now, the command crew entirely focused on the tasks at hand. Or they were too afraid to say anything; Va couldn’t be sure. He was thankful for their silence, though. He didn’t have any answers for them about his failure.
Keying in a few commands on the command panel at his station, the damage report for his ship popped up, the bridge lights flickering from the extra power draw. The Horns of Glory floated before him in hologram form. Long and slender, the ship was over two kilometers from bow to stern. At least, it had been a few hours ago. The forward 20 percent of the holographic ship was flashing red, indicating heavy damage. This was inaccurate, however, as the forward 20 percent of the ship simply wasn’t there anymore. The graceful lines and carefully crafted angles of the ship's armor were an unrecognizable slagged mess, and deep gouges had been cut into the inner decks all over the ship. Whole sections were missing amidships, two of the main reactors were offline, all the primary weapon batteries had been completely destroyed, and most of the critical systems were barely functioning. It was a miracle that she had survived the jump. That morning, Horns of Glory had been the greatest feat of Arien’Ra engineering, and it was now a barely functioning hulk.
And it had all happened under my command, thought Va.
He had no time to wallow in his failures, however, as at that moment tactical finally reconnected to the fleet command systems. The hologram of Horns of Glory quickly scaled down, appearing as a small, flashing, red point of light floating in loose formation with several other points of light. Most of them were flashing red as well. A constant stream of data and various reports scrolled down the right side of the hologram, listing in no uncertain terms the doom that Va had subjected his command to.
If Va had thought that the bridge was quiet before, it was nothing compared to the complete stillness that now settled over them. No one so much as moved a muscle, as they all sat in stunned silence, reading the reports. Occasionally, the hologram would flash, and a new point of light would join the formation, adding more data to the pile spelling out their damnation. After 30 ticks, new points of light had stopped appearing. Admiral Halon Va had lost over 60 percent of his fleet, and not a single other dreadnaught had survived the slaughter. His defeat was total, and the Federation navy was crippled.




Science Officer Beredarin Lentith had been the first member of his family not to enroll in command school in eight generations. They had been some of the finest members of the fleet the Vorqual race had ever contributed to the Federation. His brothers and sisters had all enrolled, which meant that as far as he was concerned, his family had more than fulfilled their duty to the Federation. Military life wasn’t for him, anyway; he wanted to explore. The Federation had been around for over 3000 years, and there were still vast swathes of the galaxy that they knew nothing about. They were still encountering new species every few hundred or so years, and there was nothing he wouldn’t give to find the next one. That had been the dream that directed him away from the military and into academia. The odds of actually finding a new race were so small, though. There were still at least 200,000,000 unexplored systems in the galaxy. There just wasn’t time to visit them all...
He snapped out of his reverie as he stepped over the body, or rather, what was left of the body, of a Zelnassi marine. Most of it was just a green stain on the corridor wall at this point, though there had been enough of the chitinous armored torso to partially obstruct his path. The young lieutenant quickly continued on towards the bridge.
If he was being honest with himself, becoming an expert on the area of unexplored space directly between the Federation and it’s largest military rival wasn’t the smartest of ideas. Between his family reputation and his unique knowledge base, he was just asking to get pressed into service.
Which was exactly what had happened immediately upon the recent outbreak of hostilities.
And now here he was stepping over corpses, marveling at the fact that he had somehow survived this long. He still couldn’t believe the insanity of the Dominion forces. Boarding an enemy ship MID-COMBAT. It was like something out of a youngling’s tale from before space travel. It was pure madness, but there were the bodies to prove that it had happened. He gingerly stepped around the remains of yet another Zelnassi.
The signs of battle continued all the way to the bridge, where he found security forces still holding quickly fortified positions around the bridge entrance. There were more Zelnassi bodies at their feet. Berendarin shuddered. He had been closer to death than he thought.
He quickly pushed those thoughts out of his mind. He could only imagine why he was needed on the bridge so urgently.
The door slid open, and Lentith walked into a completely silent room. Admiral Va was slouched at his command station, his enormous arm propped up on the chair arm and supporting his massive, horned head. Lentith didn’t even know that Arien’Ra COULD slouch. Nevermind that the fastidious Admiral could or would ever do such a thing. Maybe things were somehow worse than he thought. No one seemed to notice him enter, so he announced himself to the Admiral.
Though he didn’t shout, his voice echoed in the deathly silent room, startling most of the bridge command. Two of the other Vorqual officers swore, and the tiny Jezren manning the com station let out a high pitched sound somewhere between a squeak and chirp. Berendarin would have found it quite funny if the situation wasn’t so dire.
Admiral Va immediately snapped back to being the hulk of muscle and horn that imposed his will on a room just by being in it. His booming voice only added to his authority.
“Science Officer Lentith. I’m glad to see you’re still alive. Are you seriously injured?”
Berendarin had almost forgotten that he had walked the entire way to the bridge holding a bandage to his head just above his left eye. The drop out of subspace hadn’t been kind to him. He pulled the bandage away, revealing a dark orange stain on the bandage and a crack in the bone plate above his eye.
“I’m fine, sir, just one of the outer plates, and the bleeding has already stopped.”
“Good. Commander Vortith is currently overseeing the emergency repairs. Take his seat. You are going to help me find a way back home.”
“Sir? I’m sorry I don’t understand. Why don’t we just go back the way we came?”
“That’s not possible. Most of our supply ships and tenders were destroyed when that third wave of Dominion ships hit our flank. Almost all of our pre-prepared fuel reserves are gone. On top of that, some of our ships are so damaged that they don’t have another long jump in them. And if we run into any enemy ships, the whole rest of the fleet is done for. We barely qualify as a fighting force in the state we’re in.”
“Is it really that bad?”
“It’s worse, but we don’t have time to get into the details. You’re the expert on this section of the galaxy. I need you to find the fleet a hiding hole. Somewhere away from the known jump routes through the Spur. Any system where we can use the few miners we have left to scavenge up some fuel, and get some critical repairs done while we’re at it. And from there either wait for reinforcements or get ourselves patched up enough to limp home. Wherever it is, it needs to be close. I’m not leaving any ships behind because they can’t make the jump.”
“Oh. Just that?” The lieutenant knew that Arien’Ra were strict herbivores, but with the look that the Admiral shot him, he couldn’t help but think about the fact that his head would easily fit into that giant, molar filled mouth.
“And away from any known pirate hideaways. Like I said, our fleet can’t take any more fighting. And find it quickly. It won’t be long before the Dominion fleet locates us.”
“I. Uh. Sure. I’ll see what I can find.”
Berendarin shrank into the commander’s chair next to the enormous Arien’Ra, desperately wishing he had been more professional. If he had acted like a proper soldier, it might soften the blow of telling the Admiral that what he wanted was next to impossible. If he had a few weeks, he might be able to find something. So much of the Spur was still un-surveyed. The odds of there being anything useful to the Admiral in the databases was absurdly low, and there was even less of a chance he’d be able to find it in time for the information to matter. He began pouring through his notes anyway. It was better than waiting around to die, which, if the situation was as dire as the Admiral made it sound, was the only other option.
He spent the next hour lost in his notes, finding nothing, while the bridge crew went about piecing the ship and the fleet back together. The young scientist had all but given up on the Admiral’s impossible request when a raucous cheer went up from everyone on the command deck.
“Sir,” The coms officer called out, “The Consul’s Pride just dropped out of subspace and is hailing us, sir.
The main communication screen lit up, and Berendarin Lentith looked to see the face of his oldest sister on screen, strapped into the captain’s chair of her dreadnaught. He let out a sigh of relief; Baraquen was his favorite sibling. Her uniform was drenched in a deep orange blood stain at the shoulder, and she was covered in what looked like flecks of green gore from a Xelnassi. The artificial gravity was clearly malfunctioning, as the captain’s restraining harness was the only thing keeping her from floating around her bridge. But the bone plates of her jaw were turned as always into her calm, self assured smile
“My apologies for the delay in joining you, Admiral Va. We had some… guests shut down our drive mid jump. We had to deal with them before we rejoined the fleet. I assume there is a plan to get us back to federation space?”
“It’s good to see you in one piece, Captain Lentith,” the Admiral responded. He was barely able to keep the relief from his voice. “And there is indeed a plan.”
Berendarin returned to his research as the two ranking officers in the fleet went over the details of their current predicament. He was glad his sister had survived, and not just because they were close. It would have been a terrible blow to the whole family to have lost not only their future matriarch, but the ship she commanded as well. A member of his family had been commanding that dreadnaught uninterrupted for the last 5 generations. Military service had never appealed to Berendarin, but his family history was certainly still important.
And then the solution to the current problem hit him like a driver round. He let out a gasp and tore into his notes with a fervor. Both Admiral Va and his sister’s projection turned to look at him, but he didn’t notice. After a few seconds of curious silence from the rest of the onlookers, Berendarin practically jumped out of his seat.
“Admiral, I think I’ve got something that will work.” The young Lieutenant punched a few commands into his datapad, and a set of stellar coordinates popped up on the navigation terminal. “It’s a main sequence star, about 500 light years from us, fairly close to the edge of the Spur. It’s not anywhere near any established jump routes. The Consul’s Pride made me think of it.” He nodded towards his sister’s face on the ship's screen. “Our great, great grandsire took the Consul’s Pride through the system on her shakedown run a little over 300 cycles ago. Chased a band of Qorthi slavers out of the system. The outer four planets are all gas giants. If we can’t find Helium 3 there, I don’t know where else we should look.”
On screen, Captain Lentith looked impressed, but Admiral Va clearly didn’t seem too sure. “We’re supposed to be going away from Dominion forces, not into them. What were the Qorthi doing there?”
“There are also four rocky inner worlds in the system, Sir, according to reports from the encounter. Apparently, the third planet is a Class 7 Deathworld, and the Qorthi were running some experiments on the primitive lifeforms there. They were caught completely by surprise by the Consul’s Pride, and it was the first time that she fired her weapons in anger. I can’t find any reports of Dominion ships in that section of the Spur since.” There was a long pause before Va responded.
“Good work, Lieutenant. I knew my trust in you wasn’t misplaced.” Admiral Va replied, before turning to the rest of the bridge and booming “Coms! Tactical! Get those coordinates to every ship in the fleet. I want every ship we have left formed up and ready to jump as soon as possible. Any captain who feels that his drives can’t make the jump is to focus all repair efforts on getting their drives functioning immediately. I will transfer repair crews from less damaged ships to more damaged ships if that means we jump even a tick earlier. Get to it everyone. I’m not losing any more of my fleet today.”




The four revolution long jump to Science Officer Lentith’s newfound sanctuary had done wonders for Halon Va’s mental state. The initial shock of his fleet's terrible defeat had worn off, and he had been able to focus on what came next. Repair crews were able to stabilize most of his ship's core systems, and he was no longer worried about the life support systems cutting out and killing the rest of his crew. There had also been time for him to visit with the wounded. To thank them for their sacrifices. He had expected it to be an act of contrition, maybe even a chance to start begging for forgiveness. But there had been no anger in his crew, and no blame hung on his horns. Most had just been relieved that he had survived, and had expressed as much. He would be forever grateful to them for that.
Most importantly, the four revolutions in hyperspace had given the admiral time to really think about what had gone wrong in the nebula. He had barely rested in the preceding four revolutions, spending every scrap of spare time in his office, pouring over records from the battle. That’s where he found himself now, tucked behind his massive ceramic and titanium alloy desk of Tellarim design. It had been custom made for him upon his promotion to this command, a gift from the high admirals and the council. It was the only luxury that Va allowed in his office. The rest of Va’s space he kept strictly utilitarian. There were no trophies adorning his walls, as was customary for other members of his species. The plain bulkheads of his office were instead lined entirely with screens, and each of them were now filled with footage and reports from the battle, running on loop.
Va soaked it all in. The more he watched, the more a singular conclusion crystallized in his mind. He had done everything right; he was sure of that now. 1000 years of doctrine and theory for fighting the Dominion had gone into his preparation for that battle, and he had followed it to the letter. And he had been winning. Then that attack on his flank by the Zelnassi had blown all of that out of the airlock. Something significant had changed in the way the Dominion fought...
Commander Vortith’s voice rang out over the com system. ”Admiral Va, we’ll be transitioning back to real space in moments.”
“Thank you. I’ll be there shortly. And get Science Officer Lentith to the bridge. I want him nearby just in case. He’s the only one who has any idea of where we are.” The Admiral pulled himself from his desk. He would have to leave the rest of his analysis for later. There was just enough time for him to reach the bridge and settle into his command chair before the Horns of Glory snapped back to real space. This time, the inertial dampeners held.
“Tactical, status report.”
“All ships accounted for, Admiral. Though the Consul’s Pride, several cruisers, and three of our escorts are all reporting massive failures in their Drive Cores. They won’t be jumping anywhere anytime soon.”
“Wonderful.” Va wasn’t sure if he meant that sarcastically or not. “Get scans up and running and deploy the pickets that aren’t crippled in a standard scouting formation. How close are we to the nearest gas giant?”
“We’re approximately half a light tick from the system’s innermost gas giant, sir.”
“Excellent. Deploy the rest of the fleet. Put us in a high orbit around the planet in a defensive formation, and get our miners working immediately. Once our orbit is stable, I want every hand, paw and hoof in the fleet working on repairs.”
“Yes sir.”
Admiral Va settled into his command chair for a long shift.
It would be a drawn out, boring process to refuel the ships. With his fleet limping along, and only two functioning miners, it would take far longer than it should. After all the chaos of the last few revolutions, boring would be a welcome change of pace. Va started to relax, sinking into his chair’s acceleration padding. His fleet and his crews were finally safe. The first priority would be to get one of the subspace beacons repaired and to get word back to the Federation that the fleet still existed. And hopefully call for aid. He was sure to be stripped of his rank as soon as contact was made, but hopefully he would avoid a Tribunal. That was an unpleasant prospect…
“Sir, we have unidentified ship signatures appearing from around the planet we’re approaching.”
Va had never heard panic in the voice of his young sensors officer before, but it was certainly there now. Va understood the sentiment, though. He found it difficult to keep the panic from his own voice as he started issuing orders
“Bring the fleet up to combat status immediately. How many ships are there?”
“I’m showing 35 individual signatures. All approaching us at combat speed and still accelerating. At current speeds, they will intercept us in just over 30 ticks, sir.”
“I want details as soon as you have them, Lieutenant. Size, make, estimated firepower. Who they are. And keep scanning the system. Find out where they came from.” The panic had partially subsided for Va. 35 unknowns was not too terrible a threat. He still had almost 240 warships under his command. Still, if there was a way to avoid combat, he had to try. His fleet couldn’t suffer any more losses. “Coms, any attempt by these unknown ships to contact us?”
“I”m not sure, sir,” the diminutive Jezren at the coms replied. “There’s nothing on standard communications channels. The ships are transmitting something, but I can’t figure out what it is.”
“Admiral,” the Lieutenant at the sensors station called out. “I think I might have an idea of where these ships came from. Preliminary scans show there is extensive urbanization on the third and fourth planets, as well as what appear to be habitation sized artificial satellites around the second and sixth planets. One of the moons of the gas giant we’re approaching shows signs of habitation as well. All of them are emitting significant signal pollution. This system clearly already belongs to someone, and they’re broadcasting everywhere.”
Halon Va, High Admiral of the Combined Federation Fleets, turned, slowly and with as much composure as he could muster, to face the young science officer seated to his left. Berendarin sat, mouth agape, staring transfixed at the sensor readouts in front of him. Va had never seen a Vorqual more confused in his life. “I want answers, Officer Lentith.”
“I… I don’t.. This doesn’t make any sense,” the young science officer stammered. “There shouldn’t be anything here.”
“Admiral,” The comms officer cut in, “The signal that we’re picking up from the unknown ships is definitely some kind of communication. I managed to put together audio from it.”
“Play it,” commanded Va. A series of short, guttural, and completely unintelligible sounds came over the speakers in reply. There was a short pause before the sounds repeated themselves again. “Coms, what was that?”
“No idea, sir, but it’s being transmitted on loop. If it is intended as a communication, our translators have no idea what to do with it.”
“Admiral.” The voice came from Va’s left, and was barely audible. Va turned yet again to look at the young science officer. His gaze was locked on the tactical readout, and there something in his eyes that Va couldn’t recognize. A mixture of pure terror and something else. Was it wonder? The young Vorqual’s voice was still barely above a whisper when he continued to address the admiral: “I think we should run the transmission through First Contact Protocols.”




Captain Benjamin Alvarez-León slammed against his restraining harness as the USCS Aurora started it’s decel burn. He had pushed the engines on the outdated cruiser to their limits, and the ship groaned in protest as it started counteracting his rather zealous acceleration orders. He hoped that his mad scramble with his small squadron of outdated ships had been an overreaction. The alternative was something he’d rather not think about.
All Ben had was the reserves; the rest of the fleet was on maneuvers at Sirius. The Admiralty had wanted to test the new, fully modernized fleet’s maneuvering abilities in the gravwell of a binary system. And, in their infinite wisdom, they decided they needed ALL of the new fleet assets, leaving nothing in Sol except for the handful of cruisers and escorts that couldn’t match the capabilities of the modern ships.
A handful of cruisers and escorts that were now hurtling towards more than 200 unknown contacts.
It was the unknown part of all of this that was unnerving Ben. There were no familiar energy signatures. No familiar scan data. No IFF. No signals coming off the contacts of any kind for that matter. Two of the contacts were too big to even be ships. If it wasn’t for the fact that they were moving towards Jupiter in formation, Ben wouldn’t even think they WERE ships.
“So what do you think, Alexi?” Ben asked, turning towards his second in command. “You and the rest of the bridge crew are always making inane bets. Have you whipped up an over-under for what we’re throwing ourselves at yet?”
“Haven’t had time,” came the quick reply from Ben’s right. The short, stocky man from Vladivostok was missing his trademark joviality. “Though, my money is on them being Ithacan, sir.”
Ben bristled at Alexi calling him sir. They’d been friends for twenty years, damnit, and had been practically joined at the hip since going through the Academy together. Outranking him still felt a little off. Now was hardly the time to worry about formalities, though.
“What makes you think they're from Ithaca?”
“It’s the only thing that makes sense. The locals have been getting increasingly radical, and Ithaca is the only sector where reports of piracy have been increasing.”
“Yeah, I could see a rebellion coming from Ithaca,” Ben added slowly, turning over that scenario in his head. “But there’s no way they could swing something of this magnitude. There aren’t even any shipyards in the sector. And even if there were, there’s no way they could keep the construction of over two hundred ships a secret.”
Alexi could only offer him a shrug in response.
It was at that moment that the coms station informed him there was a transmission incoming from the unidentified ships. Ben instructed the ensign to play it, and the bridge was suddenly filled with a stream of grotesque bleating noises and strange grunts, with the occasional recognizable syllable interspersed throughout the transmission. Ben thought he picked out ‘dentify’ from the mess, but he wasn’t sure. There was a long moment of silence on the bridge.
“What the hell was that?”
When no one had any answers for him, Ben tapped his command console and recorded a new message to broadcast.
“This is Captain Alvarez of the USCS Aurora. Unidentified ships, please clarify. Your transmission is badly garbled. We did not receive your identification. You are still trespassing in Commonwealth space and are on an unauthorized course towards Jupiter. Begin decelerating immediately and re-identify yourselves.”
He wouldn’t admit it to the crew, but Ben was profoundly unsettled. Something was deeply, deeply wrong about this whole situation. Not only was he vastly outnumbered by these things, but they were unwilling to communicate properly. He was almost believing this whole thing was some kind of bizarre prank.
“How much longer before we can get a decent visual on these things?
“Any moment now, sir.”
A new transmission arrived just then, and Ben had it played back immediately. This time, instead of almost bovine bleats and grunts, the sounds coming over the speakers were mostly intelligible. Or, they would have been, if any of the syllables were in the right order. It was almost like a toddler was rattling off all of his new favorite sounds, spitting them out in a random order and not knowing how they went together. There were still a few heavy grunts sprinkled in, just for good measure.
Before Ben could process this new joke of a transmission, the contacts finally started slowing. In a matter of moments, the strange wall of contacts was hanging lazily in Jupiter’s orbit, barely moving fast enough to keep their orbit from decaying. They were still in perfect formation.
“Huh. Well, I guess that’s something.”
With nothing to do but sit back and wait as his ship closed the distance, Ben tried to relax and began running over all of the possibilities in his mind of what the new contacts could be. He came up with nothing. Well, nothing feasible, anyway. He took a series of long, calming breaths, trying to clear his mind and focus. This was no time for his imagination to be running wild. But he couldn’t shake the feeling that logic was failing him. Something was off. Something…
“Captain, bringing visual of the unknown contacts up on screen now.”
Ben actually felt his jaw drop. Every contact on his display was clearly a ship. Most were long and spindly, wrapped in layers of some kind of highly reflective armor; a fleet of crystalline arrows hanging in the darkness. The two largest contacts, which Ben had just moments ago thought were too big to be ships, were large enough on the screen for him to clearly see details. In addition to their immense size and strange armor, both ships were dotted with what were clearly weapons platforms, though what kind, Ben couldn’t tell.
Noticeably, almost all of the ships on his screen were heavily damaged. Chunks were missing from some ships, and most had deep lines gouged into their hulls. Any form of decorative paint or markings had been burned away. Something had put these ships through absolute hell. But still, the damage could not take away entirely from the elegance of the ship’s designs. They were graceful and sleek, completely different from anything Ben had ever seen before.
It was all so different. So strange. So very, very… Alien.
Despite every effort he had made to avoid the word, it finally forced itself to form inside Ben’s mind, and forced him to acknowledge the reality that legitimate, extra-Solar life was hanging in the darkness in front of him. It forced him to acknowledge the screams he had been suppressing in the back of his mind. The screams of his imagination crying out in glorious triumph over reality. And with those screams came a deluge of accompanying thoughts and emotions.
He was a child again, staring up at the stars above Armstrong and wondering what else, and who else, was out there. He was a teen again, signing his name to the Academy enrollment paperwork, determined to get out there between the stars and see the galaxy himself. He was a young officer again, screaming and pleading with the Admiralty to at least consider a modern First Contact scenario. He was sitting in his command chair now, hurtling towards honest-to-god aliens, all of his dreams made manifest in an instant. He was overwhelmed. He was terrified.
And he had never imagined that he could feel such elation.
It was the young warrant officer at the coms that snapped Ben out of his reverie. “Sir, the contacts are hailing us on all standard channels, requesting a video feed.” She sounded very, very nervous.
Ben immediately stood up, straightening his uniform as best he could. “If they’re anything less than genocidal monsters, I’m going to offer them aid and repairs. As long as they’re peaceful, there’s no reason not to extend them the full hospitality of humanity.”
“Ben,” Alexi asked, clearly choosing his words carefully, “Are you sure that’s the… Wisest course of action? How will the Admiralty respond to Goddamned alien ships docking at Hephaestus?”
“Alexi, in the 250 years the Commonwealth has existed, the First Contact protocols haven’t been updated since the charter was signed. No one has cared. This has been nothing but a fantasy for most people. I am NOT letting this opportunity get away. Every child that has ever looked up at the stars and wondered finally got an answer, and I will not waste this moment. We’re making friends, the Admiralty and the government be damned.”
“You do realize you’re potentially deciding the fate of our entire species on a whim, right?”
“Is there someone else you’d prefer to have making this call?”
Alexi, apparently deciding that there was not, stood up and straightened his uniform, standing next to his friend as he ordered the connection of the video feed. The channel connected, and the human bridge crew found themselves looking at the bridge of a ship crewed by not one, but three alien races.
The largest alien in the center of the screen opened its mouth to speak. This time, instead of bleats and grunts, a choppy, mechanical voice that didn’t sync up to the alien at all proclaimed from the bridge speakers in broken, stuttering English: “I. Am Admiral. Halon. Va. Of the Federation of. Sentient Races. Greetings and. Welcome. To the. Galaxy.”
Ben couldn’t suppress his smile.
“On behalf of the United Solar Commonwealth, and all of Humanity, greetings, and welcome to Sol. Your ships look like they’ve had a bad time on your way here. If there’s any way we could aid with your repairs, we’d be happy to help.”




Slave 782 slammed his right appendage onto the control console hard enough to rupture his outer membrane and smear ichor over the panel. It had been four days since the battle in the nebula, and with the latest round of reports, he finally had to admit that the rest of the Federation fleet had escaped him.
It was a minor frustration, all things considered, but the escape prevented this from being a total victory. Still, he had proven his worth to his owners in this battle, and his experiments with the Zelnassi had paid dividends beyond his wildest imagination. He had earned a command today, and with every success in that command, his ability to bargain for his people's freedom only increased. For what he would be asking, it might take the total defeat of the Federation to earn that kind of leverage. Also frustrating, but not a task that he couldn’t handle. It would be a long war, he was sure, but like his owners, he was patient.
He would earn his freedom, even if it meant reducing the entire Federation to glass.


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Video Encoding in Simple Terms

Video Encoding in Simple Terms
Nowadays, it is difficult to imagine a field of human activity, in which, in one way or another, digital video has not entered. We watch it on TV, mobile devices, and stationary computers; we record it with digital cameras ourselves, or we encounter it on the roads (unpleasant, but true), in stores, hospitals, schools and universities, and in industrial enterprises of various profiles. As a consequence, words and terms that are directly related to the digital representation of video information are becoming more firmly and widely embedded in our lives. From time to time, questions arise in this area. What are the differences between various devices or programs that we use to encode/ decode digital video data, and what do they do? Which of these devices/ programs are better or worse, and in which aspects? What do all these endless MPEG-2, H.264 / AVC, VP9, H.265 / HEVC, etc. mean? Let’s try to understand.

A very brief historical reference

The first generally accepted video compression standard MPEG-2 was finally adopted in 1996, after which a rapid development of digital satellite television began. The next standard was MPEG-4 part 10 (H.264 / AVC), which provides twice the degree of video data compression. It was adopted in 2003, which led to the development of DVB-T/ C systems, Internet TV and the emergence of a variety of video sharing and video communication services. From 2010 to 2013, the Joint Collaborative Team on Video Coding (JCT-VC) was intensively working to create the next video compression standard, which was called High Efficient Video Coding (HEVC) by the developers; it ensured the following twofold increase in the compression ratio of digital video data. This standard was approved in 2013. That same year, the VP9 standard, developed by Google, was adopted, which was supposed to not yield to HEVC in its degree of video data compression.

Basic stages of video encoding

There are a few simple ideas at the core of algorithms for video data compression. If we take some part of an image (in the MPEG-2 and AVC standards this part is called a macroblock), then there is a big possibility that, near this segment in this frame or in neighboring frames, there will be a segment containing a similar image, which differs little in pixel intensity values. Thus, to transmit information about the image in the current segment, it is enough to only transfer its difference from the previously encoded similar segment. The process of finding similar segments among previously encoded images is called Prediction. A set of difference values that determine the difference between the current segment and the found prediction is called the Residual. Here we can distinguish two main types of prediction. In the first one, the Prediction values represent a set of linear combinations of pixels adjacent to the current image segment on the left and on the top. This type of prediction is called Intra Prediction. In the second one, linear combinations of pixels of similar image segments from previously encoded frames are used as prediction (these frames are called Reference). This type of prediction is called Inter Prediction. To restore the image of the current segment, encoded with Inter prediction, when decoding, it is necessary to have information about not only the Residual, but also the frame number, where a similar segment is located, and the coordinates of this segment.
Residual values obtained during prediction obviously contain, on average, less information than the original image and, therefore, require a fewer quantity of bits for image transmission. To further increase the degree of compression of video data in video coding systems, some spectral transformation is used. Typically, this is Fourier cosine transform. Such transformation allows us to select the fundamental harmonics in two-dimensional Residual signal. Such a selection is made at the next stage of coding — quantization. The sequence of quantized spectral coefficients contains a small number of main, large values. The remaining values are very likely to be zero. As a result, the amount of information contained in quantized spectral coefficients is significantly (dozens of times) lower than in the original image.
In the next stage of coding, the obtained set of quantized spectral coefficients, accompanied by the information necessary for performing prediction when decoding, is subjected to entropy coding. The bottom line here is to align the most common values of the encoded stream with the shortest codeword (containing the smallest number of bits). The best compression ratio (close to theoretically achievable) at this stage is provided by arithmetic coding algorithms, which are mainly used in modern video compression systems.
From the above, the main factors affecting the effectiveness of a particular video compression system become apparent. First of all, these are, of course, the factors that determine the effectiveness of the Intra and Inter Predictions. The second set of factors is related to the orthogonal transformation and quantization, which selects the fundamental harmonics in the Residual signal. The third one is determined by the volume and compactness of the representation of additional information accompanying Residual and necessary for making predictions, that is, calculating Prediction, in the decoder. Finally, the fourth set has the factors that determine the effectiveness of the final stage- entropy coding.
Let’s illustrate some possible options (far from all) of the implementation of the coding stages listed above, on the example of H.264 / AVC and HEVC.

AVC Standard

In the AVC standard, the basic structural unit of the image is a macroblock — a square area of 16x16 pixels (Figure 1). When searching for the best possible prediction, the encoder can select one of several options of partitioning each macroblock. With Intra-prediction, there are three options: perform a prediction for the entire block as a whole, break the macroblock into four square blocks of 8x8 size, or into 16 blocks with a size of 4x4 pixels, and perform a prediction for each such block independently. The number of possible options of macroblock partitioning under Inter-prediction is much richer (Figure 1), which provides adaptation of the size and position of the predicted blocks to the position and shape of the object boundaries moving in the video frame.
Fig 1. Macroblocks in AVC and possible partitioning when using Inter-Prediction.
In AVC, pixel values from the column to the left of the predicted block and the row of pixels immediately above it are used for Intra prediction (Figure 2). For blocks of sizes 4x4 and 8x8, 9 methods of prediction are used. In a prediction called DC, all calculated pixels have a single value equal to the arithmetic average of the “neighbor pixels” highlighted in Fig. 2 with a bold line. In other modes, “angular” prediction is performed. In this case, the values of the “neighbor pixels” are placed inside the predicted block in the directions indicated in Fig. 2.
In the event that the predicted pixel gets between “neighbor pixels”, when moving in a given direction, an interpolated value is used for the prediction. For blocks with a size of 16x16 pixels, 4 methods of prediction are used. One of them is the DC-prediction, which was already reviewed. The other two correspond to the “angular” methods, with the directions of prediction 0 and 1. Finally, the fourth — Plane-prediction: the values of the predicted pixels are determined by the equation of the plane. The angular coefficients of the equation are determined by the values of the “neighboring pixels”.
Fig 2. “Neighboring pixels” and angular modes of Intra-Prediction in AVC
Inter- Prediction in AVC can be implemented in one of two ways. Each of these options determines the type of macroblock (P or B). As a prediction of pixel values in P-blocks (Predictive-blocks), the values of pixels from the area located on the previously coded (reference) image, are used. Reference images are not deleted from the RAM buffer, containing decoded frames (decoded picture buffer, or DPB), as long as they are needed for Inter-prediction. A reference list is created in the DPB from the indexes of these images.
The encoder signals to the decoder about the number of the reference image in the list and about the offset of the area used for prediction, with respect to the position of predicted block (this displacement is called motion vector). The offset can be determined with an accuracy of ¼ pixel. In case of prediction with non-integer offset, interpolation is performed. Different blocks in one image can be predicted by areas located on different reference images.
In the second option of Inter Prediction, prediction of the B-block pixel values (bi-predictive block), two reference images are used; their indexes are placed in two lists (list0 and list1) in the DPB. The two indexes of reference images in the lists and two offsets, that determine positions of reference areas, are transmitted to the decoder. The B-block pixel values are calculated as a linear combination of pixel values from the reference areas. For non-integer offsets, interpolation of reference image is used.
As already mentioned, after predicting the values of the encoded block and calculating the Residual signal, the next coding step is spectral transformation. In AVC, there are several options for orthogonal transformations of the Residual signal. When Intra-prediction of a whole macroblock with a size of 16x16 is implemented, the residual signal is divided into 4x4 pixel blocks; each of them is subjected to an integer analog of discrete two-dimensional 4x4 cosine Fourier transform.
The resulting spectral components, corresponding to zero frequency (DC) in each block, are then subjected to additional orthogonal Walsh-Hadamard transform. With Inter-prediction, the Residual signal is divided into blocks of 4x4 pixels or 8x8 pixels. Each block is then subjected to a 4x4 or 8x8 (respectively) two-dimensional discrete cosine Fourier Transform (DCT, from Discrete Cosine Transform).
In the next step, spectral coefficients are subjected to the quantization procedure. This leads to a decrease in bit capacity of digits representing the spectral sample values, and to a significant increase in the number of samples having zero values. These effects provide compression, i.e. reduce the number and bit capacity of digits representing the encoded image. The reverse side of quantization is the distortion of the encoded image. It is clear that the larger the quantization step, the greater is the compression ratio, but also the distortion is greater.
The final stage of encoding in AVC is entropy coding, implemented by the algorithms of Context Adaptive Binary Arithmetic Coding. This stage provides additional compression of video data without distortion in the encoded image.

Ten years later. HEVC standard: what’s new?

The new H.265/HEVC standard is the development of methods and algorithms for compressing video data embedded in H.264/AVC. Let’s briefly review the main differences.
An analog of a macroblock in HEVC is the Coding Unit (CU). Within each block, areas for calculation of Prediction are selected — Prediction Unit (PU). Each CU also specifies the limits within which the areas for calculating the discrete orthogonal transformation from the residual signal are selected. These areas are called the Transform Unit (TU).
The main distinguishing feature of HEVC here is that the split of a video frame into CU is conducted adaptively, so that it is possible to adjust the CU boundaries to the boundaries of objects on the image (Figure 3). Such adaptability allows to achieve an exceptionally high quality of prediction and, as a consequence, a low level of the residual signal.
An undoubted advantage of such an adaptive approach to frame division into blocks is also an extremely compact description of the partition structure. For the entire video sequence, the maximum and minimum possible CU sizes are set (for example, 64x64 is the maximum possible CU, 8x8 is the minimum). The entire frame is covered with the maximum possible CUs, left to right, top-to-bottom.
It is obvious that, for such coverage, transmission of any information is not required. If partition is required within any CU, then this is indicated by a single flag (Split Flag). If this flag is set to 1, then this CU is divided into 4 CUs (with a maximum CU size of 64x64, after partitioning we get 4 CUs of size 32x32 each).
For each of the CUs received, a Split Flag value of 0 or 1 can, in turn, be transmitted. In the latter case, this CU is again divided into 4 CUs of smaller size. The process continues recursively until the Split Flag of all received CUs is equal to 0 or until the minimum possible CU size is reached. Inserted CUs thus form a quad tree (Coding Tree Units, CTU). As already mentioned, within each CU, areas for calculating prediction- Prediction Units (PU) are selected. With Intra Prediction, the CU area can coincide with the PU (2Nx2N mode) or it can be divided into 4 square PUs of twice smaller size (NxN mode, available only for CU of minimum size). With Inter Prediction, there are eight possible options for partitioning each CU into PUs (Figure 3).
Fig.3 Video frame partitioning into CUs is conducted adaptively
The idea of spatial prediction in HEVC remained the same as in AVC. Linear combinations of neighboring pixel values, adjacent to the block on the left and above, are used as predicted sample values in the PU block. However, the set of methods for spatial prediction in HEVC has become significantly richer. In addition to Planar (analogue to Plane in AVC) and DC methods, each PU can be predicted by one of the 33 ways of “angular” prediction. That is, the number of ways, in which the values are calculated by “neighbor”-pixels, is increased by 4 times.
Fig. 4. Possible partitioning of the Coding Unit into Prediction Units with the spatial (Intra) and temporary (Inter) CU prediction modes
We can point out two main differences of Inter- prediction between HEVC and AVC. Firstly, HEVC uses better interpolation filters (with a longer impulse response) when calculating reference images with non-integer offset. The second difference concerns the way the information about the reference area, required by the decoder for performing the prediction, is presented. In HEVC, a “merge mode” is introduced, where different PUs, with the same offsets of reference areas, are combined. For the entire combined area, information about motion (motion vector) is transmitted in the stream once, which allows a significant reduction in the amount of information transmitted.
In HEVC, the size of the discrete two-dimensional transformation, to which the Residual signal is subjected, is determined by the size of the square area called the Transform Unit (TU). Each CU is the root of the TU quad tree. Thus, the TU of the upper level coincides with the CU. The root TU can be divided into 4 parts of half the size, each of which, in turn, is a TU and can be further divided.
The size of discrete transformation is determined by the TU size of the lower level. In HEVC, transforms for blocks of 4 sizes are defined: 4x4, 8x8, 16x16, and 32x32. These transformations are integer analogs of the discrete two-dimensional Fourier cosine transform of corresponding size. For size 4x4 TU with Intra-prediction, there is also a separate discrete transformation, which is an integer analogue of the discrete sine Fourier transform.
The ideas of the procedure of quantizing spectral coefficients of Residual signal, and also entropy coding in AVC and in HEVC, are practically identical.
Let’s note one more point which was not mentioned before. The quality of decoded images and the degree of video data compression are influenced significantly by post-filtering, which decoded images with Inter-prediction undergo before they are placed in the DPB.
In AVC, there is one kind of such filtering — deblocking filter. Application of this filter reduces the block effect resulting from quantization of spectral coefficients after orthogonal transformation of Residual signal.
In HEVC, a similar deblocking filter is used. Besides, an additional non-linear filtering procedure called the Sample Adaptive Offset (SAO) exists. Based on the analysis of pixel value distribution during encoding, a table of corrective offsets, added to the values of a part of CU pixels during decoding, is determined.
In HEVC, the size of the discrete two-dimensional transformation, to which the Residual signal is subjected, is determined by the size of the square area called the Transform Unit (TU). Each CU is the quad-tree of TU’s. Thus, the TU of the upper level coincides with the CU. The root TU can be divided into 4 parts of half the size, each of which, in turn, is a TU and can be further divided.
The size of discrete transformation is determined by the TU size of the lower level. There are four transform block sizes in HEVC: 4x4, 8x8, 16x16, and 32x32. These transforms are discrete two-dimensional Fourier cosine transform of corresponding size. For 4x4 Intra-predicted blocks, could be used another discrete transform — sine Fourier transform.
The quantization of spectral coefficients of residual signal, and entropy coding in AVC and in HEVC, are almost identical.
Let’s note one more point which was not mentioned before. The quality of decoded images, hence the degree of video data compression, is influenced significantly by post-filtering, which applied on decoded Inter-predicted images before they are placed in the DPB.
In AVC, there is one kind of such filtering — deblocking filter. It masking blocking artifacts effect originating from spectral coefficients quantization after orthogonal transformation of residual signal.
In HEVC, a similar deblocking filter is used. Besides, an additional non-linear filtering procedure called the Sample Adaptive Offset (SAO) exists. Sample level correction is based either on local neighborhood or on the intensity level of sample itself. Table of sample level corrections, added to the values of a part of CU pixels during decoding, is determined.

And what is the result?

Figures 4–7 show the results of encoding of several high-resolution (HD) video sequences by two encoders. One of the encoders compresses the video data in the H.265/HEVC standard (marked as HM on all the graphs), and the second one is in the H.264/AVC standard.
Fig. 5. Encoding results of the video sequence Aspen (1920x1080 30 frames per second)
Fig. 6. Encoding results of the video sequence BlueSky (1920x1080 25 frames per second)
Fig. 7. Encoding results of the video sequence PeopleOnStreet (1920x1080 30 frames per second)
Fig. 8. Encoding results of the video sequence Traffic (1920x1080 30 frames per second)
Coding was performed at different quantization values of spectral coefficients, hence with different levels of video image distortion. The results are presented in Bitrate (mbps) — PSNR(dB) coordinates. PSNR values characterize the degree of distortion.
On average, it can be stated that the PSNR range below 36 dB corresponds to a high level of distortion, i.e. low quality video images. The range of 36 to 40 dB corresponds to the average quality. With PSNR values above 40 dB, we can call it a high video quality.
We can roughly estimate the compression ratio provided by the encoding systems. In the medium quality area, the bit rate provided by the HEVC encoder is about 1.5 times less than the bit rate of the AVC encoder. Bitrate of an uncompressed video stream is easily determined as the product of the number of pixels in each video frame (1920 x 1080) by the number of bits required to represent each pixel (8 + 2 + 2 = 12), and the number of frames per second (30).
As a result, we get about 750 Mbps. It can be seen from the graphs that, in the area of average quality, the AVC encoder provides a bit rate of about 10–12 Mbit/s. Thus, the degree of video information compression is about 60–75 times. As already mentioned, the HEVC encoder provides compression ratio 1.5 times higher.

About the author

Oleg Ponomarev, 16 years in video encoding and signal digital processing, expert in Statistical Radiophysics, Radio waves propagation. Assistant Professor, PhD at Tomsk State University, Radiophysics department. Head of Elecard Research Lab.
submitted by VideoCompressionGuru to u/VideoCompressionGuru [link] [comments]

AJ ALMENDINGER

glimpse into the future of Roblox

Our vision to bring the world together through play has never been more relevant than it is now. As our founder and CEO, David Baszucki (a.k.a. Builderman), mentioned in his keynote, more and more people are using Roblox to stay connected with their friends and loved ones. He hinted at a future where, with our automatic machine translation technology, Roblox will one day act as a universal translator, enabling people from different cultures and backgrounds to connect and learn from each other.
During his keynote, Builderman also elaborated upon our vision to build the Metaverse; the future of avatar creation on the platform (infinitely customizable avatars that allow any body, any clothing, and any animation to come together seamlessly); more personalized game discovery; and simulating large social gatherings (like concerts, graduations, conferences, etc.) with tens of thousands of participants all in one server. We’re still very early on in this journey, but if these past five months have shown us anything, it’s clear that there is a growing need for human co-experience platforms like Roblox that allow people to play, create, learn, work, and share experiences together in a safe, civil 3D immersive space.
Up next, our VP of Developer Relations, Matt Curtis (a.k.a. m4rrh3w), shared an update on all the things we’re doing to continue empowering developers to create innovative and exciting content through collaboration, support, and expertise. He also highlighted some of the impressive milestones our creator community has achieved since last year’s RDC. Here are a few key takeaways:
And lastly, our VP of Engineering, Technology, Adam Miller (a.k.a. rbadam), unveiled a myriad of cool and upcoming features developers will someday be able to sink their teeth into. We saw a glimpse of procedural skies, skinned meshes, more high-quality materials, new terrain types, more fonts in Studio, a new asset type for in-game videos, haptic feedback on mobile, real-time CSG operations, and many more awesome tools that will unlock the potential for even bigger, more immersive experiences on Roblox.

Vibin’

Despite the virtual setting, RDC just wouldn’t have been the same without any fun party activities and networking opportunities. So, we invited special guests DJ Hyper Potions and cyber mentalist Colin Cloud for some truly awesome, truly mind-bending entertainment. Yoga instructor Erin Gilmore also swung by to inspire attendees to get out of their chair and get their body moving. And of course, we even had virtual rooms dedicated to karaoke and head-to-head social games, like trivia and Pictionary.
Over on the networking side, Team Adopt Me, Red Manta, StyLiS Studios, and Summit Studios hosted a virtual booth for attendees to ask questions, submit resumes, and more. We also had a networking session where three participants would be randomly grouped together to get to know each other.

What does Roblox mean to you?

We all know how talented the Roblox community is from your creations. We’ve heard plenty of stories over the years about how Roblox has touched your lives, how you’ve made friendships, learned new skills, or simply found a place where you can be yourself. We wanted to hear more. So, we asked attendees: What does Roblox mean to you? How has Roblox connected you? How has Roblox changed your life? Then, over the course of RDC, we incorporated your responses into this awesome mural.
📷
Created by Alece Birnbach at Graphic Recording Studio

Knowledge is power

This year’s breakout sessions included presentations from Roblox developers and staff members on the latest game development strategies, a deep dive into the Roblox engine, learning how to animate with Blender, tools for working together in teams, building performant game worlds, and the new Creator Dashboard. Dr. Michael Rich, Associate Professor at Harvard Medical School and Physician at Boston Children’s Hospital, also led attendees through a discussion on mental health and how to best take care of you and your friends’ emotional well-being, especially now during these challenging times.
📷
Making the Dream Work with Teamwork (presented by Roblox developer Myzta)
In addition to our traditional Q&A panel with top product and engineering leaders at Roblox, we also held a special session with Builderman himself to answer the community’s biggest questions.
📷
Roblox Product and Engineering Q&A Panel

2020 Game Jam

The Game Jam is always one of our favorite events of RDC. It’s a chance for folks to come together, flex their development skills, and come up with wildly inventive game ideas that really push the boundaries of what’s possible on Roblox. We had over 60 submissions this year—a new RDC record.
Once again, teams of up to six people from around the world had less than 24 hours to conceptualize, design, and publish a game based on the theme “2020 Vision,” all while working remotely no less! To achieve such a feat is nothing short of awe-inspiring, but as always, our dev community was more than up for the challenge. I’ve got to say, these were some of the finest creations we’ve seen.
WINNERS
Best in Show: Shapescape Created By: GhettoMilkMan, dayzeedog, maplestick, theloudscream, Brick_man, ilyannna You awaken in a strange laboratory, seemingly with no way out. Using a pair of special glasses, players must solve a series of anamorphic puzzles and optical illusions to make their escape.
Excellence in Visual Art: agn●sia Created By: boatbomber, thisfall, Elttob An obby experience unlike any other, this game is all about seeing the world through a different lens. Reveal platforms by switching between different colored lenses and make your way to the end.
Most Creative Gameplay: Visions of a perspective reality Created By: Noble_Draconian and Spathi Sometimes all it takes is a change in perspective to solve challenges. By switching between 2D and 3D perspectives, players can maneuver around obstacles or find new ways to reach the end of each level.
Outstanding Use of Tech: The Eyes of Providence Created By: Quenty, Arch_Mage, AlgyLacey, xJennyBeanx, Zomebody, Crykee This action/strategy game comes with a unique VR twist. While teams fight to construct the superior monument, two VR players can support their minions by collecting resources and manipulating the map.
Best Use of Theme: Sticker Situation Created By: dragonfrosting and Yozoh Set in a mysterious art gallery, players must solve puzzles by manipulating the environment using a magic camera and stickers. Snap a photograph, place down a sticker, and see how it changes the world.
OTHER TOP PICKS
HONORABLE MENTIONS
For the rest of the 2020 Game Jam submissions, check out the list below:
20-20 Vision | 20/20 Vision | 2020 Vision, A Crazy Perspective | 2020 Vision: Nyon | A Wild Trip! | Acuity | Best Year Ever | Better Half | Bloxlabs | Climb Stairs to 2021 | Double Vision (Team hey apple) | Eyebrawl | Eyeworm Exam | FIRE 2020 | HACKED | Hyperspective | Lucid Scream | Mystery Mansion | New Years at the Museum | New Year’s Bash | Poor Vision | Predict 2020 | RBC News | Retrovertigo | Second Wave | see no evil | Sight Fight | Sight Stealers | Spectacles Struggle | Specter Spectrum | Survive 2020 | The Lost Chicken Leg | The Outbreak | The Spyglass | Time Heist | Tunnel Vision | Virtual RDC – The Story | Vision (Team Freepunk) | Vision (Team VIP People ####) | Vision Developers Conference 2020 | Vision Is Key | Vision Perspective | Vision Racer | Visions | Zepto
And last but not least, we wanted to give a special shout out to Starboard Studios. Though they didn’t quite make it on time for our judges, we just had to include Dave’s Vision for good measure. 📷
Thanks to everyone who participated in the Game Jam, and congrats to all those who took home the dub in each of our categories this year. As the winners of Best in Show, the developers of Shapescape will have their names forever engraved on the RDC Game Jam trophy back at Roblox HQ. Great work!

‘Til next year

And that about wraps up our coverage of the first-ever digital RDC. Thanks to all who attended! Before we go, we wanted to share a special “behind the scenes” video from the 2020 RDC photoshoot.
Check it out:
It was absolutely bonkers. Getting 350 of us all in one server was so much fun and really brought back the feeling of being together with everyone again. That being said, we can’t wait to see you all—for real this time—at RDC next year. It’s going to be well worth the wait. ‘Til we meet again, my friends.
© 2020 Roblox Corporation. All Rights Reserved.

Improving Simulation and Performance with an Advanced Physics Solver

August

05, 2020

by chefdeletat
PRODUCT & TECH
📷In mid-2015, Roblox unveiled a major upgrade to its physics engine: the Projected Gauss-Seidel (PGS) physics solver. For the first year, the new solver was optional and provided improved fidelity and greater performance compared to the previously used spring solver.
In 2016, we added support for a diverse set of new physics constraints, incentivizing developers to migrate to the new solver and extending the creative capabilities of the physics engine. Any new places used the PGS solver by default, with the option of reverting back to the classic solver.
We ironed out some stability issues associated with high mass differences and complex mechanisms by the introduction of the hybrid LDL-PGS solver in mid-2018. This made the old solver obsolete, and it was completely disabled in 2019, automatically migrating all places to the PGS.
In 2019, the performance was further improved using multi-threading that splits the simulation into jobs consisting of connected islands of simulating parts. We still had performance issues related to the LDL that we finally resolved in early 2020.
The physics engine is still being improved and optimized for performance, and we plan on adding new features for the foreseeable future.

Implementing the Laws of Physics

📷
The main objective of a physics engine is to simulate the motion of bodies in a virtual environment. In our physics engine, we care about bodies that are rigid, that collide and have constraints with each other.
A physics engine is organized into two phases: collision detection and solving. Collision detection finds intersections between geometries associated with the rigid bodies, generating appropriate collision information such as collision points, normals and penetration depths. Then a solver updates the motion of rigid bodies under the influence of the collisions that were detected and constraints that were provided by the user.
📷
The motion is the result of the solver interpreting the laws of physics, such as conservation of energy and momentum. But doing this 100% accurately is prohibitively expensive, and the trick to simulating it in real-time is to approximate to increase performance, as long as the result is physically realistic. As long as the basic laws of motion are maintained within a reasonable tolerance, this tradeoff is completely acceptable for a computer game simulation.

Taking Small Steps

The main idea of the physics engine is to discretize the motion using time-stepping. The equations of motion of constrained and unconstrained rigid bodies are very difficult to integrate directly and accurately. The discretization subdivides the motion into small time increments, where the equations are simplified and linearized making it possible to solve them approximately. This means that during each time step the motion of the relevant parts of rigid bodies that are involved in a constraint is linearly approximated.
📷📷
Although a linearized problem is easier to solve, it produces drift in a simulation containing non-linear behaviors, like rotational motion. Later we’ll see mitigation methods that help reduce the drift and make the simulation more plausible.

Solving

📷
Having linearized the equations of motion for a time step, we end up needing to solve a linear system or linear complementarity problem (LCP). These systems can be arbitrarily large and can still be quite expensive to solve exactly. Again the trick is to find an approximate solution using a faster method. A modern method to approximately solve an LCP with good convergence properties is the Projected Gauss-Seidel (PGS). It is an iterative method, meaning that with each iteration the approximate solution is brought closer to the true solution, and its final accuracy depends on the number of iterations.
📷
This animation shows how a PGS solver changes the positions of the bodies at each step of the iteration process, the objective being to find the positions that respect the ball and socket constraints while preserving the center of mass at each step (this is a type of positional solver used by the IK dragger). Although this example has a simple analytical solution, it’s a good demonstration of the idea behind the PGS. At each step, the solver fixes one of the constraints and lets the other be violated. After a few iterations, the bodies are very close to their correct positions. A characteristic of this method is how some rigid bodies seem to vibrate around their final position, especially when coupling interactions with heavier bodies. If we don’t do enough iterations, the yellow part might be left in a visibly invalid state where one of its two constraints is dramatically violated. This is called the high mass ratio problem, and it has been the bane of physics engines as it causes instabilities and explosions. If we do too many iterations, the solver becomes too slow, if we don’t it becomes unstable. Balancing the two sides has been a painful and long process.

Mitigation Strategies

📷A solver has two major sources of inaccuracies: time-stepping and iterative solving (there is also floating point drift but it’s minor compared to the first two). These inaccuracies introduce errors in the simulation causing it to drift from the correct path. Some of this drift is tolerable like slightly different velocities or energy loss, but some are not like instabilities, large energy gains or dislocated constraints.
Therefore a lot of the complexity in the solver comes from the implementation of methods to minimize the impact of computational inaccuracies. Our final implementation uses some traditional and some novel mitigation strategies:
  1. Warm starting: starting with the solution from a previous time-step to increase the convergence rate of the iterative solver
  2. Post-stabilization: reprojecting the system back to the constraint manifold to prevent constraint drift
  3. Regularization: adding compliance to the constraints ensuring a solution exists and is unique
  4. Pre-conditioning: using an exact solution to a linear subsystem, improving the stability of complex mechanisms
Strategies 1, 2 and 3 are pretty traditional, but 3 has been improved and perfected by us. Also, although 4 is not unheard of, we haven’t seen any practical implementation of it. We use an original factorization method for large sparse constraint matrices and a new efficient way of combining it with the PGS. The resulting implementation is only slightly slower compared to pure PGS but ensures that the linear system coming from equality constraints is solved exactly. Consequently, the equality constraints suffer only from drift coming from the time discretization. Details on our methods are contained in my GDC 2020 presentation. Currently, we are investigating direct methods applied to inequality constraints and collisions.

Getting More Details

Traditionally there are two mathematical models for articulated mechanisms: there are reduced coordinate methods spearheaded by Featherstone, that parametrize the degrees of freedom at each joint, and there are full coordinate methods that use a Lagrangian formulation.
We use the second formulation as it is less restrictive and requires much simpler mathematics and implementation.
The Roblox engine uses analytical methods to compute the dynamic response of constraints, as opposed to penalty methods that were used before. Analytics methods were initially introduced in Baraff 1989, where they are used to treat both equality and non-equality constraints in a consistent manner. Baraff observed that the contact model can be formulated using quadratic programming, and he provided a heuristic solution method (which is not the method we use in our solver).
Instead of using force-based formulation, we use an impulse-based formulation in velocity space, originally introduced by Mirtich-Canny 1995 and further improved by Stewart-Trinkle 1996, which unifies the treatment of different contact types and guarantees the existence of a solution for contacts with friction. At each timestep, the constraints and collisions are maintained by applying instantaneous changes in velocities due to constraint impulses. An excellent explanation of why impulse-based simulation is superior is contained in the GDC presentation of Catto 2014.
The frictionless contacts are modeled using a linear complementarity problem (LCP) as described in Baraff 1994. Friction is added as a non-linear projection onto the friction cone, interleaved with the iterations of the Projected Gauss-Seidel.
The numerical drift that introduces positional errors in the constraints is resolved using a post-stabilization technique using pseudo-velocities introduced by Cline-Pai 2003. It involves solving a second LCP in the position space, which projects the system back to the constraint manifold.
The LCPs are solved using a PGS / Impulse Solver popularized by Catto 2005 (also see Catto 2009). This method is iterative and considers each individual constraints in sequence and resolves it independently. Over many iterations, and in ideal conditions, the system converges to a global solution.
Additionally, high mass ratio issues in equality constraints are ironed out by preconditioning the PGS using the sparse LDL decomposition of the constraint matrix of equality constraints. Dense submatrices of the constraint matrix are sparsified using a method we call Body Splitting. This is similar to the LDL decomposition used in Baraff 1996, but allows more general mechanical systems, and solves the system in constraint space. For more information, you can see my GDC 2020 presentation.
The architecture of our solver follows the idea of Guendelman-Bridson-Fedkiw, where the velocity and position stepping are separated by the constraint resolution. Our time sequencing is:
  1. Advance velocities
  2. Constraint resolution in velocity space and position space
  3. Advance positions
This scheme has the advantage of integrating only valid velocities, and limiting latency in external force application but allowing a small amount of perceived constraint violation due to numerical drift.
An excellent reference for rigid body simulation is the book Erleben 2005 that was recently made freely available. You can find online lectures about physics-based animation, a blog by Nilson Souto on building a physics engine, a very good GDC presentation by Erin Catto on modern solver methods, and forums like the Bullet Physics Forum and GameDev which are excellent places to ask questions.

In Conclusion

The field of game physics simulation presents many interesting problems that are both exciting and challenging. There are opportunities to learn a substantial amount of cool mathematics and physics and to use modern optimizations techniques. It’s an area of game development that tightly marries mathematics, physics and software engineering.
Even if Roblox has a good rigid body physics engine, there are areas where it can be improved and optimized. Also, we are working on exciting new projects like fracturing, deformation, softbody, cloth, aerodynamics and water simulation.
Neither Roblox Corporation nor this blog endorses or supports any company or service. Also, no guarantees or promises are made regarding the accuracy, reliability or completeness of the information contained in this blog.
This blog post was originally published on the Roblox Tech Blog.
© 2020 Roblox Corporation. All Rights Reserved.

Using Clang to Minimize Global Variable Use

July

23, 2020

by RandomTruffle
PRODUCT & TECH
Every non-trivial program has at least some amount of global state, but too much can be a bad thing. In C++ (which constitutes close to 100% of Roblox’s engine code) this global state is initialized before main() and destroyed after returning from main(), and this happens in a mostly non-deterministic order. In addition to leading to confusing startup and shutdown semantics that are difficult to reason about (or change), it can also lead to severe instability.
Roblox code also creates a lot of long-running detached threads (threads which are never joined and just run until they decide to stop, which might be never). These two things together have a very serious negative interaction on shutdown, because long-running threads continue accessing the global state that is being destroyed. This can lead to elevated crash rates, test suite flakiness, and just general instability.
The first step to digging yourself out of a mess like this is to understand the extent of the problem, so in this post I’m going to talk about one technique you can use to gain visibility into your global startup flow. I’m also going to discuss how we are using this to improve stability across the entire Roblox game engine platform by decreasing our use of global variables.

Introducing -finstrument-functions

Nothing excites me more than learning about a new obscure compiler option that I’ve never had a use for before, so I was pretty happy when a colleague pointed me to this option in the Clang Command Line Reference. I’d never used it before, but it sounded very cool. The idea being that if we could get the compiler to tell us every time it entered and exited a function, we could filter this information through a symbolizer of some kind and generate a report of functions that a) occur before main(), and b) are the very first function in the call-stack (indicating it’s a global).
Unfortunately, the documentation basically just tells you that the option exists with no mention of how to use it or if it even actually does what it sounds like it does. There’s also two different options that sound similar to each other (-finstrument-functions and -finstrument-functions-after-inlining), and I still wasn’t entirely sure what the difference was. So I decided to throw up a quick sample on godbolt to see what happened, which you can see here. Note there are two assembly outputs for the same source listing. One uses the first option and the other uses the second option, and we can compare the assembly output to understand the differences. We can gather a few takeaways from this sample:
  1. The compiler is injecting calls to __cyg_profile_func_enter and __cyg_profile_func_exit inside of every function, inline or not.
  2. The only difference between the two options occurs at the call-site of an inline function.
  3. With -finstrument-functions, the instrumentation for the inlined function is inserted at the call-site, whereas with -finstrument-functions-after-inlining we only have instrumentation for the outer function. This means that when using-finstrument-functions-after-inlining you won’t be able to determine which functions are inlined and where.
Of course, this sounds exactly like what the documentation said it did, but sometimes you just need to look under the hood to convince yourself.
To put all of this another way, if we want to know about calls to inline functions in this trace we need to use -finstrument-functions because otherwise their instrumentation is silently removed by the compiler. Sadly, I was never able to get -finstrument-functions to work on a real example. I would always end up with linker errors deep in the Standard C++ Library which I was unable to figure out. My best guess is that inlining is often a heuristic, and this can somehow lead to subtle ODR (one-definition rule) violations when the optimizer makes different inlining decisions from different translation units. Luckily global constructors (which is what we care about) cannot possibly be inlined anyway, so this wasn’t a problem.
I suppose I should also mention that I still got tons of linker errors with -finstrument-functions-after-inlining as well, but I did figure those out. As best as I can tell, this option seems to imply –whole-archive linker semantics. Discussion of –whole-archive is outside the scope of this blog post, but suffice it to say that I fixed it by using linker groups (e.g. -Wl,–start-group and -Wl,–end-group) on the compiler command line. I was a bit surprised that we didn’t get these same linker errors without this option and still don’t totally understand why. If you happen to know why this option would change linker semantics, please let me know in the comments!

Implementing the Callback Hooks

If you’re astute, you may be wondering what in the world __cyg_profile_func_enter and __cyg_profile_func_exit are and why the program is even successfully linking in the first without giving undefined symbol reference errors, since the compiler is apparently trying to call some function we’ve never defined. Luckily, there are some options that allow us to see inside the linker’s algorithm so we can find out where it’s getting this symbol from to begin with. Specifically, -y should tell us how the linker is resolving . We’ll try it with a dummy program first and a symbol that we’ve defined ourselves, then we’ll try it with __cyg_profile_func_enter .
[email protected]:~/src/sandbox$ cat instr.cpp int main() {} [email protected]:~/src/sandbox$ clang++-9 -fuse-ld=lld -Wl,-y -Wl,main instr.cpp /usbin/../lib/gcc/x86_64-linux-gnu/crt1.o: reference to main /tmp/instr-5b6c60.o: definition of main
No surprises here. The C Runtime Library references main(), and our object file defines it. Now let’s see what happens with __cyg_profile_func_enter and -finstrument-functions-after-inlining.
[email protected]:~/src/sandbox$ clang++-9 -fuse-ld=lld -finstrument-functions-after-inlining -Wl,-y -Wl,__cyg_profile_func_enter instr.cpp /tmp/instr-8157b3.o: reference to __cyg_profile_func_enter /lib/x86_64-linux-gnu/libc.so.6: shared definition of __cyg_profile_func_enter
Now, we see that libc provides the definition, and our object file references it. Linking works a bit differently on Unix-y platforms than it does on Windows, but basically this means that if we define this function ourselves in our cpp file, the linker will just automatically prefer it over the shared library version. Working godbolt link without runtime output is here. So now you can kind of see where this is going, however there are still a couple of problems left to solve.
  1. We don’t want to do this for a full run of the program. We want to stop as soon as we reach main.
  2. We need a way to symbolize this trace.
The first problem is easy to solve. All we need to do is compare the address of the function being called to the address of main, and set a flag indicating we should stop tracing henceforth. (Note that taking the address of main is undefined behavior[1], but for our purposes it gets the job done, and we aren’t shipping this code, so ¯\_(ツ)_/¯). The second problem probably deserves a little more discussion though.

Symbolizing the Traces

In order to symbolize these traces, we need two things. First, we need to store the trace somewhere on persistent storage. We can’t expect to symbolize in real time with any kind of reasonable performance. You can write some C code to save the trace to some magic filename, or you can do what I did and just write it to stderr (this way you can pipe stderr to some file when you run it).
Second, and perhaps more importantly, for every address we need to write out the full path to the module the address belongs to. Your program loads many shared libraries, and in order to translate an address into a symbol, we have to know which shared library or executable the address actually belongs to. In addition, we have to be careful to write out the address of the symbol in the file on disk. When your program is running, the operating system could have loaded it anywhere in memory. And if we’re going to symbolize it after the fact we need to make sure we can still reference it after the information about where it was loaded in memory is lost. The linux function dladdr() gives us both pieces of information we need. A working godbolt sample with the exact implementation of our instrumentation hooks as they appear in our codebase can be found here.

Putting it All Together

Now that we have a file in this format saved on disk, all we need to do is symbolize the addresses. addr2line is one option, but I went with llvm-symbolizer as I find it more robust. I wrote a Python script to parse the file and symbolize each address, then print it in the same “visual” hierarchical format that the original output file is in. There are various options for filtering the resulting symbol list so that you can clean up the output to include only things that are interesting for your case. For example, I filtered out any globals that have boost:: in their name, because I can’t exactly go rewrite boost to not use global variables.
The script isn’t as simple as you would think, because simply crawling each line and symbolizing it would be unacceptably slow (when I tried this, it took over 2 hours before I finally killed the process). This is because the same address might appear thousands of times, and there’s no reason to run llvm-symbolizer against the same address multiple times. So there’s a lot of smarts in there to pre-process the address list and eliminate duplicates. I won’t discuss the implementation in more detail because it isn’t super interesting. But I’ll do even better and provide the source!
So after all of this, we can run any one of our internal targets to get the call tree, run it through the script, and then get output like this (actual output from a Roblox process, source file information removed):
excluded_symbols = [‘.\boost.*’]* excluded_modules = [‘/usr.\’]* /uslib/x86_64-linux-gnu/libLLVM-9.so.1: 140 unique addresses InterestingRobloxProcess: 38928 unique addresses /uslib/x86_64-linux-gnu/libstdc++.so.6: 1 unique addresses /uslib/x86_64-linux-gnu/libc++.so.1: 3 unique addresses Printing call tree with depth 2 for 29276 global variables. __cxx_global_var_init.5 (InterestingFile1.cpp:418:22) RBX::InterestingRobloxClass2::InterestingRobloxClass2() (InterestingFile2.cpp.:415:0) __cxx_global_var_init.19 (InterestingFile2.cpp:183:34) (anonymous namespace)::InterestingRobloxClass2::InterestingRobloxClass2() (InterestingFile2.cpp:171:0) __cxx_global_var_init.274 (InterestingFile3.cpp:2364:33) RBX::InterestingRobloxClass3::InterestingRobloxClass3()
So there you have it: the first half of the battle is over. I can run this script on every platform, compare results to understand what order our globals are actually initialized in in practice, then slowly migrate this code out of global initializers and into main where it can be deterministic and explicit.

Future Work

It occurred to me sometime after implementing this that we could make a general purpose profiling hook that exposed some public symbols (dllexport’ed if you speak Windows), and allowed a plugin module to hook into this dynamically. This plugin module could filter addresses using whatever arbitrary logic that it was interested in. One interesting use case I came up for this is that it could look up the debug information, check if the current address maps to the constructor of a function local static, and write out the address if so. This effectively allows us to gain a deeper understanding of the order in which our lazy statics are initialized. The possibilities are endless here.

Further Reading

If you’re interested in this kind of thing, I’ve collected a couple of my favorite references for this kind of topic.
  1. Various: The C++ Language Standard
  2. Matt Godbolt: The Bits Between the Bits: How We Get to main()
  3. Ryan O’Neill: Learning Linux Binary Analysis
  4. Linkers and Loaders: John R. Levine
  5. https://eel.is/c++draft/basic.exec#basic.start.main-3
Neither Roblox Corporation nor this blog endorses or supports any company or service. Also, no guarantees or promises are made regarding the accuracy, reliability or completeness of the information contained in this blog.
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Binary Options Review; Best Binary Options Brokers

Binary Options Review; Best Binary Options Brokers

Binary Options Review; Best Binary Options Brokers
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submitted by Babyelijah to u/Babyelijah [link] [comments]

[META] The Rules and their Entirety

These are the rules, everything that pertains to everyone who wishes to make any sort of interaction within this sub. Per the last META, clarity has been given in regards to bulk-type sales. Since EVERYTHING is here for you all to read, we expect there to be less issues with rule infractions and general confusion as to what’s acceptable, and what isn’t. We devote our time and energy for this sub to continuously never reach a balance amongst the users.
Our goal is to ensure the subreddit itself sticks around, along with trying to keep the userbase from being taken advantage of. Our rules make sense to some, and none to others but they serve a purpose. Regardless of how you feel, these are the rules and it is expected they be followed. At the time this post becomes visible, all of what’s listed below will be enforced as a hard rule, no more wrist slaps or babysitting.

Reporting Rules

Here are the Subreddit Reportable violations. Violating these rules will get you a ban.

Reddit Rules:

Reddit Rules regarding Firearms
No firearm sales. No Ammunition sales. No primers or gunpowder, as they are considered explosives.
No selling or distributing of files related to 3D printed firearms.
If you have no idea what this is referring to, please educate yourself before posting anything related to 3D printing files by reading up on them at the following websites:
Firearms: A Firearm is considered the serialized receiver or assembly of a working firearm. If you are unsure if an item is prohibited, contact the mods prior to posting it.
80% lowers and completion kits are not included in this prohibition as they are not firearms yet.
Bump-Stocks are considered Machine Guns by the ATF and are therefore prohibited from trading on the sub.
Binary Triggers, Cranks, and Rubber bands and other such items are not (currently) affected by this prohibition (unless Admins change their minds later).
Explosives & Hazmat: Gunpowder and Live Primers are considered as explosives and Hazardous Materials and are therefore prohibited from trade.
Ammunition: Reddit Admins use the ATF definition of ammunition which is as follows:
The term “Ammunition” means ammunition or cartridge cases, primers, bullets, or propellant powder designed for use in any firearm. The term shall not include (a) any shotgun shot or pellet not designed for use as the single, complete projectile load for one shotgun hull or casing, nor (b) any unloaded, non-metallic shotgun hull or casing not having a primer. 27 § 478.11
Brass and projectiles posted here will result in an immediate suspension by Reddit Admins, so if we find it first we will remove it.
Any violation of these above rules will result in a ban by us, or a site-wide suspension by Admins and their Anti-Evil goosesteppers.
Anyone attempting to skirt Reddit Rules will be given a 7 day ban on the first offense, a 30 day ban on the second offense, and a permaban thereafter due to the fact that Admins will use the bad behavior of a few to justify shutting down the sub for good.

Posting Rules:

This sub is for private sales only. Vendors must post in Gundeals or GunAccessoryVendors
Clarification on Vendor Rule: Don't include links to your business website, we are not a referral system, do your business on here. Please see the Reddit Self Promotion page for details on that. Reddit admins don't like you cutting in on their ad revenue. We do not support VENDORS, I.E. if you buy another company's products in bulk (such as Magpul), and just act as a distributoreseller, your business is not welcome here. That is /GunDeals territory. If you have an FFL, you cannot do business on here because are considered a firearm business, and cannot solicit any transactions involving firearms.
The limit on bulk sales/bulk items is 10, that means 10 of the same individual item can be posted for sale or trade. If you have 10 Geissele triggers, but only 4 are flat and 6 are curved, that will still count as 10, as they're the same branded trigger and likely purchased at the same time. If there are 3 OD Green items and 7 FDE that are otherwise the same item, that still count as 10. If you post 10 items of the same in one day, 10 the next, and 10 the following day after that, that will be viewed as vendor activity. To keep such things from happening, it will be limited to one sale of this type, per user, per week. The ONLY EXCEPTION to this rule is old magazines, as it is common for users to purge off part of their mag collection.
Please follow these rules when creating a listing: Prefix your title with the transaction type:
[WTS] - Want To Sell
[WTB] - Want To Buy
[WTT] - Want To Trade
[GIFT] - Gun It Forward Tactically
Suffix your title with your state (e.g. (GA) or (NY)). This will help incentivize local sales and could impact shipping costs. Also, it could affect legality of some items such as magazines and those accessories deemed as "assault weapon" parts by certain states.
Postings should all follow this general format as an example: "[WTS] M16A2 Carry Handle - $60 (VA)". If you do not list the price in the title, ensure that it is listed in the comments. Include a Dollar sign ($) or the bot will remove it.
Postings without a price value may be removed after a period of time. WTB posts require valid offering prices, and will be removed if they do not have one.
Postings with prices such as "$1 for the bot" or "$1,000,000 for the bot" that are intended to bypass our rules and automated removal system instead of posting a valid price, will be removed and a temporary ban will be issued immediately.
Postings without pictures will be removed immediately, unless these posts are WTB.
Do not post an item for sale if you do not have it in your possession at the time of posting. This includes an item you may have purchased elsewhere, you decided you don’t want it and it’s on its way to you, but it has yet to arrive. If you don’t have it, don’t post it.
If you post stock images of an item in your WTS/WTT post, that will result in a temp ban if it is your first time doing so, possibly permanent if done on multiple occasions. If you post images of someone else’s photos for “your” item, this will be viewed as scamming tactics and you will receive a permaban, immediately.
If you drop your price, use the Price Drop/NSFW Tag. If your items sell, use the Complete/Spoiler tag. Please don't delete the price of an item if it sells, because that can be used by people in the future to gauge what similar items may be worth.
If your post does not receive the traction you're wanting, refrain from reposting within a 24 hour time frame. You may repost after the 24 hours has passed, and a price drop is not required, but encouraged. Deleting your post and reposting afterwards is viewed as trying to evade this rule. It will be met with removal and a temp ban, possibly longer if done more than once.
Want to Buy/Sell/Trade (WTB/WTS/WTT): These transactions all require a price value for the item. If a listing does not include a price it may be removed and re-listed once it is in compliance. Giving an unrealistic price to avoid this rule will be treated as a rule violation. Examples of this are "WTB scope, $1" or "WTT Upper, $9999". Additionally, you must list what you are looking for in [WTT] posts. Fielding offers, testing the waters or any other post attempt to try and skirt this rule will result in the post being removed.
Gifting items forward: (GIFT) If you have small odds and ends that aren't worth much and the cost of shipping is prohibitive, you are allowed to offer items for free. The gifter is allowed to request compensation for shipping only, and can request a flair upgrade in the feedback thread for the transaction. If the receiver pays for shipping, they can also request a flair upgrade, but if they get the item for free, no flair upgrades for the recipient. Flair upgrades of this type are limited in order to avoid abuse, i.e. giving away 20 A2 grips in order to get +20 rep is not authorized.
Accounts with 5 or less flair (you must have at least 6) on GAFS are NOT eligible to participate in giveaways, due to users from other subs coming to win stuff without ever participating in GAFS, or GAFS users making multiple new burner accounts to enter giveaways.
New accounts (under 30 days of age) are not able to create WTS or WTT ads, nor should they offer things for sale in the comments of other peoples' posts. To prevent scams, new users can only post Want to Buy threads. If you want to attempt to bypass this account age requirement, you must be able to provide moderators evidence of a good trading history on another reputable online forum, such as Calgunner or AR15.com where you can show a longstanding history of positive trade feedback. If this is completed, moderators may provide an exception and allow WTS/WTT posts to be submitted by new users, with a warning caveat to any potential buyers to avoid using risky payment methods until the seller has had a chance to develop a positive trading reputation.
Any new accounts that utilize this subreddit that create names that are similar to a mods (i.e. sxbbzxro, sxbzxxro, subzxro, etc.) may be removed from participating here due to the possibility of confusing/having the ability to manipulate users into thinking they are in fact a mod.
Price Checks (PC): Because PC listings were abused by many to bypass the price rule, fish for "best offers", and otherwise snipe sales, they have been disabled after overwhelming support from the community.
We have a feedback system in place. The current month's flair thread is On the Sidebar, and is usually Stickied at the top as well. Check there for the specific directions. DO NOT create a thread for a sale that has already happened, or has happened in a different sub/website/forum etc. The Flair system is only for feedback for exchanges in /GAFS. Any attempts to game the flair system will be seen as an attempt to establish trust for scam purposes, and will be banned accordingly.
Law Enforcement: Be aware, we do not offer exemptions to any individuals who may have LE credentials. Due to the difficulty of verifying employment, possible job changes, leaving/termination from said job, etc. we treat all users as civilians. Any local and federal laws apply to all individuals who utilize this subreddit. Read up and stay up-to-date on these laws and regulations, you will be expected to know and abide by them. Failure to do so may lead to a ban.
External Sales:
NO LINKS to your external sales on TacSwap, eBay, Facebook, Armslist, Gunbroker, etc. Sales in multiple locations are allowed, but don't just provide a link to sale elsewhere. Make your listing here. The only caveat to these rules is to show a price point elsewhere if someone here has an item that is grossly overpriced, or is looking for an item.
This sub is not a "highest bid gets the item" format. There are also no lotteries for items i.e. 10 chances at $10 each to purchase a $75 flashlight with a random number generated to pick the winner.
High Value or Counterfeit Items:
To deter the sale of counterfeit products, any item that is serialized must have a picture of the serial. As firearms are not allowed for sale here, this shouldn't present a privacy issue to anyone. This policy covers items such as EOTechs, Aimpoints, Trijicons, etc. Along with this, if you're selling anything that's "new-in-box", you must unseal it and show the contents of said box/package.
No Stolen Property. If you are selling a knockoff item, indicate that fact. Items such as bipods, BUIS, flashlights, holsters, and scopes/optics are known to have some gray market options. KAC USMC Stamped Rear Sights are not stolen property and are allowed on here, unless another member can provide proof from a DoD source that they are in fact considered stolen government property.
All GAFS logos, icons, banners and visual content related to this subreddit, belong to the moderator team. Do not create/manufacture/produce items with this content onto itself. It is forbidden to profit off the GAFS name, unless discussed with the modteam in advance and given permission.

Shipping/Insurance Rules:

The official policy is for the mods to not get involved with issues regarding lost packages, provided that the parties can prove it was actually lost. If you feel like insurance should be added to your transaction, please take care to add that before finalizing terms.

General Rules:

WARNING: Be aware of all state and federal laws that apply to you and any parties involved in a firearms-related transaction. You are responsible for knowing and following the law. This Subreddit and its staff are in no way responsible for informing you of the law, but will make every effort to do so. As a buyer, be familiar with your state/county/city rules. As a seller, do not knowingly sell prohibited items to areas that have laws against your items, such as certain capacity magazines. Any person, buyer, or seller, who knowingly solicits a trade that is illegal for them may be subject to a ban.
Respect all federal and local laws for any transaction you take part in. This includes federal drug laws. Drug activity tied to your account tied to any other issues is sufficient grounds for banning. Here is the ATF Letter that explains why any suspected drug activity, including marijuana, is grounds for immediate banning from the sub. Illegal gun activity such as unregistered SBRs, AOWs, destructive devices, DIAS or lightning links in your reddit profile (in or outside the sub) can be reason for banning. Do not spread bad information regarding laws.
Any item you post for sale is expected to be in your current possession. If this is not the case, you must specify this in the listing. Circumstances such as selling for a friend is allowed, but pictures of your items are required to be shared to the public. You do not need an imgur.com account in order to host pictures of your item on imgur, so that is not an excuse.
If you are scammed, inform the mods as soon as you can so that we may investigate and ban the offending parties if necessary.
Do not post the personal information of any Reddit users. The exception to this is if someone uses PayPal to scam a member, this information may be sent to the mods to prevent others from also being scammed. Doxxing people will not be tolerated.
Do not antagonize posters about their price, opinion, or sexual orientation (etc). This translates to be a general rule of "no dickish behavior". If you disagree with someone's price, and can post evidence that their item has a current or recent better price elsewhere such as a link to a vendor, that information is authorized to be posted. That is not antagonism. People may comment on prices and offer counter-offers, as long as behavior is not insulting or unprofessional. If you feel that someone is being unprofessional regarding pricing, report it and the mods will evaluate the case. They are the determining factor whether behavior warrants muting, temporary banning, or permanent banning based on severity of incident, past behavior, and other factors. If your behavior does not contribute towards the positive image of firearms ownership, your participation in this subreddit may not be welcome.
Soliciting any type of transaction regarding prohibited items may result in a ban. This includes Price Checks of firearms and other prohibited items, as this can be seen as an attempt to garner PM offers for prohibited items. Remember that there is no expectation of privacy from Reddit Admins, and that they have shown in the past that they have access to private message histories.
As a general guideline, if a buyer wants to use PayPal Goods and Services (G&S) rather than Friends and family (F&F), it is expected that they will absorb the ~3% fee for the increased protections. However, PayPal F&F, Zelle, and Venmo and similar payment methods are discouraged here due to a lack of protections.
All rules and guidelines are subject to change. The moderators have the final say in all issues in relation to the rules and how to enforce them.
submitted by SxbZxro to GunAccessoriesForSale [link] [comments]

[Table] Asteroid Day AMA – We’re engineers and scientists working on a mission that could, one day, help save humankind from asteroid extinction. Ask us anything!

Source
There are several people answering: Paolo Martino is PM, Marco Micheli is MM, Heli Greus is HG, Detlef Koschny is DVK, and Aidan Cowley is AC.
Questions Answers
Can we really detect any asteroids in space with accuracy and do we have any real means of destroying it? Yes, we can detect new asteroids when they are still in space. Every night dozens of new asteroids are found, including a few that can come close to the Earth.
Regarding the second part of the question, the goal would be to deflect them more than destroy them, and it is technologically possible. The Hera/DART mission currently being developed by ESA and NASA will demonstrate exactly this capability.
MM
I always wanted to ask: what is worse for life on Earth - to be hit by a single coalesced asteroid chunk, or to be hit by a multiple smaller pieces of exploded asteroid, aka disrupted rubble pile scenario? DVK: This is difficult to answer. If the rubble is small (centimetres to meters) it is better to have lots of small ones – they’d create nice bright meteors. If the rubble pieces are tens of meters it doesn’t help.
Let’s say that hypothetically, an asteroid the size of Rhode Island is coming at us, it will be a direct hit - you’ve had the resources and funding you need, your plan is fully in place, everything you’ve wanted you got. The asteroid will hit in 10 years, what do you do? DVK: I had to look up how big Rhode Island is – a bit larger than the German Bundesland ‘Saarland’. Ok – this would correspond to an object about 60 km in diameter, right? That’s quite big – we would need a lot of rocket launches, this would be extremely difficult. I would pray. The good news is that we are quite convinced that we know all objects larger than just a few kilometers which come close to our planet. None of them is on a collision course, so we are safe.
the below is a reply to the above
Why are you quite convinced that you know all object of that size? And what is your approach in finding new celestial bodies? DVK: There was a scientific study done over a few years (published in Icarus 2018, search for Granvik) where they modelled how many objects there are out there. They compared this to the observations we have with the telescopic surveys. This gives us the expected numbers shown here on our infographic: https://www.esa.int/ESA_Multimedia/Images/2018/06/Asteroid_danger_explained
There are additional studies to estimate the ‘completeness’ – and we think that we know everything above roughly a few km in size.
To find new objects, we use survey telescopes that scan the night sky every night. The two major ones are Catalina and Pan-STARRS, funded by NASA. ESA is developing the so-called Flyeye telescope to add to this effort https://www.esa.int/ESA_Multimedia/Images/2017/02/Flyeye_telescope.
the below is a reply to the above
Thanks for the answer, that's really interesting! It's also funny that the fist Flyeye deployed is in Sicily, at less than 100km from me, I really had no idea DVK: Indeed, that's cool. Maybe you can go and visit it one day.
the below is a reply to the original answer
What about Interstellar objects however, like Oumuamua? DVK: The two that we have seen - 'Oumuamua and comet Borisov - were much smaller than the Saarland (or Rhode Island ;-) - not sure about Borisov, but 'Oumuamua was a few hundred meters in size. So while they could indeed come as a complete surprise, they are so rare that I wouldn't worry.
Would the public be informed if an impending asteroid event were to happen? And, how would the extinction play out? Bunch of people crushed to death, knocked off our orbit, dust clouds forever? DVK: We do not keep things secret – all our info is at the web page http://neo.ssa.esa.int. The ‘risky’ objects are in the ‘risk page’. We also put info on really close approaches there. It would also be very difficult to keep things ‘under cover’ – there are many high-quality amateur astronomers out there that would notice.
In 2029 asteroid Apophis will fly really close to Earth, even closer than geostationary satellites. Can we use some of those satellites to observe the asteroid? Is it possible to launch very cheap cube sats to flyby Apophis in 2029? DVK: Yes an Apophis mission during the flyby in 2029 would be really nice. We even had a special session on that topic at the last Planetary Defense Conference in 2019, and indeed CubeSats were mentioned. This would be a nice university project – get me a close-up of the asteroid with the Earth in the background!
the below is a reply to the above
So you’re saying it was discussed and shelved? In the conference we just presented ideas. To make them happen needs funding - in the case of ESA the support of our member countries. But having something presented at a conference is the first step. One of the results of the conference was a statement to space agencies to consider embarking on such a mission. See here: https://www.cosmos.esa.int/documents/336356/336472/PDC_2019_Summary_Report_FINAL_FINAL.pdf/341b9451-0ce8-f338-5d68-714a0aada29b?t=1569333739470
Go to the section 'resolutions'. This is now a statement that scientists can use to present to their funding agencies, demonstrating that it's not just their own idea.
Thanks for doing this AMA! Did we know the Chelyabinsk meteor in 2013 (the one which had some great videos on social media) was coming? Ig not, how comes? Also, as a little side one, have there been any fatalities from impact events in the past 20 years? Unfortunately, the Chelyabinsk object was not seen in advance, because it came from the direction of the Sun where ground-based telescopes cannot look.
No known fatalities from impacts have happened in the past 20 years, although the Chelyabinsk event did cause many injuries, fortunately mostly minor.
MM
the below is a reply to the above
How often do impacts from that direction happen, compared to impacts from visible trajectories? In terms of fraction of the sky, the area that cannot be easily scanned from the ground is roughly a circle with a radius of 40°-50° around the current position of the Sun, corresponding to ~15% of the total sky. However, there is a slight enhancement of objects coming from that direction, therefore the fraction of objects that may be missed when heading towards us is a bit higher.
However, this applies only when detecting an asteroid in its "final plunge" towards the Earth. Larger asteroids can be spotted many orbits earlier, when they are farther away and visible in the night side of the sky. Their orbits can then be determined and their possible impacts predicted even years or decades in advance.
MM
There must be a trade-off when targeting asteroids as they get closer to Earth, is there a rule of thumb at what the best time is to reach them, in terms of launch time versus time to reach the asteroid and then distance from Earth? DVK: Take e.g. a ‘kinetic impactor’ mission, like what DART and Hera are testing. Since we only change the velocity of the asteroid slightly, we need to hit the object early enough so that the object has time to move away from it’s collision course. Finding out when it is possible to launch requires simulations done by our mission analysis team. They take the strength of the launcher into account, also the available fuel for course corrections, and other things. Normally each asteroid has its own best scenario.
Do you also look at protecting the moon from asteroids? Would an impact of a large enough scale potentially have major impacts on the earth? DVK: There are programmes that monitor the Moon and look for flashes from impacting small asteroids (or meteoroids) - https://neliota.astro.noa.g or the Spanish MIDAS project. We use the data to improve our knowledge about these objects. These programmes just look at what is happening now.
For now we would not do anything if we predicted a lunar impact. I guess this will change once we have a lunar base in place.
Why aren't there an international organisation comprised of countries focused on the asteroid defence? Imagine like the organisation with multi-billion $ budget and program of action on funding new telescopes, asteroid exploration mission, plans for detection of potentially dangerous NEA, protocols on action after the detection - all international, with heads of states discussing these problems? DVK: There are international entities in place, mandated by the UN: The International Asteroid Warning Network (http://www.iawn.net) and the Space Mission Planning Advisory Group (http://www.smpag.net). These groups advise the United Nations. That is exactly where we come up with plans and protocols on action. But: They don’t have budget – that needs to come from elsewhere. I am expecting that if we have a real threat, we would get the budget. Right now, we don’t have a multi-billion budget.
the below is a reply to someone else's answer
There is no actual risk of any sizable asteroids hitting earth in the foreseeable future. Any preparation for it would just be a waste of money. DVK: Indeed, as mentioned earlier, we do not expect a large object to hit is in the near future. We are mainly worried about those in the size range of 20 m to 40 m, which happen on average every few tens of years to hundreds of years. And where we only know a percent of them or even less.
President Obama wanted to send a crewed spacecraft to an asteroid - in your opinion is this something that should still be done in the future, would there be any usefulness in having a human being walk/float on an asteroid's surface? DVK: It would definitely be cool. I would maybe even volunteer to go. Our current missions to asteroids are all robotic, the main reason is that it is much cheaper (but still expensive) to get the same science. But humans will expand further into space, I am sure. If we want to test human exploration activities, doing this at an asteroid would be easier than landing on a planet.
this is another reply Yes, but I am slightly biased by the fact that I work at the European astronaut centre ;) There exist many similarities to what we currently do for EVA (extra vehicular activities) operations on the International Space Station versus how we would 'float' around an asteroid. Slightly biased again, but using such a mission to test exploration technologies would definitely still have value. Thanks Obama! - AC
I've heard that some asteroids contains large amounts of iron. Is there a possibility that we might have "space mines" in the far away future, if our own supply if iron runs out? Yes, this is a topic in the field known as space mining, part of what we call Space Resources. In fact, learning how we can process material we might find on asteroids or other planetary bodies is increasingly important, as it opens up the opportunities for sustainable exploration and commercialization. Its a technology we need to master, and asteroids can be a great target for testing how we can create space mines :) - AC
By how much is DART expected to deflect Didymos? Do we have any indication of the largest size of an asteroid we could potentially deflect? PM: Didymos is a binary asteroid, consisting of a main asteroid Didymos A (~700m) and a smaller asteroid Didymos B (~150m) orbiting around A with a ~12 hours period. DART is expected to impact Didymos B and change its orbital period w.r.t. Didymos A of ~1%. (8 mins)
The size of Didymos B is the most representative of a potential threat to Earth (the highest combination of probability and consequence of impacts), meaning smaller asteroids hit the Earth more often but have less severe consequences, larger asteroids can have catastrophic consequences but their probability of hitting the earth is very very low.
the below is a reply to the above
Why is there less probability of larger asteroids hitting earth? DVK: There are less large objects out there. The smaller they are, the more there are.
the below is a reply to the original answer
Is there any chance that your experiment will backfire and send the asteroid towards earth? PM: Not at all, or we would not do that :) Actually Dimorphos (the Didymos "moon") will not even leave its orbit around Didymos. It will just slightly change its speed.
I'm sure you've been asked this many times but how realistic is the plot of Armageddon? How likely is it that our fate as a species will rely on (either) Bruce Willis / deep sea oil drillers? Taking into consideration that Bruce Willis is now 65 and by the time HERA is launched he will be 69, I do not think that we can rely on him this time (although I liked the movie).
HERA will investigate what method we could use to deflect asteroid and maybe the results will show that we indeed need to call the deep sea oil drillers.
HG
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So then would it be easier to train oil drillers to become astronauts, or to train astronauts to be oil drillers? I do not know which one would be easier since I have no training/experience of deep see oil drilling nor becoming an astronaut, but as long as the ones that would go to asteroid have the sufficient skills and training (even Bruce Willis), I would be happy.
HG
If budget was no object, which asteroid would you most like to send a mission to? Nice question! For me, I'd be looking at an asteroid we know something about, since I would be interested in using it for testing how we could extract resources from it. So for me, I would choose Itokawa (https://en.wikipedia.org/wiki/25143_Itokawa), which was visited by Hayabusa spacecraft. So we already have some solid prospecting carried out for this 'roid! - AC
this is another reply Not sure if it counts as an asteroid, but Detlef and myself would probably choose ʻOumuamua, the first discovered interstellar object.
MM
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Do we even have the capability to catch up to something like that screaming through our solar system? That thing has to have a heck of a velocity to just barrel almost straight through like that. DVK: Correct, that would be a real challenge. We are preparing for a mission called 'Comet Interceptor' that is meant to fly to an interstellar object or at least a fresh comet - but it will not catch up with it, it will only perform a short flyby.
https://www.esa.int/Science_Exploration/Space_Science/ESA_s_new_mission_to_intercept_a_comet
After proving to be able to land on one, could an asteroid serve as a viable means to transport goods and or humans throughout the solar system when the orbit of said asteroid proves beneficial. While it is probably quite problematic to land the payload, it could save fuel or am I mistaken? Neat idea! Wonder if anyone has done the maths on the amount of fuel you would need/save vs certain targets. - AC
PM: To further complement, the saving is quite marginal indeed because in order to land (softly) on the asteroid you actually need to get into the very same orbit of that asteroid . At that point your orbit remains the same whether you are on the asteroid or not..
can the current anti-ballistic missiles systems intercept a terminal phase earth strike asteroid? or it is better to know beforehand and launch an impacting vehicle into space? DVK: While I do see presentations on nuclear explosions to deflect asteroids at our professional meetings, I have not seen anybody yet studying how we could use existing missile systems. So it's hard to judge whether existing missiles would do the job. But in general, it is better to know as early as possible about a possible impact and deflect it as early as possible. This will minimize the needed effort.
How much are we prepared against asteroid impacts at this moment? DVK: 42… :-) Seriously – I am not sure how to quantify ‘preparedness’. We have international working groups in place, mentioned earlier (search for IAWN, SMPAG). We have a Planetary Defence Office at ESA, a Planetary Defense Office at NASA (who spots the difference?), search the sky for asteroids, build space missions… Still we could be doing more. More telescopes to find the object, a space-based telescope to discover those that come from the direction of the Sun. Different test missions would be useful, … So there is always more we could do.
Have you got any data on the NEO coverage? Is there estimations on the percentage of NEOs we have detected and are tracking? How can we improve the coverage? How many times have asteroids been able to enter earths atmosphere without being detected beforehand? Here’s our recently updated infographics with the fraction of undiscovered NEOs for each size range: https://www.esa.int/ESA_Multimedia/Images/2018/06/Asteroid_danger_explained
As expected, we are now nearly complete for the large ones, while many of the smaller ones are still unknown.
In order to improve coverage, we need both to continue the current approach, centered on ground-based telescopes, and probably also launch dedicated telescopes to space, to look at the fraction of the sky that cannot be easily observed from the ground (e.g., towards the Sun).
Regarding the last part of your question, small asteroids enter the Earth atmosphere very often (the infographics above gives you some numbers), while larger ones are much rarer.
In the recent past, the largest one to enter our atmosphere was about 20 meters in diameter, and it caused the Chelyabinsk event in 2013. It could not be detected in advance because it came from the direction of the Sun.
We have however detected a few small ones before impact. The first happened in 2008, when a ~4-meter asteroid was found to be on a collision course less than a day before impact, it was predicted to fall in Northern Sudan, and then actually observed falling precisely where (and when) expected.
MM
this is another reply >After
DVK: And to add what MM said - Check out http://neo.ssa.esa.int. There is a ‘discovery statistics’ section which provides some of the info you asked about. NASA is providing similar information here https://cneos.jpl.nasa.gov/stats/. To see the sky which is currently covered by the survey telescopes, you need to service of the Minor Planet Center which we all work together with: http://www.minorplanetcenter.org, ‘observers’, ‘sky coverage’. That is a tool we use to plan where we look with our telescopes, so it is a more technical page.
Are there any automatic systems for checking large numbers of asteroids orbits, to see if the asteroid's orbit is coming dangerously close to Earth, or is it done by people individually for every asteroid? I ask it because LSST Rubin is coming online soon and you know it will discover a lot of new asteroids. Yes, such systems exist, and monitor all known and newly discovered asteroids in order to predict possible future impacts.
The end result of the process is what we call "risk list": http://neo.ssa.esa.int/risk-page
It is automatically updated every day once new observational data is processed.
MM
What are your favourite sci-fi series? DVK: My favorites are ‘The Expanse’, I also liked watching ‘Salvation’. For the first one I even got my family to give me a new subscription to a known internet streaming service so that I can see the latest episodes. I also loved ‘The Jetsons’ and ‘The Flintstones’ as a kid. Not sure the last one counts as sci-fi though. My long-time favorite was ‘Dark Star’.
this is another reply Big fan of The Expanse at the moment. Nice, hard sci-fi that has a good impression of being grounded in reality - AC
this is another reply When I was a kid I liked The Jetsons, when growing up Star Trek, Star wars and I also used to watch with my sister the 'V'.
HG
When determining the potential threat of a NEA, is the mass of an object a bigger factor or size? I'm asking because I'm curious if a small but massive object (say, with the density of Psyche) could survive atmospheric entry better than a comparatively larger but less massive object. The mass is indeed what really matters, since it’s directly related with the impact energy.
And as you said composition also matters, a metal object would survive atmospheric entry better, not just because it’s heavier, but also because of its internal strength.
MM
What are your thoughts on asteroid mining as portrayed in sci-fi movies? Is it feasible? If so would governments or private space programs be the first to do so?What type of minerals can be found on asteroids that would merit the costs of extraction? Certainly there is valuable stuff you can find on asteroids. For example, the likely easiest material you can harvest from an asteroid would be volatiles such as H2O. Then you have industrial metals, things like Iron, Nickel, and Platinum group metals. Going further, you can break apart many of the oxide minerals you would find to get oxygen (getting you closer to producing rocket fuel in-situ!). Its feasible, but still needs alot of testing both here on Earth and eventually needs to be tested on a target. It may be that governments, via agencies like ESA or NASA, may do it first, to prove the principles somewhat, but I know many commercial entities are also aggresively working towards space mining. To show you that its definitely possible, I'd like to plug the work of colleagues who have processed lunar regolith (which is similar to what you may find on asteroids) to extract both oxygen and metals. Check it out here: http://www.esa.int/ESA_Multimedia/Images/2019/10/Oxygen_and_metal_from_lunar_regolith
AC
Will 2020's climax be a really big rock? DVK: Let's hope not...
Considering NASA, ESA, IAU etc. is working hard to track Earth-grazing asteroids, how come the Chelyabinsk object that airburst over Russia in 2013 came as a total surprise? The Chelyabinsk object came from the direction of the Sun, where unfortunately ground-based telescopes cannot look at. Therefore, it would not have been possible to discover it in advance with current telescopes. Dedicated space telescopes are needed to detect objects coming from this direction in advance.
MM
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Is this to say that it was within specific solid angles for the entire time that we could have observed it given its size and speed? Yes, precisely that. We got unlucky in this case.
MM
Have any of you read Lucifer's Hammer by Larry Niven? In your opinion, how realistic is his depiction of an asteroid strike on Earth? DVK: I have – but really long ago, so I don’t remember the details. But I do remember that I really liked the book, and I remember I always wanted to have a Hot Fudge Sundae when reading it.
I was thinking about the asteroid threat as a teen and came up with this ideas (Hint: they are not equally serious, the level of craziness goes up real quick). Could you please comment on their feasibility? 1. Attaching a rocket engine to an asteroid to make it gradually change trajectory, do that long in advance and it will miss Earth by thousands of km 2. Transporting acid onto asteroid (which are mainly metal), attaching a dome-shaped reaction chamber to it, using heat and pressure to then carry out the chemical reaction to disintegrate asteroids 3. This one is even more terrible than a previous one and totally Dan Brown inspired — transporting antimatter on asteroid, impacting and causing annihilation. Thank you for this AMA and your time! DVK: Well the first one is not so crazy, I have seen it presented... the difficulty is that all asteroids are rotating in one way or another. So if you continuously fire the engine it would not really help. You'd need to switch the engine on and off. Very complex. And landing on an asteroid is challenging too. Just using the 'kinetic impactor' which we will test with DART/Hera (described elsewhere in this chat) is simpler. Another seriously proposed concept is to put a spacecraft next to an asteroid and use an ion engine (like we have on our Mercury mission BepiColombo) to 'push' the asteroid away.
As for 2 and 3 I think I will not live to see that happening ;-)
What is the process to determine the orbit of a newly discovered asteroid? The process is mathematically quite complex, but here's a short summary.
Everything starts with observations, in particular with measurements of the position of an asteroid in the sky, what we call "astrometry". Discovery telescopes extract this information from their discovery images, and make it available to everybody.
These datapoints are then used to calculate possible trajectories ("orbits") that pass through them. At first, with very few points, many orbits will be possible.
Using these orbits we can extrapolate where the asteroid will be located during the following nights, use a telescope to observe that part of the sky, and locate the object again.
From these new observations we can extract new "astrometry", add it to the orbit determination, and see that now only some of the possible orbits will be compatible with the new data. As a result, we now know the trajectory better than before, because a few of the possible orbits are not confirmed by the new data.
The cycle can then continue, with new predictions, new observations, and a more accurate determination of the object's orbit, until it can be determined with an extremely high level of accuracy.
MM
What are some asteroids that are on your "watchlist"? We have exactly that list on our web portal: http://neo.ssa.esa.int/risk-page
It's called "risk list", and it includes all known asteroids for which we cannot exclude a possible impact over the next century. It is updated every day to include newly discovered asteroids, and remove those that have been excluded as possible impactors thanks to new observations.
MM
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That's quite a list!! Do you guys ever feel stressed or afraid when you have to add another dangerous candidate (and by dangerous I mean those above 200m) is added to this Risk List? Yes, when new dangerous ones are added it's important that we immediately do our best to gather more data on them, observing them with telescopes in order to get the information we need to improve our knowledge of their orbit.
And then the satisfaction of getting the data needed to remove one from the list is even greater!
MM
What inspired you to go into this field of study? I was fascinated by astronomy in general since I was a kid, but the actual "trigger" that sparked my interest in NEOs was a wonderful summer course on asteroids organized by a local amateur astronomers association. I immediately decided that I would do my best to turn this passion into my job, and I'm so happy to have been able to make that dream come true.
MM
this is another reply DVK: I started observing meteors when I was 14, just by going outside and looking at the night sky. Since then, small bodies in the solar system were always my passion.
As a layperson, I still think using nuclear weapons against asteroids is the coolest method despite better methods generally being available. Do you still consider the nuclear option the cool option, or has your expertise in the field combined with the real-life impracticalities made it into a laughable/silly/cliche option? DVK: We indeed still study the nuclear option. There are legal aspects though, the ‘outer space treaty’ forbids nuclear explosions in space. But for a large object or one we discover very late it could be useful. That’s why we have to focus on discovering all the objects out there as early as possible – then we have time enough to use more conventional deflection methods, like the kinetic impactor (the DART/Hera scenario).
It seems like doing this well would require international cooperation, particularly with Russia. Have you ever reached out to Russia in your work? Do you have a counterpart organization there that has a similar mission? DVK: Indeed international cooperation is important - asteroids don't know about our borders! We work with a Russian team to perform follow-up observations of recently discovered NEOs. Russia is also involved in the UN-endorsed working groups that we have, IAWN and SMPAG (explained in another answer).
how much can experts tell from a video of a fireball or meteor? Can you work out what it's made of and where it came from? https://www.reddit.com/space/comments/hdf3xe/footage_of_a_meteor_at_barrow_island_australia/?utm_source=share&utm_medium=web2x If multiple videos or pictures, taken from different locations, are available, then it's possible to reconstruct the trajectory, and extrapolate where the object came from.
Regarding the composition, it's a bit more difficult if nothing survives to the ground, but some information can be obtained indirectly from the fireball's color, or its fragmentation behavior. If a spectral analysis of the light can be made, it's then possible to infer the chemical composition in much greater detail.
MM
I've always wanted to know what the best meteorite buying site is and what their average price is?? DVK: Serious dealers will be registered with the 'International Meteorite Collectors Association (IMCA)' - https://www.imca.cc/. They should provide a 'certificate of authenticity' where it says that they are member there. If you are in doubt, you can contact the association and check. Normally there are rough prices for different meteorite types per gram. Rare meteorites will of course be much more expensive than more common ones. Check the IMCA web page to find a dealer close to you.
Just read through Aidans link to the basaltic rock being used as a printing material for lunar habitation. There is a company called Roxul that does stone woven insulation that may be able to shed some light on the research they have done to minimize their similarity to asbestos as potentially carcinogenic materials deemed safe for use in commercial and residential applications. As the interior surfaces will essentially be 3D printed lunar regolith what are the current plans to coat or dampen the affinity for the structure to essentially be death traps for respiratory illness? At least initially, many of these 3d printed regolith structures would not be facing into pressurised sections, but would rather be elements placed outside and around our pressure vessels. Such structures would be things like radiation shields, landing pads or roadways, etc. In the future, if we move towards forming hermetically sealed structures, then your point is a good one. Looking into terrestrial solutions to this problem would be a great start! - AC
What kind of career path does it take to work in the asteroid hunting field? It's probably different for each of us, but here's a short summary of my own path.
I became interested in asteroids, and near-Earth objects in particular, thanks to a wonderful summer course organized by a local amateur astronomers association. Amateur astronomers play a great role in introducing people, and young kids in particular, to these topics.
Then I took physics as my undergrad degree (in Italy), followed by a Ph.D. in astronomy in the US (Hawaii in particular, a great place for astronomers thanks to the exceptional telescopes hosted there).
After finishing the Ph.D. I started my current job at ESA's NEO Coordination Centre, which allowed me to realize my dream of working in this field.
MM
this is another reply DVK: Almost all of us have a Master's degree either in aerospace engineering, mathematics, physics/astronomy/planetary science, or computer science. Some of us - as MM - have a Ph.D. too. But that's not really a requirement. This is true for our team at ESA, but also for other teams in other countries.
What is the likelihood of an asteroid hitting the Earth In the next 200 years? It depends on the size, large ones are rare, while small ones are much more common. You can check this infographics to get the numbers for each size class: https://www.esa.int/ESA_Multimedia/Images/2018/06/Asteroid_danger_explained
MM
Have you played the Earth Defence Force games and if you have, which one is your favourite? No I have not played the Earth Defence Force games, but I just looked it up and I think I would liked it. Which one would you recommend?
HG
How close is too close to earth? Space is a SUPER vast void so is 1,000,000 miles close, 10,000,000? And if an asteroid is big enough can it throw earth off its orbit? DVK: Too close for my taste is when we compute an impact probability > 0 for the object. That means the flyby distance is zero :-) Those are the objects on our risk page http://neo.ssa.esa.int/risk-page.
If an object can alter the orbit of another one, we would call it planet. So unless we have a rogue planet coming from another solar system (verrry unlikely) we are safe from that.
How can I join you when I'm older? DVK: Somebody was asking about our career paths... Study aerospace engineering or math or physics or computer science, get a Masters. Possibly a Ph.D. Then apply for my position when I retire. Check here for how to apply at ESA: https://www.esa.int/About_Us/Careers_at_ESA/Frequently_asked_questions2#HR1
How much is too much? DVK: 42 again
Are you aware of any asteroids that are theoretically within our reach, or will be within our reach at some point, that are carrying a large quantity of shungite? If you're not aware, shungite is like a 2 billion year old like, rock stone that protects against frequencies and unwanted frequencies that may be traveling in the air. I bought a whole bunch of the stuff. Put them around the la casa. Little pyramids, stuff like that. DVK: If I remember my geology properly, Shungite forms in water sedimental deposits. This requires liquid water, i.e. a larger planet. So I don't think there is a high chance to see that on asteroids.
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