Kostya's Boring Codec World

A year ago I wrote why I’d like to be excited by RISC-V but can’t. I viewed it (and still view) as slightly freshened up MIPS (with the same problems as MIPS had). But the real question is what does it offer me as a developer of multimedia framework?

Not that much, as it turns out. RISC-V is often lauded as a free ISA any vendor can edit but what does it give me as an end user? It’s not that I can build a powerful enough chip even if hardware specifications are available (flashing an FPGA is an option but see “powerful enough” above) so I’m still dependent on what various vendors can offer me and from that point of view almost all CPU architectures are the same. The notable exceptions are russian Elbrus-2000 where instruction set documentation is under NDA (because its primary application being for russian military systems) and some Chinese chips they refuse to sell abroad (was it Loongson family?).

Anyway, as a multimedia framework developer I care about SIMD capabilities offered by CPU—modern codecs are too complex to write them in assembly and with a medium- or high-level language compiler you don’t care about CPU details much—except for SIMD-accelerated blocks that make sense to write using assembly (or intrinsics for POWER). And that’s where RISC-V sucks.

In theory RISC-V supports V extension (for variable-length SIMD processing), in practice hardly any CPUs support it. Essentially there is only one core on the market that support RISC-V V extension (or RVV for short)—C920 from T-Head and it’s v0.7.1 only (here’s a link to Rémi’s report on what’s changed between RVVv0.7.1 and RVVv1.0). Of course there’s a newer revision of that core that features RVVv1.0 support but currently there’s only one (rather underpowered) board using it and it’s not possible to buy anyway. Also I heard about SiFive designing a CPU with RVVv1.0 support but I don’t remember seeing products built on it.

And before you offer to use an emulator—emulation is skewed and proper simulation is too slow for practical purposes. Here’s a real-world example: when Macs migrated from PowerPC to x86, developers discovered that the vector shuffle instruction that was fast on PowerPC was much slower on Rosetta emulation (unlike the rest of code). Similarly there’s a story about NEON optimisations not giving any speed-up—when tested in QEMU—but made a significant performance boost on real hardware. That’s why I’d rather have a small development board (something like the original BeagleBoard) to test the optimisations if I can’t get a proper box to develop stuff on it directly.

This also rises a question not only about when CPUs with RVV support should be more accessible but why they are so rare. I can understand the problems with designing a modern performant CPU in general let alone with vector extension and on rather short term but since some have accomplished it already, why is it not more common? Particularly SiFive, if you have one chip with RVV what prevents adding it to other chips which are supposedly desktop- and server-oriented? I have only one answer and I’d like to be proven wrong (as usual): while the chip designers can implement RVV, they were unable to make it performant without hurting the rest of CPUs (either too large transistor budget or power requirements; or maybe its design interferes with the rest of the core too much) so we have it mostly on underwhelming Chinese cores and some SiFive CPU not oriented for a general user. Hopefully in the future the problems will be solved and we’ll see more mainline RISC-V CPUs with RVV. Hopefully.

So far though it reminds me of a story about Nv*dia and its first Tegra SoCs. From what I heard, the company managed to convince various vendors to use it in their infotainment systems and those who used it discovered that its hardware H.264 decoder worked only for files with certain resolutions and they somehow used a CPU without SIMD (IIRC the first Tegra lacked even FPU) so you could not even attempt to decode stuff there with a software decoder. As the result those vendors were disappointed and made a pass on the following SoCs (resulting in a rather funny Tegra-powered microwave oven). I fear that RISC-V might lose interest of the multimedia developers with both the need to rewrite code from RVVv0.7.1 to RVVv1.0 and the lack of appealing hardware supporting RVVv1.0 anyway—so when it’s ready nobody will be interested any longer. And don’t repeat again the same words about open and royalty-free ISA. We have free Theora format that sucked and was kept alive because “it’s free”—when it was improved to be about as good as MPEG-4 ASP there was a much better open and free VP8 codec available. Maybe somebody will design a less fragmented ISA targeting more specific use cases than “anything from simple microcontrollers to server CPUS” and RISC-V will join OpenRISC and others (…and nothing of the value will be lost).

P.S. Of course multimedia is far from the most important use case but it involves a good deal of technologies used in other places. And remember, SSE was marketed as something that speeds-up working with Internet (I like to end posts on a baffling note).

In some cases authoritarian governments come suddenly, usually as the result of a coup or a legal loophole (Article 48 of Weimar Constitution is an example codified in ages), in other cases the power grab goes gradually like in the famous frog-in-the-boiling-water metaphor. It’s easy to act surprised, as the things are almost the same as they were yesterday or last year, but usually there are tell-tale signs of a country going into authoritarianism. Here I’d like to remind about them.

Probably the most important of them is the judicial branch reform that de facto cancels its independency as the government controls who gets appointed as a judge. After you get loyal judges who’s going to stop your unlawful reforms? We had such situation in Ukraine during 2010-2014 (even without any factual reform; but more about Ukraine later), Poland tries to get it (and that’s disturbing), Hungary has done it (of course), Israel is doing it right now (which may end too bad for the country) and so on. But usually at this stage the things are so bad that the actual dictatorship (or demokratur) is merely the next step, are there any earlier signs?

Again, one of the important but rather late signs is unwillingness to part with power. It may happen in any circumstances but usually it’s parliamentary republic with a dominating party and the same prime minister for decades. There may be a president but he or she is a nominal figure while the prime minister remains at power (see Georgia, Germany, Hungary or Israel). Of course it may still not work out like with Merkel, who had to retire after sixteen years, without leaving a good successor candidate in her own party; IMO she should’ve got a prison sentence for serving russian interests but she got awarded a Grand Cross for that instead. I feel the maximum term for any such post should be about twelve years and anybody, who like the current (since 2010) Hungarian prime minister say they want to remain for another twenty years, should be put to prison immediately. South Korea has a good idea with its presidents, a good deal of them were either shot or imprisoned after their term was over. In Fourecks they imprison politicians right after they’re elected (so save time)—but alas it’s a fictional continent.

But usually it’s not one single person but somebody with a support of major party. And, surprisingly enough, those parties usually have something in common: they rely on populism, promoting “traditional values” to the extent of being against anything new, and very often seeing USA and “the West” as their enemies. In other words, promising to return the country to the times of past glory (or at least when the situation was not so bleak) and blaming foreigners and their agents on everything bad that has happened since those times (I’m sorry if that does not reduce the list of possible candidates by much, that’s the state of modern politics). I should probably add another thing to cheap populism: creating show by solving issues nobody had like renaming a country. I can understand why Congo does not want its capital named after the Belgian king who is responsible for mass genocide in the country (and for the same reason Ukraine renames its towns and streets), I can understand why a country renames itself from Rhodesia, I can understand when a country introduces a preferred name while still recognizing the old one (like Czechia or Sakartvelo). But demanding that your country called abroad differently without any apparent reason for renaming sounds like a cheap gesture to show your own people that your country is proud and how others have to comply with it (while drawing attention from more important issues). In case it’s not obvious I’m talking about The Country Formerly Known As Turkey and The Country Most Likely To Be Known As Modi Raj.

The very minor signs would be the corruption potential: if a party serves interests of an oligarch or an oligarch group it is naïve to expect from it to have no attempts to seize power and hold it as long as possible to exercise it for profit and to avoid prosecution. And a thing related to it—friendship with russia (usually paid from the russian side).

In the end I’d like to talk about Ukraine to serve as an example. There were two and a half attempts to grab power in its recent history. First attempt was made by the second president, Leonid Kuchma: back in the day he even traded some presidential privileges for some additional executive functions he could perform. Over the years he increased his power, often with a help of shady people like Pavlo Lazarenko (famous for being a Ukrainian prime minister, a citizen of Panama and building so wide corruption network that he served a prison sentence in the USA for it) or Yuriy Kravchenko (who turned police into his personal mob). Kuchma often solved problems by firing the current prime minister and selecting a new candidate. Still that has not saved him from the consequences of murdering Gongadze and the Cassette Scandal. Another fun fact is that Ukrainian oligarch Pinchuk had a nickname “Kuchma’s-son-in-law” (because he really was one). It is also said that he tried to game the system by trying to organise 2004 elections in such a way that both candidates would lose and he would remain by default. Those elections and rigged counting though caused so much public outrage (called the first Maidan) that they had to repeat the vote.

The second attempt was when viktor yanukovich assumed the post of the president and the Party of Regions (from which he came) got the majority in the parliament. Those were dark times when he used kangaroo courts to deal with his opponents (because no judge could be appointed at that time without approval from the President’s Office) and cancel previous constitutional reform limiting presidential power; people affiliated with him (“the Family”) could raid and steal other businesses and it is said they managed to steal a sixth of the country budget every year in addition to that. As you know, it ended by him selling Ukraine to russia, fleeing the country and starting the war that goes to this day. It is less remembered that during his last days of presidency his party tried to pass the same laws as in russia to limit the freedoms and allow to prosecute the protesters easily. It did not work out.

The half-attempt is when Volodymyr Zelensky became a president and his party got majority in the parliament (mostly thanks to his image). He had not so great decisions in the beginning (and the parliament supported them) so it could end badly. But then a führer decided to take Kyiv in three days and the Ukrainian nation united against the enemy once again. Since then Zelensky (and somewhat his party) act decently because it’s the matter of survival. Who knows how it will go after the victory but for now I have nothing else to say about him.

I hope this brief review of Ukrainian political history served an example of how important it is to stop authoritarianism when you can still do it without human casualties. Revolutions often take a much higher price…

Don’t get me wrong, the idea behind it is sound but it got overhyped and misapplied. Of course I’m talking about one of an early attempts at lossy image compression called block truncation coding, what did you think about?

For those who forgot about it (and is too lazy to read its description), the method replaces values in a block with two values below/above block mean value using that mean value, standard deviation and that number of values that were above the mean value. This algorithm is often quoted as being the one on which many video codecs (especially the ones used in various games but some standard ones like Micro$oft Video 1 and A**le Graphics(SMC) and Video(RPZA) as well) are built. And that part is a bullshit which many used to believe mostly because nobody who heard it took any time to evaluate that statement (I was no exception).

Actually I should’ve started doubting it much earlier as I’ve tried to apply it to colour quantisation (like in Video 1 encoder) and failed. The method is applicable to scalar values only (and pixels are vectors of three components in our case, you can map them to greyscale but how would you calculate two distinct colours to segment block into?) and its results are worse than using Linde-Buzo-Gray method for vector quantisation (which was presented in the paper the following year). Wikipedia has an article describing a proper image compression algorithm proposed in 1986 called color cell compression that definitely looks like the perfect candidate for all the following codecs: it describes compressing image by splitting it into 4×4 tiles, grouping pixels in those tiles using average luminance as the discriminator and calculating two colours to paint the tile as averages of those two groups. That’s how vector quantisation works and unlike BTC it does not require calculating square roots and can be implemented trivially using integer maths only. So it’s practical, gives better results (in terms of MSE of greyscale images when compared to BTC) and works on actual pixel data.

While BTC was innovative for its time and probably an important stepping stone for further methods, its relevance to the modern compression schemes is minimal (unlike colour cell compression) and calling it the base for the codecs with two-colour vector quantisation is as stupid as calling Cyrano de Bergerac the father of space flight because he mentioned travel to the Moon using gunpowder rockets in a novel of his.

Since K&R times it’s traditional to make a programming language print “Hello, world!” as the introduction to it. Recently I had a thought that formatting a number in output tells you the essentials of the programming language itself.

So if you want to print not just a constant string but, say, a number expanded to a certain length (e.g. printf("%4d\n", val);), how can you do it?

Essentially there are three major approaches: using WRITE with optional specifiers for each element, using one format string with arguments to follow and having just basic output with utilities to format elements using some pattern and string concatenation. And there’s C++.

The first approach can be found in the old venerable languages like FORTRAN or ALGOL. It is also somewhat funny that in Pascal its writeln() can’t be implemented in the language itself so the compiler has to convert it to a sequence of formatting and writes or string concatenations (exactly the third way). The same is true for Rust as well (which belongs to the second category) but at least println!() outright tells you that it’s not a normal function but rather a macro or a compiler plug-in.

The second approach even if not invented got popularised by C. You have a template string with recognizable percent signs to signal where arguments should be substituted and in what form. Of course this is not the safest approach since you may pass a template with not enough arguments and read garbage from the stack (and that’s not counting the dreaded %n). In the recent years another template format got popular (probably thanks to Python, with an influence from bash or PHP): instead of percent sign and type there are braces with an optional format arguments or variable name inside. Speaking of Python, you can use print with the old printf-style or new f-string formatting and it will put a newline at the end by default (reminding once again that Python is all about whitespaces). As for the implementation, in some languages it’s a built-in function (i.e. you can’t implement it in the language itself but the compiler/interpreter takes care of it), in C it’s implemented by parsing the stack more or less directly, in many modern languages variable-argument function simply passes those arguments as an array of the most generic object types (so you can implement something like printf() yourself). I think I can also mention here the third pattern format mostly used for formatting binary output—the one used in Perl pack() function (and whatever languages borrowed it), its syntax reminds me of the classic languages from the first category.

The third approach is too primitive so usually languages try to use some syntactic sugar to make it easier to use (see Pascal or Rust mentioned above). I should probably mention INTERCAL where outputting a single character might pose a challenge for an uninitiated but that’s part of the charm of the language.

And finally C++. In the original version of the language you were supposed to use cout << setw(4) << val << endl; and while it demonstrates the advantages of the operator overloading, in the same time it suffers from the extreme verbosity and side effects (that width modifier will be applied to all the following argument in all following prints until you change it). In the modern C++ you should use std::cout, std::setw() and std::endl() instead. As the result people mostly use printf() or some third-party formatting library (you may even get it with one of your string class implementations for free).

As you can see, the way you can print a formatted number (both the syntax and the implementation) can tell you a lot about the programming language in a rather short time. Of course there are exceptions but the lack of such functionality tells you at least about the kind of language you're dealing with.

Disclaimer: the question presented in this post does not affect me in any way but it’s still perplexing enough to make it public. Also please note I don’t mention names (neither of people nor software) as this post is not about shaming them.

As any other area of human activity, multimedia has its own share of, ahem, eccentric people that are obsessed a bit too much about their project. For example, there’s a guy who constantly informs the world about even the slightest advancements of his image codec with his own unique image quality metric. Theoretically it should be interesting but the author keeps ignoring the useful advice he gets (like making his code work with a different image size or explaining how his metric is better than the others) in hope that somebody else will get interested enough to fix that for him, as his lack of free time prevents him from doing anything but minor improvements to the code. Maybe it’s not the wisest approach but it does not harm anybody so good luck to him, maybe one day there will be a breakthrough and it will get at least a limited fame. But there’s another example that came to my attention recently, which is significantly more disturbing.

So there’s a certain codec that has niche popularity for its speed and decent compression ratio. Since it was proprietary and somewhat popular, a certain person (not me) has reverse-engineered it and added decoding support for the format to FFmpeg. The reaction from the creator was rather baffling at the time, it was like he felt the control of that codec was wrestled from him. Oh well, enough time has passed with no other issues arising. But last week the same person who REd the decoder announced about that he’s working on an opensource encoder for it, and that’s when the situation exploded. The format creator in a tone that I think is called passive-aggressive told that it’s essentially a stolen work and that it made him stop on a new version of the work. And what is significantly worse and greatly disturbing, his words sound like he got a depression from it or even suicidal thoughts. Even while I have reasons to believe that the encoder in question is going to be an original work (i.e. not a plagiarism; REing format to ensure compatibility is also permitted by the law in many countries) the possible consequences are still deeply disturbing, to say the least.

Thus several questions arise: what should be the best course of action to resolve situations like this one? Was an opensource implementation even for a decoder a mistake and should it be removed entirely? Should the author better communicate his wishes that there should be no alternative implementations whatsoever in the first place and should the others honour it if the product becomes too popular for its own good? Even if the law permits it, what about the morals?

I can only be happy for the fact that I’m not involved in it at all. In either case it would be nice to know the answers—and even nicer is they will never ever be useful.

P.S. Corporations are not people so do not try to project the situation to them. And if they feel offended their lawyers will tell you that (so far I think only N*llym*ser tried it).

P.P.S. If you think I also suffer from similar psychological issues—maybe you’re right, I’m not be eligible to judge. At least I do not try to force my stuff onto others, I don’t even post anything at public places except in this very easy to ignore blog.

As I mentioned in one of my previous posts on this topic, I consider russians to be rather a viral mindset than a nation: they don’t have clearly defined territory (as they consider they whole world to be it), they have no own culture (it’s either stolen or for-display set pieces that get no relation or acceptance with russians; well, you can argue that their widespread prison subculture is their own but how does that make things any better?), they lack human qualities like compassion required in this age (i.e. a millennium or two ago russians would be no different from many other nations but the times have changed), and the worst of all—they try to convert everything they come in contact with into russia (either by conquering the territories and committing cultural and actual genocide or by demanding that the other countries do everything their way because it’s too hard for russians to learn other country language and customs). And yet there are naïve people believing that there are “good” russians even that’s an oxymoron. Usually that comes from a belief that if russian say they’re against war and current government that implies they’re against other things as well. Here I’ll try to stratify russians by their empathy and activity:

• plankton—like the namesake those russians have almost no will of their own and are merely flowing with the currents. If you ask them about their position, it will be more “for all good and against all bad” and they never take interest in politics. They’re always supporting the government but when it changes they’ll support the new government equally half-heartedly (just remember what happened in Rostov during the laughable coup attempt). The sad thing is that they’ll readily resort to violence if they’re permitted by the authorities. They have no compassion (there’s enough evidence how they’ll cheer to the war crimes their army commits and to the spectacle of the same war criminals dying as long as it’s a good show). Slave-owners and dictators may call them good but since I’m neither I can’t;
• moths—those are almost the same as the previous category but they can have their own opinion not fully in line with the mainstream one and even—gasp—be against the government. The only problem is that they don’t act on their words, saying that they’re mere moths and can’t do anything. Of course they’ve never tried to find it out if they can actually do anything or not. For those I have only mild despise because they don’t deserve a strong emotion;
• sell-outs—not originally russians but who became ones usually by being seduced with russian money. You might’ve heard about russian actors like Steven Seagal or Gérard Depardieu. There’s nothing wrong with coming to another country in pursuit of better work opportunities. But there’s a difference between selling your skills and selling your dignity and calling such people good is like calling a native advertisement a good article;
• chameleons—those russians actually have a position, the problem is that it changes depending on circumstances and who asks about it. To give a concrete example, in the first days of February 24th some propagandists from russian television said to their friends that they wear their half-swastika symbols but mean it as a hidden support for Zelensky. Obviously they may voice support for anything but in reality they’re concerned only about their own well-being. Somebody not familiar with that feature may call them good, not knowing that the words they heard were empty, I call them disgusting;
• white coats—that is a semi-official term for those who put themselves over the others like in the famous scene from Monty Python and the Holy Grail: —Must be a king. —Why? —He hasn’t got shit all over him (I vaguely remember a russian joke about somebody first spraying shit over others and then appearing in a clean white coat, that must be the origin). Such people pose themselves as morally superior to others, impartial judges and so on—forgetting they have no ground for that or trying to proactively evade the possible blame. As with the previous category, somebody naïve enough to believe their words without checking their background may believe they’re good but they should know better;
• armchair Napoleons—those do not even try to hide their ambitions. In the “worst” case they want russian army to be better equipped and fighting (forgetting that russian traditions like stealing and corruption prevent it), in the “best” case they want russia to conquer all of the world. Or if it all fails they’re fine with russia nuking the rest of the world. You need to be a psychopath to call them good (again, search elsewhere);
• and finally russians with human faces. Those pretend to be actual humans and often serve as an example of “good russians” in the West. In reality though sooner or later they show their real russian face. They might be against the current government but what are they going to do? There’s a post by some random russian that sums it up the best: “This regime will fall, Navalny will become a president and restore the country. And then we’ll get back at you, Ukrainians!” You can dismiss it as being just a single deviant voice, but in reality prominent figures from russian “opposition” demonstrated the same behaviour and chauvinism as the officials (like spreading the false claims about blown up Kakhovka HPP or not understanding why not everybody would like to interact with russians in general). To me it seems that they try to maintain the usual russian imperialism by keeping up ties with other countries (so when russia has more strength it can come there “in order to protect oppressed russian-speaking citizens”). So they’re about as good as telemarketers are your friends.

If you think this does not apply to somebody specific, try to get the honest answers for the following questions: are you against the current war? are you against the war just because it inconveniences your life (with sanctions and possible partial mobilisation)? do you think only the russian government is responsible for starting the war? do you think that russia should be held responsible for the war crimes it committed (e.g. paying reparations)? do you think that Crimea belongs to russia? do you think that russia should withdraw its forces from all occupied areas (Abkhazia, Armenia, Belarus, Ossetia, Syria) as well? do you think that something substantial should be done about russia in order not to make this scenario repeat again? do you consider the idea of dissolution of russia in order to make national republics acceptable? do you understand that russian writers often followed imperialistic agenda and thus other nations have reasons to ban their works? and finally, do you agree that russians are not superior to other nations? Hint: not all of those yes-no questions have “yes” as the right answer so you need to think before answering them.

russians usually give themselves away by starting to cry that Crimea is russian, always has been and giving it to Ukraine was a historical mistake as the existence of Ukraine itself. On the other hand, if somebody passes the test perfectly then probably you’re not dealing with a russian at all.

Meanwhile the only real good russians are mentioned in reports like this one: