The disturbing similarities between France and russia

March 11th, 2023

Dedicated to yet another piece of news about French company deciding to increase its business presence in russia instead of leaving the “market”.

In general I enjoy learning a bit about various foreign languages but I never had a desire to learn French language and when asked why I always answered that I know russian language already. But with the time I saw many more common things between France and russia than their language policy. This year of 1939 (will it end already?) brought even more examples of russia behaving like France and the French Empire(s) of old. Which makes me wonder if it is a certain type of country and what makes it such.

To me it looks the root of all problems is that both countries grew too large in territory, incorporating different nations in the process and relying too much on the central power (come to think about it, Temporarily Occupied West Taiwan comes to mind as well). The only way they could keep it going was to create “single nation”, by means of the cultural or physical genocide if required, and stealing the history while at it.

Below I’ll try to group things that are similar in the both countries by category.


Both countries originated as the outskirts of some larger country that were overrun by the invaders. As the result they ended up as something semi-fictional: why do you think territory formerly known as Gallia (and proud of Galls) is called after some Bavarians (and IIRC it even had a war with them over the name, so one ended as France and another one as Franconia)? Similarly why a country in a place originally inhabited by Finno-Ugric people, where only the nobility was of Slavic origin (with their blood heavily diluted by Mongols) would boast their completely Slavic lineage (forgetting about all those Finno-Ugric, Turkic and Caucasian nations living on the majority of its territory)? And of course both countries claimed the title of the One True Heir of Roman Empire. Let’s skip most of the Medieval history, remarking only such details as St. Bartholomew’s Day massacre and the genocide of Novgorod Republic, and move to the more modern days. The French Revolution (the first and most famous one)—and the revolutionary terror of course—set the standard of how to do such things (which russia copied later). It’s worth noting that for the majority of XXth century France and russia remained friends: first the Entente, after WWII France willingly returned to the Soviet Union people who fled russia even before USSR was created (or it was russian territory at all), then (after France decided to leave NATO) Soviet-French friendship prospered (to the point possible by the foundational principles of Soviet Union), even now the French president tries hard to be russian advocate (the same can be said about Germany but despite some common things the countries were not similar throughout the majority of the history).

Country structure.

I notice that both countries occupy a large territory but despite that a significant part of the population lives in the metropolitan area of the capital: about one fifth for France, and one seventh for russia (for comparison, for Germany, Ukraine or Kazakhstan those numbers are below one tenth). Additionally the capitals in both countries are considered to be the only place to live (in case of russia their former capital is regarded in the same way too) and locals (whose ancestors probably lived far away from that capital) sneeze down at all those newcomers who don’t live in the capital and don’t speak the capital dialect either. Then there’s the whole question of the empire…

The main difference here is that russia was never good at maintaining overseas colonies (Fort Ross and Alaska were sold and the pirate nest of Septinsular Republic could not be hold) so it resorted to occupying and controlling neighbouring countries. For example, during Soviet times Mongolia was controlled by the Irkutsk division of The Party. Maybe that’s why they always wanted more oceanic ports.

France, on the other hand, had its colonies all around the world and keeps some of them under the name of overseas departments. For more exquisite things there’s Andorra. And of course there are “military advisors” in various African countries (former French colonies by coincidence). Now that France does not want or can’t maintain its presence, those are withdrawn and are usually replaced by the troops of the infamous russian military company (hopefully it’ll find its end at Bakhmut soon).

And finally, if you think that russia is the only country that tried to create puppet republics in Europe in order to annex them later you’d be wrong. When in 1945 several countries agreed to occupy parts of Germany in order to make it a decent civilised country, USSR almost immediately made its zone of responsibility into a socialistic puppet state that had been the best friends to its end and even after that (see Angela Merkel). France, meanwhile, tried to pull a similar trick with Saarland. They tried to convert Saar Protectorate into a puppet People’s Republic of Saarland but (since they could not falsify elections) the result was unfavourable for them and in 1957 Saarland joined Germany for good. Considering how Saarland plays about the same role as Donetsk and Luhansk regions in Ukraine it’s hard not to see parallels to russia’s actions in 2014 and 2018.

Language and cultural policies.

Here I’m not going to talk about the influence of the for-export version of the country culture (writers, composers, ballet and so on) on other nations but rather what they did inside their own territory.

I observe the same approach: cultural genocide and forcing the One True Language. russia did that to many of its colonised nations, see Ems decree as one of such example (I’ve been there recently BTW and spat and the bust of Alexander II installed in the local park). Nobody talks about France in this aspect but it did rather well to eliminate Occitan and Basque languages from its territory (and if you think what Basques have to do with it—learn about the history of Gascony fist). Similarly it forced French as the first language in the schools—unlike, say, British Empire where people could learn their native language first and English later. As the result many people from “former” French colonies speak perfect French while people from British Commonwealth have all kinds of accents and dialects.

Of course (in both countries) you have language chauvinism extended past beyond that when they refuse to learn and speak the language of any other country (one philologist who emigrated from USSR once said that the purpose of studying foreign languages there was mostly to incite hate to that language). And now both countries have laws for protecting their language purity against foreign influences too.

Another aspect of such language chauvinism is demanding to support their language on the state level (you might’ve heard about the situation in Canada where exists essentially a language police from a certain province that checks that all inscriptions in this predominantly English-speaking country have translations in French next to it in the same size; and of course even the most liberal russians demand the same from any country they take residence in).

And the last thing about the language is its writing complexity. By that I mean the fact that there’s not a very strong connection between the way the words are written and spoken (to the point where sometimes you need to know the context in order to pronounce the word properly). And reforms are often met with hard resistance (see France, 2016 or russia, 1918) probably because they cherish the elite status of the language and do not want to make it more available to the common folk. There are other languages with similar characteristics, but in case of English it was essentially arbitrarily picked from various dialects (of several languages) for printing convenience (i.e. it was not something forced by a government) and people curse William Caxton to this day; in case of Chinese it’s used to hide the fact that different parts of the country speak different languages so if they don’t write in the same way they would be completely disconnected (which goes against the imperial narrative of a single Han nation); in case of Japanese it’s mostly a consequence of adapting Chinese writing system for their language that is built on very different principles (it has a completely different grammar and mostly different lexis even if it has a good share of Chinese loanwords); and Hebrew as a Semitic language has little regard for vowels so they’re omitted where possible and usually indicated in full only in the texts for children and the religious texts. In either case it’s not done just to make scribes feel more important.

I could also mention how they all like to overlook the fact that a good deal of their famous people and inventions have a different origin (starting with that guy from freshly conquered Italian territory by the name of Napoleone Buonaparte or the famous russian explorer from Danemark Vitus Bering) but IMO that’s pretty normal when you’re building a unified empire based on a single culture forced onto everybody as the mean of unification. A certain country in the East comes to mind as well with its Uyghur re-education camps.

And when I talk about cultural genocide I mean not only forcing the master language and culture onto the colonised nations but also destroying (or at least hiding) the remnants of native civilisation so that the nations won’t get wrong ideas. In Soviet Union the representatives of state security always accompanied archaeological expeditions and denied publishing the findings if they were contradicting the state narratives (for example, the real age of Trypillia or Carpathian settlements as they undermined the narrative about russians being the oldest nation). Similarly I read a story over two decades ago that in French Indochina the explorers discovered an impressive city or temple complex (was it Angkor Wat?) that was kept in obscurity so it would not inspire any national liberation movements and it was effectively rediscovered in 1960s or so.


Here’s a quote from Mark Twain:

Yet even France rose at last — and would have retired to its warren again quite contented with a cuff and a bonbon if the foolish King had offered them, but it was not his style to do the needful thing at the needful time, so the chance went by. Then the nation cast its rabbit skin and put on its other national garment, the tiger skin; being closely pressed by Europe in arms, it went a step further and asserted its manhood, and was doubtless surprised to find how much it had of it. Napoleon, the great foreigner, brought the people’s soldiership up to the last summit of perfection; and when he got ready he dressed the nation in their rabbit skins again and put his foot on their necks, and they glorified him for it. Napoleon III accommodated them in the same way, to their vast satisfaction.

The same largely applies to russians as well: they never had real uprisings against the sovereign, only protests addressed to him (the only real uprisings were started by other nations, like Ukrainians or Bashkorts) but when they were allowed to display their repressed feelings we got East Prussia in 1945 or Yahidne, Mariupol’ or Izyum this year. And if you look at russians they’re meekly going to war if they can’t avoid it and their relatives blame Ukraine for their subsequent deaths (instead of the führer who sent them there to die).

And if you look at what historical figures russians worship and despise, they mostly worship tyrants who oppressed them and wasted them in countless wars and despise rulers who tried to have more peaceful and liberal politics (because it was usually a sign of them being weak). I don’t know much about the French but considering the Penguin Island novel I expect about the same. At least nowadays they have strikes to vent off their negative feelings…


As I mentioned in the beginning, I suspect there’s a reason why both countries have acted similarly throughout the ages. Maybe it was the absolute power of the monarch and the abundance of initial territories, maybe it was something else. For example, British Empire grew up a lot thanks to the private initiative (names like Cecil Rhodes or East India Company come to mind immediately); USA (with such “unincorporated territories” as Puerto Rico or American Samoa) seem to retain its satellites a lot thanks to the fact that it’s better to be part of USA and get involved in its economic processes—and for the rest there’s U.S. Navy (which reminds me a lot of Roman Empire). With russia it was the opposite—the conquered countries tried hard to get independent from it (all of the Baltic states immediately and Ukraine, even if it took it more years after 1991 to realize why). French colonies are known to have been treated some of the worst (not as bad as Belgian king’s and later simply Belgian Congo though)—Haiti is the poorest country of Americas and I urge you to compare how many of the world poorest countries are former French colonies.

So it is no wonder that the countries with similar mindset would keep doing business together as long as the public opinion permits. At least France seems to improve albeit slowly while I see only two realistic ways for russia—balkanisation or turning into another North Korea. In either case maybe the future historians will explain what was wrong with both countries and why they went different ways eventually.

NihAV: towards RealMedia encoding support

March 10th, 2023

Since I have nothing better to do with my life, I’ve decided to add a rudimentary support for encoding into RealMedia. I’ve written a somewhat working RMVB muxer (it lacks logical stream support that is used to describe the streaming capabilities, it also has some quirks in audio and video support but it seems to produce something that other players understand) and now I’ve made a Cook audio encoder as well.

Somebody who knows me knows that I fail spectacularly at writing non-trivial lossy audio encoders but luckily here we have a format which even I can’t botch much. It is based on parametric bit-allocation derived from band energies. So all it takes is to perform slightly modified MDCT, calculate band energies, convert them to scale factors, perform bit allocation based on them, pack band contents depending on band categories and adjust the categories until all bands fit the frame. All of these steps are well-defined (including the order in which bands should be adjusted) so making it all work is rather trivial. But what about determining the frame size and coupling mode?

As it turns out, RealMedia supports only certain codec profiles (or “flavors” in its terminology), so Cook has about 32 different flavours defined for different combinations of sample rates, number of channels and bitrates. And each flavour has an internally bitrate parameters (frame size and which coupling parameters to use) for each channel pair so you just pick a fitting profile and go on with it. In theory it’s possible to add a custom profile but it’s not worth the hassle IMO.

And now here are some fun facts about it. Apparently there are three internal revisions of the codec: the original version for RealMedia G2, version 2 for RealMedia 8 and multichannel encoder (introduced in RealMedia 10, when they’ve switched to AAC already). Version 2 is the one supporting joint-stereo coding. The codec is based on G.722.1 (the predecessor of CELT even if Xiph folks keep denying that) but, because Cook frames are 256-1024 samples instead of fixed 320-sample frames, they’ve introduced gains to adjust better for volume changes inside the frame (but I haven’t bothered implementing that part). That is probably the biggest principal change in the format (not counting the different frame sizes and joint stereo support in the version 2). And finally I should probably mention that there are some flavours with the same bitrate that differ by the frequency range and where the joint stereo part starts (some of those are called “high response music” whatever that means).

Time to move to the video encoder…

FFhistory: the most annoying format

March 3rd, 2023

Looks like the series was misunderstood by the public, especially by those who did not read the prologue and were disappointed by the conclusion. Oh well, I can still post random bits of FFhistory with some inconvenient truths even if nobody is going to read them.

There are many codecs and container formats that are annoying to support: “industrial” formats like MXF have their own Internet of documentation (i.e. lots of various documents referring to other documents, most of them are paywalled as well), other formats suffer from being too flexible or too bloated that it’s next to impossible to implement support for all possible features (e.g. JPEG-2000 or H.264 scalable and multi-view extensions). There are formats that are abused to death (MPEG-TS and MP3 come to mind), there are formats that are annoying to reverse engineer and there’s too little interest going there (you would not believe how much time it took to support Windows Media 3, from basic decoder to the interlaced mode support, something tells me we won’t see completed Bink 2 decoder any time soon either), there are formats that require writing an emulator for some system (like CGDI codec that recorded GDI commands), but there’s yet another candidate that I consider the most annoying one in the whole FFhistory since it annoyed the project in many different ways.
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366th day of February 24

February 24th, 2023

So it’s been a calendar year since February 24 started along with year 1939 (the dates since February 2020 got really messed up). Let’s see how it went.

russia decided to mimic Nazi Germany and started the war “against NATO threat” by using its own Gleiwitz incident (which they first executed a couple days before the full-scale invasion and then back-pedalling—they can’t do anything right). They committed every possible war crime, if they have missed some that’s only because they either overlooked it or didn’t know how to do it. The occupied territories suffered from the genocide (direct and cultural), not occupied territories suffer from their terrorist strikes (mostly on civilian infrastructure). And all of this happens because of some deranged führer in the bunker with a resentment about russia losing the Cold War. And while many world leaders try their hardest to not see the parallels, Hungary was eager to become its ally (it’s the only Axis country country where a 1944 coup changed pro-Nazi government with even more pro-Nazi government after all).

In either case, in the first days of February many believed russian propaganda about its power yet it turned out to be not a colossus with feet of clay but rather a colossus made from shit and sticks on brick legs. Their plan was to bribe various officials, make some precise strikes and during the confusion seize the control of various crucial positions and use them for fast occupation of Ukraine. The first step had some limited success since while certain people are willing take bribes, not all of them are eager to work for it or use those received money for further bribes (it is said that medvedchuk received a billion dollars for that purpose and he used them for his own benefit). The second step also had issues since russian weaponry was not that precise as they hoped. The third step largely failed since Ukrainian authorities were prepared so people acted on their own even without the communications to the centre so e.g. in my home city the head of local state security division acted by russian orders and yet he failed to cause enough confusion and seize control, so the city did not fall to russia forces. Sadly there were enough traitors in Kherson and some parts of Kharkiv region to surrender local towns to russian forces.

Yet the main thing that allowed russians to occupy large portions of Ukraine were their reserves of Soviet weapons and munition plus modernisations of them. Neither of their newer wunderwaffen have proved to be any good (does anybody remember how their deployed some laser weapons for shooting down drones in May? has anybody seen seen their new Armata tanks in action? what about independently verified proofs of their Su-57 usage?). Initially they could use the usual World War II military tactics but then Ukrainian air defence (which they claimed to have fully obliterated in the first days) brought down enough of their planes and Ukrainian soldiers with Javelins and NLAWs destroyed enough of their tanks so they had to resort to the World War I tactics (shelling by artillery and then sending their hordes in) but nowadays with HIMARS “cottoning” their front line munition depots and the overall depleting of the reserves (they can’t produce enough and have to hope that DPRK and China will send more) nowadays it’s mostly sending their poorly-equipped hordes plus terrorist attacks on the civilian infrastructure by various missiles they have (who cares that a good deal of them malfunctions or explodes near the launch site?) and Iranian drones.

And there’s one thing they’ve threatened the world with—nuclear weapons. From what I heard, their de-escalation strategy includes escalation by exploding a small nuke somewhere to demonstrate that they have them and they won’t hesitate to use them. So far nothing like that has happened, I heard several reasons why: USA threatening to obliterate russian forces on Ukrainian territory by conventional means, russian allies (China and India) not willing to accept that either (because everybody will lose then), or even that they tried it but either it was sabotaged on some lower level or their devices simply failed to work. In either case, in the first days of the 24th of February it was easy to believe in their nuclear threats, nowadays nobody takes them seriously. And even them taking nuclear power plants as hostages is now seen mostly just as another war crime they’ll have to pay for later (and somewhat tricky place to liberate).

War is a very horrible thing but it also shows true colours of the people and tests your claims against reality. russia has boasted its army as the second most powerful in the world and its weapons as unparalleled. When they’ve finally decided to continue the 2014 war it turned out that their tanks lose to Ukrainian tractors, none of their advertised weapons are that good (and can’t work without Western chips) and “we’ll take Kyiv in three days and whole Ukraine in a week” turned into “we need to fight for preserving the integrity of russia”. It also turned out that making Hungary a member of anything was a big mistake and that the most of European politicians lack spine. Ukrainians turned out to be the nation that unites against the common threat and demonstrates unexpected strength while russians turned out to be non-thinking thieves and liars deeply infected by imperialistic chauvinism (it’s hard to hide behind the great artists of the past, most of whom are not of russian origin anyway, when all your soldiers do is loot, rape and shitting and their relatives are mostly fighting over compensations for their relatives killed in action).

Meanwhile though they’re seemingly trying to turn it into a religion like building communism before (and with the same rhetoric)—it will be all good sometime in the future when we achieve the goal (but we’re not going to disclose it), so you should stand up to the difficulties created by our self-imposed isolation (the country is doing great by the way and anybody claiming otherwise will be prosecuted as a heretic) and be ready to lay down your life for the country in Afghani… err Syr… err Ukraine.

I hope this day will end soon, and russia will follow the suit. Hopefully then the enslaved minor nations of russia will have a chance to build their own states (now they’re mostly sent to die in Ukraine which russians approve with the notion “why should we go to die when those exist”) and the carbuncle of this world won’t be able to threaten other countries ever again (also maybe China will get a lesson from this but I shan’t bet on it).

A failed attempts on writing Duck TrueMotion S encoder

February 23rd, 2023

So, my attempt to write a semi-decent TrueMotion 1 encoder has failed (mostly because I’m too annoyed to continue it). Here I’ll describe how the codec works and what I’ve implemented.

In essence, Horizons Technology PVEZ is a rather simple delta-compression based codec that codes RGB15 (or ARGB20) and RGB24 using prediction from three neighbours and Tunstall codes (I’m aware only of one other codec, CRI P256, that employs it). For convenience there are three possible fixed sets of deltas and three fixed codebooks as well. Videos from (3DO version IIRC) Star Control II: The Ur-Quan Masters used custom codebooks (data for cutscenes was stored in several files and one of them was the codebook specification), and later TM2X allowed using per-frame custom codebooks and deltas but nobody remembers it. The second revision of the codec (do not confuse it with TrueMotion 2 though) introduced inter frames where some of the 2×4 blocks could be marked as skipped.

Initially I had no idea on how to do it properly so I tried brute forcing it by creating a search tree limited to maximum of 256 nodes at each level but as you can expect it took about a minute to encode two frames in VGA resolution. Thus I decided to look at the codebook closer and eventually found out that it’s a prefix one (i.e. for each chain of codes there’s its non-empty prefix in the codebook as well) so I can use greedy approach by simply accumulating codes in a sequence and writing codebook entry ID when the sequence can’t be extended further (or when adding the next code forms a sequence not in the codebook). Which leaves the question of deltas.

There are two kinds of deltas there, both occurring in pairs: C-deltas that update red and blue components (depending on coding parameters there may be 1-4 deltas per 2×4 block of pixels) and Y-deltas that update all pixel components (and for all pixels as well). The problem here was to keep deltas in order so they produce sane pixel values (i.e. without wraparounds) and that’s where I failed. I used the same approach as the decoders and grouped delta pairs into single value. The problem is that I could not keep the result value from causing overflows even if I tried all possible deltas and did not check C-deltas result (as Y-deltas are added immediately after that). And I also made a mistake of using pixel value with its components stored separately (the deltas apparently exploit carries and subtracting with borrows for higher components). I suppose I’d have better luck if I use 32-bit pixel value (converting it to bytes for checking the differences and such) and if I use individual deltas and probably with a trellis search for 4-8 deltas to make sure the result does not deviate much from the original pixel values…—but I was annoyed enough at this point so I simply gave up. And that is before getting to the stage when I have to figure out how to select delta values set (probably just calculate the deltas for the whole frame and see what set fits there the best), what codebook to pick and how to control bitrate (by zeroing small deltas?).

Oh well, I’m sure I’ll find something else to work at.

P.S. I’ve also tried to look at the reference encoder but CODUCK.DLL was not merely a horrible pun but an obfuscated (you were supposed to pay for the encoder and use serial numbers and such after all) 16-bit code that made Ghidra decompiler commit suicide so I gave up on it as well.

P.P.S. I might return to it one day but it seems unlikely as this codec is not that interesting or useful for me.

Indeo 3 encoder: done

February 16th, 2023

After fixing some bugs I think my encoder requires no further improvement (there are still things left out there to improve but they are not necessary). The only annoying problem is that decoding some videos with the original VfW binary gives artefacts. Looks like this happens because of its peculiar way to generate and then handle codebooks: corrector pairs and quads are stored as single 32-bit word and its top bit is also used to signal if it’s a dyad or a quad. And looks like for some values (I suspect that for large negative ones) the system does not work so great so while e.g. XAnim module does what is expected, here it mistakes a result for another corrector type and decodes the following bytestream in a wrong way. Of course I’m not going to deal with that annoyance and I doubt anybody will care.

Also I’ve pruned one stupid bug from my MS Video 1 encoder so it should be done as well. The third one, Cinepak, is in laughable state (well, it encodes data but it does not do that correctly let alone effectively); hopefully I’ll work on it later.

For now, as I see no interesting formats to support (suggestions are always welcome BTW), I’ll keep writing toy encoders that nobody will use (and hopefully return to improving Cinepak encoder eventually).

Indeo 3, the MP3 of video codecs

February 14th, 2023

I know that MPEG-4 ASP is a better-known candidate for this role, but Indeo 3 is a strong contender too.

Back in the day it was ubiquitous, patented, and as I re-implemented a decoder for it I discovered another fun similarity with MP3: checksums.

Each Indeo 3 frame has a checksum value embedded in it, calculated as XOR of all pairs of pixels. I had an intent to use it to validate the decoder output but after playing a bit I’ve given up. Some files agree on checksums, others disagree while the output from the reference decoder is exactly the same, in yet another files checksums are correct but byte-swapped and one file has only zeroes for checksums. This is exactly like MP3, and like there Indeo 3 decoders ignore that field.

Also I’ve encountered other fun quirks. For example, one Indeo file is 160×120 but its frame header claims it’s 160×240 (but you still have to decode it as 160×120). You’d think it’s the rule but I know some VMD files from Urban Runner game where the first or last frame are double the size. Another file errors out on the first frame because of the inappropriate opcode encountered (essentially “skip to the line 2” right after “skip to the line 2”) but it turns out that VfW decoder does not check that case and simply uses that opcode as a codebook index.

At least my new decoder should be good enough to iron out the obvious bugs from the encoder and after that I shall forget about that codec again for a long time.

Revisiting MSVideo1 encoder

February 8th, 2023

Recently somebody asked me a question about my MS Video 1 encoder (not the one in NihAV though) and I’ve decided to look if my current encoder can be improved, so I took Ghidra and went to read the binary specification.

Essentially it did what I expected: it understands quality only, for which it calculates thresholds for skip and fill blocks to be used immediately, clustering is done in the usual K-means way and the only curious trick is that it used luminance for that.

So I decided to use that idea for improving my own encoder. I ditched the generic median cut in favour of specially crafted clustering in two groups (I select the largest cluster axis—be it luma, red, green or blue—split 4 or 16 pixels into two groups by being above average or not and calculate the average of those two groups). This made encoding about two times faster. I’ve also fixed a bug with 8-colour blocks so now it encodes data properly (previously it would result in a distorted block). And of course I’ve finally made quality affect encoding process (also by generating thresholds, but with a different formula—unlike the original my encoder uses no floating-point maths anywhere).

Also I’ve added palette mode support. The idea is simple: internally I operate on pixel quads (red, green, blue, luma) so for palette mode I just need to replace an actual pixel value with the index of the most similar palette entry. For that task I reused one of the approaches from my palettiser (it should be faster than iterating over the whole palette every time). Of course the proper way would be to map colour first to have the proper distortion calculated (because the first suitable colour may be far from perfect) but I decided not to pursue this task further, even if it results in some badly-coded features sometimes. It’s still not a serious encoder after all.

Now this member of the early 90s video codecs ruling triumvirate should be good enough. Cinepak encoder is still rather primitive so I’ll have to re-check it. Indeo 3 encoder seems to produce buggy output on complex high-motion scenes (I suspect it’s related to the number of motion vectors exceeding the limit) but it will have to wait until I rewrite the decoder. And then hopefully more interesting experiments will happen.

Indeo 3 encoder: done

February 6th, 2023

I’ve done what I wanted with the encoder, it seems to work and so I declare it to be finished. It can encode videos that other decoders can decode, it has some adjustable options and even a semblance of rate control.

Of course I’ll return to it if I ever use it and find some bugs but for now I’ll move to other things. For instance, Indeo 3 decoder needs to be rewritten now that I understand the codec better. Also I have some ideas for improving MS Video 1 encoder. And there’s TrueMotion 1 that I wanted to take a stab at. And there are some non-encoder things as well.

There’s a lot of stuff to keep me occupied (provided that I actually get myself occupied with it in the first place).

Indeo 3: codebooks

February 4th, 2023

As you probably remember, Indeo 3 has 21 codebook. In theory you’d expect them to correspond to coarser quantisers, in reality it’s not that easy. For starters, codebooks 8-15 trigger requantisation of the reference, i.e. in intra mode the top line used for prediction is replaced with coarser values. Yes, it really modifies previously decoded data. And for inter mode it does the same on the previous frame for the first line of the reference block. I’ve decided to enable codebooks 8-15 only for intra mode and not even attempt to use codebooks 16-20 at all. So, what can I achieve with those?

I’ve started experimenting with rate control so I encoded various kinds of samples (albeit small and short) and here are the results:

  • codebook set 0-7 and 8-15 give about the same frame sizes (i.e. it does not matter if you take e.g. codebook 2 or 10);
  • an average intra frame size decreases with codebook number but with inter frames some codebooks result in larger frames (sometimes codebook 2 resulted in larger P-frames than with any other codebook but codebook 6; in other case codebook 5 gave the smallest frames);
  • not forcing a codebook noticeably improves compression of P-frames compared to always using codebook 0 and has almost no effect on I-frames;
  • I-frame to P-frame size ratio varies greatly on the content: for realistic content with a lot of changes it is about 1:1, for videos with low motion and changes it can get to 1:3 or even more.

Maybe the compression ratio can be improved by fiddling with the (completely arbitrary) thresholds I use for some decisions (e.g. if the cell should be coded or marked as skipped). I’ve made them options so all zero people who want to play with it should be able to do that.

So far I think I’ll make rate control in a simple manner: all frames will be treated as potentially of equal size, codebook number will be adjusted depending on the expected and obtained frame sizes and if it overshoots I’ll try to re-encode it with a neighbouring codebook (as this may change frame size drastically).

I’ll write about the results when I have them.