Kostya's Boring Codec World

In the previous post I’ve mentioned that one of the levels contain an unfinished witch puzzle probably based on Match Two that also contains various photos of the (presumably team and their families (about a dozen of them actually). I also wanted to tell a bit more about it and since I’m working on boring parts of NihAV and it will take a while, why not tell the story now?
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I guess everybody else has reacted on his post about MPEG crisis so I can do that as well. So, $postname—most people just don’t understand his outlook. If you interpret his words from his point of view it’s clear he’s right for most of the things.
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Sweden has a lot of local bus routes and every region (or län) has its own most popular bus route:

• for Stockholm and Örebro län it’s “Ej i trafik” (something like “not participating in public transit service”, “trafik” in Swedish often means both [car] traffic and public transport service);
• for Södermanland it’s “Är ej i trafik” (“Is not in service”);
• in Östergötland it’s “Tyvärr, ej i tjänst” (“Sorry, not in service”).

The joke is that while there are many numbered bus routes (hundreds in Stockholm län), the regulations make bus drivers rest after completing a route so quite often a bus arrives to the end station, unloads all passengers, changes its route number to the one above and goes away; then, obviously, another bus (or the same one after the driver has rested) comes to pick passengers. Since I almost never travel by bus in Germany (we have trams here after all), most of my bus trips happened in Ukraine and Sweden—and those countries differ in approach to drivers indeed.

Another interesting thing is the variety of buses: in Stockholm län you have buses going on trunk lines—quite often those are articulated buses and they’re always painted blue—and ordinary buses (always red); some buses are double-deckers, like on bus route 676 (Stockholm-Norrtälje) and some coaches are double-deckers too (I still fondly remember travelling on top floor of one from Luleå to Sundsvall—no fond memories about Ukrainian bus trips though). And in Norrland they still have skvaders (aka buses with additional cargo departments). Also buses in Stockholm län quite often have USB chargers for every seat and even WiFi—everything for passenger comfort.

It’s quite interesting that some bus routes are operated by two buses: for example, if I want to get from Bromma to Portugal (a place on Adelsö island near Stockholm) I’d take bus 312 which goes to Sjöangen, there I’d step out, get into new bus 312 waiting there while the previous bus goes to the rest. Also it’d travel on a ferry which I also like for some reason.

So there’s something interesting about Swedish buses after all. But railways are still much better (more comfort, higher speeds, less problems from car traffic etc etc) and definitely more awesome (I’ve witnessed rail bus pushing a fallen fir from the tracks less than a week ago—try finding an ordinary bus doing that). But it’s still nice to know that Sweden has good things beside people, trains, food, drinks and nature.

P.S. This seems to have gone a bit further than just describing how popular bus routes differ in various Swedish regions. Hopefully my upcoming NowABitClearerVideo post would go the same way.

So, it has come to this. How does bitstream reading might work. Here I’ll try to present several ways to read bits and variable-length codes.
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Unfortunately I was not able to visit Sweden this Easter season — it was merely 6 days in Stockholm. Yet I’ve managed to try one of the reasons I come to Sweden — påskmust. For those who don’t know what it is — shame on you! For the rest here’s my incomplete and biased guide.

Some old julmust photo. Left to right: Nygårda, Eldorado (Hemköp), ICA, Coop, Wasa, Apotekarnes. Lying is the Lidl julmust.

Some old påskmust photo (probably from 2011). Left to right: Mora, Nygårda, Apotekarnes, ICA, probably Lidl, Eldorado (Hemköp), Coop. Lying are ordinary and special Wasa påskmust. Front bottle is from Guttsta Källa.

This year catch. Back row: Wasa special, ICA, Apotekarnes. Front row: Nyckelbryggeri, Zeunerts, Grebbestads bryggeri, Mora, Nygarda, Danish abomination.

So one can divide julmust/påskmust into four categories:

1. Widespread must from large producers or supermarket chains. That includes Apotekarnes, Nygårda and must made for Coop, Hemköp, ICA and Lidl. But not for Netto, see category four for that.
2. Must from Norrland breweries. Nyckelbryggeri, Wasa and Zeunerts are most known. And maybe Mora.
3. Must from non-Norrland breweries. Guttsta Källa, Grebbestads, Hammars (I have to try that one yet).
4. Abominations from people who don’t know how to make proper must. That includes Bjäre must from C*ca-cola, Harboe must from Netto (made in Denmark) and whatever Danish stuff I tried this year. Concentrate for making must at home probably belongs here too.

The taste is hard to describe but it’s really nice and makes me think of liquid bread for some reason. The main difference is Norrland/non-Norrland must. Julmust and påskmust in Norrland style is less sweet and usually has a hint of coffee. Must from large producers is usually sweeter than the rest. Wasa bryggeri produces two kinds of must — special, available only in Norrland and made after Norrland traditions, and ordinary, available in Svealand and with taste closer to the more widespread varieties.

Danish must is either bland or plainly wrong. The one I tried this year is not actually bad, it’s just completely wrong — it contains e.g. raspberry juice and cola extract. If I drink påskmust I want to be påskmust, not a weird mix of Pommac and Trocadero that probably has only water and sugar in common with the other påskmust recipes.

And now is the actual guide. If you want to try it then start with widespread påskmust you can find in any Swedish supermarket, it should be fine. If you like it that way then be happy, if you want something less sweet then try smaller breweries and especially Norrland ones (it’s hard to find it outside Norrland though). And if you are not in season then you can still try something similar — bordsdricka from Wasa or sommarmust from Nyckelbryggeri should be available (in Norrland).

P.S. You can extrapolate it to Trocadero as well except there’s less variation in taste and there’s no supermarket or Danish version.

As you might remember, alternative history genre is modelling events based on real history but with something gone differently. Here’s what could’ve happened with H.265 but didn’t.

So, finally there’s a new standard released — ITU H.265. It promises twice as low bitrate for the same picture quality in H.264. Yet people do not care much about it since industry leaders offer their solutions:

China introduces their new standard for video coding — Hybrid Enhanced Video Standard or HEVS for short. It features quadtree representation of coding blocks, more than thirty spatial prediction modes, block transforms from 4×4 to 32×32 and has one unique feature — motion vectors that implicitly take mirror references from reference picture lists. This standard is nominated for main video coding standard on CUVRD (China ultraviolet ray disc) but gains little popularity outside China.

On2 makes a new codec named VP9 that has no open specifications. After tedious reverse engineering it turns out to employ coding scheme from VP5 times, spatial and motion prediction from H.265 with slightly altered coefficients and overall coding scheme from H.265 drafts.

Re… buffering… alNetworks releases NGV at last (fourcc RV50). Again, after long studies of binary specification, it turns out to be based on H.265 drafts with some in-house improvements: using context-specific codebooks for elements coding, ?-pel motion compensation (which is implemented as motion vectors pretended to be ?-pel but in reality several different positions are handled by the same function). The codec goes very popular in China for some reason.

Sorenson releases SVQ7. It is based on old H.265 draft and employs ?- and ?-pel motion compensation. It has some additional features like watermarking and quickly becomes the codec of choice for QuickTime.

P.S. Good thing nothing like this has really happened.

An excerpt from a book that I have to refer sometimes (here’s the source, it really tells a lot about proper relationship. Ask a nearby German for a translation if you need it.

P.S. Next post will be about a codec technical description, I promise.

Italy is a good country (piecewise) — nice scenery, decent food (and pasta), nice architecture…
There’s but one thing that annoys me, I think you’ll be able to spot it on those two pictures.

Milan, a corner of via Vitruvio and via Benedetto Marcello.

Turin, largo Cassini.

I cannot say it for sure but I remember Ukrainian markets (right after closing time) being cleaner than that.

I’ve finally bought a DVD with an anime I wanted to watch. And it was awesome. Here are some screenshots.

P.S. I should probably visit Småland next summer.

More than two years ago I’ve posted what I considered should be high priority Libav projects. Let’s see what has been finished, what’s left and what should probably be added.

User tools

• Working avserver — fixed in the clean way (by removing it completely);
• Proper filter system. When I say “proper” I mean the one that allows dynamic reconfiguring, handles errors and works for arbitrary inputs and outputs — some claim it’s been fixed;
• libswscale replacement. The one that doesn’t sap sanity when you look at its code. Maybe with a nicer API too. And better pixel format support.

RealMedia support

• Improve RM demuxer or maybe rewrite it from scratch — there’s a demuxer reimplementation from scratch is in the works, hopefully it will succeed;
• Add proper support for multirate RM streams — hopefully will be handled;
• Add IVR format demuxer — noone cares;
• Add ClearVideo decoder (that’s the last codec in RM that we don’t support, hopefully not for long) — noone cares and I lost interest too.

Other Intel codecs support

• Improve Indeo4 decoder (it still has some features lacking) — B-frames support was added, transparency support is still not there;
• Improve Intel Audio Coder decoder — fixed too.

On2 codecs support

• On2 VP7 decoder (we still can implement it faster than certain Baidu rival releases its source code) — nothing to say except “many thanks, Peter!” and “Baidu, I’ve not expected anything else from you”(and indeed we got what we expected, i.e. total lack of support);
• On2 VP4 decoder;
• On2 AVC decoder (that stands for “Audio for Video Codec”) — done.

Micro$oft (screen) codecs support

• Add M$ Screen Codec 1 decoder;
• Add M$ Screen Codec 2 decoder;
• Add M$ Expression Encoder Screen Codec decoder;
• Add beta Windows Media Video 9 interlaced decoding — maybe it’s better left unfixed.
• Fix beta Windows Media Video 9 P-frames decoding — again, it’s unlikely to ever happen because there are not so many people who can RE intended behaviour and even less people who can RE libavcodec/vc1dec.c to put the fix there.

QuickTime codecs support

• Add Rottenfruit Intermediate Codec decoder;
• Add any other codec decoder — noone cares about Pixlet, noone cares enough to add QDesign Music 1 etc..

Other codecs

• Add GoToMeeting 2-4 decoder — GoToWebinary aka G2M4 is done, the rest is permanently stalled (and I’ve passed stalling duties to Diego);
• Add more screen codec decoders — someone asked for FIC Video and got it;
• Add more game format decoders (especially Discworld Noir BMV) — I should return to it;
• Add more audio (especially speech) codec decoders — Opus decoder is enough.

So, if the tast was moderately interesting it was done, fringe stuff was not taken, serious stuff was not taken either (most people I know agree that swscaler should be replaced yet noone wants to work on the replacement).

And what high priority projects for Libav do I see in the future? None really. Just none.