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Comment by zamadatix | Hacker News Reader

I think you're eating into quality loss if you're getting 33%-25% size, most every benchmark puts it at about 50%-60% size for equal quality to h264.

Pirating scene hasn't been using av1 at all because the bitstream hadn't been stabilized (an encode you made last month probably won't work on versions from this month) and, as a result of work still being done on the bitstream, no encoding hardware or software optimizations are available making it on the order of 3 magnitudes slower than existing options. Towards the start of 2019 you should start to see more hardware support pop up though.

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> I think you're eating into quality loss if you're getting 33%-25% size, most every benchmark puts it at about 50%-60% size for equal quality to h264.

Do the benchmarks include animation? Perhaps flat surfaces like one sees in anime compress a lot better than average in x265?

Often, oddly enough. Anime groups in particular are obsessive about bitdepth, quality, and file size to the point it's not hard to find comparisons of lossless compression in newer codecs.

On the development and academic benchmarking side any comparison worth it's salt should have more than 5 different categories of video style. The paper linked in the article based their results on 20 different sequences, 3 or 4 of which looked to be animated.

One of the main reasons for the anime groups obsessing about the comparisons is that it's a lot easier to measure final quality on anime, with it's clearly-delineated artwork, instant transitions, and (comparatively) simple backgrounds.

I would also have guessed that many approaches for video/image compression like assuming lots of nice smooth gradients without hard edges, and so flat shaded but detailed drawn things might fare badly.

Hard edges are difficult for the DCT/DST used in most video codecs. A wavelet-based codec would most likely be better suited.

However, all modern codecs that I know of have directional intra prediction, which should be pretty effective in anime. Basically, what it does is that the decoder is able to follow lines with a variety of angles.

There are other things that help compression in anime: static frames, large flat areas, lack of film grain in computer drawn animation.

I would guess so, but looking at Nyaa atleast, there seem to be very little content encoded in HEVC compared to h264, which seems weird given how the 'anime scene' saw adoption of x264 10bit which is not even hardware accelerated.

With the supposed savings of HEVC versus h264, and the rather widespread HEVC hardware support in devices, I would have guessed that they would have embraced it at a larger scale by now.

Will be interesting to see what happens with AV1.

Thanks for correcting me on quality. I'm getting confused because often the H.265 releases have low bitrate 2.0 audio compared to high quality 5.1 in the bigger file releases. They're optimizing for size, not fidelity. (I'm blessed with a tin ear and tin eye.)

Does AV1 do subtitles? The reason most pirated videos use MKV instead of mp4 is because it does subtitles easily.

Subtitles have (almost) nothing to do with the video codec. AVI, MKV, MP4, etc. are container formats that are used to multiplex multiple streams of media (video, audio, subtitles) into a single stream/file. In contrast, AV1, x264, HEVC, etc. are video codecs stored inside a multiplex. Perhaps confusingly, he MPEG LA (which standardised x264 and HEVC) is also responsible for the MP4 container.

> the MPEG LA (which standardised x264 and HEVC) is also responsible for the MP4 container.

The MPEG LA is just a licensing administrator formed by companies owning MPEG patents, they didn't standardize anything nor are they responsible for MP4 container.

The standards working group is MPEG, and according to Wikipedia the two are not affiliated ( https://en.wikipedia.org/wiki/MPEG_LA ).

You're absolutely right, sorry for getting this wrong. My mistake was to assume that the body that sells you the license is also responsible for the standardisation, but as you described, this is not true.

This is correct. The reason that the scene uses MKV is because it has better support for multiple audio, video, and subtitle streams and handles streaming as well as "streaming" from RAR compressed and split archive files.

x264 is an AVC encoding software by VideoLAN.

Damn. How embarrassing! Two major factual mistakes in two sentences while nitpicking at someone else's mistakes on the internet. I of course meant to write h264 ;-)

Unless you encode the subtitles directly on the video stream, this is a container solution, the previous Google codecs (vp8/vp9) uses webm, which in turn is based upon mkv, so I would assume AV1 supports subtitles as easily if it uses webm as well.

AV1 is a video format, it has absolutely nothing to do with subtitles. AV1 videos are usually inside MKVs anyway.

AV1 is most expected to be used inside webm, though mkv can also package it.

Furthermore webm/Matroska AV1 mapping isn't finalized, same situation with MP4.

webm is just a subset of MKV. They limited the codecs/options so that it would be easier have complete webm compatibility. (Whereas "full" MKV compatibility doesn't really make sense because it has ~infinite codecs you would need to support)

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