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Dav2d

jbkempf.com

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Re: Dav2d

#31

Post by mrbluecoat »

jordand wrote: post #5

'AV2 decoding is roughly five times more complex than AV1 decoding. In practice, that means software running on today’s hardware will struggle to decode AV2 in real time without careful, architecture-specific optimization' AV1 software decoding is already very intensive so AV2 decoding benchmarks are the next thing that would be really interesting (or mortifying) to see.

I came to post this as well. Until widespread, inexpensive hardware catches up to a 2018 codec, AV# will remain a niche ideal.

Re: Dav2d

#32

Post by cogman10 »

poly2it wrote: post #7

Sorry if this sounds naive, but does it make sense to write a codec library in C/ASM considering how well Rust is progressing, especially when, as the author puts it, AV2 decoding is roughly five times more complex than AV1 decoding ?

Encoder and decoder writers frequently need extremely fine grain control over SIMD instructions in order to get good performance.

The way they weave these instructions can be very hard to express with a high level language.

Further, there's a ton of work with arrays and importantly parts of arrays. They can, for example, need to extract every other element up to 1/2 the array. Unfortunately, rust has runtime array bounds checks which make writing that sort of code slower. The compiler can elade those checks, but usually only in simple cases.

The authors would be writing a bunch of unsafe rust to get the performance they want and rust makes that more painful on purpose.

I like rust, but C/ASM really is the right choice here. This is one of the few cases where rust's safety is a major detriment.

Re: Dav2d

#33

Post by WhrRTheBaboons »

latexr wrote: post #29

When AV1 was first announced, I got the impression the name was chosen partly as a pun/reference/homage to AVI, the classic but outdated format with used to be popular. Then when I saw Dav1d, OK, good way to continue the pun. But now with AV2 and Dav2d, that completely breaks. Are we eventually going to get AV3/Dav3d and AV4/Dav4d, which will read like Ave/Daved and Ava/Davad? Seems a bit awkward. Was the idea from t…

> experience Dav... Now in 3D!

Re: Dav2d

#34

Post by zamadatix »

Eldodi wrote: post #10
AndrewDucker wrote: post #6

Earlier quoted context omitted.

How does that prove anything? They're claiming that there are patents, but that doesn't mean there are.

Dolby is only the most recent case, Sisvel consorsium actually bills licences per device: Consumer Display Device: EUR 0.32 Consumer Non-Display Device: EUR 0.11 (source here: https://www.sisvel.com/licensing-programmes/audio-and-video-... )

Sisvel allows you to pay them if you believe their claims, they haven't actually taken anyone not paying to court yet to prove that. The only court cases for VP9/AV1 from Sisvel so far have been their patents being found invalid/irrelevant.

Dolby is somewhat more interesting in that rather than scare tactics, media hype, and attempting to form a pool about it they are actually taking a patent assertion claim to court.

Re: Dav2d

#36

Post by remix2000 »

> Make it fast on older desktop, by writing asm for SSSE3+ chips

I guess 5 years ago (around the time when Intel stopped making SSE-only chips) is technically "older", but I wouldn't prioritize avx2 when devices intended for consuming media definitely experience much less pressure to upgrade than workstations…

Re: Dav2d

#37

Post by muhbaasu »

poly2it wrote: post #7

Sorry if this sounds naive, but does it make sense to write a codec library in C/ASM considering how well Rust is progressing, especially when, as the author puts it, AV2 decoding is roughly five times more complex than AV1 decoding ?

The ffmpeg devs have said many times in public that they routinely get speedups of 10x or more over C code. I'm not a reputable source on this myself but I highly recommend looking into their channels, mails, or posts.

Re: Dav2d

#38

Post by jl6 »

latexr wrote: post #29

When AV1 was first announced, I got the impression the name was chosen partly as a pun/reference/homage to AVI, the classic but outdated format with used to be popular. Then when I saw Dav1d, OK, good way to continue the pun. But now with AV2 and Dav2d, that completely breaks. Are we eventually going to get AV3/Dav3d and AV4/Dav4d, which will read like Ave/Daved and Ava/Davad? Seems a bit awkward. Was the idea from t…

1dav2codecs?

2av2furious?

Re: Dav2d

#39

Post by Arubis »

latexr wrote: post #29

When AV1 was first announced, I got the impression the name was chosen partly as a pun/reference/homage to AVI, the classic but outdated format with used to be popular. Then when I saw Dav1d, OK, good way to continue the pun. But now with AV2 and Dav2d, that completely breaks. Are we eventually going to get AV3/Dav3d and AV4/Dav4d, which will read like Ave/Daved and Ava/Davad? Seems a bit awkward. Was the idea from t…

Da5id could potentially work as a Snow Crash reference.

Re: Dav2d

#40

Post by breve »

mrbluecoat wrote: post #31
jordand wrote: post #5

'AV2 decoding is roughly five times more complex than AV1 decoding. In practice, that means software running on today’s hardware will struggle to decode AV2 in real time without careful, architecture-specific optimization' AV1 software decoding is already very intensive so AV2 decoding benchmarks are the next thing that would be really interesting (or mortifying) to see.

I came to post this as well. Until widespread, inexpensive hardware catches up to a 2018 codec, AV# will remain a niche ideal.

Hardly niche. My laptop isn't new and it has hardware AV1 decoding and encoding. My 10 year old iPhone 7 can play 1080p AV1 video in software for over 200 minutes with VLC. The iPhone 7 was released in 2016, a year and a half before AV1. The dav1d decoder is mighty.

Netflix uses AV1: https://netflixtechblog.com/av1-now-powering-30-of-netflix-s...

YouTube uses AV1. It's tough to be more mainstream than that.

Right click on a YouTube video and select Stats for Nerds. If your system is capable of it, chances are it will be playing back in AV1.

Most of the YouTube videos I watch these days are AV1 encodes. Sometimes it's in VP9 and occasionally it's H.264.

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