dav1d accelerated AV1 decoder

[Blue_MiSfit]

Downloadable content is often SD to reduce size for product reasons:

"oops I'm at the airport gate and forgot I want some shows to watch! I want them ASAP! Also my connection is currently congested WiFi / LTE"

DRM requirements for SD are quite lax (software DRM is usually fine), so new codecs with software decoders are often okay there

[hajj_3]

mpc-be 1.5.6.5797 beta has been released which includes dav1d 0.8.0 it also adds lots of other av1 related things: https://sourceforge.net/p/mpcbe/code.../Changelog.txt

[benwaggoner]

for dav1d 0.8.0, what's the per-thread decoder perf difference for 8-bit and 10-bit content these days?

[sneaker_ger]

On SSSE3 like factor 5 or something? There still isn't optimization for 10 bit AVX2 nor 10 bit SSSE3.

[benwaggoner]

Originally Posted by sneaker_ger

On SSSE3 like factor 5 or something? There still isn't optimization for 10 bit AVX2 nor 10 bit SSSE3.

I hope that optimization gets done and is effective. With AV1 we finally have a codec with mandatory 10-bit support, but it's too slow to be practical on the platforms where AV1 is most advantageous. The big 2021 win with AV1 would be Chrome/Firefox as it's an upgrade from H.264. Without 10-bit, there's no HDR, and no option to look better than H.264, just lower bitrate.

[soresu]

Originally Posted by benwaggoner

I hope that optimization gets done and is effective. With AV1 we finally have a codec with mandatory 10-bit support, but it's too slow to be practical on the platforms where AV1 is most advantageous. The big 2021 win with AV1 would be Chrome/Firefox as it's an upgrade from H.264. Without 10-bit, there's no HDR, and no option to look better than H.264, just lower bitrate.

Unfortunately unless a private entity sponsors x86 10 bpc SIMD asm as Netflix did for ARM64 NEON I would not expect it to happen soon as it is a pretty low priority on the dav1d roadmap - below even AVX512 8 bpc work, which is not even close to as far along as AVX2 or SSSE3 for completeness right now.

With any luck Netflix might take pity on us desktop users and get someone to do the x86 10 bpc work after their current hire has finished doing the ARM32 10 bpc optimisations which are coming along pretty well at the moment.

[sneaker_ger]

Originally Posted by soresu

Unfortunately unless a private entity sponsors x86 10 bpc SIMD asm

They supposedly do have that sponsorship already but as you say it's not the highest priority.

It's good 10bpc is mandatory in the most basic profile but they should have taken it one step further and just got rid of 8bpc coding altogether.

[Jamaika]

Maybe someone knows how to set config parameters dav1d 0.8.0-7424f8e for gcc windows 16bit with SSE2.
For 8bit the decoder works but for 16bit no. Maybe increase memory size.
WINVER=0x0602, _WIN32_WINNT=0x0602, ARCH_X86_64=1, CONFIG_16BPC, BITDEPTH=16, HAVE_ALIGNED_MALLOC

[nevcairiel]

Originally Posted by Jamaika

Maybe someone knows how to set config parameters dav1d 0.8.0-7424f8e for gcc windows 16bit with SSE2.
For 8bit the decoder works but for 16bit no. Maybe increase memory size.
WINVER=0x0602, _WIN32_WINNT=0x0602, ARCH_X86_64=1, CONFIG_16BPC, BITDEPTH=16, HAVE_ALIGNED_MALLOC

AV1 does not support 16-bit. its only 8, 10 and 12. Hence a decoder cannot support anything that the codec does not provide.

If you build it with full default settings, dav1d will support all these bitdepths natively out of the box. You can turn off 8 bit or 10/12 bit, but unless you are very much size constrained, there is no reason to do so.

[Jamaika]

Originally Posted by nevcairiel

AV1 does not support 16-bit. its only 8, 10 and 12. Hence a decoder cannot support anything that the codec does not provide.

If you build it with full default settings, dav1d will support all these bitdepths natively out of the box. You can turn off 8 bit or 10/12 bit, but unless you are very much size constrained, there is no reason to do so.

For dav1d there are no settings to define 10 or 12bit only for total of 10,12,16bit. I understand that in practice dav1d doesn't support 10.12bit

[nevcairiel]

Originally Posted by Jamaika

I understand that in practice dav1d doesn't support 10.12bit

You are wrong. dav1d supports the entire AV1 spec fully.

[Jamaika]

Originally Posted by nevcairiel

You are wrong. dav1d supports the entire AV1 spec fully.

Well then how to set the config. BITDEPTH value can't be 10 or 12.

[nevcairiel]

Just build dav1d with default config, no changes, and it'll support everything.

[Blue_MiSfit]

Unfortunately unless a private entity sponsors x86 10 bpc SIMD asm as Netflix did for ARM64 NEON I would not expect it to happen soon as it is a pretty low priority on the dav1d roadmap - below even AVX512 8 bpc work, which is not even close to as far along as AVX2 or SSSE3 for completeness right now.

I'm honestly pretty surprised there's so little interest. Why is this? Is it just that the real hope for short term AV1 adoption via software decode is wide/shallow engagement content like social / user generated?

I suppose in this world it matters more to have comprehensive optimization for 8 bit content across even very old hardware. Seems odd to prioritize AVX512 for 8 bit over something like AVX2 for 10 bit tho :/

Of course all hollywood content is mastered in 10+ bit (even SDR) and is frequently delivered in 10 bit HEVC today. If I was building an AV1 encoding pipeline it sure would be ideal if I could just encode 10 bit and not worry about 8 bit at all..

[nevcairiel]

If I had to make a guess, I would say that desktop PC media consumption is not a priority for Netflix, Amazon etc, and a large part of their traffic is mobile or straight to TV or streaming devices, while YouTube sees a larger share on PC consumption.

[foxyshadis]

People watching on a PC/laptop generally won't click away just because the fans spin up, either, they'll just turn it up if they aren't already wearing headphones. Big difference from stuttering.

I wonder if SVT-AV1's assembly routines could be adapted; I don't know nearly enough about dav1d to know if Rust or the way data is set up would be a blocker, but at least the licensing is taken care of since the move.

[sneaker_ger]

Rust? I think you have dav1d confused with Rav1e. Both SVT-AV1 and dav1d are written in C (+assembly/intrinsics).

[foxyshadis]

Originally Posted by sneaker_ger

Rust? I think you have dav1d confused with Rav1e. Both SVT-AV1 and dav1d are written in C (+assembly/intrinsics).

Brain fart, yes.

[hajj_3]

Originally Posted by Blue_MiSfit

I'm honestly pretty surprised there's so little interest. Why is this? Is it just that the real hope for short term AV1 adoption via software decode is wide/shallow engagement content like social / user generated?

I suppose in this world it matters more to have comprehensive optimization for 8 bit content across even very old hardware. Seems odd to prioritize AVX512 for 8 bit over something like AVX2 for 10 bit tho :/

Of course all hollywood content is mastered in 10+ bit (even SDR) and is frequently delivered in 10 bit HEVC today. If I was building an AV1 encoding pipeline it sure would be ideal if I could just encode 10 bit and not worry about 8 bit at all..

Few people have HDR monitors or 10bit monitors. I'm sure that 10bit support will be good at some point next year.

[Blue_MiSfit]

Originally Posted by hajj_3

Few people have HDR monitors or 10bit monitors. I'm sure that 10bit support will be good at some point next year.

To the contrary, 4k TVs are widely popular, and they all have 10 bit HDR & WCG panels.

I'll agree that the vast majority of PC / Mac systems do not have HDR / 10 bit displays