[FFmpeg-devel] Re: [Question] Learning about VVC and wasm

[Sidd via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>]

Hi Frank,

Thanks for the reply, it seems like there is a lot for me to cover.

Regarding the assembly, since FFmpeg is known for handcrafting it, are
there any references of help in their docs regarding this? I have gone
through their ASM lessons and know the basics of them but am quite far
from being good at writing it. And if I may ask, what exactly are the
current drawbacks of the current C implementation?

Thank you for taking your time to answer my questions.

On Thu, Nov 13, 2025 at 11:13 PM Frank Plowman via ffmpeg-devel
<ffmpeg-devel@ffmpeg.org> wrote:
>
> On 13/11/2025 16:46, Sidd via ffmpeg-devel wrote:
> > Hi, I was curious on learning more about VVC and wasm within the
> > ffmpeg project and would like some guidance on where to find the docs
> > and references to go through
> >
> > I am simply trying to get my hands dirty with a past GSoC project to
> > get the feel of working on the source code (hopefully to understand it
> > better)
> >
> > Any help on this would be much appreciated
>
> If you have prior experience with AVC and HEVC, [1] is an overview of
> what was introduced in VVC.  If not, a good place to start would be with
> Iain E. Richardson's "The H.264 Advanced Video Compression Standard".
> He's also got a new book out, "Coding Video: A Practical Guide to HEVC
> and Beyond", but I'm not sure if that’s a good introductory text or
> whether it assumes some knowledge.
>
> As far as FFmpeg’s implementation goes, probably the most notable thing
> is the wavefront parallel processing (WPP) multithreading model, which
> is documented to some extent at [2].  The code for the multithreading
> aspect is pretty well-contained to libavcodec/vvc/thread.c so you can
> get a sense of how the decoder works at a high level there.  There
> aren't many docs for the decoder though really: it's an implementation
> of the standard.  In terms of the progress on the decoder and what needs
> work, its C code is in a good state but it needs more assembly written
> for it, particularly on x86.
>
> If you have any specific questions about VVC or the FFmpeg
> implementation, feel free to ask me.  I don't know anything about wasm.
>
> [1] https://ieeexplore.ieee.org/document/9503377/
> [2] https://archive.fosdem.org/2024/events/attachments/fosdem-2024-3538-
> ffmpeg-vvc-decoder/slides/22900/VVC_decoder_in_FFmpeg_Handout-1_FP3o8rS.pdf
>
> --
> All the best,
> Frank
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