[FFmpeg-devel] [PATCH v5] avcodec/cbs_vp8: Add support for VP8 codec bitstream

[Ronald S. Bultje]

Hi,

On Sun, Nov 5, 2023 at 7:56 PM Dai, Jianhui J <
jianhui.j.dai-at-intel.com at ffmpeg.org> wrote:

> This commit adds support for VP8 bitstream read methods to the cbs
> codec. This enables the trace_headers bitstream filter to support VP8,
> in addition to AV1, H.264, H.265, and VP9. This can be useful for
> debugging VP8 stream issues.
>
> The CBS VP8 implements a simple VP8 boolean decoder using GetBitContext
> to read the bitstream.
>

Is it possible to re-use the existing vp56rac decoder for this? Having two
arithmetic bool decoders that do the same thing is a bit weird.


> +static const uint8_t vp8_token_update_probs[4][8][3][11] = {
>

It would be nice if these symbols could be re-used from the existing vp8
native decoder, instead of duplicating them? Both source + binary size are
relevant here.

I'm also wondering if - longer-term - it makes sense to try to merge some
of these concepts back into the native decoders, objects like
Vp8RawFameHeader, but I'm guessing that's not super-urgent...

Ronald