[FFmpeg-devel] [PATCH] lavc/vvc: Invalidate PPSs which refer to a changed SPS

[Anton Khirnov]

Quoting Mark Thompson (2024-06-16 17:26:26)
> Is there some requirement in H.266 that in a single stream the PPS precedes the SPS?
> 
> Currently we effectively require that for a single stream because we use the SPS to enforce constraints on the PPS in both H.265 and H.266, but I'm not seeing a hard dependency and it looks like it will currently work on later stream starts as long as the parameters don't change too much.
> 
> In H.264 there is an explicit dependency because you need chroma_format_idc to parse scaling lists, but again this will usually work because it's unlikely to change inline.

IIRC the spec requirement is about PPS activation, not order in the
bytestream. Our decoder does impose constraints on the order, and I
don't recall it ever causing problems, but it does not follow from the
spec.

-- 
Anton Khirnov