[FFmpeg-devel] [PATCH 1/2] avcodec/s302m: enable non-PCM decoding

[Kieran Kunhya]

On Tue, 23 Jan 2024 at 14:51, Devin Heitmueller <
devin.heitmueller at ltnglobal.com> wrote:

> On Tue, Jan 23, 2024 at 4:05 AM Kieran Kunhya <kierank at obe.tv> wrote:
> > Yes, and the other uncertainty is that the PTS must be cotimed with the
> > video so you have to guess whether it's the previous PTS or the next one.
>
> Isn't the correct behavior to determine the offset within the raw PCM
> payload, and use that to determine the actual PTS of the embedded
> non-PCM packet?  Unless I"m misreading the code, it seems like it's
> simply setting the PTS of the non-pcm packet to be the PTS of the
> original S302 packet, which will result in incorrect A/V sync.
>

Quite the opposite, Dolby E by design is cotimed with the video frame and
S302M PTS is also cotimed with the video frame.
The ambiguity is when Dolby E is misaligned, is it misaligned to the next
video frame, or the previous one.

For AC-3 yes, the offset matters but that's a different story.

Kieran