[FFmpeg-devel] Ticket 6375, Too many packets buffered for output stream

[Reimar Döffinger]

On 09.07.2017, at 13:09, Michael Niedermayer <michael at niedermayer.cc> wrote:

> Hi all
> 
> It does appear this regression affects alot of people, judging from
> the multiple different people in the ticket.
> Also people ask me about this, for example baptiste yesterday hit it
> too.
> 
> I belive multiple people where in favour of the change that caused
> this regression. Does someone who was in favor of this change have
> time to fix this ticket ?
> 
> I belive its important to fix this as it seems affecting many people.
> 
> Thanks
> 
> For reference:
> Ticket: https://trac.ffmpeg.org/ticket/6375
> Regressing Commit: https://github.com/FFmpeg/FFmpeg/commit/af1761f7b5b1b72197dc40934953b775c2d951cc

Huh? I don't know if the commit message is accurate, but if it is the basic concept of this patch is utterly broken and can never work.
There can be hours of video data before you actually get a frame on one of the "missing" streams (subtitles might be the most obvious case, but there are others), and buffering that much data simply is not possible.
You can do something like it if instead of failing when the buffering limit is reached you then force stream processing of what is available, which is kind of a compromise that usually works well but also makes things a bit unpredictable.
Though since it seems to cause issues with audio files with cover image there's probably also bugs in the implementation itself, since handling those correctly is entirely possible...