[FFmpeg-devel] [Bounty] Impl. check if input h264 P/B frame ref's frame prior to last I

Andrey Utkin andrey_utkin at fastmail.com
Mon Feb 22 19:04:31 CET 2016


On Mon, 22 Feb 2016 17:23:06 +0000 (UTC)
Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:

> Andrey Utkin <andrey_utkin <at> fastmail.com> writes:
> 
> > As it was discussed today on #ffmpeg and #ffmpeg-devel, 
> > only IDR frames are considered safe seek points by design 
> > of H.264.  
> 
> Since valid H264 streams without IDR (and without I) frames 
> exist, this cannot be true.

Haven't heard of such streams, but let's take it granted. Why does it
mean that above statement is false? If there's no IDR frames, then
it is safe to assume that this stream has no seek points guaranteed to
be valid (unless we introspect the references between frames). I don't
see anything wrong with such statement.

> Do I understand correctly that your issue is that FFmpeg 
> doesn't tell you if an I-frame in an H264 stream is an 
> IDR frame or not?

Yes.


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