[Libav-user] Criteria for h.264 key-frame detection

[salsaman]

Carl,
sorry to butt in, but you mentioned earlier:

"I was under the impression that lavf/lavc support recovery
points very well (even in slightly broken streams), ie
that you (as a user) can choose if you only want to seek to
a recovery point (slower, done by ffplay) or to some frame
no matter if it is a recovery point or not (faster, this
is what MPlayer does)."


Just out interest how does one force seeking only to recovery points in
lavf/lavc programmatically ? I have never been able to achieve this, in
fact I have had to implement my own demuxers just for this purpose.

Regards,
Salsaman.





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On Tue, Oct 22, 2013 at 10:36 AM, Robert Krüger <krueger at lesspain.de> wrote:

> On Tue, Oct 22, 2013 at 3:06 PM, Carl Eugen Hoyos <cehoyos at ag.or.at>
> wrote:
> > Robert Krüger <krueger at ...> writes:
> >
> >> >> > Afaict, the 27th frame is not shown, ffmpeg "thinks"
> >> >> > that it is no random access point.
> >> >>
> >> >> What do you mean by "not shown"?
> >> >
> >> > It is not decoded unless flags2 showall is used because
> >> > FFmpeg thinks the 27th frame is not a random access
> >> > point.
> >
> >> You are probably talking about an ffmpeg command line you
> >> used for testing. I am only guessing you made ffmpeg seek
> >> or something like that?
> >
> > No.
> > Which command does decode the 27th frame for you?
> > It is not decoded here unless I use -flags2 showall.
>
> I have an application built on libavformat/libavcodec that
> demuxes/decodes the frame fine. I am not using ffmpeg to test because
> there is so much more stuff going on like rate control that just
> decoding the sequence of pictures appears to be the easiest way to
> check if the stream can be decoded from that frame without any other
> thing interfering. I tested the command line and it indeed seems to
> duplicate the second frame of the truncated file. Anyway, let me know
> what is supposed to happen with this issue.
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