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

Robert Krüger krueger at lesspain.de
Tue Oct 22 15:36:30 CEST 2013

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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