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

Robert Krüger krueger at lesspain.de
Tue Oct 22 14:50:42 CEST 2013

On Tue, Oct 22, 2013 at 2:00 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.

This must be a misunderstanding. You are probably not saying ffmpeg
only decodes frames at random access points. Again, I checked the
frame and the number of frames that were decoded in my application and
that frame is decoded just fine using the file produced by cutting off
anything before the 27th frame's packet.

You are probably talking about an ffmpeg command line you used for
testing. I am only guessing you made ffmpeg seek or something like

What is your suggestion how I should proceed? Make a ticket and
reference this thread? I guess it would be interesting to have
Michael's opinion as h264 maintainer, if he thinks this stream is
handled correctly or the handling could be improved as far as key
frame detection/seeking is concerned.

Again, if there is no interest in looking at this, I will probably
hack something in our application. In any case, I will share anything
I find out with regard to the handling of that specific stream.

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