Sorry for replying myself but I think I found something out. I use ffplay to 
compare the original stream recorded by my receiver and the cutted one by me. 
I see that the cutted version plays a lot slower in compare with the recorded 
one. I read something about that PAFF-stuff. Could it be that PAFF is the 
source of my problems? I mean does av_read_frame has problems with PAFF 
frames? If yes, how can I fix that, is it possible to recognize a paff-coded 
picture and to read this frame with av_read_frame twice???

regards, 
Sven

Am Sunday 16 August 2009 14:49:37 schrieb Sven Alisch:
> Hello,
>
> I want to enhance my app with h.264-cut support. My problem is, that my
> streams does not have an idr-Frame. The stream only contains slices (I-,
> P-, B-) and SPS/PPS Values but no IDR-Frames. What I have done is
> following:
>
> I read all AVPackets and save the info about their PTS-values from the
> Keyframes. libav seems to recognize all I-Slices as key-frames (I suppose
> because of the SPS/PPS-Packets in front of them). After that little parsing
> process I can seek thru my stream by jumping from I-Slice to I-Slice. This
> works fine. After the selection of the cut-points I begin to cut before an
> I-Slice. Now comes the first problem. The PTS-Values after that I-Slice are
> smaller. I think this is so cause of the frames referencing pictures before
> that I-Slice correct? Ok. At the moment I throw that pictures away, and
> waiting for pictures with greater PTS-Values. Does exists a better solution
> for that? It is silly that the broadcasting stations does not send
> IDR-Frames.
>
> The second problem is that it seems that av_read_frame does only read slice
> wise. Possible? I mean if one slice is the same like one picture/frame,
> then it is no problem. But could it be that some slices of an h.264 stream
> belong to the same picture/frame? If yes, how can I check/find it out???
> Has anyone an idea?
>
> regards,
> Sven
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