RE: [developer question] losing frame after a seek (not aproblem because this frame isn't a key frame)

Actually this problem only occurs with avi encoded with DivX codec (5.2.1)

Any thought?

Regards,

Nicolas

-----Message d'origine-----
De : ffmpeg-user-bounces@xxxxxxxxxxxx [mailto:ffmpeg-user-bounces@xxxxxxxxxxxx] 
De la part de Munier Nicolas
Envoyé : jeudi 20 avril 2006 10:50
À : ffmpeg-user@xxxxxxxxxxxx
Objet : [Ffmpeg-user] [developer question] losing frame after a seek (not 
aproblem because this frame isn't a key frame)

Hi everybody,

I am a newbie using ffmpeg libraries. I am trying to build an application which 
will retrieve each frame of a video independently of its encoding.
I use a method similar to what Martin Böhme describes in its example.

My first problem was that in order to identify the video stream and the codec, 
it uses some video stream packet and then the first frame retrieved is not the 
first frame of the video (at least not for mpeg4 like encoding). As the first 
frame is a key frame and was not decoded I was carrying errors in my frames 
until the next intra-only key frame.

To solve this problem I perform a seek to come back at the beginning of the 
video stream using av_seek_frame.
It seems to work for most of my video except one. For this one I retrieve the 
first frame without problem but I lose some of the next frames. (The 3rd and 
fourth and then a key frame of scenery change) It comes back in order after 
around the 30th frame but I carry some errors (due to false predictions) for a 
long stretch due to the loss of a key frame (that's what first warns me).

Does anyone know what can cause this (bug?) and what can I do to solve this 
problem.

Thanks in advance,

Nicolas

PS: I'd be happy to give some more precisions if you need.

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