[FFmpeg-user] Bug in I-Frame Retrieval?

Zbigniew Zdziarski zdziarze at cs.tcd.ie
Mon Jul 14 19:40:19 CEST 2014

On 14-07-2014 14:29, Zbigniew Zdziarski wrote:
> Hello,
> I'm trying to extract I frames from mpeg files but I've noticed
> something weird happening. The frames that are saved in my folder by
> ffmpeg do not match the frames marked as I frames either by ffprobe 
> or
> ffmpeg with parameter "-loglevel debug".
> The command I'm using is the following:
> ffmpeg -i C:\vid1.mp4 -vf select='eq(pict_type\,I)' -vsync 0
> C:\%03d.jpg -loglevel debug 2> vid1.txt
> For some videos, the first few frames saved are correct. For some
> videos, all but the first frame are incorrectly saved.
> Is my command incorrect or is there a bug???
> Cheers,
> Zig
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> ffmpeg-user at ffmpeg.org
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I did some more digging around and found that this problem doesn't 
occur for all videos. E.g. the last 2 frames
saved by the command above for the following video are different to 
those marked as being I-frames:

But all works fine for this video:


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