[FFmpeg-user] Image extraction broken with ffmpeg, but not with mencoder. How can I fix this?

Paul B Mahol onemda at gmail.com
Mon Sep 2 23:25:09 CEST 2013

On 9/2/13, James Board <jpboard2 at yahoo.com> wrote:
>>Sorry, but how can I reproduce that bug?
> I run ffmpeg on a file to produce jpeg (or pnm or whatever) images as
> output.
> At seemingly random locations in the sequence, some image files
> are duplicated. This causes the frame numbers of those files
> to be incorrect.  Why?  Because those are extra frames not present in
> the original source video.  For example, let's say my input video
> had frames like this
>     A B C D E
> When I use ffmpeg to extract jpeg images from the video, I might get
>     A B C D D E
> See the difference?  In one sequence, there is a single 'D'.  In the other
> there are two 'D's.  That means there will be one extra image file in the
> output.  Also, all file names, which hold the frame number, after 'D' will
> then be incorrect.  And if you're video editor is based on ffmpeg to
> do this, it will be incorrect.
> This is a bug with ffmpeg.  If I run the same test with mencoder (actually
> mplayer),

Why you think this is bug?
By default ffmpeg creates cfr output.
So probably your input is vfr and that is why some frames are duplicated.

> then I don't see the bug.  For example, if the input video had frames like
> this
>     A B C D E
> When I use mencoder to extract jpeg images from the video, I get
>     A B C D E
> mencoder produces the correct files.
> _______________________________________________
> ffmpeg-user mailing list
> ffmpeg-user at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-user

More information about the ffmpeg-user mailing list