[FFmpeg-trac] #1607(avformat:new): av_seek_frame() without AVSEEK_FLAG_ANY on mpg files returns success without seeking to a keyframe

FFmpeg trac at avcodec.org
Tue Aug 7 10:38:13 CEST 2012


#1607: av_seek_frame() without AVSEEK_FLAG_ANY on mpg files returns success
without seeking to a keyframe
------------------------------------+------------------------------------
             Reporter:  mbradshaw   |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  normal      |                Component:  avformat
              Version:  git-master  |               Resolution:
             Keywords:              |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
------------------------------------+------------------------------------

Comment (by cehoyos):

 Replying to [comment:5 mbradshaw]:
 > Replying to [comment:4 cehoyos]:
 > > Replying to [comment:3 DonMoir]:
 > > > mpeg2video failing sample file (6 MB):
 > > >
 > > > http://sms.pangolin.com/temp/mpeg2video_seek_to_non_keyframe.mpg
 > > I failed to extract a non-keyframe out of this sample with ffmpeg.
 > > If it is possible, please provide the command together with complete,
 uncut console output.
 > Can you describe how you were able to extract only keyframes out of this
 sample?

 $ ffmpeg -ss 1 -i mpeg2video_seek_to_non_keyframe.mpg out.png
 $ ffmpeg -ss 2 -i mpeg2video_seek_to_non_keyframe.mpg out.png
 $ ffmpeg -ss 3 -i mpeg2video_seek_to_non_keyframe.mpg out.png
 $ ffmpeg -ss 4 -i mpeg2video_seek_to_non_keyframe.mpg out.png
 $ ffmpeg -ss 5 -i mpeg2video_seek_to_non_keyframe.mpg out.png
 $ ffmpeg -ss 6 -i mpeg2video_seek_to_non_keyframe.mpg out.png
 $ ffmpeg -ss 7 -i mpeg2video_seek_to_non_keyframe.mpg out.png

 > The problem isn't that you get a junk frame out (the decoder makes sure
 you don't).

 I wonder what this sentence means: There are many samples that return gray
 frames for above command line (including some sample that you pointed to).

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1607#comment:10>
FFmpeg <http://ffmpeg.org>
FFmpeg issue tracker


More information about the FFmpeg-trac mailing list