[FFmpeg-trac] #3399(undetermined:new): Scaling MP4 Video results in bad output MP4

FFmpeg trac at avcodec.org
Tue Feb 18 22:53:40 CET 2014


#3399: Scaling MP4 Video results in bad output MP4
--------------------------------------+----------------------------------
             Reporter:  mressler      |                     Type:  defect
               Status:  new           |                 Priority:  normal
            Component:  undetermined  |                  Version:  2.1.3
             Keywords:                |               Blocked By:
             Blocking:                |  Reproduced by developer:  0
Analyzed by developer:  0             |
--------------------------------------+----------------------------------
 Summary of the bug:

 Attempting to scale an MP4/H264 1920x1080 source video to 1024:-1 (also
 Mp4/H264) results in odd playback in different players. VLC shows green
 box artifacts, QuickTime and MPlayer both show jerky/slow playback.

 How to reproduce:

 (Grab source from:
 https://www.dropbox.com/s/thy8zxbvx1ygqru/VID_20130619_161750_449.mp4)
 {{{
 % ffmpeg -i VID_20130619_161750_449.mp4 -vf "scale=1024:-1" VID_scaled.mp4
 }}}

 VID_scaled.mp4 ends up with green artifacts in VLC and doesn't play
 appropriately in QuickTime or MPlayer.

 Interestingly, if I clip the video first via:

 {{{
 % ffmpeg -i VID_20130619_161750_449.mp4 -ss 18 -t 15 -c:v copy -c:a copy
 clip2.mp4
 }}}

 And then run the scale command:

 {{{
 % ffmpeg -i clip2.mp4 -vf "scale=1024:-1" VID_clip_scaled.mp4
 }}}

 The resulting video plays fine in VLC, QuickTime, and MPlayer.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/3399>
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