[FFmpeg-trac] #1008(undetermined:new): Can't generate video with undefined aspect

FFmpeg trac at avcodec.org
Tue Feb 21 02:25:16 CET 2012

#1008: Can't generate video with undefined aspect
             Reporter:  hadmut       |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |

 I'm currently converting several videos (most from mpeg2 or mpeg4 with
 wrong aspect ratio) for efficient storing, watching with a streamer (such
 as WD TV Live) and iPad2. Usually using x264/aac as codecs, converting to
 ?x720, depending on the required ratio (in most cases 1280x720).

 The problem: iPad2's computation power seems to be limited. While it can
 properly display most videos of my collection (especially with lower
 resolutions), it has trouble, hangs or even stops playing 1280x720 videos
 generated with ffmpeg. Lower resolutions solve the problem, but obviously
 reduce quality.

 But then, I have other videos downloaded from the Web (or youtube) which
 as well are 1280x720, H264, AAC, and they are displayed correctly on the

 The only difference I have figured out so far is that in those videos iPad
 can play without problems the Video Aspect (as reported by mplayer) is
 undefined. I guess that this might cause the iPad to rescale images and
 waste computation time.

 The problem with ffmpeg: I can't remove the aspect ratio. If I omit the
 -aspect parameter, ffmpeg copies the (wrong) aspect ratio from the MPEG2
 (=1.333). If I use the -aspect parameter, ffmpeg rejects giving 0 as a

 So I don't see any way to create a video with ffmpeg where the aspect is
 not set (i.e. just use the width/height).

 (ffmpeg version is 0.7.3 as of ubuntu latest, but this ticket system does
 not offer this version for selection)


Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1008>
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