[FFmpeg-trac] #491(FFmpeg:new): ffmpeg's -b option (bitrate) overrides audio bitrate

FFmpeg trac at avcodec.org
Tue Sep 20 12:37:39 CEST 2011

#491: ffmpeg's -b option (bitrate) overrides audio bitrate
               Reporter:  jbm          |                  Owner:  michael
                   Type:  defect       |                 Status:  new
               Priority:  normal       |              Component:  FFmpeg
                Version:  unspecified  |               Keywords:
             Blocked By:               |               Blocking:
Reproduced by developer:  0            |  Analyzed by developer:  0
 Using today's git (I don't know when that issue appeared), the "-b"
 bitrate option in FFmpeg sets both video AND audio bitrate.

 The FFmpeg documentation says:

 * To set the video bitrate of the output file to 64kbit/s:
 ffmpeg -i input.avi -b 64k output.avi

 However, in current git, trying for example:

 ffmpeg -i sample.MTS -b 2000k test.mpg

 Fails with the following error:
 [mp2 @ 0x80cbb20] bitrate 2000 is not allowed in mp2

 ffmpeg -i sample.MTS -ab 128k -b 2000k test.mpg

 Also fails because '-b' overrides '-ab', so the only solution is to do:

 ffmpeg -i sample.MTS -b 2000k -ab 128k test.mpg

 This seems a bug to me, it was not working that way before, and it breaks
 the encoding profiles that we use in our application (Kdenlive). If this
 change was made on purpose, the documentation should be updated.

Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/491>
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