[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
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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
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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
Trying:
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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