[FFmpeg-trac] #3599(undetermined:new): mp3 encoder set wrong bitrate or version flag

[FFmpeg]

#3599: mp3 encoder set wrong bitrate or version flag
-------------------------------------+-------------------------------------
             Reporter:  ltzliwe      |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 when i convert a audio to mp3, and detect it by command[file], it return
 wrong bitrate info.

 {{{
 % ffmpeg -i input.mp3 -b:a 32k -c:a libmp3lame output.mp3
 ffmpeg version
 10769 ~/av » ffmpeg
 ffmpeg version 2.1.3 Copyright (c) 2000-2013 the FFmpeg developers
   built on Jan 17 2014 09:39:01 with llvm-gcc 4.2.1 (LLVM build
 2336.11.00)
   configuration: --prefix=/Volumes/Ramdisk/sw --enable-gpl --enable-
 pthreads --enable-version3 --enable-libspeex --enable-libvpx --disable-
 decoder=libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis
 --enable-libx264 --enable-avfilter --enable-libopencore_amrwb --enable-
 libopencore_amrnb --enable-filters --enable-libgsm --arch=x86_64 --enable-
 runtime-cpudetect
   libavutil      52. 48.101 / 52. 48.101
   libavcodec     55. 39.101 / 55. 39.101
   libavformat    55. 19.104 / 55. 19.104
   libavdevice    55.  5.100 / 55.  5.100
   libavfilter     3. 90.100 /  3. 90.100
   libswscale      2.  5.101 /  2.  5.101
   libswresample   0. 17.104 /  0. 17.104
   libpostproc    52.  3.100 / 52.  3.100

 % file output.mp3
 output.mp3: Audio file with ID3 version 2.4.0, contains: MPEG ADTS, layer
 III, v2,  56 kbps, 22.05 kHz, Stereo
 }}}

 command [file] detect mp3 by its frame header according to
 http://mpgedit.org/mpgedit/mpeg_format/MP3Format.html.

 is it possible ffmpeg set the wrong frame header or other reasons?

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Ticket URL: <https://trac.ffmpeg.org/ticket/3599>
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