title: ffmpeg caps audio bitrate to 128kb/s
body: <p>I want to upconvert a file to 256kb/s. (I understand I am losing quality and all
  that, I know that I <strong>really</strong> want to upconvert a 64kb/s=>256kb/s)</p>
  
  <p>The command I am using</p>
  
  <pre class="lang-sh prettyprint-override"><code>ffmpeg -i "Same Love.m4a" -acodec libfaac "Same Love.m4a" -b:a 256kb \
    -loglevel debug
  </code></pre>
  
  <p>I have used every combination that I can think of and ffmpeg will only upconvert
  to 128kbs!</p>
  
  <p>Here is a log of my output</p>
  
  <pre>
  $ ffmpeg -i "Same Love.m4a" -acodec libfaac "ready_to_import_to_itunes/Same Love.m4a" -b:a 256kb -loglevel debug
  ffmpeg version 1.0 Copyright (c) 2000-2012 the FFmpeg developers
    built on Oct 12 2012 12:31:30 with Apple clang version 4.1 (tags/Apple/clang-421.11.66) (based on LLVM 3.1svn)
    configuration: --prefix=/usr/local/Cellar/ffmpeg/1.0 --enable-shared --enable-gpl --enable-version3 --enable-nonfree --enable-hardcoded-tables --cc=cc --host-cflags= --host-ldflags= --enable-libx264 --enable-libfaac --enable-libmp3lame --enable-libxvid
    libavutil      51. 73.101 / 51. 73.101
    libavcodec     54. 59.100 / 54. 59.100
    libavformat    54. 29.104 / 54. 29.104
    libavdevice    54.  2.101 / 54.  2.101
    libavfilter     3. 17.100 /  3. 17.100
    libswscale      2.  1.101 /  2.  1.101
    libswresample   0. 15.100 /  0. 15.100
    libpostproc    52.  0.100 / 52.  0.100
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc6ab006600] Format mov,mp4,m4a,3gp,3g2,mj2 probed with size=2048 and score=100
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc6ab006600] ISO: File Type Major Brand: mp42
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc6ab006600] File position before avformat_find_stream_info() is 30844
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc6ab006600] All info found
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc6ab006600] File position after avformat_find_stream_info() is 31216
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Same Love.m4a':
    Metadata:
      major_brand     : mp42
      minor_version   : 0
      compatible_brands: mp42isom3gp63g2a3gp4
      creation_time   : 2012-08-11 09:56:26
    Duration: 00:05:18.71, start: 0.000000, bitrate: 64 kb/s
      Stream #0:0(und), 1, 1/44100: Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, s16, 64 kb/s
      Metadata:
        creation_time   : 2012-08-11 09:56:26
        handler_name    : soun
  [abuffer @ 0x7fc6aac0e560] Setting entry with key 'time_base' to value '1/44100'
  [abuffer @ 0x7fc6aac0e560] Setting entry with key 'sample_rate' to value '44100'
  [abuffer @ 0x7fc6aac0e560] Setting entry with key 'sample_fmt' to value 's16'
  [abuffer @ 0x7fc6aac0e560] Setting entry with key 'channel_layout' to value '0x3'
  [graph 0 input from stream 0:0 @ 0x7fc6aac0e660] tb:1/44100 samplefmt:s16 samplerate:44100 chlayout:0x3
  [aformat @ 0x7fc6aac0eba0] Setting entry with key 'sample_fmts' to value 's16'
  [aformat @ 0x7fc6aac0eba0] Setting entry with key 'channel_layouts' to value '0x4,0x3,0x7,0x107,0x37,0x3f'
  Output #0, ipod, to 'ready_to_import_to_itunes/Same Love.m4a':
    Metadata:
      major_brand     : mp42
      minor_version   : 0
      compatible_brands: mp42isom3gp63g2a3gp4
      encoder         : Lavf54.29.104
      Stream #0:0(und), 0, 1/44100: Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, s16, 128 kb/s
      Metadata:
        creation_time   : 2012-08-11 09:56:26
        handler_name    : soun
  Stream mapping:
    Stream #0:0 -> #0:0 (aac -> libfaac)
  Press [q] to stop, [?] for help
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc6ab006600] demuxer injecting skip 1024
  [aac @ 0x7fc6ab02f600] skip 2048 samples due to side data
  [aac @ 0x7fc6ab02f600] skip whole frame, skip left: 0
  EOF on sink link output stream 0:0:default.28.0kbits/s
  No more output streams to write to, finishing.
  size=    5028kB time=00:05:18.71 bitrate= 129.2kbits/s
  video:0kB audio:4974kB subtitle:0 global headers:0kB muxing overhead 1.093817%
  [AVIOContext @ 0x7fc6aac0ca20] Statistics: 2580581 bytes read, 0 seeks
  </pre>
  
  <p>What I <strong>think</strong> is happening is that ffmpeg determines that there is really no
  benifit from going to 256k so caps it at 128.</p>
  
  <p>How do I <em>force</em> it to output the file at the bitrate specified? (I have tried
  with mp3 too and the samething happens)</p>