title: FFmpeg works out mp3 duration with file input, but fails with pipe?
body: <p>I am trying to get PCM data from mp3's using ffmpeg, but the files are stored on a database, gridfs, so I am trying to use pipes to give ffmpeg the data with some sucess, however there is one file which ffmpeg handles correctlt if fed the filename as an input, and incorrectly when given the file as a pipe :( any idea why?</p>
  
  <pre><code>ffmpeg -i - -f s16le -acodec pcm_s16le output.raw &lt; testMp3s/test-corrupt.mp3 
  </code></pre>
  
  <p>gives</p>
  
  <pre><code>ffmpeg version 0.11.1 Copyright (c) 2000-2012 the FFmpeg developers
  built on Jun  9 2012 13:50:13 with gcc 4.7.0 20120505 (prerelease)
  configuration: --prefix=/usr --enable-libmp3lame --enable-libvorbis --enable-libxvid --        enable-libx264 --enable-libvpx --enable-libtheora --enable-libgsm --enable-libspeex -- enable-postproc --enable-shared --enable-x11grab --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libschroedinger --enable-libopenjpeg --enable-librtmp --enable-libpulse --enable-libv4l2 --enable-gpl --enable-version3 --enable-runtime-cpudetect --  disable-debug --disable-static
  libavutil      51. 54.100 / 51. 54.100
  libavcodec     54. 23.100 / 54. 23.100
  libavformat    54.  6.100 / 54.  6.100
  libavdevice    54.  0.100 / 54.  0.100
  libavfilter     2. 77.100 /  2. 77.100
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0. 15.100 /  0. 15.100
  libpostproc    52.  0.100 / 52.  0.100
  [mp3 @ 0x16d7100] Unknown attached picture mimetype: JPG, skipping.
  [mp3 @ 0x16d7100] max_analyze_duration 5000000 reached at 5015510
  [mp3 @ 0x16d7100] Estimating duration from bitrate, this may be inaccurate
  Input #0, mp3, from 'pipe:':
  Metadata:
  album           : FreshNewMusik.Com
  encoded_by      : iTunes 10.6.3
  title           : No Lie (Freestyle)
  artist          : Lil Wayne
  album_artist    : Lil Wayne
  genre           : Hip-Hop/Rap
  TT3             : twitter.com/jakejarvis
  date            : 2012
  Duration: N/A, start: 0.000000, bitrate: 320 kb/s
  Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16, 320 kb/s
  </code></pre>
  
  <p>Yet</p>
  
  <pre><code>ffmpeg -i testMp3s/test-corrupt.mp3 -f s16le -acodec pcm_s16le output.raw 
  </code></pre>
  
  <p>gives</p>
  
  <pre><code>ffmpeg version 0.11.1 Copyright (c) 2000-2012 the FFmpeg developers
  built on Jun  9 2012 13:50:13 with gcc 4.7.0 20120505 (prerelease)
  configuration: --prefix=/usr --enable-libmp3lame --enable-libvorbis --enable-libxvid --    enable-libx264 --enable-libvpx --enable-libtheora --enable-libgsm --enable-libspeex --enable-postproc --enable-shared --enable-x11grab --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libschroedinger --enable-libopenjpeg --enable-librtmp --enable-libpulse --enable-libv4l2 --enable-gpl --enable-version3 --enable-runtime-cpudetect --disable-debug --disable-static
  libavutil      51. 54.100 / 51. 54.100
  libavcodec     54. 23.100 / 54. 23.100
  libavformat    54.  6.100 / 54.  6.100
  libavdevice    54.  0.100 / 54.  0.100
  libavfilter     2. 77.100 /  2. 77.100
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0. 15.100 /  0. 15.100
  libpostproc    52.  0.100 / 52.  0.100
  [mp3 @ 0xf33100] Unknown attached picture mimetype: JPG, skipping.
  [mp3 @ 0xf33100] max_analyze_duration 5000000 reached at 5015510
  [mp3 @ 0xf33100] Estimating duration from bitrate, this may be inaccurate
  Input #0, mp3, from 'testMp3s/test-corrupt.mp3':
  Metadata:
  album           : FreshNewMusik.Com
  encoded_by      : iTunes 10.6.3
  title           : No Lie (Freestyle)
  artist          : Lil Wayne
  album_artist    : Lil Wayne
  genre           : Hip-Hop/Rap
  TT3             : twitter.com/jakejarvis
  date            : 2012
  Duration: 00:02:33.86, start: 0.000000, bitrate: 320 kb/s
  Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16, 320 kb/s
  </code></pre>
  
  <p>How do I get the duration with the pipe? (the data is available on memory in a python app)</p>