ffmpeg -i test070.mp4 test070_audio.wav
ffmpeg version 1.1.git Copyright (c) 2000-2013 the FFmpeg developers
  built on Mar  4 2013 11:40:27 with Apple clang version 4.1 (tags/Apple/clang-421.11.66) (based on LLVM 3.1svn)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-nonfree --enable-hardcoded-tables --enable-avresample --cc=cc --host-cflags= --host-ldflags= --enable-libx264 --enable-libfaac --enable-libmp3lame --enable-libxvid --enable-libfreetype --enable-ffplay
  libavutil      52. 17.103 / 52. 17.103
  libavcodec     54. 92.100 / 54. 92.100
  libavformat    54. 63.102 / 54. 63.102
  libavdevice    54.  3.103 / 54.  3.103
  libavfilter     3. 41.100 /  3. 41.100
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test070.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42mp41
    creation_time   : 2013-03-03 23:45:20
  Duration: 00:00:06.83, start: 0.000000, bitrate: 282 kb/s
    Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 83 kb/s, 24 fps, 24 tbr, 24k tbn, 48 tbc
    Metadata:
      creation_time   : 2013-03-03 23:45:20
      handler_name    : Mainconcept MP4 Video Media Handler
    Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 189 kb/s
    Metadata:
      creation_time   : 2013-03-03 23:45:20
      handler_name    : Mainconcept MP4 Sound Media Handler
File 'test070_audio.wav' already exists. Overwrite ? [y/N] y
Output #0, wav, to 'test070_audio.wav':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42mp41
    ISFT            : Lavf54.63.102
    Stream #0:0(eng): Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, stereo, s16, 1536 kb/s
    Metadata:
      creation_time   : 2013-03-03 23:45:20
      handler_name    : Mainconcept MP4 Sound Media Handler
Stream mapping:
  Stream #0:1 -> #0:0 (aac -> pcm_s16le)
Press [q] to stop, [?] for help
size=    1280kB time=00:00:06.82 bitrate=1536.1kbits/s
video:0kB audio:1280kB subtitle:0 global headers:0kB muxing overhead 0.006104%