~$ ffmpeg -i /media/LinuxData/Dropbox/Falschbetoner.mp4 -acodec libmp3lame -ab 320 -ar 44100 /media/LinuxData/Dropbox/Falschbetoner.mp3
ffmpeg version 0.8.4-4:0.8.4-0ubuntu0.12.04.1, Copyright (c) 2000-2012 the Libav developers
  built on Nov  6 2012 16:51:33 with gcc 4.6.3
*** THIS PROGRAM IS DEPRECATED ***
This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.

Seems stream 1 codec frame rate differs from container frame rate: 49.96 (24981/500) -> 24.98 (24981/1000)
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/media/LinuxData/Dropbox/Falschbetoner.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isomavc1mp42
    creation_time   : 2009-09-24 13:35:28
  Duration: 00:01:45.11, start: 0.000000, bitrate: 2149 kb/s
    Stream #0.0(und): Audio: aac, 44100 Hz, stereo, s16, 125 kb/s
    Metadata:
      creation_time   : 2009-09-24 13:35:28
    Stream #0.1(und): Video: h264 (High), yuv420p, 1280x720 [PAR 1:1 DAR 16:9], 2021 kb/s, 24.98 fps, 24.98 tbr, 24981 tbn, 49.96 tbc
    Metadata:
      creation_time   : 2009-09-24 13:35:28
Unknown encoder 'libmp3lame'