sammel@sammel-ub:~/Videos/youtube/felsen$ ffmpeg -i 946_1265.MOV -s 640x480 -b 800k -acodec libfaac -ab 64k -vcodec mpeg4 -vtag xvid test.mp4
ffmpeg version git-2012-06-01-7980a26 Copyright (c) 2000-2012 the FFmpeg developers
  built on Jun  1 2012 21:02:15 with gcc 4.4.3
  configuration: --enable-gpl --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-nonfree --enable-version3 --enable-x11grab
  libavutil      51. 56.100 / 51. 56.100
  libavcodec     54. 23.100 / 54. 23.100
  libavformat    54.  6.101 / 54.  6.101
  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
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '946_1265.MOV':
  Metadata:
    major_brand     : qt
    minor_version   : 0
    compatible_brands: qt
    creation_time   : 2012-04-27 04:45:32
    comment         : KODAK Zi8 Pocket Video Camera
    comment-eng     : KODAK Zi8 Pocket Video Camera
  Duration: 00:00:20.72, start: 0.000000, bitrate: 13921 kb/s
    Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 13780 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc
    Metadata:
      creation_time   : 2012-04-27 04:45:32
      handler_name    : Ambarella AVC
    Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, s16, 128 kb/s
    Metadata:
      creation_time   : 2012-04-27 04:45:32
      handler_name    : Ambarella AAC
Please use -b:a or -b:v, -b is ambiguous
File 'test.mp4' already exists. Overwrite ? [y/N] y
w:1280 h:720 pixfmt:yuv420p tb:1/90000 sar:1/1 sws_param:flags=2
[buffersink @ 0xa0571c0] No opaque field provided
[scale @ 0xa0573a0] w:1280 h:720 fmt:yuv420p sar:1/1 -> w:640 h:480 fmt:yuv420p sar:4/3 flags:0x4
[mp4 @ 0xa04c5c0] Tag xvid/0x64697678 incompatible with output codec id '13' ( [0][0][0])
Output #0, mp4, to 'test.mp4':
  Metadata:
    major_brand     : qt
    minor_version   : 0
    compatible_brands: qt
    creation_time   : 2012-04-27 04:45:32
    comment         : KODAK Zi8 Pocket Video Camera
    comment-eng     : KODAK Zi8 Pocket Video Camera
    Stream #0:0(eng): Video: mpeg4 (xvid / 0x64697678), yuv420p, 640x480 [SAR 4:3 DAR 16:9], q=2-31, 800 kb/s, 90k tbn, 29.97 tbc
    Metadata:
      creation_time   : 2012-04-27 04:45:32
      handler_name    : Ambarella AVC
    Stream #0:1(eng): Audio: aac, 48000 Hz, stereo, s16, 64 kb/s
    Metadata:
      creation_time   : 2012-04-27 04:45:32
      handler_name    : Ambarella AAC
Stream mapping:
  Stream #0:0 -> #0:0 (h264 -> mpeg4)
  Stream #0:1 -> #0:1 (aac -> libfaac)
Could not write header for output file #0 (incorrect codec parameters ?): Invalid data found when processing input