ffmpeg -i /Volumes/Untitled/saal1.wmv -f mp4 output.mp4
ffmpeg version 0.7.6, Copyright (c) 2000-2011 the FFmpeg developers
  built on Nov  5 2011 13:13:49 with gcc 4.2.1 (Apple Inc. build 5666) (dot 3)
  configuration: --prefix=/opt/local --enable-gpl --enable-postproc --enable-swscale --enable-avfilter --enable-libmp3lame --enable-libvorbis --enable-libtheora --enable-libdirac --enable-libschroedinger --enable-libopenjpeg --enable-libxvid --enable-libx264 --enable-libvpx --enable-libspeex --mandir=/opt/local/share/man --enable-shared --enable-pthreads --cc=/usr/bin/gcc-4.2 --arch=x86_64 --enable-yasm --enable-nonfree --enable-libfaac
  libavutil    50. 43. 0 / 50. 43. 0
  libavcodec   52.122. 0 / 52.122. 0
  libavformat  52.110. 0 / 52.110. 0
  libavdevice  52.  5. 0 / 52.  5. 0
  libavfilter   1. 80. 0 /  1. 80. 0
  libswscale    0. 14. 1 /  0. 14. 1
  libpostproc  51.  2. 0 / 51.  2. 0
[wmv3 @ 0x7fa83b83fc00] WMV3 Complex Profile is not fully supported
[wmv3 @ 0x7fa83b83fc00] Read 16 bits in overflow
[asf @ 0x7fa83b84ac00] Estimating duration from bitrate, this may be inaccurate

Seems stream 1 codec frame rate differs from container frame rate: 1000.00 (1000/1) -> 25.00 (25/1)
Input #0, asf, from '/Volumes/Untitled/saal1.wmv':
  Metadata:
    title           : 28th Chaos Communication Congress
    artist          : Chaos Computer Club e.V.
    copyright       : Licenced to the public under http://creativecommons.org/licenses/by-nc-nd/2.0/de/
    WMFSDKVersion   : 9.00.00.4509
    WMFSDKNeeded    : 0.0.0.0000
    IsVBR           : 0
  Duration: 00:04:23.78, start: 0.000000, bitrate: 1128 kb/s
    Stream #0.0(ger): Audio: wmav2, 48000 Hz, 2 channels, s16, 128 kb/s
    Stream #0.1(ger): Video: wmv3 (Complex), yuv420p, 720x576, 1000 kb/s, PAR 16:11 DAR 20:11, 25 tbr, 1k tbn, 1k tbc
[buffer @ 0x7fa83b4334e0] w:720 h:576 pixfmt:yuv420p tb:1/1000000 sar:16/11 sws_param:
[wmv3 @ 0x7fa83b83fc00] WMV3 Complex Profile is not fully supported
[wmv3 @ 0x7fa83b83fc00] Read 16 bits in overflow
Output #0, mp4, to 'output.mp4':
  Metadata:
    title           : 28th Chaos Communication Congress
    artist          : Chaos Computer Club e.V.
    copyright       : Licenced to the public under http://creativecommons.org/licenses/by-nc-nd/2.0/de/
    WMFSDKVersion   : 9.00.00.4509
    WMFSDKNeeded    : 0.0.0.0000
    IsVBR           : 0
    encoder         : Lavf52.110.0
    Stream #0.0(ger): Video: mpeg4, yuv420p, 720x576 [PAR 16:11 DAR 20:11], q=2-31, 200 kb/s, 25 tbn, 25 tbc
    Stream #0.1(ger): Audio: libfaac, 48000 Hz, 2 channels, s16, 64 kb/s
Stream mapping:
  Stream #0.1 -> #0.0
  Stream #0.0 -> #0.1
Press [q] to stop, [?] for help
[asf @ 0x7fa83b84ac00] ff asf bad header 30  at:48034257.72 bitrate= 300.5kbits/s
[asf @ 0x7fa83b84ac00] invalid padsize 36469 at:4803427
[asf @ 0x7fa83b84ac00] ff asf bad header e4  at:4811713
[asf @ 0x7fa83b84ac00] invalid packet_length -2025736568 at:4811718
[asf @ 0x7fa83b84ac00] ff asf bad header 2  at:4820295
[asf @ 0x7fa83b84ac00] packet_obj_size invalid
[asf @ 0x7fa83b84ac00] ff asf bad header b0  at:4829181
[asf @ 0x7fa83b84ac00] invalid padsize 46087 at:4829183
[asf @ 0x7fa83b84ac00] ignoring invalid packet_obj_size (18808 2319 17016 47923)
[asf @ 0x7fa83b84ac00] ignoring invalid packet_obj_size (21127 5217 17016 47923)
[asf @ 0x7fa83b84ac00] ignoring invalid packet_obj_size (26344 7966 17016 47923)
[asf @ 0x7fa83b84ac00] ignoring invalid packet_obj_size (34310 1514 17016 47923)
[asf @ 0x7fa83b84ac00] ignoring invalid packet_obj_size (35824 3036 3036 47923)
[asf @ 0x7fa83b84ac00] ignoring invalid packet_obj_size (38860 2876 2876 47923)
[asf @ 0x7fa83b84ac00] ignoring invalid packet_obj_size (41736 476 4056 47923)
[asf @ 0x7fa83b84ac00] ignoring invalid packet_obj_size (42212 3580 4056 47923)
[asf @ 0x7fa83b84ac00] ignoring invalid packet_obj_size (45792 1616 4122 47923)
[asf @ 0x7fa83b84ac00] freeing incomplete packet size 47923, new 4122
[asf @ 0x7fa83b84ac00] freeing incomplete packet size 4122, new 2415
Error while decoding stream #0.0    1096kB time=00:00:30.00 bitrate= 299.1kbits/s dup=0 drop=585