FFmpeg version SVN-r8404, Copyright (c) 2000-2007 Fabrice Bellard, et al.
  configuration:  --enable-shared --enable-mp3lame --enable-faad --enable-gpl
  libavutil version: 49.3.0
  libavcodec version: 51.38.0
  libavformat version: 51.10.0
  built on Mar 14 2007 03:21:42, gcc: 4.1.1 20070105 (Red Hat 4.1.1-51)

Seems stream 1 codec frame rate differs from container frame rate: 1000.00 (1000/1) -> 30.00 (30/1)
Input #0, asf, from '21102.wmv':
  Duration: 00:03:11.0, start: 5.000000, bitrate: 167 kb/s
  Stream #0.0: Audio: wmav2, 44100 Hz, stereo, 112 kb/s
  Stream #0.1: Video: WVP2 / 0x32505657, 640x480, 30.00 fps(r)
Output #0, flv, to '21102.flv':
  Stream #0.0: Video: flv, yuv420p, 640x480, q=2-31, 400 kb/s, 30.00 fps(c)
  Stream #0.1: Audio: mp3, 44100 Hz, stereo, 64 kb/s
Stream mapping:
  Stream #0.1 -> #0.0
  Stream #0.0 -> #0.1
Unsupported codec (id=0) for input stream #0.1