janis@janis-silent-pc:~/gnash$ ffmpeg -c:v rawvideo -i test2.raw
ffmpeg version git-2012-07-17-22a2795 Copyright (c) 2000-2012 the FFmpeg developers
  built on Jul 17 2012 16:02:54 with gcc 4.6.3
  configuration: --enable-gpl --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-librtmp --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-nonfree --enable-version3 --enable-x11grab --enable-libass
  libavutil      51. 65.100 / 51. 65.100
  libavcodec     54. 40.100 / 54. 40.100
  libavformat    54. 16.104 / 54. 16.104
  libavdevice    54.  1.100 / 54.  1.100
  libavfilter     3.  2.100 /  3.  2.100
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0. 15.100 /  0. 15.100
  libpostproc    52.  0.100 / 52.  0.100
[rawvideo @ 0x23db9c0] Pixel format was not specified and cannot be detected
    Last message repeated 1 times
[image2 @ 0x23d51c0] Stream #0: not enough frames to estimate rate; consider increasing probesize
[image2 @ 0x23d51c0] Could not find codec parameters (Video: rawvideo)
test2.raw: could not find codec parameters