[MEncoder-users] How to convert from uncompressed yuv420 video to rgb 24?

[gerlos]

Hello everyone!
I captured  many uncompressed videos (tens of GBs) from my webcam for
astronomical processing.
The format is YUV420, but my processing software doesn't understand this
format, and need rgb24, so I need a way (possibly an automatic
way) to convert all these files.

Reading the documentation it seems to me that it's possible with
mencoder, but so far I couldn't find how... any clue?

Here's what ffmpeg says about one of my videos:
$ ffmpeg -i test_20090222_1645_018.avi
FFmpeg version SVN-r14161, Copyright (c) 2000-2008 Fabrice Bellard, et al.
  configuration: --prefix=/usr --enable-shared --libdir=/usr/lib
--shlibdir=/usr/lib --incdir=/usr/include --enable-liba52
--enable-postproc --enable-gpl --enable-pthreads --enable-libnut
--enable-libtheora --enable-libvorbis --enable-x11grab --enable-swscale
--enable-libmp3lame --enable-libfaad --enable-libfaac --enable-libx264
--enable-libxvid
  libavutil version: 49.7.0
  libavcodec version: 51.60.0
  libavformat version: 52.17.0
  libavdevice version: 52.0.0
  built on Jan 16 2009 00:30:15, gcc: 4.3.2
Input #0, avi, from 'test_20090222_1645_018.avi':
  Duration: 00:00:05.00, start: 0.000000, bitrate: 25806 kb/s
    Stream #0.0: Video: rawvideo, yuv420p, 640x480,  7.00 tb(r)
Must supply at least one output file


I'm sorry for the maybe silly question, but I'm a newbie and searching
google didn't help...

Thanks in advance for your attention
regards
gerlos