Record Your Desktop With recordMyDesktop, Part 2 - page 3
Recording From a Microphone
recordMyDesktop uses only Ogg Theora for video encoding, Ogg Vorbis for audio, and it's probably going to stay that way. There are Ogg clients for all platforms, but there will probably be situations that require you to convert to another format such as AVI or MPEG4. AVI, like Ogg, isn't a single codec, but a container for multiple audio and video codecs.
mencoder, which comes with MPlayer, is a good conversion tool with hundreds of options for manipulating your movies. This is a simple way to convert a video file with no audio:
$ mencoder videofile.ogg -ovc lavc -o videofile.aviIf it has an audio track, try this:
$ mencoder videofile.ogg -ovc lavc -oac lavc -o videofile.avivideofile.ogg is your source file that you want to convert, and videofile.avi is the final, converted file. lavc, by default, converts Ogg Vorbis to MP3 format. ovc means "output video codec". oac is "output audio codec". lavc selects the libavcodec codecs for high video quality. You may also select other codecs--run mencoder -oac help and mencoder -ovc help to see your options.
If you need to resize your video, mencoder can do that too. For example, YouTube shrivels everything down to 320x240. The mencoder option is -vf scale=320:240.