If you want to play your AVI videos in your iPhone, iPod Touch or iPad, you must convert them to MP4 or H.264 format.
The following instruction is to let you convert your AVI video files to MP4 files.
1. You must have MPlayer and Mencoder. For more information about MPlayer and Mencoder, please refer Wikipedia at:
In Ubuntu, you can use install them as following command:
sudo apt-get install mplayer mencoder
2. If your AVI file is baby.avi and you want to create a MP4 called baby.mp4, you can type following command:
mencoder baby.avi -o baby.mp4 -oac copy -ovc lavc -lavcopts vcodec=mpeg1video -of mpeg
3. You can test the new MP4 file you just created using the MPlayer as below: