How to convert avi to flv in Linux.I did a couple of tests and these are the results that Ive come up with.Needless to say that I am no expert,they are personal opinions,see them as a starting point.

In the examples we will convert “.avi” to “.flv”,and simply copy the sound.

A typical command, then, would be:

explanation:
ffmpeg the program
-i input.avi the input file
-b 1024k the output bitrate
-s 320×240 the output resolution
-r 25 the output frames per second
-acodec copy the output audio codec
movie_1024_320_25_.flv the output file

via How to convert avi to flv in Linux – Liveleak Forums.