Video Format Conversion
The program ffmpeg has been depricated, use avconv instead.
Find video information
$ mplayer -vo null -ao null -identify -frames 0 filename.avi
$ ffmpeg -i filename.avi
$ tcprobe -i filename.avi
Find ffmpeg codecs
$ ffmpeg -codecs
Older version of ffmpeg, use -formats. This also works in newer version, but gives confusing results.
$ ffmpeg -formats
Convert file types
This is real simple and only needs one line.
$ ffmpeg -i filename.ext -ab <audio bitrate> -b <video bitrate> -s <change to what you want ex.320x240> filename.ext
The two .ext extensions should obviously be different. Also, the new size -s could be whatever you want.
To keep the size the same but just convert.
$ ffmpeg -i InputFile.avi -ab <audio bitrate> -b <video bitrate> -vcodec mpeg4 OutputFile.mp4