Some wonderful OSX tools to manipulate and convert audio/video.
Audacity - Open Source audio editor
Gimp - Open Source graphic editor
ffmpeg - Open Source audio/video conversion software
iFFMPEG - GUI front end to OSX version of ffmpeg (Video Conversion)
iMediaHUD - Free utility to see the specs of AV files
Mpeg Streamclip - Converter (supports many formats)
VLC - Media player that can also transcode and convert in many formats
Handbrake - Rip DVD's to MP4, directly into iPod/iPhone formats as well as others.
All the above utilities are free. You can download them and use them to perform many tasks. Mpeg Streamclip also includes a "Save as AVI" quicktime component. I use all these utilities on a regular basis when I need to convert video into different formats for our video needs.
