QTCoffee is a set of command-line Mac OS X utilities for manipulating QuickTime movies and other QuickTime readable media (AVIs, MPEGs, as well as audio files such as MP3s and AACs).
* Joining (concatenating) movies or audio files, so they play one after the other, with special support for pass-through joining of MPEG-4 video and AAC audio to MPEG-4 files.
* Multiplexing of movies so they play at the same time. Useful for:
o Putting together audio and video tracks from other utilities
o Masking unwanted (noisy) parts of a video
o Letterboxing content
o Picture-in-picture effect
o Watermarking video
* Scaling movie tracks (for resizing video content)
* Changing the playback rate of movies or audio
* Extracting or removing tracks
* Extracting or removing chapters
* Splitting a movie into equal duration pieces or at specified times
* Splitting a movie into individual chapters
* Creating chapters or connecting chapter tracks and creating chapter files for AAC podcasts to be processed with Apple's ChapterTool