Short explanation of the whole thing

I have started using Gource to create movie files, which on its own only supports PPM output using a multi-image file.

Multi-image files are not supported by most ppm reading programs, they will just process the first image. For ffmpeg a sequence of individual files are needed.

I didn't find a program that worked well enough to process a multi-GB movie file, so I hacked up a perl script to separate the files.

For now this is pretty limited since it assumes fixed file names and doesn't process all pnm file types, this leaves some room for improvement.