These C files are quick little Cairo applications used to generate
images for the various animations in the Xiph Episode II video
"Digital Show & Tell".  Each one generates a series of PNG images that
are then stitched together into an animation using a utility like
ffmpeg or mplayer, or an editor like Cinelerra.

Compile each with the commandline:

gcc inname.c -o outname -lm -lcairo -lfftw3f

ch4-samplequant.c also requires the 'squishyio' library from Xiph.org
SVN and the commandline:

gcc ch4-samplequant.c -o ch4-samplequant -lm -lcairo -lfftw3f -lsquishyio

The source is mostly cut-and-paste spaghetti of the worst kind.
However, it wasn't intended to be used at any point in the future,
just spit out some images and done.  So... point and laugh if you
like, but try not to rupture anything.  It's not worth it!