wavdraw is a nice utility written on top of btprnt that draws a waveform of a mono wav file.

wavdraw exists as both a standalone commandline interface and as a janet function.

to use the CLI:

monolith wavdraw in.wav out.pbm

This will generate a file called out.pbm.

The pbm file format can then be converted to png using ImageMagick:

convert out.pbm out.png

The woven source code for this program can be found at wavdraw.c.

Someday, words for using wavdraw in Janet will exist here.