Once again I'm meddling around with trying to create animation on youtube directly from a directory full of (procedurally generated) .png files. After looking around various internet things for how to use ffmpeg to get good quality for crisp, stereotypical .png-ish sort of images, I did:

$  ffmpeg -i audio.mp3 -r 24  -i /tmp/frames/%5d.png -vb 20M myvideo.mpg

and got quite tolerable results: