What's the best way to control the speed of playback from a soundfile? I want to have two channels of the same soundfile, one playing slightly slower than the other so that they get increasingly out of synch.

Depends on how long the files are. If they're under about 5 minutes (I think) you can load them into tables using [soundfiler], making sure to use the -resize flag and, if they're over about 90 seconds, the -maxsize flag with a large enough table size as its argument. -maxsize has a hard-coded limit, though, and I'm pretty sure it amounts to about 5 minutes. Then play them back with separate [vline~]s, one lasting longer than the other.

If they're longer than that (or even not, of course), then you could play them back with [readsf~] and delay one channel using a [delread~] and [vd~] pair. Then just slowly increase the delay length of [vd~] using [vline~].

Thanks Maelstorm, I'll give that a try and let you know.