here is a rewrite of an AU plugin that i made a few years back. it is called buffer reverser and it pretty much just does what the name implies. it takes incoming audio and records it into a pair buffers. once one is full it plays what it recorded backwards while the next buffer begins recording in order to keep the cycle going. there is a crossfader so that you can mix between the original and the reversed signal and a drop down menu so that you can choose between full speed and half time playback.
in order to use buffer reverser you’ll need to download + install sonicbirth (it is free but mac only, sorry windows people) and then drop the buffer reverser into the folder where you normally keep your audio units.
special thanks to brian for sending me a copy of the original one that i built years ago so that i could be reminded of how the guts worked the first time.
hope some of you find it useful.
buffer reverser AU (.zip)
(updated: i added a volume slider for the reversed signal and fixed a few things with waveform display)