This is a VST plugin (PC only) by Tobybear (www.tobybear.de) and
Bram (www.smartelectronix.com) with full Delphi source included!
It is available on Bram's truly excellent DSP source code page
What does it do?
Well, as Bram puts it: it is a "ultrafast and lofi pitchshifter", where the pitch of the audio is changed in realtime while the
tempo is preserved.
You can adjust the pitch in semitones (+/- 24 semitones) and
with finetuning. Furthermore a delay line with feedback is
included and the obligatory LP/HP filter with resonance!
Extra special feature: you can use MIDI note messages to pitch
the audio in realtime up or down, relatively to a root key.
Furthermore a randomizer, dry/wet and output adjustments enhance
the fun :-)