[CM] Changing the playtime of a file with snd

[Bill Schottstaedt]

> I'd like to know if its possible to change the playtime
> of a file while keeping the pitch.

There are three built-in ways; the most robust is the "expand" control
in the control panel (it uses granular synthesis); the oldest is the
phase vocoder ("that old trick never works"); the best is rubber-sound
in rubber.scm, but it's slow and only works on "well-behaved" sounds.