[CM] Snd and envelopes

Richard Liston liston@cc.gatech.edu
Mon, 15 Mar 2004 15:36:27 -0500

Question 2:

I create a simple sound:

(with-sound ()
  (scm-simp 0 3 660 .2)
  (scm-simp 0 3 440 .8))

Now, I'd like to get rid of the initial and ending pops when
the sound plays by applying a quick ramp up and ramp down
envelope. If I define an envelope like this,

(define e '(0 0 .001 1 .999 1 1 0))

I don't get fine-grained control over how much the waveform is
tapered at the start and end --- it seems to me that the amount
of taper depends on the length of the sound, no? My question is
how do I create and apply an envelope that will cause a sound
of any length to ramp up in a fixed amount of time - say, .05 sec
- at the beginning and ramp down in a fixed amount of time at
the end?