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Toot 3: Envelopes

Although in the second instrument we could control and vary the overall amplitude from note to note, it would be more musical if we could contour the loudness during the course of each note. To do this we'll need to employ an additional unit generator linen, which the Csound reference manual defines as follows:
   kr   linen     kamp, irise, idur, idec
   ar   linen     xamp, irise, idur, idec
linen is a signal modifier, capable of computing its output at either control or audio rates. Since we plan to use it to modify the amplitude envelope of the oscillator, we'll choose the latter version. Three of linen's arguments expect i-rate variables. The fourth expects in one instance a k-rate variable (or anything slower), and in the other an x-variable (meaning a-rate or anything slower). Our linen we will get its amp from p4.

The output of the linen (k1) is patched into the kamp argument of an oscil. This applies an envelope to the oscil. The orchestra and score files now appear as:

   instr 3 
     k1   linen   p4, p6, p3, p7 ; p4=amp
     a1   oscil   k1, p5, 1      ; p5=freq
          out     a1             ; p6=attack time
   endin                         ; p7=release time


   f1  0  4096  10  1                        ; sine wave 
;instr  start  duration  amp(p4)  freq(p5)  attack(p6)  release(p7)
   i3     0     1        10000     440       .05         .7
   i3     1.5   1        10000     440       .9          .1
   i3     3     1         5000     880       .02         .99
   i3     4.5   1         5000     880       .7          .01
   i3     6     2        20000     220       .5          .5
 e

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Prepared from the MIT Media Lab Csound Manual, PJN, Nov 1994.