<- C I ->
Toot Contents

Toot 2: "P-Fields"

The first instrument was not interesting because it could play only one note at one amplitude level. We can make things more interesting by allowing the pitch and amplitude to be defined by parameters in the score. Each column in the score constitutes a parameter field, numbered from the left. The first three parameter fields of the i-statement have a reserved function:
  p1 = instrument number
  p2 = start time
  p3 = duration
All other parameter fields are determined by the way the sound designer defines his instrument. In the instrument below, the oscillator's amplitude argument is replaced by p4 and the frequency argument by p5. Now we can change these values at i-time, i.e. with each note in the score. The orchestra and score files now look like:
  instr   2
    a1    oscil     p4, p5, 1         ; p4=amp
          out       a1                ; p5=freq
  endin


      f1     0     4096   10    1     ; sine wave
; instrument   start  duration    amp(p4)   freq(p5)
      i2       0      1          2000       880
      i2       1.5    1          4000       440
      i2       3      1          8000       220
      i2       4.5    1         16000       110
      i2       6      1         32000       55
e
<- C I ->
Toot Contents
Prepared from the MIT Media Lab Csound Manual, PJN, Nov 1994.