expsegr — Trace a series of exponential segments between specified points including a release segment.
Trace a series of exponential segments between specified points including a release segment.
ares expsegr ia, idur1, ib [, idur2] [, ic] [...], irel, iz
kres expsegr ia, idur1, ib [, idur2] [, ic] [...], irel, iz
ia -- starting value. Zero is illegal for exponentials.
ib, ic, etc. -- value after dur1 seconds, etc. For exponentials, must be non-zero and must agree in sign with ia.
idur1 -- duration in seconds of first segment. A zero or negative value will cause all initialization to be skipped.
idur2, idur3, etc. -- duration in seconds of subsequent segments. A zero or negative value will terminate the initialization process with the preceding point, permitting the last-defined line or curve to be continued indefinitely in performance. The default is zero.
irel, iz -- duration in seconds and final value of a note releasing segment.
These units generate control or audio signals whose values can pass through 2 or more specified points. The sum of dur values may or may not equal the instrument's performance time: a shorter performance will truncate the specified pattern, while a longer one will cause the last-defined segment to continue on in the same direction.
expsegr is amongst the Csound “r” units that contain a note-off sensor and release time extender. When each senses an event termination or MIDI noteoff, it immediately extends the performance time of the current instrument by irel seconds, and sets out to reach the value iz by the end of that period (no matter which segment the unit is in). “r” units can also be modified by MIDI noteoff velocities. For two or more extenders in an instrument, extension is by the greatest period.
Here is an example of the expsegr opcode. It uses the files expsegr.orc and expsegr.sco.
Example 123. Example of the expsegr opcode.
/* expsegr.orc */ ; Initialize the global variables. sr = 44100 kr = 4410 ksmps = 10 nchnls = 1 ; Instrument #1. instr 1 ; p4 = frequency in pitch-class notation. kcps = cpspch(p4) ; Use an amplitude envelope with second-long release. kenv expsegr 0.01, p3/2, 1, p3/2, 0.01, 1, 1 kamp = kenv * 30000 a1 oscil kamp, kcps, 1 out a1 endin /* expsegr.orc */
/* expsegr.sco */ ; Table #1, a sine wave. f 1 0 16384 10 1 ; Make sure the score lasts for four seconds. f 0 4 ; p4 = frequency (in pitch-class notation). ; Play Instrument #1 for a half-second, p4=8.00 i 1 0 0.5 8.00 ; Play Instrument #1 for a half-second, p4=8.01 i 1 1 0.5 8.01 ; Play Instrument #1 for a half-second, p4=8.02 i 1 2 0.5 8.02 ; Play Instrument #1 for a half-second, p4=8.03 i 1 3 0.5 8.03 e /* expsegr.sco */