adsr
adsr — Calculates the classical ADSR envelope using linear segments.
Initialization
iatt -- duration of attack phase
idec -- duration of decay
islev -- level for sustain phase
irel -- duration of release phase
idel -- period of zero before the envelope starts
Performance
The envelope is the range 0 to 1 and may need to be scaled further. The envelope may be described as:
Picture of an ADSR envelope.
The length of the sustain is calculated from the length of the note. This means adsr is not suitable for use with MIDI events. The opcode madsr uses the linsegr mechanism, and so can be used in MIDI applications.
adsr is new in Csound version 3.49.
Examples
Here is an example of the adsr opcode. It uses the file adsr.csd.
Example 28. Example of the adsr opcode.
See the sections Real-time Audio and Command Line Flags for more information on using command line flags.
<CsoundSynthesizer> <CsOptions> ; Select audio/midi flags here according to platform ; Audio out Audio in No messages -odac -iadc -d ;;;RT audio I/O ; For Non-realtime ouput leave only the line below: ; -o adsr.wav -W ;;; for file output any platform </CsOptions> <CsInstruments> ; Initialize the global variables. sr = 44100 kr = 4410 ksmps = 10 nchnls = 1 ; Instrument #1 - a simple instrument. instr 1 ; Set the amplitude. kamp init 20000 ; Get the frequency from the fourth p-field. kcps = cpspch(p4) a1 vco kamp, kcps, 1 out a1 endin ; Instrument #2 - instrument with an ADSR envelope. instr 2 iatt = 0.05 idec = 0.5 islev = 0.08 irel = 0.008 ; Create an amplitude envelope. kenv adsr iatt, idec, islev, irel kamp = kenv * 20000 ; Get the frequency from the fourth p-field. kcps = cpspch(p4) a1 vco kamp, kcps, 1 out a1 endin </CsInstruments> <CsScore> ; Table #1, a sine wave. f 1 0 16384 10 1 ; Set the tempo to 120 beats per minute. t 0 120 ; Play a melody with Instrument #1. ; p4 = frequency in pitch-class notation. i 1 0 1 8.04 i 1 1 1 8.04 i 1 2 1 8.05 i 1 3 1 8.07 i 1 4 1 8.07 i 1 5 1 8.05 i 1 6 1 8.04 i 1 7 1 8.02 i 1 8 1 8.00 i 1 9 1 8.00 i 1 10 1 8.02 i 1 11 1 8.04 i 1 12 2 8.04 i 1 14 2 8.02 ; Repeat the melody with Instrument #2. ; p4 = frequency in pitch-class notation. i 2 16 1 8.04 i 2 17 1 8.04 i 2 18 1 8.05 i 2 19 1 8.07 i 2 20 1 8.07 i 2 21 1 8.05 i 2 22 1 8.04 i 2 23 1 8.02 i 2 24 1 8.00 i 2 25 1 8.00 i 2 26 1 8.02 i 2 27 1 8.04 i 2 28 2 8.04 i 2 30 2 8.02 e </CsScore> </CsoundSynthesizer>