sndloop — A sound looper with pitch control.
This opcode records input audio and plays it back in a loop with user-defined duration and crossfade time. It also allows the pitch of the loop to be controlled, including reversed playback.
asig -- output sig
krec -- 'rec on' signal, 1 when recording, 0 otherwise
kpitch -- pitch control (transposition ratio); negative values play the loop back in reverse
ktrig -- trigger signal: when 0, processing is bypassed. When switched on (ktrig >= 1), the opcode starts recording until the loop memory is full. It then plays the looped sound until it is switched off again (ktrig = 0). Another recording can start again with ktrig >= 1.
Here is an example of the sndloop opcode. It uses the file sndloop.csd.
Example 997. Example of the sndloop 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 -odac ;;;realtime audio out ;-iadc ;;;uncomment -iadc if realtime audio input is needed too ; For Non-realtime ouput leave only the line below: ; -o sndloop.wav -W ;;; for file output any platform </CsOptions> <CsInstruments> sr = 44100 ksmps = 32 0dbfs = 1 nchnls = 2 instr 1 itrig = p4 asig diskin2 "drumsMlp.wav", 1, 0, 1 ;get the signal in, loop it ktrig line 0, itrig, 1 ;when to trigger signal = p4 kpitch line 1.2, p3, .5 ;vary pitch of recorded signal aout,krec sndloop asig, kpitch, ktrig, .4, 0.05 ;rec starts at p4 sec, for .4 secs and 0.05 crossfade printk2 krec ; prints the recording signal outs aout, aout endin </CsInstruments> <CsScore> i1 0 5 .5 ;trigger in seconds (=p4) i1 + 5 .8 i1 + 10 1.2 e </CsScore> </CsoundSynthesizer>
The example above shows the basic operation of sndloop. Pitch can be controlled at the k-rate, recording is started as soon as the trigger value is >= 1. Recording can be restarted by making the trigger 0 and then 1 again.