Description

A 4-channel variable delay opcode with high quality interpolation.

Syntax

aout1, aout2, aout3, aout4 vdelayxq ain1, ain2, ain3, ain4, adl, imd, iws [, ist]

Initialization

imd -- max. delay time (seconds)

iws -- interpolation window size (see below)

ist (optional) -- skip initialization if not zero

Performance

aout1, aout2, aout3, aout4 -- output audio signals.

ain1, ain2, ain3, ain4 -- input audio signals.

adl -- delay time in seconds

This opcode uses high quality (and slow) interpolation, that is much more accurate than the currently available linear and cubic interpolation. The iws parameter sets the number of input samples used for calculating one output sample (allowed values are any integer multiply of 4 in the range 4 - 1024); higher values mean better quality and slower speed.

The multichannel opcodes (eg. vdelayxq) allow delaying 2 or 4 variables at once (stereo or quad signals); this is much more efficient than using separate opcodes for each channel.

Notes

Delay time is measured in seconds (unlike in vdelay and vdelay3), and must be a-rate. The minimum allowed delay is iws/2 samples. Using the same variables as input and output is allowed in these opcodes. In vdelayxw*, changing the delay time has some effects on output volume: a = 1 / (1 + dt) where a is the output gain, and dt is the change of delay time per seconds. These opcodes are best used in the double-precision version of Csound.

Examples

Here is an example of the vdelayxq opcode. It uses the file vdelayxq.csd.

<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 vdelayxq.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

sr = 44100
ksmps = 32
nchnls = 4
0dbfs  = 1

instr 1 

ims   =	.5						;maximum delay time in seconds
iws   =	1024						;window size
adl   =	.5
aout1  diskin2 "drumsMlp.wav", 1, 0, 1			;loop drumsMlp.wav
aout2  diskin2 "fox.wav", 1, 0, 1			;loop fox.wav
aout3  diskin2 "Church.wav", 1, 0, 1			;loop Church.wav
aout4  diskin2 "flute.aiff", 1, 0, 1			;loop flute.aiff
a2    poscil .1, .5, 1					;make an LFO, 1 cycle per 2 seconds
adl   = a2 + ims/2      				;offset the LFO so that it is positive
aout1, aout2, aout3, aout4 vdelayxq aout1, aout2, aout3, aout4, adl, ims, iws; Use the LFO to control delay time
      outq aout1, aout2, aout3, aout4

endin
</CsInstruments>
<CsScore>
f1 0 8192 10 1

i 1 0 10 

e
</CsScore>
</CsoundSynthesizer> 

Two important points here. First, the delay time must be always positive. And second, even though the delay time can be controlled in k-rate, it is not advised to do so, since sudden time changes will create clicks.

See also

Delay