Description

Variable delay opcodes with high quality interpolation.

Syntax

aout1, aout2 vdelayxws ain1, ain2, adl, imd, iws [, ist]

Initialization

imd -- max. delay time (seconds)

iws -- interpolation window size (see below)

ist (optional) -- skip initialization if not zero

Performance

ain1, ain2 -- input audio signals

aout1, aout2 -- output audio signals

adl -- delay time in seconds

These opcodes use 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 vdelayxw opcodes change the position of the write tap in the delay line (unlike all other delay ugens that move the read tap), and are most useful for implementing Doppler effects where the position of the listener is fixed, and the sound source is moving.

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 use of the vdelayxws opcode. Play vdelayxws.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 vdelayxws.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

; by Menno Knevel 2022

sr = 44100
ksmps = 32
nchnls = 2
0dbfs  = 1

instr 1 

ims  =	.5						;maximum delay time in seconds
iws  =	512						;window size
adl  =	.5						;delay time
asig1, asig2 diskin2 "drumsSlp.wav", 1, 0, 1		;loop stereo file drumsSlp.wav
a2   poscil .2, .25  					;make an LFO, 4 cycle per 10 seconds
adl  = a2 + ims/2      					;offset the LFO so that it is positive
aoutL, aoutR vdelayxws asig1, asig2, adl, ims, iws	;use the LFO to control delay time
     outs aoutL * .8, aoutR * .8

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

i 1 0 11

e
</CsScore>
</CsoundSynthesizer> 

See Also

vdelayx, vdelayxq, vdelayxs, vdelayxw, vdelayxwq