Description

Variable delay opcodes with high quality interpolation.

Syntax

aout vdelayxw ain, adl, imd, iws [, ist]

Initialization

imd -- max. delay time (seconds)

iws -- interpolation window size (see below)

ist (optional) -- skip initialization if not zero

Performance

aout -- output audio signal

ain -- input audio signal

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.

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 vdelayxw opcode. It uses the file vdelayxw.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 vdelayxw.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

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

instr 1 

ims  =	.5				;maximum delay time in seconds
iws  =	1024				;best quality
adl  =	.5				;delay time
asig diskin2 "flute.aiff", .5, 0, 1	;loop flute.aiff at half speed
a2   poscil3 .2, .1, 1			;make an LFO, 1 cycle per 2 seconds
adl  = a2 + ims/2      			;offset the LFO so that it is positive
aout vdelayxw asig, adl, ims, iws	;use the LFO to control delay time
     outs aout, aout

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

i 1 0 10

e
</CsScore>
</CsoundSynthesizer> 

See Also

vdelayx, vdelayxq, vdelayxs, vdelayxwq, vdelayxws