Description

Tap a delay line at variable offset times.

Syntax

ares deltapn xnumsamps

Performance

xnumsamps -- specifies the tapped delay time in number of samples. Each can range from 1 control period to the full delay time of the read/write pair; however, since there is no internal check for adherence to this range, the user is wholly responsible. Each argument can be a constant, a variable, or a time-varying signal.

deltapn is identical to deltapi, except delay time is specified in number of samples, instead of seconds (Hans Mikelson).

This opcode can tap into a delayr/delayw pair, extracting delayed audio from the idlt seconds of stored sound. There can be any number of deltap and/or deltapi units between a read/write pair. Each receives an audio tap with no change of original amplitude.

This opcode can provide multiple delay taps for arbitrary delay path and feedback networks. They can deliver either constant-time or time-varying taps, and are useful for building chorus effects, harmonizers, and Doppler shifts. Constant-time delay taps (and some slowly changing ones) do not need interpolated readout; they are well served by deltap. Medium-paced or fast varying dlt's, however, will need the extra services of deltapi.

delayr/delayw pairs may be interleaved. To associate a delay tap unit with a specific delayr unit, it not only has to be located between that delayr and the appropriate delayw unit, but must also precede any following delayr units. See Example 2. (This feature added in Csound version 3.57 by Jens Groh and John ffitch).

N.B. k-rate delay times are not internally interpolated, but rather lay down stepped time-shifts of audio samples; this will be found quite adequate for slowly changing tap times. For medium to fast-paced changes, however, one should provide a higher resolution audio-rate timeshift as input.

Examples

Here is an example of the deltapn opcode. Play deltapn.csd

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-odac     ;;;RT audio out
;-iadc    ;;;uncomment -iadc if RT audio input is needed too
; For Non-realtime ouput leave only the line below:
; -o deltap3.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

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

gasig  init 0   
gidel  = 1		;delay time in seconds
                                                             
instr 1
	
ain  pluck .7, 440, 1000, 0, 1
     outs ain, ain

vincr gasig, ain	;send to global delay
endin

instr 2	

ifeedback = p4	

abuf2	delayr	gidel
adelL 	deltapn	4000		;first tap (on left channel)
adelM 	deltapn	44100		;second tap (on middle channel)
	delayw	gasig + (adelL * ifeedback)

abuf3	delayr	gidel
kdel	line    100, p3, 1	;vary delay time
adelR 	deltapn  100 * kdel	;one pitch changing tap (on the right chn.)
	delayw	gasig + (adelR * ifeedback)
;make a mix of all deayed signals	
	outs	adelL + adelM, adelR + adelM

clear	gasig
endin

</CsInstruments>
<CsScore>

i 1 0 1
i 1 3 1
i 2 0 3  0	;no feedback
i 2 3 8 .8	;lots of feedback
e
</CsScore>
</CsoundSynthesizer>

See Also

deltap, deltap3, deltapi