vcomb
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## vcomb

vcomb — Variably reverberates an input signal with a “colored” frequency response.

## Description

Variably reverberates an input signal with a “colored” frequency response.

## Syntax

    ares vcomb asig, krvt, xlpt, imaxlpt [, iskip] [, insmps]

## Initialization

imaxlpt -- maximum loop time for klpt

iskip (optional, default=0) -- initial disposition of delay-loop data space (cf. reson). The default value is 0.

insmps (optional, default=0) -- delay amount, as a number of samples.

## Performance

krvt -- the reverberation time (defined as the time in seconds for a signal to decay to 1/1000, or 60dB down from its original amplitude).

xlpt -- variable loop time in seconds, same as ilpt in comb. Loop time can be as large as imaxlpt.

This filter reiterates input with an echo density determined by loop time xlpt. The attenuation rate is independent and is determined by krvt, the reverberation time (defined as the time in seconds for a signal to decay to 1/1000, or 60dB down from its original amplitude). Output will appear only after ilpt seconds.

## Examples

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

Example 1171. Example of the vcomb 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
    ; Audio out   Audio in
    -odac           -iadc       -M0 ;;;RT audio I/O with MIDI in
    </CsOptions>
    <CsInstruments>

    ; Example by Jonathan Murphy and Charles Gran 2007
      sr	    =  44100
      ksmps	    =  10
      nchnls    =  2

            ; new, and important. Make sure that midi note events are only
            ; received by instruments that actually need them.

    	; turn default midi routing off
    	massign		0, 0
    	; route note events on channel 1 to instr 1
    	massign		1, 1

    ; Define your midi controllers
    #define C1 #21#
    #define C2 #22#
    #define C3 #23#

    ; Initialize MIDI controllers
    	    initc7    1, $C1, 0.5 		  ;delay send
    	    initc7    1, $C2, 0.5 		  ;delay: time to zero
    	    initc7    1, $C3, 0.5 		  ;delay: rate

      gaosc	    init      0

    ; Define an opcode to "smooth" the MIDI controller signal
        opcode smooth, k, k
      kin       xin
      kport	    linseg    0, 0.0001, 0.01, 1, 0.01
      kin       portk     kin, kport
                xout      kin
        endop

    instr   1
     ; Generate a sine wave at the frequency of the MIDI note that triggered the intrument
      ifqc	    cpsmidi
      iamp	    ampmidi   10000
      aenv	    linenr    iamp, .01, .1, .01 	  ;envelope
      a1	    oscil     aenv, ifqc, 1
    ; All sound goes to the global variable gaosc
      gaosc	    =  gaosc + a1
        endin

        instr     198 ; ECHO
      kcmbsnd   ctrl7     1, $C1, 0, 1 		  ;delay send
      ktime	    ctrl7     1, $C2, 0.01, 6 		  ;time loop fades out
      kloop	    ctrl7     1, $C3, 0.01, 1 		  ;loop speed
    ; Receive MIDI controller values and then smooth them
      kcmbsnd   smooth    kcmbsnd
      ktime	    smooth    ktime
      kloop	    smooth    kloop
      imaxlpt   =  1 				  ;max loop time
    ; Create a variable reverberation (delay) of the gaosc signal
      acomb	    vcomb     gaosc, ktime, kloop, imaxlpt, 1
      aout	    =  (acomb * kcmbsnd) + gaosc * (1 - kcmbsnd)
    	    outs      aout, aout
      gaosc	    =  0
        endin

    </CsInstruments>

    <CsScore>
    f1 0 16384 10 1
    i198 0 10000
    e
    </CsScore>
    </CsoundSynthesizer>

## See also

Reverberation

## Credits

Author: William “Pete” Moss
University of Texas at Austin
Austin, Texas USA
January 2002

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