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locsend

Distributes the audio signals of a previous locsig opcode.

The number of output signals must match the number in the previous locsig. The output signals from locsend are derived from the values given for distance and reverb in the locsig and are ready to be sent to local or global reverb units (see example below). The reverb amount and the balance between the 2 or 4 channels are calculated in the same way as described in the Dodge book (an essential text!).

Syntax

a1, a2 locsend
a1, a2,  a3, a4 locsend

Examples

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  asig some audio signal
  kdegree            line    0, p3, 360
  kdistance          line    1, p3, 10
  a1, a2, a3, a4     locsig  asig, kdegree, kdistance, .1
  ar1, ar2, ar3, ar4 locsend
  ga1 = ga1+ar1
  ga2 = ga2+ar2
  ga3 = ga3+ar3
  ga4 = ga4+ar4
                     outq    a1, a2, a3, a4
endin

instr 99 ; reverb instrument
  a1                 reverb2 ga1, 2.5, .5
  a2                 reverb2 ga2, 2.5, .5
  a3                 reverb2 ga3, 2.5, .5
  a4                 reverb2 ga4, 2.5, .5
                     outq    a1, a2, a3, a4
  ga1=0
  ga2=0
  ga3=0
  ga4=0

In the above example, the signal, asig, is sent around a complete circle once during the duration of a note while at the same time it becomes more and more “distant” from the listeners' location. locsig sends the appropriate amount of the signal internally to locsend. The outputs of the locsend are added to global accumulators in a common Csound style and the global signals are used as inputs to the reverb units in a separate instrument. For an example, see locsig.

locsig is useful for quad and stereo panning as well as fixed placed of sounds anywhere between two loudspeakers. Below is an example of the fixed placement of sounds in a stereo field. It uses the file locsend_stereo.csd.

Example of the locsend opcode.
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<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 locsend_stereo.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

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

ga1 init 0
ga2 init 0

instr 1

krevsend  = p4
aout      diskin2 "drumsMlp.wav", 1, 0, 1
kdegree   line 0, p3, 180 ;left to right
kdistance line 1, p3, 30
a1, a2    locsig aout, kdegree, kdistance, p4
ar1, ar2  locsend
ga1 = ga1+ar1
ga2 = ga2+ar2
          outs a1, a2

endin

instr 99 ; reverb instrument
a1      reverb2 ga1, 2.5, .5
a2      reverb2 ga2, 2.5, .5
        outs    a1, a2
ga1 = 0
ga2 = 0

endin
</CsInstruments>
<CsScore>
; sine wave.
f 1 0 16384 10 1

i 1 0 4 .1      ;with reverb
i 1 + 4 0       ;no reverb
i99 0 7
e
</CsScore>
</CsoundSynthesizer>

A few notes:

;place the sound in the left speaker and near:
i1 0 1 0 1

;place the sound in the right speaker and far:
i1 1 1 90 25

;place the sound equally between left and right and in the middle ground distance:
i1 2 1 45 12
e

The next example shows a simple intuitive use of the distance value to simulate Doppler shift. The same value is used to scale the frequency as is used as the distance input to locsig.

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kdistance          line    1, p3, 10
kfreq = (ifreq * 340) / (340 + kdistance)
asig               oscili  iamp, kfreq, 1
kdegree            line    0, p3, 360
a1, a2, a3, a4     locsig  asig, kdegree, kdistance, .1
ar1, ar2, ar3, ar4 locsend

See also

Panning and Spatialization: Amplitude spatialization

Credits

Author: Richard Karpen
Seattle, WA USA
1998

New in Csound version 3.48