LOCSIG, LOCSEND

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locsig, locsend

a1, a2 locsig asig, kdegree, kdistance, kreverbsend

a1, a2, a3, a4 locsig asig, kdegree, kdistance, kreverbsend

a1, a2 locsend

a1, a2, a3, a4 locsend

DESCRIPTION

locsig takes an input signal and distributes it among 2 or 4 channels using values in degrees to calculate the balance between adjacent channels. It also takes arguments for distance (used to attenuate signals that are to sound as if they are some distance further than the loudspeaker itself), and for the amount the signal that will be sent to reverberators. This unit is based upon the example in the Charles Dodge/Thomas Jerse book, "Computer Music," page 320.

locsend depends upon the existence of a previously defined locsig. 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!).

PERFORMANCE

kdegree - value between 0 and 360 for placement of the signal in a 2 or 4 channel space configured as: a1=0, a2=90, a3=180, a4=270 (kdegree=45 would balanced the signal equally between a1 and a2). locsig maps kdegree to sin and cos functions to derive the signal balances (ie.: asig=1, kdegree=45, a1=a2=.707).

kdistance - value >= 1 used to attenuate the signal and to calculate reverb level to simulate distance cues. As kdistance gets larger the sound should get softer and somewhat more reverberant (assuming the use of locsend in this case).

kreverbsend - the percentage of the direct signal that will be factored along with the distance and degree values to derive signal amounts that can be sent to a reverb unit such as reverb, or reverb2.

EXAMPLE:

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.

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.

instr 1
...
a1, a2 locsig asig, p4, p5, .1
ar1, ar2 locsend

    ga1        =          ga1+ar1
    ga2        =          ga2+ar2
               outs       a1, a2
endin

instr 99 ; reverb....
....
endin

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.

     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

AUTHOR:

Richard Karpen
Seattle, Wash.
1998

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