SuperCollider CLASSES (extension)

VBAP
ExtensionExtension

Vector Base Amplitude Panner

Description

An implementation of Vector Base Amplitude Panning.1 This allows for equal power panning of a source over an arbitrary array of equidistant speakers. Normally this would be a ring, a dome, or partial dome.

VBAP was created by Ville Pulkki. For more information on VBAP see http://www.acoustics.hut.fi/research/cat/vbap/

Class Methods

*ar (numChans, in, bufnum, azimuth: 0, elevation: 1, spread: 0)

*kr (numChans, in, bufnum, azimuth: 0, elevation: 1, spread: 0)

Arguments:

numChans

The number of output channels.

in

The signal to be panned.

bufnum

A Buffer or its bufnum containing data calculated by an instance of VBAPSpeakerArray. Its number of channels must correspond to numChan above.

azimuth

+/- 180 degrees from the median plane (i.e. straight ahead)

elevation

+/- 90 degrees from the azimuth plane.

spread

A value from 0-100. When 0, if the signal is panned exactly to a speaker location the signal is only on that speaker. At values higher than 0, the signal will always be on more than one speaker. This can smooth the panning effect by making localisation blur more constant.

Inherited class methods

Instance Methods

Inherited instance methods

Examples

Server.default = s = Server.internal;
// 2D
a = VBAPSpeakerArray.new(2, [0, 45, 90, 135, 180, -135, -90, -45]); // 8 channel ring

a.speakers[1].dump;

b = a.loadToBuffer;

(
x = { |azi = 0, ele = 0, spr = 0|
VBAP.ar(8, PinkNoise.ar(0.2), b.bufnum, azi, ele, spr);
}.scope;
)

// test them out
{[45, 90, 135, 180, -135, -90, -45, 0].do({|ang| x.set(\azi, ang); 1.wait; }) }.fork;

// try the spread
x.set(\spr, 20);
x.set(\spr, 100); // all speakers

x.free; b.free;

// 3D
a = VBAPSpeakerArray.new(3, [[-22.5, 14.97], [22.5, 14.97], [-67.5, 14.97], [67.5, 14.97], [-112.5, 14.97], [112.5, 14.97], [-157.5, 14.97], [157.5, 14.97], [-45, 0], [45, 0], [-90, 0], [90, 0], [-135, 0], [135, 0], [0, 0], [180, 0]]); // zig zag partial dome

b = Buffer.loadCollection(s, a.getSetsAndMatrices);

(
// pan around the circle up and down
x = { |azi = 0, ele = 0, spr = 0|
var source;
source = PinkNoise.ar(0.2);
VBAP.ar(16, source, b.bufnum, LFSaw.kr(0.5, 0).range(-180, 180) * -1, SinOsc.kr(3, 0).range(0, 14.97), spr);
}.play;
)

//////// 5.1 GUI example with CircleRamp

(
var speakerList, x=200, y=150, targx=200, targy=150;
var atorad = (2pi) / 360, rtoang = 360.0 / (2pi);
var targRotate, actRotate, targPoint, actPoint;
var maxShiftPerFrame = 20, frameInterval = 0.01;
var resched = false, count = 0;
var panBus, widthBus, recButton;
var a, b, c, e;

maxShiftPerFrame = maxShiftPerFrame * atorad;
actPoint = Point(x, y) - Point(200, 200);
panBus = Bus.control;
widthBus = Bus.control.set(60);

w = Window.new("5.1 Panner", Rect(128, 64, 400, 450)).front;
w.view.background_(Color.grey(0.3));
w.view.decorator = FlowLayout(w.view.bounds);
speakerList = [[-30, "L"], [30, "R"], [0, "C"], [-110, "Ls"], [110, "Rs"]];
c = UserView.new(w,Rect(0, 0, 400, 380));
c.canFocus = false;

c.drawFunc = {
    Color.grey(0.8).set;
    // draw the speaker layout
    Pen.translate(200,200);
    ((actPoint.theta + (0.5pi)).wrap2(pi) * rtoang).round(0.01).asString.drawCenteredIn(Rect.aboutPoint(0@170, 30, 10), Font.new("Arial", 10), Color.grey(0.8));
    Pen.strokeOval(Rect.aboutPoint(0@0, 150, 150));
    Pen.rotate(pi);
    speakerList.do({|spkr|
        Pen.use({
            Pen.rotate(spkr[0] * atorad);
            Pen.moveTo(0@170);
            Pen.strokeRect(r = Rect.aboutPoint(0@170, 30, 10));
            if(spkr[0].abs < 90, {
                Pen.use({
                    Pen.translate(0, 170); 
                    Pen.rotate(pi);
                    spkr[1].drawCenteredIn(Rect.aboutPoint(0@0, 30, 10), 
                        GUI.font.new("Arial", 10), Color.grey(0.8));
                });
            },{ 
                spkr[1].drawCenteredIn(r, GUI.font.new("Arial", 10), Color.grey(0.8));
            });
        });
    });

    Pen.moveTo(0@0);

    // draw the pan point
    Pen.rotate(actPoint.theta + 0.5pi);
    targPoint = Point(x, y) - Point(200, 200);
    // trunc to avoid loops due to fp math
    targRotate = (targPoint.theta - actPoint.theta).trunc(1e-15);
    // wrap around
    if(targRotate.abs > pi, {targRotate = (2pi - targRotate.abs) * targRotate.sign.neg}); 
    actRotate = targRotate.clip2(maxShiftPerFrame).trunc(1e-15);
    actPoint = actPoint.rotate(actRotate);
    Pen.rotate(actRotate);
    Pen.lineTo(0@150);
    Pen.stroke;
    Pen.fillOval(Rect.aboutPoint(0@150, 7, 7));
    Pen.addWedge(0@0, 140, neg(e.value * 0.5) * atorad + 0.5pi, e.value * atorad);
    Pen.stroke;
    Color.grey(0.8).alpha_(0.1).set;
    Pen.addWedge(0@0, 140, neg(e.value * 0.5) * atorad + 0.5pi, e.value * atorad);
    Pen.fill;

    if((actRotate.abs > 0), {AppClock.sched(frameInterval, {w.refresh})}, {count = 0;});
    if(count%4 == 0, {panBus.set((actPoint.theta + (0.5pi)).wrap2(pi) * rtoang)});
};
c.mouseMoveAction_({|v,inx,iny| x = inx; y = iny; w.refresh;});
c.mouseDownAction_({|v,inx,iny| x = inx; y = iny; w.refresh;});
e = EZSlider.new(w, 380@20, "Stereo Width", [0, 180].asSpec, {arg ez; widthBus.set(ez.value); w.refresh}, labelWidth: 80);
e.labelView.setProperty(\stringColor,Color.grey(0.8));

w.refresh;

// VBAP

a = VBAPSpeakerArray.new(2, speakerList.collect(_.first));
b = a.loadToBuffer;

SynthDef('VBAP 5 chan', { |azi = 0, ele = 0, spr = 0, width = 60, vbapBuf|
var panned, source;
source = SinOsc.ar([440, 660], 0, Decay2.ar(Impulse.ar([1, 0.9]), 0.1, 0.2));
azi = azi.circleRamp;
panned = VBAP.ar(5, source, vbapBuf, [azi - (0.5 * width), azi + (0.5 * width)], ele, spr);
// 'standard' channel order for 5.1
[0, 1, 2, 4, 5].do({arg bus, i; Out.ar(bus, panned[0][i])});
[0, 1, 2, 4, 5].do({arg bus, i; Out.ar(bus, panned[1][i])});

}).play(s, [vbapBuf: b.bufnum, azi: panBus.asMap, width: widthBus.asMap]);

)
[1] - This version of VBAP for SC was ported from the ver. 0.99 PD code by Scott Wilson, as part of the BEASTMulch project. Development was partially funded by the Arts and Humanities Research Council: http://www.ahrc.ac.uk