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Update Amplitude and Biquad Filter for single-sample ticking
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@oampo
oampo committed Feb 10, 2012
1 parent 4d60da6 commit 7d5d04e
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Showing 2 changed files with 48 additions and 128 deletions.
69 changes: 15 additions & 54 deletions src/dsp/Amplitude.js
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Original file line number Diff line number Diff line change
Expand Up @@ -31,84 +31,45 @@ var Amplitude = function(audiolet, attack, release) {
this.linkNumberOfOutputChannels(0, 0);

this.followers = [];
var sampleRate = this.audiolet.device.sampleRate;

// attack = Math.pow(0.01, 1 / (attack * sampleRate));
this.attack = new AudioletParameter(this, 1, attack || 0.01);

// release = Math.pow(0.01, 1 / (release * sampleRate));
this.release = new AudioletParameter(this, 2, release || 0.01);
};
extend(Amplitude, AudioletNode);

/**
* Process a block of samples
*
* @param {AudioletBuffer[]} inputBuffers Samples received from the inputs.
* @param {AudioletBuffer[]} outputBuffers Samples to be sent to the outputs.
*/
Amplitude.prototype.generate = function(inputBuffers, outputBuffers) {
var inputBuffer = inputBuffers[0];
var outputBuffer = outputBuffers[0];

if (inputBuffer.isEmpty) {
outputBuffer.isEmpty = true;
return;
}
Amplitude.prototype.generate = function() {
var input = this.inputs[0];
var output = this.outputs[0];

var followers = this.followers;
var numberOfFollowers = followers.length;

var sampleRate = this.audiolet.device.sampleRate;

// Local processing variables
var attackParameter = this.attack;
var attack, attackChannel;
if (attackParameter.isStatic()) {
attack = Math.pow(0.01, 1 / (attackParameter.getValue() *
sampleRate));
}
else {
attackChannel = attackParameter.getChannel();
}

// Local processing variables
var releaseParameter = this.release;
var release, releaseChannel;
if (releaseParameter.isStatic()) {
release = Math.pow(0.01, 1 / (releaseParameter.getValue() *
sampleRate));
}
else {
releaseChannel = releaseParameter.getChannel();
}
var attack = this.attack.getValue();
attack = Math.pow(0.01, 1 / (attack * sampleRate));
var release = this.release.getValue();
release = Math.pow(0.01, 1 / (release * sampleRate));

var numberOfChannels = inputBuffer.numberOfChannels;
var numberOfChannels = input.samples.length;
for (var i = 0; i < numberOfChannels; i++) {
if (i >= numberOfFollowers) {
followers.push(0);
}
var follower = followers[i];

var inputChannel = inputBuffer.getChannelData(i);
var outputChannel = outputBuffer.getChannelData(i);
var bufferLength = inputBuffer.length;
for (var j = 0; j < bufferLength; j++) {
var value = Math.abs(inputChannel[j]);
if (attackChannel) {
attack = Math.pow(0.01, 1 / (attackChannel[j] * sampleRate));
}
if (releaseChannel) {
release = Math.pow(0.01, 1 / (releaseChannel[j] * sampleRate));
}
if (value > follower) {
follower = attack * (follower - value) + value;
}
else {
follower = release * (follower - value) + value;
}
outputChannel[j] = follower;
var value = Math.abs(input.samples[i]);
if (value > follower) {
follower = attack * (follower - value) + value;
}
else {
follower = release * (follower - value) + value;
}
output.samples[i] = follower;
followers[i] = follower;
}
};
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107 changes: 33 additions & 74 deletions src/dsp/BiquadFilter.js
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Original file line number Diff line number Diff line change
Expand Up @@ -62,42 +62,19 @@ BiquadFilter.prototype.calculateCoefficients = function(frequency) {
* @param {AudioletBuffer[]} inputBuffers Samples received from the inputs.
* @param {AudioletBuffer[]} outputBuffers Samples to be sent to the outputs.
*/
BiquadFilter.prototype.generate = function(inputBuffers, outputBuffers) {
var inputBuffer = inputBuffers[0];
var outputBuffer = outputBuffers[0];

if (inputBuffer.isEmpty) {
outputBuffer.isEmpty = true;
return;
}

BiquadFilter.prototype.generate = function() {
var input = this.inputs[0];
var output = this.outputs[0]
var xValueArray = this.xValues;
var yValueArray = this.yValues;

var inputChannels = [];
var outputChannels = [];
var numberOfChannels = inputBuffer.numberOfChannels;
for (var i = 0; i < numberOfChannels; i++) {
inputChannels.push(inputBuffer.getChannelData(i));
outputChannels.push(outputBuffer.getChannelData(i));
if (i >= xValueArray.length) {
xValueArray.push([0, 0]);
yValueArray.push([0, 0]);
}
}
var frequency = this.frequency.getValue();

// Local processing variables
var frequencyParameter = this.frequency;
var frequency, frequencyChannel;
if (frequencyParameter.isStatic()) {
frequency = frequencyParameter.getValue();
if (frequency != this.lastFrequency) {
// Recalculate the coefficients
this.calculateCoefficients(frequency);
this.lastFrequency = frequency;
}
else {
frequencyChannel = frequencyParameter.getChannel();
}


var lastFrequency = this.lastFrequency;

var a0 = this.a0;
var a1 = this.a1;
Expand All @@ -106,52 +83,34 @@ BiquadFilter.prototype.generate = function(inputBuffers, outputBuffers) {
var b1 = this.b1;
var b2 = this.b2;

var bufferLength = outputBuffer.length;
for (var i = 0; i < bufferLength; i++) {
if (frequencyChannel) {
var frequency = frequencyChannel[i];
}

if (frequency != lastFrequency) {
// Recalculate and make the coefficients local
this.calculateCoefficients(frequency);
lastFrequency = frequency;
a0 = this.a0;
a1 = this.a1;
a2 = this.a2;
b0 = this.b0;
b1 = this.b1;
b2 = this.b2;
var numberOfChannels = input.samples.length;
for (var i = 0; i < numberOfChannels; i++) {
if (i >= xValueArray.length) {
xValueArray.push([0, 0]);
yValueArray.push([0, 0]);
}

for (var j = 0; j < numberOfChannels; j++) {
var inputChannel = inputChannels[j];
var outputChannel = outputChannels[j];

var xValues = xValueArray[j];
var x1 = xValues[0];
var x2 = xValues[1];
var yValues = yValueArray[j];
var y1 = yValues[0];
var y2 = yValues[1];

var x0 = inputChannel[i];
var y0 = (b0 / a0) * x0 +
(b1 / a0) * x1 +
(b2 / a0) * x2 -
(a1 / a0) * y1 -
(a2 / a0) * y2;

outputChannel[i] = y0;


xValues[0] = x0;
xValues[1] = x1;
yValues[0] = y0;
yValues[1] = y1;
}
var xValues = xValueArray[i];
var x1 = xValues[0];
var x2 = xValues[1];
var yValues = yValueArray[i];
var y1 = yValues[0];
var y2 = yValues[1];

var x0 = input.samples[i];
var y0 = (b0 / a0) * x0 +
(b1 / a0) * x1 +
(b2 / a0) * x2 -
(a1 / a0) * y1 -
(a2 / a0) * y2;

output.samples[i] = y0;

xValues[0] = x0;
xValues[1] = x1;
yValues[0] = y0;
yValues[1] = y1;
}
this.lastFrequency = lastFrequency;
};

/**
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