77 lines
1.8 KiB
JavaScript
77 lines
1.8 KiB
JavaScript
var
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Readable = require('stream').Readable,
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util = require('util'),
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Input = require('./input.js')
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;
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function Mixer(args) {
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if (typeof args === 'undefined') args = {};
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if (args.channels != 1 && args.channels != 2) args.channels = 2;
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if (typeof args.sampleRate === 'number' || args.sampleRate < 1) args.sampleRate = 44100;
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this.bitDepth = args.bitDepth;
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if (args.bitDepth == 8) {
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this.readSample = Buffer.readInt8;
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this.writeSample = Buffer.writeInt8;
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this.sampleByteLength = 1;
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}
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else if (args.bitDepth == 32) {
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this.readSample = Buffer.readInt32LE;
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this.writeSample = Buffer.writeInt32LE;
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this.sampleByteLength = 4;
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}
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else {
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args.bitDepth = 16;
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this.readSample = Buffer.readInt16LE;
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this.writeSample = Buffer.writeInt16LE;
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this.sampleByteLength = 2;
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}
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this.channels = args.channels;
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this.sampleRate = args.sampleRate;
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this.inputs = [];
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}
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util.inherits(Mixer, Readable);
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Mixer.prototype._read = function() {
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var samples = 9007199254740992;
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this.inputs.forEach(function (input) {
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var as = input.availSamples();
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if (as < samples) samples = as;
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});
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if (samples > 0) {
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var mixedBuffer = new Buffer(samples * this.sampleByteLength);
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for (var i = 0; i < samples; i++) {
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var mixedSample = 0;
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for (var j = 0; j < this.inputs.length; j++) {
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mixedSample += this.inputs[j].readSample.call(this.inputs[j], i * this.inputs[j].sampleByteLength);
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}
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this.writeSample.call(mixedBuffer, Math.round(mixedSample / this.inputs.length), i * this.sampleByteLength);
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}
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this.push(mixedBuffer);
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}
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}
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Mixer.prototype.input = function (args) {
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if (typeof args === 'undefined') args = {};
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var input = new Input({
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mixer: this,
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channels: args.channels || this.channels,
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bitDepth: args.bitDepth || this.bitDepth,
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sampleRate: args.sampleRate || this.sampleRate
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});
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this.inputs.push(input);
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return input;
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}
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module.exports = Mixer;
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