118 lines
3.4 KiB
JavaScript
118 lines
3.4 KiB
JavaScript
var
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Writable = require('stream').Writable,
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util = require('util'),
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int24 = require('int24')
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;
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function Input(args) {
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Writable.call(this, 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.buffer = new Buffer(0);
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if (args.channels == 1) this.readMono = this.read;
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if (args.channels == 2) this.readStereo = this.read;
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if (args.bitDepth == 8) {
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this.readSample = this.buffer.readInt8;
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this.writeSample = this.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 = this.buffer.readInt32LE;
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this.writeSample = this.buffer.writeInt32LE;
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this.sampleByteLength = 4;
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}
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else if (args.bitDepth == 24) {
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this.readSample = function (offset) {
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return int24.readInt24LE(this.buffer, offset);
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};
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this.writeSample = function (offset, value) {
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int24.writeInt24LE(this.buffer, offset, value);
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};
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this.sampleByteLength = 3;
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}
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else {
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args.bitDepth = 16;
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this.readSample = this.buffer.readInt16LE;
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this.writeSample = this.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.bitDepth = args.bitDepth;
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this.sampleRate = args.sampleRate;
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this.getMoreData = null;
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}
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util.inherits(Input, Writable);
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Input.prototype.read = function (samples) {
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var bytes = samples * (this.bitDepth / 8) * this.channels;
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if (this.buffer.length < bytes) bytes = this.buffer.length;
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var r = this.buffer.slice(0, bytes);
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this.buffer = this.buffer.slice(bytes);
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if (this.buffer.length <= 131072 && this.getMoreData !== null) {
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var getMoreData = this.getMoreData;
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this.getMoreData = null;
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process.nextTick(getMoreData);
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}
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return r;
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};
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Input.prototype.readMono = function (samples) {
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// This function will be overridden by this.read, if input already is mono.
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var stereoBuffer = this.read(samples);
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var monoBuffer = new Buffer(stereoBuffer.length / 2);
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var s = this.availSamples(stereoBuffer.length);
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for (var i = 0; i < s; i++) {
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var l = this.readSample.call(stereoBuffer, i * this.sampleByteLength * 2);
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var r = this.readSample.call(stereoBuffer, (i * this.sampleByteLength * 2) + this.sampleByteLength);
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this.writeSample.call(monoBuffer, Math.round((l + r) / 2), i * this.sampleByteLength);
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}
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return monoBuffer;
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};
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Input.prototype.readStereo = function (samples) {
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// This function will be overridden by this.read, if input already is stereo.
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var monoBuffer = this.read(samples);
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var stereoBuffer = new Buffer(monoBuffer.length * 2);
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var s = this.availSamples(monoBuffer.length);
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for (var i = 0; i < s; i++) {
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var m = this.readSample.call(monoBuffer, i * this.sampleByteLength);
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this.writeSample.call(stereoBuffer, m, i * this.sampleByteLength * 2);
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this.writeSample.call(stereoBuffer, m, (i * this.sampleByteLength * 2) + this.sampleByteLength);
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}
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return stereoBuffer;
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};
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Input.prototype.availSamples = function (length) {
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if (typeof length === 'undefined') length = this.buffer.length;
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return Math.floor(length / ((this.bitDepth / 8) * this.channels));
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};
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Input.prototype._write = function (chunk, encoding, next) {
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/*
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if (!Buffer.isBuffer(chunk)) {
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chunk = new Buffer(chunk, encoding);
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}
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*/
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this.buffer = Buffer.concat([this.buffer, chunk]);
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if (this.buffer.length > 131072) {
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this.getMoreData = next;
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} else {
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next();
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}
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};
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module.exports = Input;
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