export function PCMPlayer(option) {
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this.init(option)
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}
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PCMPlayer.prototype.init = function(option) {
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var defaults = {
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encoding: "16bitInt",
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channels: 1,
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sampleRate: 8000,
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flushingTime: 1000
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}
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this.option = Object.assign({}, defaults, option)
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this.samples = new Float32Array()
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this.flush = this.flush.bind(this)
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this.interval = setInterval(this.flush, this.option.flushingTime)
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this.maxValue = this.getMaxValue()
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this.typedArray = this.getTypedArray()
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this.createContext()
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}
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PCMPlayer.prototype.getMaxValue = function() {
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var encodings = {
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"8bitInt": 128,
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"16bitInt": 32768,
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"32bitInt": 2147483648,
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"32bitFloat": 1
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}
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return encodings[this.option.encoding] ? encodings[this.option.encoding] : encodings["16bitInt"]
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}
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PCMPlayer.prototype.getTypedArray = function() {
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var typedArrays = {
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"8bitInt": Int8Array,
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"16bitInt": Int16Array,
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"32bitInt": Int32Array,
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"32bitFloat": Float32Array
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}
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return typedArrays[this.option.encoding] ? typedArrays[this.option.encoding] : typedArrays["16bitInt"]
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}
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PCMPlayer.prototype.createContext = function() {
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this.audioCtx = new (window.AudioContext || window.webkitAudioContext)()
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this.gainNode = this.audioCtx.createGain()
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this.gainNode.gain.value = 1
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this.gainNode.connect(this.audioCtx.destination)
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this.startTime = this.audioCtx.currentTime
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}
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PCMPlayer.prototype.isTypedArray = function(data) {
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return data.byteLength && data.buffer && data.buffer.constructor == ArrayBuffer
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}
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PCMPlayer.prototype.feed = function(data) {
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if (!this.isTypedArray(data)) return
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data = this.getFormatedValue(data)
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var tmp = new Float32Array(this.samples.length + data.length)
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tmp.set(this.samples, 0)
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tmp.set(data, this.samples.length)
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this.samples = tmp
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}
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PCMPlayer.prototype.getFormatedValue = function(data) {
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var data = new this.typedArray(data.buffer),
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float32 = new Float32Array(data.length),
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i
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for (i = 0; i < data.length; i++) {
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float32[i] = data[i] / this.maxValue
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}
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return float32
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}
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PCMPlayer.prototype.volume = function(volume) {
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this.gainNode.gain.value = volume
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}
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PCMPlayer.prototype.destroy = function() {
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if (this.interval) {
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clearInterval(this.interval)
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}
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this.samples = null
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this.audioCtx.close()
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this.audioCtx = null
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}
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PCMPlayer.prototype.flush = function() {
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if (!this.samples.length) return
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var bufferSource = this.audioCtx.createBufferSource(),
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length = this.samples.length / this.option.channels,
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audioBuffer = this.audioCtx.createBuffer(this.option.channels, length, this.option.sampleRate),
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audioData,
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channel,
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offset,
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i,
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decrement
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for (channel = 0; channel < this.option.channels; channel++) {
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audioData = audioBuffer.getChannelData(channel)
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offset = channel
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decrement = 50
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for (i = 0; i < length; i++) {
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audioData[i] = this.samples[offset]
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/* fadein */
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if (i < 50) {
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audioData[i] = (audioData[i] * i) / 50
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}
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/* fadeout*/
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if (i >= length - 51) {
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audioData[i] = (audioData[i] * decrement--) / 50
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}
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offset += this.option.channels
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}
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}
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if (this.startTime < this.audioCtx.currentTime) {
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this.startTime = this.audioCtx.currentTime
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}
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//console.log('start vs current '+this.startTime+' vs '+this.audioCtx.currentTime+' duration: '+audioBuffer.duration);
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bufferSource.buffer = audioBuffer
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bufferSource.connect(this.gainNode)
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bufferSource.start(this.startTime)
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this.startTime += audioBuffer.duration
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this.samples = new Float32Array()
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}
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PCMPlayer.prototype.getTimestamp = function() {
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if (this.audioCtx) {
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return this.audioCtx.currentTime
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} else {
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return 0
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}
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}
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PCMPlayer.prototype.play = function(data) {
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if (!this.isTypedArray(data)) {
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return
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}
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data = this.getFormatedValue(data)
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if (!data.length) {
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return
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}
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var bufferSource = this.audioCtx.createBufferSource(),
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length = data.length / this.option.channels,
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audioBuffer = this.audioCtx.createBuffer(this.option.channels, length, this.option.sampleRate),
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audioData,
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channel,
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offset,
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i,
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decrement
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for (channel = 0; channel < this.option.channels; channel++) {
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audioData = audioBuffer.getChannelData(channel)
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offset = channel
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decrement = 50
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for (i = 0; i < length; i++) {
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audioData[i] = data[offset]
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/* fadein */
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if (i < 50) {
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audioData[i] = (audioData[i] * i) / 50
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}
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/* fadeout*/
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if (i >= length - 51) {
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audioData[i] = (audioData[i] * decrement--) / 50
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}
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offset += this.option.channels
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}
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}
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if (this.startTime < this.audioCtx.currentTime) {
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this.startTime = this.audioCtx.currentTime
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}
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//console.log('start vs current '+this.startTime+' vs '+this.audioCtx.currentTime+' duration: '+audioBuffer.duration);
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bufferSource.buffer = audioBuffer
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bufferSource.connect(this.gainNode)
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bufferSource.start(this.startTime)
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this.startTime += audioBuffer.duration
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}
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PCMPlayer.prototype.pause = function() {
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if (this.audioCtx.state === "running") {
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this.audioCtx.suspend()
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}
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}
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PCMPlayer.prototype.resume = function() {
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if (this.audioCtx.state === "suspended") {
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this.audioCtx.resume()
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}
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}
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