microsoft-cognitiveservices-speech-sdk
Version:
Microsoft Cognitive Services Speech SDK for JavaScript
192 lines (190 loc) • 7.83 kB
JavaScript
;
// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT license.
Object.defineProperty(exports, "__esModule", { value: true });
exports.AudioStreamFormatImpl = exports.AudioStreamFormat = exports.AudioFormatTag = void 0;
// eslint-disable-next-line max-classes-per-file
var AudioFormatTag;
(function (AudioFormatTag) {
AudioFormatTag[AudioFormatTag["PCM"] = 1] = "PCM";
AudioFormatTag[AudioFormatTag["MuLaw"] = 2] = "MuLaw";
AudioFormatTag[AudioFormatTag["Siren"] = 3] = "Siren";
AudioFormatTag[AudioFormatTag["MP3"] = 4] = "MP3";
AudioFormatTag[AudioFormatTag["SILKSkype"] = 5] = "SILKSkype";
AudioFormatTag[AudioFormatTag["OGG_OPUS"] = 6] = "OGG_OPUS";
AudioFormatTag[AudioFormatTag["WEBM_OPUS"] = 7] = "WEBM_OPUS";
AudioFormatTag[AudioFormatTag["ALaw"] = 8] = "ALaw";
AudioFormatTag[AudioFormatTag["FLAC"] = 9] = "FLAC";
AudioFormatTag[AudioFormatTag["OPUS"] = 10] = "OPUS";
AudioFormatTag[AudioFormatTag["AMR_WB"] = 11] = "AMR_WB";
AudioFormatTag[AudioFormatTag["G722"] = 12] = "G722";
})(AudioFormatTag = exports.AudioFormatTag || (exports.AudioFormatTag = {}));
/**
* Represents audio stream format used for custom audio input configurations.
* @class AudioStreamFormat
*/
class AudioStreamFormat {
/**
* Creates an audio stream format object representing the default audio stream
* format (16KHz 16bit mono PCM).
* @member AudioStreamFormat.getDefaultInputFormat
* @function
* @public
* @returns {AudioStreamFormat} The audio stream format being created.
*/
static getDefaultInputFormat() {
return AudioStreamFormatImpl.getDefaultInputFormat();
}
/**
* Creates an audio stream format object with the specified format characteristics.
* @member AudioStreamFormat.getWaveFormat
* @function
* @public
* @param {number} samplesPerSecond - Sample rate, in samples per second (Hertz).
* @param {number} bitsPerSample - Bits per sample, typically 16.
* @param {number} channels - Number of channels in the waveform-audio data. Monaural data
* uses one channel and stereo data uses two channels.
* @param {AudioFormatTag} format - Audio format (PCM, alaw or mulaw).
* @returns {AudioStreamFormat} The audio stream format being created.
*/
static getWaveFormat(samplesPerSecond, bitsPerSample, channels, format) {
return new AudioStreamFormatImpl(samplesPerSecond, bitsPerSample, channels, format);
}
/**
* Creates an audio stream format object with the specified pcm waveformat characteristics.
* @member AudioStreamFormat.getWaveFormatPCM
* @function
* @public
* @param {number} samplesPerSecond - Sample rate, in samples per second (Hertz).
* @param {number} bitsPerSample - Bits per sample, typically 16.
* @param {number} channels - Number of channels in the waveform-audio data. Monaural data
* uses one channel and stereo data uses two channels.
* @returns {AudioStreamFormat} The audio stream format being created.
*/
static getWaveFormatPCM(samplesPerSecond, bitsPerSample, channels) {
return new AudioStreamFormatImpl(samplesPerSecond, bitsPerSample, channels);
}
}
exports.AudioStreamFormat = AudioStreamFormat;
/**
* @private
* @class AudioStreamFormatImpl
*/
class AudioStreamFormatImpl extends AudioStreamFormat {
/**
* Creates an instance with the given values.
* @constructor
* @param {number} samplesPerSec - Samples per second.
* @param {number} bitsPerSample - Bits per sample.
* @param {number} channels - Number of channels.
* @param {AudioFormatTag} format - Audio format (PCM, alaw or mulaw).
*/
constructor(samplesPerSec = 16000, bitsPerSample = 16, channels = 1, format = AudioFormatTag.PCM) {
super();
let isWavFormat = true;
/* 1 for PCM; 6 for alaw; 7 for mulaw */
switch (format) {
case AudioFormatTag.PCM:
this.formatTag = 1;
break;
case AudioFormatTag.ALaw:
this.formatTag = 6;
break;
case AudioFormatTag.MuLaw:
this.formatTag = 7;
break;
default:
isWavFormat = false;
}
this.bitsPerSample = bitsPerSample;
this.samplesPerSec = samplesPerSec;
this.channels = channels;
this.avgBytesPerSec = this.samplesPerSec * this.channels * (this.bitsPerSample / 8);
this.blockAlign = this.channels * Math.max(this.bitsPerSample, 8);
if (isWavFormat) {
this.privHeader = new ArrayBuffer(44);
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView
const view = new DataView(this.privHeader);
/* RIFF identifier */
this.setString(view, 0, "RIFF");
/* file length */
view.setUint32(4, 0, true);
/* RIFF type & Format */
this.setString(view, 8, "WAVEfmt ");
/* format chunk length */
view.setUint32(16, 16, true);
/* audio format */
view.setUint16(20, this.formatTag, true);
/* channel count */
view.setUint16(22, this.channels, true);
/* sample rate */
view.setUint32(24, this.samplesPerSec, true);
/* byte rate (sample rate * block align) */
view.setUint32(28, this.avgBytesPerSec, true);
/* block align (channel count * bytes per sample) */
view.setUint16(32, this.channels * (this.bitsPerSample / 8), true);
/* bits per sample */
view.setUint16(34, this.bitsPerSample, true);
/* data chunk identifier */
this.setString(view, 36, "data");
/* data chunk length */
view.setUint32(40, 0, true);
}
}
/**
* Retrieves the default input format.
* @member AudioStreamFormatImpl.getDefaultInputFormat
* @function
* @public
* @returns {AudioStreamFormatImpl} The default input format.
*/
static getDefaultInputFormat() {
return new AudioStreamFormatImpl();
}
/**
* Creates an audio context appropriate to current browser
* @member AudioStreamFormatImpl.getAudioContext
* @function
* @public
* @returns {AudioContext} An audio context instance
*/
/* eslint-disable */
static getAudioContext(sampleRate) {
// Workaround for Speech SDK bug in Safari.
const AudioContext = window.AudioContext // our preferred impl
|| window.webkitAudioContext // fallback, mostly when on Safari
|| false; // could not find.
// https://developer.mozilla.org/en-US/docs/Web/API/AudioContext
if (!!AudioContext) {
if (sampleRate !== undefined && navigator.mediaDevices.getSupportedConstraints().sampleRate) {
return new AudioContext({ sampleRate });
}
else {
return new AudioContext();
}
}
else {
throw new Error("Browser does not support Web Audio API (AudioContext is not available).");
}
}
/* eslint-enable */
/**
* Closes the configuration object.
* @member AudioStreamFormatImpl.prototype.close
* @function
* @public
*/
close() {
return;
}
get header() {
return this.privHeader;
}
setString(view, offset, str) {
for (let i = 0; i < str.length; i++) {
view.setUint8(offset + i, str.charCodeAt(i));
}
}
}
exports.AudioStreamFormatImpl = AudioStreamFormatImpl;
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