import { RecordingAdapter } from './RecordingAdapter'; const logger = require('jitsi-meet-logger').getLogger(__filename); /** * Base class for {@code AudioContext}-based recording adapters. */ export class AbstractAudioContextAdapter extends RecordingAdapter { /** * The {@code AudioContext} instance. */ _audioContext = null; /** * The {@code ScriptProcessorNode} instance. */ _audioProcessingNode = null; /** * The {@code MediaStreamAudioSourceNode} instance. */ _audioSource = null; /** * The {@code MediaStream} instance, representing the current audio device. */ _stream = null; /** * Sample rate. */ _sampleRate = 44100; /** * Constructor. */ constructor() { super(); // sampleRate is browser and OS dependent. // Setting sampleRate explicitly is in the specs but not implemented // by browsers. // See: https://developer.mozilla.org/en-US/docs/Web/API/AudioContext/ // AudioContext#Browser_compatibility // And https://bugs.chromium.org/p/chromium/issues/detail?id=432248 this._audioContext = new AudioContext(); this._sampleRate = this._audioContext.sampleRate; logger.log(`Current sampleRate ${this._sampleRate}.`); } /** * Sets up the audio graph in the AudioContext. * * @protected * @param {string} micDeviceId - The current microphone device ID. * @param {Function} callback - Callback function to * handle AudioProcessingEvents. * @returns {Promise} */ _initializeAudioContext(micDeviceId, callback) { if (typeof callback !== 'function') { return Promise.reject('a callback function is required.'); } return this._getAudioStream(micDeviceId) .then(stream => { this._stream = stream; this._audioSource = this._audioContext.createMediaStreamSource(stream); this._audioProcessingNode = this._audioContext.createScriptProcessor(4096, 1, 1); this._audioProcessingNode.onaudioprocess = callback; logger.debug('AudioContext is set up.'); }) .catch(err => { logger.error(`Error calling getUserMedia(): ${err}`); return Promise.reject(err); }); } /** * Connects the nodes in the {@code AudioContext} to start the flow of * audio data. * * @protected * @returns {void} */ _connectAudioGraph() { this._audioSource.connect(this._audioProcessingNode); this._audioProcessingNode.connect(this._audioContext.destination); } /** * Disconnects the nodes in the {@code AudioContext}. * * @protected * @returns {void} */ _disconnectAudioGraph() { this._audioProcessingNode.onaudioprocess = undefined; this._audioProcessingNode.disconnect(); this._audioSource.disconnect(); } /** * Replaces the current microphone MediaStream. * * @protected * @param {string} micDeviceId - New microphone ID. * @returns {Promise} */ _replaceMic(micDeviceId) { if (this._audioContext && this._audioProcessingNode) { return this._getAudioStream(micDeviceId).then(newStream => { const newSource = this._audioContext .createMediaStreamSource(newStream); this._audioSource.disconnect(); newSource.connect(this._audioProcessingNode); this._stream = newStream; this._audioSource = newSource; }); } return Promise.resolve(); } }