Babylon.js/Babylon/Audio/babylon.audioEngine.ts

module BABYLON {
    export class AudioEngine {
        private _audioContext: AudioContext = null;
        private _audioContextInitialized = false;
        public canUseWebAudio: boolean = false;
        public masterGain: GainNode;

        private _connectedAnalyser: Analyser;
        public WarnedWebAudioUnsupported: boolean = false;

        public get audioContext(): AudioContext {
            if (!this._audioContextInitialized) {
                this._initializeAudioContext();
            }
            return this._audioContext;
        }

        constructor() {
            if (typeof AudioContext !== 'undefined' || typeof webkitAudioContext !== 'undefined') {
                window.AudioContext = window.AudioContext || window.webkitAudioContext;
                this.canUseWebAudio = true;
            }
        }

        private _initializeAudioContext() {
            try {
                if (this.canUseWebAudio) {
                    this._audioContext = new AudioContext();
                    // create a global volume gain node 
                    this.masterGain = this._audioContext.createGain();
                    this.masterGain.gain.value = 1;
                    this.masterGain.connect(this._audioContext.destination);
                    this._audioContextInitialized = true;
                }
            }
            catch (e) {
                this.canUseWebAudio = false;
                Tools.Error("Web Audio: " + e.message);
            }
        }

        public dispose() {
            if (this.canUseWebAudio && this._audioContextInitialized) {
                if (this._connectedAnalyser) {
                    this._connectedAnalyser.stopDebugCanvas();
                    this._connectedAnalyser.dispose();
                    this.masterGain.disconnect();
                    this.masterGain.connect(this._audioContext.destination);
                    this._connectedAnalyser = null;
                }
                this.masterGain.gain.value = 1;
            }
            this.WarnedWebAudioUnsupported = false;
        }

        public getGlobalVolume(): number {
            if (this.canUseWebAudio && this._audioContextInitialized) {
                return this.masterGain.gain.value;
            }
            else {
                return -1;
            }
        }

        public setGlobalVolume(newVolume: number) {
            if (this.canUseWebAudio && this._audioContextInitialized) {
                this.masterGain.gain.value = newVolume;
            }
        }

        public connectToAnalyser(analyser: Analyser) {
            if (this._connectedAnalyser) {
                this._connectedAnalyser.stopDebugCanvas();
            }
            if (this.canUseWebAudio && this._audioContextInitialized) {
                this._connectedAnalyser = analyser;
                this.masterGain.disconnect();
                this._connectedAnalyser.connectAudioNodes(this.masterGain, this._audioContext.destination);
            }
        }
    }
}