source: gs3-extensions/web-audio/trunk/js-mad/sink.js-master/src/sinks/workers.js@ 28388

(function (Sink) {

/**
 * A Sink class for the Media Streams Processing API and/or Web Audio API in a Web Worker.
*/

Sink.sinks('worker', function () {
    var self        = this,
        global      = (function(){ return this; }()),
        soundData   = null,
        outBuffer   = null,
        zeroBuffer  = null;
    self.start.apply(self, arguments);

    // Let's see if we're in a worker.

    importScripts();

    function mspBufferFill (e) {
        if (!self.isReady) {
            self.initMSP(e);
        }

        self.ready();

        var channelCount    = self.channelCount,
            l       = e.audioLength,
            n, i;

        soundData   = soundData && soundData.length === l * channelCount ? soundData : new Float32Array(l * channelCount);
        outBuffer   = outBuffer && outBuffer.length === soundData.length ? outBuffer : new Float32Array(l * channelCount);
        zeroBuffer  = zeroBuffer && zeroBuffer.length === soundData.length ? zeroBuffer : new Float32Array(l * channelCount);

        soundData.set(zeroBuffer);
        outBuffer.set(zeroBuffer);

        self.process(soundData, self.channelCount);

        for (n=0; n<channelCount; n++) {
            for (i=0; i<l; i++) {
                outBuffer[n * e.audioLength + i] = soundData[n + i * channelCount];
            }
        }

        e.writeAudio(outBuffer);
    }

    function waBufferFill(e) {
        if (!self.isReady) {
            self.initWA(e);
        }

        self.ready();

        var outputBuffer    = e.outputBuffer,
            channelCount    = outputBuffer.numberOfChannels,
            i, n, l     = outputBuffer.length,
            size        = outputBuffer.size,
            channels    = new Array(channelCount),
            tail;
        
        soundData   = soundData && soundData.length === l * channelCount ? soundData : new Float32Array(l * channelCount);
        zeroBuffer  = zeroBuffer && zeroBuffer.length === soundData.length ? zeroBuffer : new Float32Array(l * channelCount);
        soundData.set(zeroBuffer);

        for (i=0; i<channelCount; i++) {
            channels[i] = outputBuffer.getChannelData(i);
        }

        self.process(soundData, self.channelCount);

        for (i=0; i<l; i++) {
            for (n=0; n < channelCount; n++) {
                channels[n][i] = soundData[i * self.channelCount + n];
            }
        }
    }

    global.onprocessmedia   = mspBufferFill;
    global.onaudioprocess   = waBufferFill;

    self._mspBufferFill = mspBufferFill;
    self._waBufferFill  = waBufferFill;

}, {
    ready: false,

    initMSP: function (e) {
        this.channelCount   = e.audioChannels;
        this.sampleRate     = e.audioSampleRate;
        this.bufferSize     = e.audioLength * this.channelCount;
        this.ready      = true;
        this.emit('ready', []);
    },

    initWA: function (e) {
        var b = e.outputBuffer;
        this.channelCount   = b.numberOfChannels;
        this.sampleRate     = b.sampleRate;
        this.bufferSize     = b.length * this.channelCount;
        this.ready      = true;
        this.emit('ready', []);
    }
});

}(this.Sink));