plugins/noise.cracked.js

/**
 * noise parametrized noise node
 *
 * [See more noise examples](examples/noise.html)
 *
 * @plugin
 * @category Noise
 * @function
 * @memberof cracked
 * @name cracked#noise
 * @public
 * @param {Object} [params] map of optional values
 * @param {String} [params.type=white]
 */
cracked.noise = function (params) {
    var userParams = params || {};
    if (userParams.type === "brown") {
        __.begin("noise", userParams).brown(userParams).end("noise");
    } else if (userParams.type === "pink") {
        __.begin("noise", userParams).pink(userParams).end("noise");
    } else {
        __.begin("noise", userParams).white(userParams).end("noise");
    }
    return cracked;
};
/**
 * Pink Noise
 *
 * [See more noise examples](examples/noise.html)
 *
 * @plugin
 * @category Noise
 * @function
 * @memberof cracked
 * @name cracked#pink
 * @public
 * @param {Object} [params] map of optional values
 * @param {Number} [params.channels=1]
 * @param {Number} [params.length=1]
 */
cracked.pink = function (params) {
//http://noisehack.com/generate-noise-web-audio-api/
    var userParams = params || {};
    var channels = userParams.channels || 1;
    var length = userParams.length || 1;
    __().begin("pink", userParams).buffer({
        fn: buildBuffer,
        loop: true
    }).end("pink");
    return cracked;
    function buildBuffer(audioContext) {
        var buf = audioContext.createBuffer(channels, (length * audioContext.sampleRate), audioContext.sampleRate);
        var buflen = buf.length;
        var bufNum = buf.numberOfChannels;
        var buffArr = []; //call only once and cache
        for (var k = 0; k < bufNum; k++) {
            buffArr.push(buf.getChannelData(k));
        }
        for (var i = 0; i < buflen; i++) {
            for (var j = 0; j < bufNum; j++) {
                buffArr[j][i] = Math.random() * 2 - 1;
            }
        }
        pinkify(buf, buffArr);
        function pinkify(buf, buffArr) {
            var buffer = buf,
                b = [0, 0, 0, 0, 0, 0, 0],
                channelData, white, i, j, pink = [],
                bufNum = buffer.numberOfChannels, buflen = buffer.length;
            for (i = 0; i < bufNum; i++) {
                pink[i] = new Float32Array(buflen);
                channelData = buffArr[i];
                for (j = 0; j < buflen; j++) {
                    white = channelData[j];
                    b[0] = 0.99886 * b[0] + white * 0.0555179;
                    b[1] = 0.99332 * b[1] + white * 0.0750759;
                    b[2] = 0.96900 * b[2] + white * 0.1538520;
                    b[3] = 0.86650 * b[3] + white * 0.3104856;
                    b[4] = 0.55000 * b[4] + white * 0.5329522;
                    b[5] = -0.7616 * b[5] - white * 0.0168980;
                    pink[i][j] = b[0] + b[1] + b[2] + b[3] + b[4] + b[5] + b[6] + white * 0.5362;
                    pink[i][j] *= 0.11;
                    b[6] = white * 0.115926;
                }
                b = [0, 0, 0, 0, 0, 0, 0];
            }
            for (i = 0; i < bufNum; i++) {
                for (j = 0; j < buflen; j++) {
                    buffArr[i][j] = pink[i][j];
                }
            }
        }
        return buf;
    }
};
/**
 * White Noise
 *
 * [See more noise examples](examples/noise.html)
 *
 * @plugin
 * @category Noise
 * @function
 * @memberof cracked
 * @name cracked#white
 * @public
 * @param {Object} [params] map of optional values
 * @param {Number} [params.channels=1]
 * @param {Number} [params.length=1]
 */
cracked.white = function (params) {
//http://noisehack.com/generate-noise-web-audio-api/
    var userParams = params || {};
    var channels = userParams.channels || 1;
    var length = userParams.length || 1;
    __().begin("white", userParams).buffer({
        fn: buildBuffer,
        loop: true
    }).end("white");
    return cracked;
    function buildBuffer(audioContext) {
        var buffer = audioContext.createBuffer(channels, (length * audioContext.sampleRate), audioContext.sampleRate);
        var buflen = buffer.length;
        var bufNum = buffer.numberOfChannels;
        var buffArr = []; //call only once and cache
        for (var k = 0; k < bufNum; k++) {
            buffArr.push(buffer.getChannelData(k));
        }
        for (var i = 0; i < buflen; i++) {
            for (var j = 0; j < bufNum; j++) {
                buffArr[j][i] = (Math.random() * 2 - 1) * 0.44;
            }
        }
        return buffer;
    }
};
/**
 * Brown Noise
 *
 * [See more noise examples](examples/noise.html)
 *
 * @plugin
 * @category Noise
 * @function
 * @memberof cracked
 * @name cracked#brown
 * @public
 * @param {Object} [params] map of optional values
 * @param {Number} [params.channels=1]
 * @param {Number} [params.length=1]
 */
cracked.brown = function (params) {
//http://noisehack.com/generate-noise-web-audio-api/
    var userParams = params || {};
    var channels = userParams.channels || 1;
    var length = userParams.length || 1;
    __().begin("brown", userParams).buffer({
        fn: buildBuffer,
        loop: true
    }).end("brown");
    return cracked;
    function buildBuffer(audioContext) {
        var buffer = audioContext.createBuffer(channels, (length * audioContext.sampleRate), audioContext.sampleRate),
            lastOut = 0.0, bufLen = buffer.length, bufNum = buffer.numberOfChannels;
        var buffArr = []; //call only once and cache
        for (var k = 0; k < bufNum; k++) {
            buffArr.push(buffer.getChannelData(k));
        }
        for (var i = 0; i < bufLen; i++) {
            for (var j = 0; j < bufNum; j++) {
                var white = Math.random() * 2 - 1;
                buffArr[j][i] = (lastOut + (0.02 * white)) / 1.02;
                lastOut = buffArr[j][i];
                buffArr[j][i] *= 3.5; // (roughly) compensate for gain
            }
        }
        return buffer;
    }
};