flocking/src/ugens/listening.js

Creative audio synthesis for the Web

/*
 * Flocking Listening Unit Generators
 * https://github.com/continuing-creativity/flocking
 *
 * Copyright 2011-2014, Colin Clark
 * Dual licensed under the MIT and GPL Version 2 licenses.
 */

/*global require*/
/*jshint white: false, newcap: true, regexp: true, browser: true,
    forin: false, nomen: true, bitwise: false, maxerr: 100,
    indent: 4, plusplus: false, curly: true, eqeqeq: true,
    freeze: true, latedef: true, noarg: true, nonew: true, quotmark: double, undef: true,
    unused: true, strict: true, asi: false, boss: false, evil: false, expr: false,
    funcscope: false*/

var fluid = fluid || require("infusion"),
    flock = fluid.registerNamespace("flock");

(function () {
    "use strict";

    flock.ugen.amplitude = function (inputs, output, options) {
        var that = flock.ugen(inputs, output, options);

        that.gen = function (numSamps) {
            var m = that.model,
                source = that.inputs.source.output,
                out = that.output,
                prevAtt = m.attackTime,
                nextAtt = that.inputs.attack.output[0],
                prevRel = m.releaseTime,
                nextRel = that.inputs.release.output[0],
                prevVal = m.prevVal,
                attCoef = m.attackCoef,
                relCoef = m.releaseCoef,
                i,
                val,
                coef;

            // Convert 60 dB attack and release times to coefficients if they've changed.
            if (nextAtt !== prevAtt) {
                m.attackTime = nextAtt;
                attCoef = m.attackCoef =
                    nextAtt === 0.0 ? 0.0 : Math.exp(flock.LOG01 / (nextAtt * m.sampleRate));
            }

            if (nextRel !== prevRel) {
                m.releaseTime = nextRel;
                relCoef = m.releaseCoef =
                    (nextRel === 0.0) ? 0.0 : Math.exp(flock.LOG01 / (nextRel * m.sampleRate));
            }

            for (i = 0; i < numSamps; i++) {
                val = Math.abs(source[i]);
                coef = val < prevVal ? relCoef : attCoef;
                out[i] = prevVal = val + (prevVal - val) * coef;
            }

            m.unscaledValue = m.prevVal = prevVal;
            that.mulAdd(numSamps);
            m.value = flock.ugen.lastOutputValue(numSamps, out);
        };

        that.onInputChanged();
        return that;
    };

    flock.ugenDefaults("flock.ugen.amplitude", {
        rate: "audio",
        inputs: {
            source: null,
            attack: 0.01,
            release: 0.01,
            mul: null,
            add: null
        },
        ugenOptions: {
            model: {
                prevVal: 0.0,
                unscaledValue: 0.0,
                value: 0.0
            }
        }
    });

}());