qambi/dist/sample.js

MIDI sequencer, loads MIDI files, can record and playback MIDI, uses WebMIDI and WebAudio

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.Sample = undefined;

var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();

exports.fadeOut = fadeOut;

var _init_audio = require('./init_audio.js');

var _util = require('./util.js');

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

var Sample = exports.Sample = function () {
  function Sample(sampleData, event) {
    _classCallCheck(this, Sample);

    this.event = event;
    this.sampleData = sampleData;
  }

  _createClass(Sample, [{
    key: 'start',
    value: function start(time) {
      var _sampleData = this.sampleData,
          sustainStart = _sampleData.sustainStart,
          sustainEnd = _sampleData.sustainEnd;
      //console.log(sustainStart, sustainEnd)

      if (sustainStart && sustainEnd) {
        this.source.loop = true;
        this.source.loopStart = sustainStart;
        this.source.loopEnd = sustainEnd;
      }
      this.source.start(time);
    }
  }, {
    key: 'stop',
    value: function stop(time, cb) {
      var _this = this;

      var _sampleData2 = this.sampleData,
          releaseDuration = _sampleData2.releaseDuration,
          releaseEnvelope = _sampleData2.releaseEnvelope,
          releaseEnvelopeArray = _sampleData2.releaseEnvelopeArray;
      //console.log(releaseDuration, releaseEnvelope)

      this.source.onended = cb;

      if (releaseDuration && releaseEnvelope) {
        this.startReleasePhase = time;
        this.releaseFunction = function () {
          fadeOut(_this.output, {
            releaseDuration: releaseDuration,
            releaseEnvelope: releaseEnvelope,
            releaseEnvelopeArray: releaseEnvelopeArray
          });
        };
        try {
          this.source.stop(time + releaseDuration);
        } catch (e) {
          // in Firefox and Safari you can not call stop more than once
        }
        this.checkPhase();
      } else {
        try {
          this.source.stop(time);
        } catch (e) {
          // in Firefox and Safari you can not call stop more than once
        }
      }
    }
  }, {
    key: 'checkPhase',
    value: function checkPhase() {
      //console.log(context.currentTime, this.startReleasePhase)
      if (_init_audio.context.currentTime >= this.startReleasePhase) {
        this.releaseFunction();
        return;
      }
      requestAnimationFrame(this.checkPhase.bind(this));
    }
  }]);

  return Sample;
}();

function fadeOut(gainNode, settings) {
  var now = _init_audio.context.currentTime;
  var values = void 0,
      i = void 0,
      maxi = void 0;

  //console.log(settings)
  try {
    switch (settings.releaseEnvelope) {

      case 'linear':
        gainNode.gain.linearRampToValueAtTime(gainNode.gain.value, now);
        gainNode.gain.linearRampToValueAtTime(0.0, now + settings.releaseDuration);
        break;

      case 'equal power':
      case 'equal_power':
        values = (0, _util.getEqualPowerCurve)(100, 'fadeOut', gainNode.gain.value);
        gainNode.gain.setValueCurveAtTime(values, now, settings.releaseDuration);
        break;

      case 'array':
        maxi = settings.releaseEnvelopeArray.length;
        values = new Float32Array(maxi);
        for (i = 0; i < maxi; i++) {
          values[i] = settings.releaseEnvelopeArray[i] * gainNode.gain.value;
        }
        gainNode.gain.setValueCurveAtTime(values, now, settings.releaseDuration);
        break;

      default:
    }
  } catch (e) {
    // in Firefox and Safari you can not call setValueCurveAtTime and linearRampToValueAtTime more than once

    //console.log(values, now, settings.releaseDuration)
    //console.log(e, gainNode)
  }
}