webdaw-modules/heartbeat/audio_track.js

a set of modules for building a web-based DAW

/*
    controls the playback of the audio events in a track
*/
function audioTrack() {
  "use strict";

  var slice = Array.prototype.slice,
    //import
    typeString, // → defined in utils.js
    createAudioRecorder, // → defined in audio_recorder.js
    unscheduleCallback,
    AudioTrack;

  AudioTrack = function (track) {
    this.track = track;
    this.className = "AudioTrack";
    this.scheduledSamples = {};
    // this.recorder = createAudioRecorder(track);
  };

  unscheduleCallback = function (sample) {
    //console.log(sample.id, 'has been unscheduled');
    delete this.scheduledSamples[sample.id];
    sample = null;
  };

  AudioTrack.prototype.setAudioRecordingLatency = function (
    recordId,
    value,
    callback
  ) {
    this.recorder.setAudioRecordingLatency(recordId, value, callback);
  };

  AudioTrack.prototype.processEvent = function (audioEvent) {
    var sample = sequencer.createSample({
      buffer: audioEvent.buffer,
      track: audioEvent.track,
    });
    audioEvent.sample = sample;
    //console.log(audioEvent.sampleOffset, audioEvent.playheadOffset, audioEvent.latencyCompensation);
    audioEvent.offset = audioEvent.sampleOffset + audioEvent.playheadOffset; // + audioEvent.latencyCompensation;
    //audioEvent.time -= audioEvent.latencyCompensation;
    // set playheadOffset to 0 after the event has been scheduled
    audioEvent.playheadOffset = 0;
    //sample.start(audioEvent.time/1000, 127, audioEvent.offsetMillis/1000, audioEvent.durationMillis/1000);

    // console.log(sample);
    sample.start(audioEvent);
    //console.log(time, time + audioEvent.durationMillis/1000);
    //sample.stop(time + audioEvent.durationMillis/1000, function(){});

    this.scheduledSamples[sample.id] = sample;
  };

  /*
        AudioTrack.prototype.playEvent = function(audioEvent, seconds){
        };
    */

  AudioTrack.prototype.mute = function (audioEvent, mute) {
    console.log(audioEvent.sample);
    if (audioEvent.sample === undefined) {
      return;
    }
    audioEvent.sample.output.gain = mute ? 0 : 1;
  };

  AudioTrack.prototype.stopSample = function (audioEvent, seconds) {
    //console.log('stopping', audioEvent.id);
    if (audioEvent.sample === undefined) {
      return;
    }
    audioEvent.sample.stop(seconds, unscheduleCallback.bind(this));
  };

  AudioTrack.prototype.allNotesOff = function () {
    var sampleId,
      sample,
      scheduledSamples = this.scheduledSamples;

    for (sampleId in scheduledSamples) {
      if (scheduledSamples.hasOwnProperty(sampleId)) {
        //console.log('allNotesOff', sampleId);
        sample = scheduledSamples[sampleId];
        if (sample) {
          sample.unschedule(0, unscheduleCallback.bind(this));
        }
      }
    }
    this.scheduledSamples = {};
  };

  AudioTrack.prototype.prepareForRecording = function (recordId, callback) {
    if (this.recorder === false) {
      return false;
    }
    this.recorder.prepare(recordId, callback);
  };

  AudioTrack.prototype.stopRecording = function (callback) {
    this.recorder.stop(function (recording) {
      callback(recording);
    });
  };

  sequencer.protectedScope.createAudioTrack = function (track) {
    return new AudioTrack(track);
  };

  sequencer.protectedScope.addInitMethod(function () {
    typeString = sequencer.protectedScope.typeString;
    createAudioRecorder = sequencer.protectedScope.createAudioRecorder;
  });
}