audio5.js

/*!
 * Audio5js: HTML5 Audio Compatibility Layer
 * https://github.com/zohararad/audio5js
 * License MIT (c) Zohar Arad 2013
 */
(function ($win, ns, factory) {
  "use strict";
  /*global define */
  /*global swfobject */

  if (typeof (module) !== 'undefined' && module.exports) { // CommonJS
    module.exports = factory(ns, $win);
  } else if (typeof (define) === 'function' && define.amd) { // AMD
    define(function () {
      return factory(ns, $win);
    });
  } else { // <script>
    $win[ns] = factory(ns, $win);
  }

}(window, 'Audio5js', function (ns, $win) {

  "use strict";

  var ActiveXObject = $win.ActiveXObject;

  /**
   * AudioError Class
   * @param {String} message error message
   * @constructor
   */
  function AudioError(message) {
    this.message = message;
  }

  AudioError.prototype = new Error();

  /**
   * Clones an object
   * @param obj object to clone
   * @return {Object} cloned object
   */
  function cloneObject(obj) {
    var clone = {}, i;
    for (i in obj) {
      if (typeof (obj[i]) === "object") {
        clone[i] = cloneObject(obj[i]);
      } else {
        clone[i] = obj[i];
      }
    }
    return clone;
  }

  /**
   * Extend an object with a mixin
   * @param {Object} target target object to extend
   * @param {Object} mixin object to mix into target
   * @return {*} extended object
   */
  var extend = function (target, mixin) {
    var name, m = cloneObject(mixin);
    for (name in m) {
      if (m.hasOwnProperty(name)) {
        target[name] = m[name];
      }
    }
    return target;
  };

  /**
   * Extend an object's prototype with a mixin
   * @param {Object} target target object to extend
   * @param {Object} mixin object to mix into target
   * @return {*} extended object
   */
  var include = function (target, mixin) {
    return extend(target.prototype, mixin);
  };

  var Pubsub = {
    /**
     * Subscribe to event on a channel
     * @param {String} evt name of channel / event to subscribe
     * @param {Function} fn the callback to execute on message publishing
     * @param {Object} ctx the context in which the callback should be executed
     */
    on: function (evt, fn, ctx) {
      this.subscribe(evt, fn, ctx, false);
    },
    /**
     * Subscribe to a one-time event on a channel
     * @param {String} evt name of channel / event to subscribe
     * @param {Function} fn the callback to execute on message publishing
     * @param {Object} ctx the context in which the callback should be executed
     */
    one: function(evt, fn, ctx) {
      this.subscribe(evt, fn, ctx, true);
    },
    /**
     * Unsubscribe from an event on a channel
     * @param {String} evt name of channel / event to unsubscribe
     * @param {Function} fn the callback used when subscribing to the event
     */
    off: function (evt, fn) {
      if (this.channels[evt] === undefined) { return; }
      var i, l;
      for (i = 0, l = this.channels[evt].length; i  < l; i++) {
        var sub = this.channels[evt][i].fn;
        if (sub === fn) {
          this.channels[evt].splice(i, 1);
          break;
        }
      }
    },
    /**
     * Add event subscription to channel. Called by `on` and `one`
     * @param {String} evt name of channel / event to subscribe
     * @param {Function} fn the callback to execute on message publishing
     * @param {Object} ctx the context in which the callback should be executed
     * @param {Boolean} once indicate if event should be triggered once or not
     */
    subscribe: function (evt, fn, ctx, once) {
      if (this.channels === undefined) {
        this.channels = {};
      }
      this.channels[evt] = this.channels[evt] || [];
      this.channels[evt].push({fn: fn, ctx: ctx, once: (once || false)});
    },
    /**
     * Publish a message on a channel. Accepts **args** after event name
     * @param {String} evt name of channel / event to trigger
     */
    trigger: function (evt) {
      if (this.channels && this.channels.hasOwnProperty(evt)) {
        var args = Array.prototype.slice.call(arguments, 1);

        // temp array to store all subscribers for the channel evt that must be stored in state
        var evtSubscribers = [];
        // temp array to store all subscribers for the channel evt that is being triggered that must be executed.
        var evtSubscribersForExec = [];

        while(this.channels[evt].length > 0) {
          var sub = this.channels[evt].shift();

          if ( !sub.once ){
            // for any channel event triggers that are not marked as once only, we need to keep.
            evtSubscribers.push(sub);
          }

          // if we have a function with the channel subscription, store in temp array ready to call after all proceeded
          if (typeof (sub.fn) === 'function') {
            // every subscriber we've processed will be executed
            evtSubscribersForExec.push(sub);
          }
        }

        // before we execute any of the subscribers to the trigger, we must make sure keep this.channels[evt] up to date in case any sub fns call off
        this.channels[evt] = evtSubscribers;

        // run all the event subscribers that need executing
        while(evtSubscribersForExec.length > 0) {
          var eventSub = evtSubscribersForExec.shift();
          eventSub.fn.apply(eventSub.ctx, args);
        }
      }
    }
  };

  var util = {
    /**
     * Flash embed code string with cross-browser support.
     */
  flash_embed_code: function (id, swf_location, ts) {
      var prefix;
      var elemId = ns + id;
      var s = '<param name="movie" value="' + swf_location + '?playerInstanceNumber=' + id + '&datetime=' + ts + '"/>' +
        '<param name="wmode" value="transparent"/>' +
        '<param name="allowscriptaccess" value="always" />' +
        '</object>';
      if (ActiveXObject) {
        prefix = '<object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" width="1" height="1" id="' + elemId + '">';
      } else {
        prefix = '<object type="application/x-shockwave-flash" data="' + swf_location + '?playerInstanceNumber=' + id + '&datetime=' + ts + '" width="1" height="1" id="' + elemId + '" >';
      }

      return prefix + s;
    },
    /**
     * Check if browser supports audio mime type.
     * @param {String} mime_type audio mime type to check
     * @return {Boolean} whether browser supports passed audio mime type
     */
    can_play: function (mime_type) {
      var a = document.createElement('audio');
      var mime_str;
      switch (mime_type) {
        case 'mp3':
          mime_str = 'audio/mpeg;';
          break;
        case 'vorbis':
          mime_str = 'audio/ogg; codecs="vorbis"';
          break;
        case 'opus':
          mime_str = 'audio/ogg; codecs="opus"';
          break;
        case 'webm':
          mime_str = 'audio/webm; codecs="vorbis"';
          break;
        case 'mp4':
          mime_str = 'audio/mp4; codecs="mp4a.40.5"';
          break;
        case 'wav':
          mime_str = 'audio/wav; codecs="1"';
          break;
      }
      if (mime_str !== undefined) {
        if (mime_type === 'mp3' && navigator.userAgent.match(/Android/i) && navigator.userAgent.match(/Firefox/i)) {
          return true;
        }
        try {
          return !!a.canPlayType && a.canPlayType(mime_str) !== '';
        } catch (e) {
          return false;
        }
      }
      return false;
    },
    /**
     * Boolean flag indicating whether the browser has Flash installed or not
     */
    has_flash: (function () {
      var r = false;
      if (navigator.plugins && navigator.plugins.length && navigator.plugins['Shockwave Flash']) {
        r = true;
      } else if (navigator.mimeTypes && navigator.mimeTypes.length) {
        var mimeType = navigator.mimeTypes['application/x-shockwave-flash'];
        r = mimeType && mimeType.enabledPlugin;
      } else {
        try {
          var ax = new ActiveXObject('ShockwaveFlash.ShockwaveFlash');
          r = typeof (ax) === 'object';
        } catch (e) {}
      }
      return r;
    }()),
    /**
     * Embed Flash MP3 player SWF to DOM
     * @param {String} swf_location location of MP3 player SWF
     * @param {String} id swf unique ID used for resolving callbacks from ExternalInterface to Javascript
     */
    embedFlash: function (swf_location, id) {
      var d = document.createElement('div');
      d.style.position = 'absolute';
      d.style.width = '1px';
      d.style.height = '1px';
      d.style.top = '1px';
      document.body.appendChild(d);
      if(typeof($win.swfobject) === 'object'){
        var fv = {
          playerInstance: 'window.'+ ns + '_flash.instances[\''+id+'\']'
        };
        var params = {
          allowscriptaccess: 'always',
          wmode: 'transparent'
        };
        d.innerHTML = '<div id="'+ ns + id +'"></div>';
        swfobject.embedSWF(swf_location + '?ts='+(new Date().getTime() + Math.random()), ns + id, "1", "1", "9.0.0", null, fv, params);
      } else {
        var ts = new Date().getTime() + Math.random(); // Ensure swf is not pulled from cache
        d.innerHTML = this.flash_embed_code(id, swf_location, ts);
      }
      return document.getElementById(id);
    },
    /**
     * Formats seconds into a time string hh:mm:ss.
     * @param {Number} seconds seconds to format as string
     * @return {String} formatted time string
     */
    formatTime: function (seconds) {
      var hours = parseInt(seconds / 3600, 10) % 24;
      var minutes = parseInt(seconds / 60, 10) % 60;
      var secs = parseInt(seconds % 60, 10);
      var result, fragment = (minutes < 10 ? "0" + minutes : minutes) + ":" + (secs  < 10 ? "0" + secs : secs);
      if (hours > 0) {
        result = (hours < 10 ? "0" + hours : hours) + ":" + fragment;
      } else {
        result = fragment;
      }
      return result;
    }
  };

  util.use_flash = util.can_play('mp3');

  var Audio5js, FlashAudioPlayer, HTML5AudioPlayer;

  /**
   * Common audio attributes object. Mixed into audio players.
   * @type {Object}
   */
  var AudioAttributes = {
    playing: false, /** {Boolean} player playback state  */
    vol: 1, /** {Float} audio volume */
    duration: 0, /** {Float} audio duration (sec) */
    position: 0, /** {Float} audio position (sec) */
    load_percent: 0, /** {Float} audio file load percent (%) */
    seekable: false, /** {Boolean} is loaded audio seekable */
    ready: null /** {Boolean} is loaded audio seekable */
  };

  /**
   * Global object holding flash-based player instances.
   * Used to create a bridge between Flash's ExternalInterface calls and FlashAudioPlayer instances
   * @type {Object}
   */
  var globalAudio5Flash = $win[ns + '_flash'] = $win[ns + '_flash'] || {
    instances: [] /** FlashAudioPlayer instance hash */
  };

  /**
   * Flash MP3 Audio Player Class
   * @constructor
   */
  FlashAudioPlayer = function () {
    if (util.use_flash && !util.has_flash) {
      throw new Error('Flash Plugin Missing');
    }
  };

  FlashAudioPlayer.prototype = {
    /**
     * Initialize the player
     * @param {String} swf_src path to audio player SWF file
     */
    init: function (swf_src) {
      globalAudio5Flash.instances.push(this);
      this.id = globalAudio5Flash.instances.length - 1;
      this.embed(swf_src);
    },
    /**
     * Embed audio player SWF in page and assign reference to audio instance variable
     * @param {String} swf_src path to audio player SWF file
     */
    embed: function (swf_src) {
      util.embedFlash(swf_src, this.id);
    },
    /**
     * ExternalInterface callback indicating SWF is ready
     */
    eiReady: function () {
      this.audio = document.getElementById(ns + this.id);
      this.trigger('ready');
    },
    /**
     * ExternalInterface audio load started callback. Fires when audio starts loading.
     */
    eiLoadStart: function(){
      this.trigger('loadstart');
    },
    /**
     * ExternalInterface audio metadata loaded callback. Fires when audio ID3 tags have been loaded.
     */
    eiLoadedMetadata: function(){
      this.trigger('loadedmetadata');
    },
    /**
     * ExternalInterface audio can play callback. Fires when audio can be played.
     */
    eiCanPlay: function () {
      this.trigger('canplay');
    },
    /**
     * ExternalInterface timeupdate callback. Fires as long as playhead position is updated (audio is being played).
     * @param {Float} position audio playback position (sec)
     * @param {Float} duration audio total duration (sec)
     * @param {Boolean} seekable is audio seekable or not (download or streaming)
     */
    eiTimeUpdate: function (position, duration, seekable) {
      this.position = position;
      this.duration = duration;
      this.seekable = seekable;
      this.trigger('timeupdate', position, (this.seekable ? duration : null));
    },
    /**
     * ExternalInterface download progress callback. Fires as long as audio file is downloaded by browser.
     * @param {Float} percent audio download percent
     * @param {Float} duration audio total duration (sec)
     * * @param {Boolean} seekable is audio seekable or not (download or streaming)
     */
    eiProgress: function (percent, duration, seekable) {
      this.load_percent = percent;
      this.duration = duration;
      this.seekable = seekable;
      this.trigger('progress', percent);
    },
    /**
     * ExternalInterface audio load error callback.
     * @param {String} msg error message
     */
    eiLoadError: function (msg) {
      this.trigger('error', msg);
    },
    /**
     * ExternalInterface audio play callback. Fires when audio starts playing.
     */
    eiPlay: function () {
      this.playing = true;
      this.trigger('play');
      this.trigger('playing');
    },
    /**
     * ExternalInterface audio pause callback. Fires when audio is paused.
     */
    eiPause: function () {
      this.playing = false;
      this.trigger('pause');
    },
    /**
     * ExternalInterface audio ended callback. Fires when audio playback ended.
     */
    eiEnded: function () {
      this.pause();
      this.trigger('ended');
    },
    /**
     * ExternalInterface audio seeking callback. Fires when audio is being seeked.
     */
    eiSeeking: function(){
      this.trigger('seeking');
    },
    /**
     * ExternalInterface audio seeked callback. Fires when audio has been seeked.
     */
    eiSeeked: function(){
      this.trigger('seeked');
    },
    /**
     * Resets audio position and parameters. Invoked once audio is loaded.
     */
    reset: function () {
      this.seekable = false;
      this.duration = 0;
      this.position = 0;
      this.load_percent = 0;
    },
    /**
     * Load audio from url.
     * @param {String} url URL of audio to load
     */
    load: function (url) {
      this.reset();
      this.audio.load(url);
    },
    /**
     * Play audio
     */
    play: function () {
      this.audio.pplay();
    },
    /**
     * Pause audio
     */
    pause: function () {
      this.audio.ppause();
    },
    /**
     * Get / Set audio volume
     * @param {Float} v audio volume to set between 0 - 1.
     * @return {Float} current audio volume
     */
    volume: function (v) {
      if (v !== undefined && !isNaN(parseInt(v, 10))) {
        this.audio.setVolume(v);
        this.vol = v;
      } else {
        return this.vol;
      }
    },
    /**
     * Seek audio to position
     * @param {Float} position audio position in seconds to seek to.
     */
    seek: function (position) {
      try {
        this.audio.seekTo(position);
        this.position = position;
      } catch (e) {}
    },
    /**
     * This feature was not implemented for Flash
     */
    rate: function () {
      // Not implemented
    },
    /**
     * Destroy audio object and remove from DOM
     */
    destroyAudio: function() {
      if(this.audio){
        this.pause();
        this.audio.parentNode.removeChild(this.audio);
        delete globalAudio5Flash.instances[this.id];
        globalAudio5Flash.instances.splice(this.id, 1);
        delete this.audio;
      }
    }
  };

  include(FlashAudioPlayer, Pubsub);
  include(FlashAudioPlayer, AudioAttributes);

  /**
   * HTML5 Audio Player
   * @constructor
   */
  HTML5AudioPlayer = function () {};

  HTML5AudioPlayer.prototype = {
    /**
     * Initialize the player instance
     */
    init: function () {
      this._rate = 1;
      this.trigger('ready');
    },
    /**
     * Create new audio instance
     */
    createAudio: function(){
      this.audio = new Audio();
      this.audio.autoplay = false;
      this.audio.preload = 'auto';
      this.audio.autobuffer = true;
      this.audio.playbackRate = this._rate;
      this.bindEvents();
    },
    /**
     * Destroy current audio instance
     */
    destroyAudio: function(){
      if(this.audio){
        this.pause();
        this.unbindEvents();
        try {
          this.audio.setAttribute('src', '');
        } finally {
          delete this.audio;
        }
      }
    },
    /**
     * Sets up audio event listeners once so adding / removing event listeners is always done
     * on the same callbacks.
     */
    setupEventListeners: function(){
      this.listeners = {
        loadstart: this.onLoadStart.bind(this),
        canplay: this.onLoad.bind(this),
        loadedmetadata: this.onLoadedMetadata.bind(this),
        play: this.onPlay.bind(this),
        playing: this.onPlaying.bind(this),
        pause: this.onPause.bind(this),
        ended: this.onEnded.bind(this),
        error: this.onError.bind(this),
        timeupdate: this.onTimeUpdate.bind(this),
        seeking: this.onSeeking.bind(this),
        seeked: this.onSeeked.bind(this)
      };
    },
    /**
     * Bind DOM events to Audio object
     */
    bindEvents: function() {
      if(this.listeners === undefined){
        this.setupEventListeners();
      }
      this.audio.addEventListener('loadstart', this.listeners.loadstart, false);
      this.audio.addEventListener('canplay', this.listeners.canplay, false);
      this.audio.addEventListener('loadedmetadata', this.listeners.loadedmetadata, false);
      this.audio.addEventListener('play', this.listeners.play, false);
      this.audio.addEventListener('playing', this.listeners.playing, false);
      this.audio.addEventListener('pause', this.listeners.pause, false);
      this.audio.addEventListener('ended', this.listeners.ended, false);
      this.audio.addEventListener('error', this.listeners.error, false);
      this.audio.addEventListener('timeupdate', this.listeners.timeupdate, false);
      this.audio.addEventListener('seeking', this.listeners.seeking, false);
      this.audio.addEventListener('seeked', this.listeners.seeked, false);
    },
    /**
     * Unbind DOM events from Audio object
     */
    unbindEvents: function() {
      this.audio.removeEventListener('loadstart', this.listeners.loadstart);
      this.audio.removeEventListener('canplay', this.listeners.canplay);
      this.audio.removeEventListener('loadedmetadata', this.listeners.loadedmetadata);
      this.audio.removeEventListener('play', this.listeners.play);
      this.audio.removeEventListener('playing', this.listeners.playing);
      this.audio.removeEventListener('pause', this.listeners.pause);
      this.audio.removeEventListener('ended', this.listeners.ended);
      this.audio.removeEventListener('error', this.listeners.error);
      this.audio.removeEventListener('timeupdate', this.listeners.timeupdate);
      this.audio.removeEventListener('seeking', this.listeners.seeking);
      this.audio.removeEventListener('seeked', this.listeners.seeked);
    },
    /**
     * Audio load start event handler. Triggered when audio starts loading
     */
    onLoadStart: function(){
      this.trigger('loadstart');
    },
    /**
     * Audio canplay event handler. Triggered when audio is loaded and can be played.
     * Resets player parameters and starts audio download progress timer.
     */
    onLoad: function () {
      if(!this.audio){
        return setTimeout(this.onLoad.bind(this), 100);
      }
      this.seekable = this.audio.seekable && this.audio.seekable.length > 0;
      if (this.seekable) {
        this.timer = setInterval(this.onProgress.bind(this), 250);
      }
      this.trigger('canplay');
    },
    /**
     * Audio ID3 load event handler. Triggered when ID3 metadata is loaded.
     */
    onLoadedMetadata: function(){
      this.trigger('loadedmetadata');
    },
    /**
     * Audio play event handler. Triggered when audio starts playing.
     */
    onPlay: function () {
      this.playing = true;
      this.trigger('play');
    },
    /**
     * Audio play event handler. Triggered when audio starts playing.
     */
    onPlaying: function () {
      this.playing = true;
      this.trigger('playing');
    },
    /**
     * Audio pause event handler. Triggered when audio is paused.
     */
    onPause: function () {
      this.playing = false;
      this.trigger('pause');
    },
    /**
     * Audio ended event handler. Triggered when audio playback has ended.
     */
    onEnded: function () {
      this.playing = false;
      this.trigger('ended');
    },
    /**
     * Audio timeupdate event handler. Triggered as long as playhead position is updated (audio is being played).
     */
    onTimeUpdate: function () {
      if (this.audio && this.playing) {
        try{
          this.position = this.audio.currentTime;
          this.duration = this.audio.duration === Infinity ? null : this.audio.duration;
        } catch (e){}
        this.trigger('timeupdate', this.position, this.duration);
      }
    },
    /**
     * Audio download progress timer callback. Check audio's download percentage.
     * Called periodically as soon as the audio loads and can be played.
     * Cancelled when audio has fully download or when a new audio file has been loaded to the player.
     */
    onProgress: function () {
      if (this.audio && this.audio.buffered !== null && this.audio.buffered.length) {
        this.duration = this.audio.duration === Infinity ? null : this.audio.duration;
        this.load_percent = parseInt(((this.audio.buffered.end(this.audio.buffered.length - 1) / this.duration) * 100), 10);
        this.trigger('progress', this.load_percent);
        if (this.load_percent >= 100) {
          this.clearLoadProgress();
        }
      }
    },
    /**
     * Audio error event handler
     * @param e error event
     */
    onError: function (e) {
      this.trigger('error', e);
    },
    /**
     * Audio seeking event handler. Triggered when audio seek starts.
     */
    onSeeking: function(){
      this.trigger('seeking');
    },
    /**
     * Audio seeked event handler. Triggered when audio has been seeked.
     */
    onSeeked: function(){
      this.trigger('seeked');
    },
    /**
     * Clears periodical audio download progress callback.
     */
    clearLoadProgress: function () {
      if (this.timer !== undefined) {
        clearInterval(this.timer);
        delete this.timer;
      }
    },
    /**
     * Resets audio position and parameters.
     */
    reset: function () {
      this.clearLoadProgress();
      this.seekable = false;
      this.duration = 0;
      this.position = 0;
      this.load_percent = 0;
    },
    /**
     * Load audio from url.
     * @param {String} url URL of audio to load
     */
    load: function (url) {
      this.reset();
      this.trigger('pause');
      //this.destroyAudio();
      if(this.audio === undefined){
        this.createAudio();
      }
      this.audio.setAttribute('src', url);
      this.audio.load();
    },
    /**
     * Play audio
     */
    play: function () {
      if(this.audio) {
        var playPromise = this.audio.play();
        this.audio.playbackRate = this._rate;
        return playPromise;
      }
    },
    /**
     * Pause audio
     */
    pause: function () {
      if(this.audio) {
        this.audio.pause();
      }
    },
    /**
     * Get / Set audio volume
     * @param {Float} v audio volume to set between 0 - 1.
     * @return {Float} current audio volume
     */
    volume: function (v) {
      if (v !== undefined && !isNaN(parseInt(v, 10))) {
        var vol = v < 0 ? 0 : Math.min(1, v);
        this.audio.volume = vol;
        this.vol = vol;
      } else {
        return this.vol;
      }
    },
    /**
     * Seek audio to position
     * @param {Float} position audio position in seconds to seek to.
     */
    seek: function (position) {
      var playing = this.playing;
      this.position = position;
      this.audio.currentTime = position;
      if (playing) {
        this.play();
      } else {
        if (this.audio.buffered !== null && this.audio.buffered.length) {
          this.trigger('timeupdate', this.position, this.duration);
        }
      }
    },
    /**
     * Define the playback rate
     * @param {Float} v playback rate value to be set
     */
    rate: function (v) {
      if (v === undefined || isNaN(parseFloat(v))) {
        return this._rate;
      }
      this._rate = v;
      if (this.audio) {
          this.audio.playbackRate = v;
      }
    }
  };

  include(HTML5AudioPlayer, Pubsub);
  include(HTML5AudioPlayer, AudioAttributes);

  /**
   * Default settings object
   * @type {Object}
   */
  var settings = {
    /**
     * {String} path to Flash audio player SWF file
     */
    swf_path: '/swf/audiojs.swf',
    /**
     * {Boolean} flag indicating whether to throw errors to the page or trigger an error event
     */
    throw_errors: true,
    /**
     * {Boolean} flag indicating whether to format player duration and position to hh:mm:ss or pass as raw seconds
     */
    format_time: true,
    /**
     * {Array} list of codecs to try and use when initializing the player. Used to selectively initialize the internal audio player based on codec support
     */
    codecs: ['mp3']
  };

  /**
   * Audio5js Audio Player
   * @param {Object} s player settings object
   * @constructor
   */
  Audio5js = function (s) {
    s = s || {};
    var k;
    for (k in settings) {
      if (settings.hasOwnProperty(k) && !s.hasOwnProperty(k)) {
        s[k] = settings[k];
      }
    }
    this.init(s);
  };

  /**
   * Check if browser can play a given audio mime type.
   * @param {String} mime_type audio mime type to check.
   * @return {Boolean} is audio mime type supported by browser or not
   */
  Audio5js.can_play = function (mime_type) {
    return util.can_play(mime_type);
  };

  Audio5js.prototype = {
    /**
     * Initialize player instance.
     * @param {Object} s player settings object
     */
    init: function (s) {
      this.ready = false;
      this.settings = s;
      this.audio = this.getPlayer();
      this.bindAudioEvents();
      if (this.settings.use_flash) {
        this.audio.init(s.swf_path);
      } else {
        this.audio.init();
      }
    },
    /**
     * Gets a new audio player instance based on codec support as defined in settings.codecs array.
     * Defaults to MP3 player either HTML or Flash based.
     * @return {FlashAudioPlayer,HTML5AudioPlayer} audio player instance
     */
    getPlayer: function () {
      var i, l, player, codec;
      if(this.settings.use_flash){
        player = new FlashAudioPlayer();
        this.settings.player = {
          engine: 'flash',
          codec: 'mp3'
        };
      } else {
        for (i = 0, l = this.settings.codecs.length; i < l; i++) {
          codec = this.settings.codecs[i];
          if (Audio5js.can_play(codec)) {
            player = new HTML5AudioPlayer();
            this.settings.use_flash = false;
            this.settings.player = {
              engine: 'html',
              codec: codec
            };
            break;
          }
        }
        if (player === undefined) {
          // here we double check for mp3 support instead of defaulting to Flash in case user overrode the settings.codecs array with an empty array.
          this.settings.use_flash = !Audio5js.can_play('mp3');
          player = this.settings.use_flash ? new FlashAudioPlayer() : new HTML5AudioPlayer();
          this.settings.player = {
            engine: (this.settings.use_flash ? 'flash' : 'html'),
            codec: 'mp3'
          };
        }
      }
      return player;
    },
    /**
     * Bind events from audio object to internal callbacks
     */
    bindAudioEvents: function () {
      this.audio.on('ready', this.onReady, this);
      this.audio.on('loadstart', this.onLoadStart, this);
      this.audio.on('loadedmetadata', this.onLoadedMetadata, this);
      this.audio.on('play', this.onPlay, this);
      this.audio.on('pause', this.onPause, this);
      this.audio.on('ended', this.onEnded, this);
      this.audio.on('canplay', this.onCanPlay, this);
      this.audio.on('timeupdate', this.onTimeUpdate, this);
      this.audio.on('progress', this.onProgress, this);
      this.audio.on('error', this.onError, this);
      this.audio.on('seeking', this.onSeeking, this);
      this.audio.on('seeked', this.onSeeked, this);
    },
    /**
     * Bind events from audio object to internal callbacks
     */
    unbindAudioEvents: function () {
      this.audio.off('ready', this.onReady);
      this.audio.off('loadstart', this.onLoadStart);
      this.audio.off('loadedmetadata', this.onLoadedMetadata);
      this.audio.off('play', this.onPlay);
      this.audio.off('pause', this.onPause);
      this.audio.off('ended', this.onEnded);
      this.audio.off('canplay', this.onCanPlay);
      this.audio.off('timeupdate', this.onTimeUpdate);
      this.audio.off('progress', this.onProgress);
      this.audio.off('error', this.onError);
      this.audio.off('seeking', this.onSeeking);
      this.audio.off('seeked', this.onSeeked);
    },
    /**
     * Load audio from URL
     * @param {String} url URL of audio to load
     */
    load: function (url) {
      var that = this;
      var f = function(u){
        that.audio.load(u);
        that.trigger('load');
      };

      if(this.ready){
        f(url);
      } else {
        this.on('ready', f);
      }
    },
    /**
     * Play audio
     */
    play: function () {
      if(!this.playing){
        return this.audio.play();
      }
    },
    /**
     * Pause audio
     */
    pause: function () {
      if(this.playing){
        this.audio.pause();
      }
    },
    /**
     * Toggle audio play / pause
     */
    playPause: function () {
      this[this.playing ? 'pause' : 'play']();
    },
    /**
     * Get / Set audio volume
     * @param {Float} v audio volume to set between 0 - 1.
     * @return {Float} current audio volume
     */
    volume: function (v) {
      if (v !== undefined && !isNaN(parseInt(v, 10))) {
        this.audio.volume(v);
        this.vol = v;
      } else {
        return this.vol;
      }
    },
    /**
     * Seek audio to position
     * @param {Float} position audio position in seconds to seek to.
     */
    seek: function (position) {
      this.audio.seek(position);
      this.position = position;
    },
    /**
     * Define the playback rate
     * @param {Float} value playback rate value to be set
     */
    rate: function (value) {
        return this.audio.rate(value);
    },
    /**
     * Destroy audio object and remove from DOM
     */
    destroy: function() {
      this.unbindAudioEvents();
      this.audio.destroyAudio();
    },
    /**
     * Callback for audio ready event. Indicates audio is ready for playback.
     * Looks for ready callback in settings object and invokes it in the context of player instance
     */
    onReady: function () {
      this.ready = true;
      if (typeof (this.settings.ready) === 'function') {
        this.settings.ready.call(this, this.settings.player);
      }
      this.trigger('ready');
    },
    /**
     * Audio load start event handler
     */
    onLoadStart: function(){
      this.trigger('loadstart');
    },
    /**
     * Audio metadata loaded event handler
     */
    onLoadedMetadata: function(){
      this.trigger('loadedmetadata');
    },
    /**
     * Audio play event handler
     */
    onPlay: function () {
      this.playing = true;
      this.trigger('play');
    },
    /**
     * Audio pause event handler
     */
    onPause: function () {
      this.playing = false;
      this.trigger('pause');
    },
    /**
     * Playback end event handler
     */
    onEnded: function () {
      this.playing = false;
      this.trigger('ended');
    },
    /**
     * Audio error event handler
     */
    onError: function () {
      var error = new AudioError('Audio Error. Failed to Load Audio');
      if (this.settings.throw_errors) {
        throw error;
      } else {
        this.trigger('error', error);
      }
    },
    /**
     * Audio canplay event handler. Triggered when enough audio has been loaded to by played.
     */
    onCanPlay: function () {
      this.trigger('canplay');
    },
    /**
     * Audio seeking event handler
     */
    onSeeking: function(){
      this.trigger('seeking');
    },
    /**
     * Audio seeked event handler
     */
    onSeeked: function(){
      this.trigger('seeked');
    },
    /**
     * Playback time update event handler
     * @param {Float} position play head position (sec)
     * @param {Float} duration audio duration (sec)
     */
    onTimeUpdate: function (position, duration) {
      this.position = this.settings.format_time ? util.formatTime(position) : position;
      this.duration = this.settings.format_time && duration !== null ? util.formatTime(duration) : duration;
      this.trigger('timeupdate', this.position, this.duration);
    },
    /**
     * Audio download progress event handler
     * @param {Float} loaded audio download percent
     */
    onProgress: function (loaded) {
      this.duration = this.audio.duration;
      this.load_percent = loaded;
      this.trigger('progress', loaded);
    }
  };

  include(Audio5js, Pubsub);
  include(Audio5js, AudioAttributes);

  return Audio5js;

}));