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soundObject.getBytesLoaded()

Returns

An integer representing the number of bytes that have finished downloading to the Player. Divide by 1024 to convert bytes to kilobytes (KB).

Description

The getBytesLoaded( ) method tells us the number of bytes of an external sound file that have downloaded into the Flash Player due to a loadSound( ) call. For a new Sound object, getBytesLoaded( ) returns undefined. Immediately after each call to loadSound( ), getBytesLoaded( ) also returns undefined. As data arrives, getBytesLoaded( ) returns the number of bytes transferred so far (from 0 to getBytesTotal( )), until the entire sound has loaded. From then on, it returns the total number of bytes last transferred, until the next call to loadSound( ).

For Sound objects, getBytesLoaded( ) is used with getBytesTotal( ) to determine (and display, normally) the load progress of a downloading sound file. However, merely detecting the completion of a load operation does not require getBytesLoaded( ); the onLoad( ) event handler is executed automatically when a sound finishes loading.

Example

The following code adds a new method, preloadSound( ), to all Sound objects. It operates in the same way as loadSound( ), except that it uses getBytesLoaded( ) to report load progress while the sound is loading. The onLoad( ) handler responds to completion of the sound load operation, as usual. Note that as is, the code cannot load multiple sounds simultaneously because it does not queue preload requests. A queuing preloader is left as an exercise for the reader.

/*
 * Method: Sound.checkLoadProgress()
 *   Desc: Checks progress of a load(). Called only by preload().
 *         Reports progress by invoking a custom Sound.onBytesLoaded() handler.
 */
Sound.prototype.checkLoadProgress = function () {
  // Check how many KB have loaded.
  var kbLoaded = Math.floor(this.getBytesLoaded()/1024);
  // Check the size of the file loading, in KB.
  var kbTotal = Math.floor(this.getBytesTotal()/1024);
  // Calculate the percent complete.
  var percentDone = isNaN(Math.floor(kbLoaded/kbTotal * 100)) ?
                    0 : Math.floor(kbLoaded/kbTotal * 100);
  // Execute onBytesLoaded(), which typically would display load progress.
  this.onBytesLoaded(this.getBytesLoaded(), this.getBytesTotal(),
                     kbLoaded, kbTotal, percentDone);
  // If the amount loaded is equal to the total file size,
  // the file is finished loading. However, we must ensure
  // that getBytesLoaded() returns a value greater than 0
  // because both getBytesLoaded() and getBytesTotal()
  // return 0 until the first bit of data arrives.
  if (this.getBytesLoaded() > 5
      && this.getBytesLoaded() =  = this.getBytesTotal()) {
    // ...stop calling checkLoadProgress().
    this.clearLoadCheck();
  }
}
   
/*
 *  Method: Sound.clearLoadCheck()
 *   Desc: Cancels an interval calling checkLoadProgress().
 */
Sound.prototype.clearLoadCheck = function () {
  // If there is a load interval for this Sound object...
  if (this.loaderID) {
    // ...stop calling it.
    clearInterval(this.loaderID);
  }
}
   
/*
 * Method: Sound.preloadSound()
 *   Desc: Begins the download of a sound file and executes
 *         checkLoadProgress() every 200 ms until the file has loaded.
 */
Sound.prototype.preloadSound = function (url, isStreaming) {
  // Always stop any previous preload before proceeding.
  this.clearLoadCheck();
   
  // Load the Sound file.
  this.loadSound(url, isStreaming);
  // Call checkLoadProgress() every 200 milliseconds.
  this.loaderID = setInterval(this, "checkLoadProgress", 200);
}
   
// Usage:
// Create a Sound object.
music = new Sound();
// Assign an onLoad() callback.
music.onLoad = function (success) {
  // If the load was successful...
  if (success) {
    // ...use the new sound.
    trace("done loading!");
    this.start();
  } else {
    // ...otherwise, perform failure operations and
    // cancel the preload interval (REQUIRED!).
    trace("load failed");
    this.clearLoadCheck();
  }
}
// Assign an onBytesLoaded() callback. This is where each individual 
// Sound object can decide what to do with the preload information.
music.onBytesLoaded = function (bytesLoaded, bytesTotal,
                                kbLoaded, kbTotal, percentLoaded) {
  trace("Loading: " + kbLoaded +  " of " + kbTotal);
  trace(percentLoaded + " percent complete.");
}
   
// Load a streaming sound.
music.preloadSound("http://www.yoursite.com/sounds/song.mp3", true);

See Also

setInterval( ), Sound.getBytesTotal( ), Sound.onLoad( )

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