Working with streaming sound files

When a sound file or video file is playing back while its data is still being loaded, it is said to be streaming. External sound files that are loaded from a remote server are often streamed so that the user doesn't have to wait for all the sound data to load before listening to the sound.

The SoundMixer.bufferTime property represents the number of milliseconds of sound data that Flash Player or AIR should gather before letting the sound play. In other words, if the bufferTime property is set to 5000, Flash Player or AIR loads at least 5000 milliseconds worth of data from the sound file before the sound begins to play. The default SoundMixer.bufferTime value is 1000.

Your application can override the global SoundMixer.bufferTime value for an individual sound by explicitly specifying a new bufferTime value when loading the sound. To override the default buffer time, first create a new instance of the SoundLoaderContext class, set its bufferTime property, and then pass it as a parameter to the Sound.load() method, as shown below:

import flash.media.Sound;
import flash.media.SoundLoaderContext;
import flash.net.URLRequest;

var s:Sound = new Sound();
var req:URLRequest = new URLRequest("bigSound.mp3");
var context:SoundLoaderContext = new SoundLoaderContext(8000, true);
s.load(req, context);
s.play();

As playback continues, Flash Player and AIR try to keep the sound buffer at the same size or greater. If the sound data loads faster than the playback speed, playback will continue without interruption. However, if the data loading rate slows down because of network limitations, the playhead could reach the end of the sound buffer. If this happens, playback is suspended, though it automatically resumes once more sound data has been loaded.

To find out if playback is suspended because Flash Player or AIR is waiting for data to load, use the Sound.isBuffering property.