Recipe 15.14. Changing the Volume or Pan of a Sound

Problem

You want to change the volume of a sound, making it softer or louder, or set the pan (amount of left/right balance) of a sound.

Solution

Create a new SoundTransform object, specifying the volume at which you want the sound to play, or the amount and direction of panning you want to apply. Pass this to the soundTransform property of the SoundChannel object associated with the sound you want to control.

Discussion

In previous versions of ActionScript, you could set the volume and panning of a sound directly on the Sound object itself. Now these aspects of the sound playback are abstracted into the SoundTransform class.

A SoundChannel object has a soundTransform property, which is an instance of the SoundTransform class. To change a sound's volume or panning, create a new SoundTransform object and set the desired values. Next, set the SoundChannel's soundTransform property to this new object. For example, the following sets the sound volume to 50 percent:

var _sound:Sound = new Sound(new URLRequest("song.mp3")); var channel:SoundChannel = _sound.play(  ); var transform:SoundTransform = new SoundTransform(  ); transform.volume = .5; channel.soundTransform = transform;

As you can gather, the volume can range from 0.0 (silent) to 1.0 (full volume). Similarly, you can set the panning of a sound:

var channel:SoundChannel = _sound.play(  ); var transform:SoundTransform = new SoundTransform(  ); transform.pan = -1.0; channel.soundTransform = transform;

This sets the sound to play only in the left speaker, as the values here can range from -1.0 (full left) to 1.0 (full right).

You can also pass the volume and pan amounts straight to the SoundTransform's constructor, like so:

var channel:SoundChannel = _sound.play(  ); var transform:SoundTransform = new SoundTransform(.5, -1.0); channel.soundTransform = transform;

The first parameter is volume, and the second is pan.

See Also

Recipe 15.13