Audio Management

You can manage multiple streams of audio using various audio policies.

The policies control audio ducking (referred to as simply ducking), audio ramping (referred to as simply ramping), and using audio preemption (referred to as simply preemption).

Ducking is an audio effect that's used to manage concurrent audio playback where the playing of one audio stream causes the volume of another to decrease. The decision whether one audio stream causes another stream to duck (lower in volume) is based on priorities that you configure.

Ramping is an audio effect that gradually increases or decreases the volume of an audio stream so that it fades in or fades out. This effect gradually increases or decreases the volume so that when ducking occurs, it's less abrupt.

Preemption is a configuration option that causes the system to temporarily suspend the playing of an audio stream based on audio management policies in place in the system. Automatically suspending or pausing audio is an option that can be specified on an audio type in the audio policy configuration file.

These audio policies can be configured on a system using the audio policy configuration file, which can be specified when you start io-audio or using the policy_conf in the audio configuration file. If your application needs to monitor any audio management changes your system, you can use control events. For more information, see Control events in the “Audio Architecture” chapter of this guide.
Tip: If you have Audio component BuildID 594—January 17, 2018 (7.0.594.S201801171044) or a later update installed, the following applies:

Previously, the location of the audio policy configuration file was specified using the policy_conf key in the [GLOBAL] section. With this update, you must specify the location of audio policy configuration file using the policy_conf key in the [AUDIOMGMT] section of the audio configuration file. In addition, with this update you can't specify the location of the audio policy configuration file as an option when you run io-audio.

Tip: If you have Audio component BuildID 594—January 17, 2018 (7.0.594.S201801171044) the following applies:

Previously, the audio management policies were defined in a single audio policy configuration file and applied to all audio types and devices on the system as a single context.

With this update, you can now configure multiple audio management contexts. Each audio management context has its own audio policy configuration file and associated mixer device.

Also with this update, audio type volume controls are available to let you apply volume settings to all audio streams of a particular audio type. For more information, see Understanding audio type volume controls in this chapter.