Higher priority audio types can each apply a ducking level to a lower priority audio type, which creates a cumulative ducking level.
This behavior ensures that the relative ducking levels are correct. For example, using the file shown in “Example of an audio policy configuration file”, a system plays three active audio streams that match the audio types voice, ringtone, and multimedia. Each stream starts with a volume level of 100:
voice = 100 ringtone = 100 multimedia = 100
The volume decreases to the following levels after ducking occurs:
voice = 100 ringtone = 50 multimedia = 10
The voice audio type's duck_lower_prio_percent key causes both the lower priority audio types to adjust to 50% volume (50), but because the ringtone audio type's duck_lower_prio_percent key is set to 20, ringtone applies additional ducking to the lower priority audio type, multimedia. In this case, 20% of 50 is a volume level of 10.
[audio_type] name=voice prio=same duck_same_prio_policy=last_wins duck_same_prio_percent=0 duck_lower_prio_percent=50 [audio_type] name=ringtone # priority of the audio type is decreased by one from previous audio type prio=decr # ducking policy of same priority is last_wins, i.e., the last added # audio stream can duck previously added audio streams of same priority duck_same_prio_policy=last_wins duck_same_prio_percent=50 duck_lower_prio_percent=20 [audio_type] name=nav prio=decr duck_same_prio_policy=last_wins # Channel 0 ducked to 50 percent, Channel 1 remains at 100 percent # Ducking values default to 100 (no ducking) for channels not listed duck_same_prio_percent=ch0:50,ch1:100 duck_lower_prio_percent=ch0:50,ch1:100 [audio_type] name=tts_front prio=decr duck_same_prio_policy=last_wins # Ducking values apply to all channels duck_same_prio_percent=50 duck_lower_prio_percent=50 [audio_type] name=tts_back prio=same duck_same_prio_policy=last_wins duck_same_prio_percent=50 duck_lower_prio_percent=50 [audio_type] name=multimedia prio=decr duck_same_prio_policy=last_wins duck_same_prio_percent=0 duck_lower_prio_percent=50 [audio_type] name=default prio=decr # Mix audio streams at same priority with the below ducking configuration duck_same_prio_policy=mix # 100 percent means that no ducking is performed duck_same_prio_percent=100 duck_lower_prio_percent=noducking