audio policy manager: stream volume per device

Improve volume management by keeping track of volume for each type
of device independently.

AudioPolicyManagerBase now keeps track of stream volumes for each device
and apply volume according to current device selection.
Methods to set and get stream volume now specify the device class.
A value for "default" device is always present for each stream and is used
if a device is selected and no specific volume was ever set for this device.

Change-Id: I06d8f43aa151a09014f7e47e81304c73ff82e9f8

1 files changed, 13 insertions, 4 deletions

diff --git a/include/hardware_legacy/AudioPolicyInterface.h b/include/hardware_legacy/AudioPolicyInterface.h
index 1ee0e20..a1c1fd5 100644
--- a/include/hardware_legacy/AudioPolicyInterface.h
+++ b/include/hardware_legacy/AudioPolicyInterface.h
@@ -128,10 +128,19 @@ public:
                                       int indexMin,
                                       int indexMax) = 0;
 
-    // sets the new stream volume at a level corresponding to the supplied index
-    virtual status_t setStreamVolumeIndex(AudioSystem::stream_type stream, int index) = 0;
-    // retreive current volume index for the specified stream
-    virtual status_t getStreamVolumeIndex(AudioSystem::stream_type stream, int *index) = 0;
+    // sets the new stream volume at a level corresponding to the supplied index for the
+    // supplied device. By convention, specifying AUDIO_DEVICE_OUT_DEFAULT means
+    // setting volume for all devices
+    virtual status_t setStreamVolumeIndex(AudioSystem::stream_type stream,
+                                          int index,
+                                          audio_devices_t device) = 0;
+
+    // retrieve current volume index for the specified stream and the
+    // specified device. By convention, specifying AUDIO_DEVICE_OUT_DEFAULT means
+    // querying the volume of the active device.
+    virtual status_t getStreamVolumeIndex(AudioSystem::stream_type stream,
+                                          int *index,
+                                          audio_devices_t device) = 0;
 
     // return the strategy corresponding to a given stream type
     virtual uint32_t getStrategyForStream(AudioSystem::stream_type stream) = 0;