AudioPolicyManager: Use "safe" speaker for notifications if available

On particularly loud devices, unexpected audio bursts can be harmful.
For longer audio events, the conventional mitigation strategy is to
somehow soft-start (ramp) the loudspeaker volume, but this strategy
can severely impact the audibility of short audio events.

Use of the "safe" speaker path hints to AudioHAL to immediately output
at best allowable level for transient audio events.

SPEAKER_SAFE is aliased to SPEAKER for purposes of volume control.

Bug: 17319721
Change-Id: I75187c23f3d1f18e9f638c5d14e7b0bf805a67bc

1 files changed, 21 insertions, 0 deletions

diff --git a/services/audiopolicy/AudioPolicyManager.cpp b/services/audiopolicy/AudioPolicyManager.cpp
index 6adcde4..22c4e04 100644
--- a/services/audiopolicy/AudioPolicyManager.cpp
+++ b/services/audiopolicy/AudioPolicyManager.cpp
@@ -64,6 +64,7 @@ struct StringToEnum {
 const StringToEnum sDeviceNameToEnumTable[] = {
     STRING_TO_ENUM(AUDIO_DEVICE_OUT_EARPIECE),
     STRING_TO_ENUM(AUDIO_DEVICE_OUT_SPEAKER),
+    STRING_TO_ENUM(AUDIO_DEVICE_OUT_SPEAKER_SAFE),
     STRING_TO_ENUM(AUDIO_DEVICE_OUT_WIRED_HEADSET),
     STRING_TO_ENUM(AUDIO_DEVICE_OUT_WIRED_HEADPHONE),
     STRING_TO_ENUM(AUDIO_DEVICE_OUT_BLUETOOTH_SCO),
@@ -3824,6 +3825,14 @@ audio_devices_t AudioPolicyManager::getDevicesForStream(audio_stream_type_t stre
             break;
         }
     }
+
+    /*Filter SPEAKER_SAFE out of results, as AudioService doesn't know about it
+      and doesn't really need to.*/
+    if (devices & AUDIO_DEVICE_OUT_SPEAKER_SAFE) {
+        devices |= AUDIO_DEVICE_OUT_SPEAKER;
+        devices &= ~AUDIO_DEVICE_OUT_SPEAKER_SAFE;
+    }
+
     return devices;
 }
 
@@ -3926,12 +3935,20 @@ audio_devices_t AudioPolicyManager::getDeviceForStrategy(routing_strategy strate
             //   the isStreamActive() method only informs about the activity of a stream, not
             //   if it's for local playback. Note also that we use the same delay between both tests
             device = getDeviceForStrategy(STRATEGY_SONIFICATION, false /*fromCache*/);
+            //user "safe" speaker if available instead of normal speaker to avoid triggering
+            //other acoustic safety mechanisms for notification
+            if (device == AUDIO_DEVICE_OUT_SPEAKER && (availableOutputDeviceTypes & AUDIO_DEVICE_OUT_SPEAKER_SAFE))
+                device = AUDIO_DEVICE_OUT_SPEAKER_SAFE;
         } else if (isStreamActive(AUDIO_STREAM_MUSIC, SONIFICATION_RESPECTFUL_AFTER_MUSIC_DELAY)) {
             // while media is playing (or has recently played), use the same device
             device = getDeviceForStrategy(STRATEGY_MEDIA, false /*fromCache*/);
         } else {
             // when media is not playing anymore, fall back on the sonification behavior
             device = getDeviceForStrategy(STRATEGY_SONIFICATION, false /*fromCache*/);
+            //user "safe" speaker if available instead of normal speaker to avoid triggering
+            //other acoustic safety mechanisms for notification
+            if (device == AUDIO_DEVICE_OUT_SPEAKER && (availableOutputDeviceTypes & AUDIO_DEVICE_OUT_SPEAKER_SAFE))
+                device = AUDIO_DEVICE_OUT_SPEAKER_SAFE;
         }
 
         break;
@@ -4668,6 +4685,10 @@ audio_devices_t AudioPolicyManager::getDeviceForVolume(audio_devices_t device)
         }
     }
 
+    /*SPEAKER_SAFE is an alias of SPEAKER for purposes of volume control*/
+    if (device == AUDIO_DEVICE_OUT_SPEAKER_SAFE)
+        device = AUDIO_DEVICE_OUT_SPEAKER;
+
     ALOGW_IF(popcount(device) != 1,
             "getDeviceForVolume() invalid device combination: %08x",
             device);