commit b387fb45d2e339afee274cdf9db4bcde9765e149
author Eric Laurent <elaurent@google.com> Tue May 03 18:19:35 2022 +0200
committer Andy Hung <hunga@google.com> Tue Sep 06 18:11:08 2022 -0700
tree 5bc8104eb096f7a2349217ef4041d2c25300a48f
parent 6f9534fb373d96f7b2a9b5c4314e07ae9d657e1e

Spatializer: control audio HAL latency mode

Add support of HAL stream latency mode control to Spatializer
effect controller.
- Query supported latency modes when attached to a new output stream
and register a callback to be notified of changes
- Only use a head tracker sensor if the HAL stream supports low
  latency or does not support latency mode control.
- Set the requested latency mode according to head tracking state.

Bug: 218273231
Test: make
Merged-In: Ia78156d1e190bb49a67988567df066c1ab90f9bd
Change-Id: Ia78156d1e190bb49a67988567df066c1ab90f9bd

services/audiopolicy/service/Spatializer.cpp

diff --git a/services/audiopolicy/service/Spatializer.cpp b/services/audiopolicy/service/Spatializer.cpp
index 3860bbd..b420199 100644
--- a/services/audiopolicy/service/Spatializer.cpp
+++ b/services/audiopolicy/service/Spatializer.cpp
@@ -769,7 +769,9 @@
             mEngine->setEnabled(false);
             mEngine.clear();
             mPoseController.reset();
+            AudioSystem::removeSupportedLatencyModesCallback(this);
         }
+
         // create FX instance on output
         AttributionSourceState attributionSource = AttributionSourceState();
         mEngine = new AudioEffect(attributionSource);
@@ -785,6 +787,13 @@
         outputChanged = mOutput != output;
         mOutput = output;
         mNumActiveTracks = numActiveTracks;
+        AudioSystem::addSupportedLatencyModesCallback(this);
+
+        std::vector<audio_latency_mode_t> latencyModes;
+        status = AudioSystem::getSupportedLatencyModes(mOutput, &latencyModes);
+        if (status == OK) {
+            mSupportedLatencyModes = latencyModes;
+        }
 
         checkEngineState_l();
         if (mSupportsHeadTracking) {
@@ -815,6 +824,7 @@
         // remove FX instance
         mEngine->setEnabled(false);
         mEngine.clear();
+        AudioSystem::removeSupportedLatencyModesCallback(this);
         output = mOutput;
         mOutput = AUDIO_IO_HANDLE_NONE;
         mPoseController.reset();
@@ -827,6 +837,15 @@
     return output;
 }
 
+void Spatializer::onSupportedLatencyModesChanged(
+        audio_io_handle_t output, const std::vector<audio_latency_mode_t>& modes) {
+    std::lock_guard lock(mLock);
+    if (output == mOutput) {
+        mSupportedLatencyModes = modes;
+        checkSensorsState_l();
+    }
+}
+
 void Spatializer::updateActiveTracks(size_t numActiveTracks) {
     std::lock_guard lock(mLock);
     if (mNumActiveTracks != numActiveTracks) {
@@ -838,17 +857,25 @@
 }
 
 void Spatializer::checkSensorsState_l() {
-    if (mSupportsHeadTracking && mPoseController != nullptr) {
+    audio_latency_mode_t requestedLatencyMode = AUDIO_LATENCY_MODE_FREE;
+    bool lowLatencySupported = mSupportedLatencyModes.empty()
+            || (std::find(mSupportedLatencyModes.begin(), mSupportedLatencyModes.end(),
+                    AUDIO_LATENCY_MODE_LOW) != mSupportedLatencyModes.end());
+    if (mSupportsHeadTracking && mPoseController != nullptr && lowLatencySupported) {
         if (mNumActiveTracks > 0 && mLevel != SpatializationLevel::NONE
             && mDesiredHeadTrackingMode != HeadTrackingMode::STATIC
             && mHeadSensor != SpatializerPoseController::INVALID_SENSOR) {
             mPoseController->setHeadSensor(mHeadSensor);
             mPoseController->setScreenSensor(mScreenSensor);
+            requestedLatencyMode = AUDIO_LATENCY_MODE_LOW;
         } else {
             mPoseController->setHeadSensor(SpatializerPoseController::INVALID_SENSOR);
             mPoseController->setScreenSensor(SpatializerPoseController::INVALID_SENSOR);
         }
     }
+    if (mOutput != AUDIO_IO_HANDLE_NONE) {
+        AudioSystem::setRequestedLatencyMode(mOutput, requestedLatencyMode);
+    }
 }
 
 void Spatializer::checkEngineState_l() {