commit ee398adb9ee4abbeceb3c377c5282faec1a82af2
author Eric Laurent <elaurent@google.com> Tue May 03 18:19:35 2022 +0200
committer Eric Laurent <elaurent@google.com> Fri Jul 01 17:09:53 2022 +0000
tree b5a8146969b28d3c82e87de7cca25f60a6116ff8
parent 68a40a846bae80a56713dcee659f01bd616172ce

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
Change-Id: Ia78156d1e190bb49a67988567df066c1ab90f9bd

services/audiopolicy/service/Spatializer.cpp

diff --git a/services/audiopolicy/service/Spatializer.cpp b/services/audiopolicy/service/Spatializer.cpp
index c199a76..e8b599a 100644
--- a/services/audiopolicy/service/Spatializer.cpp
+++ b/services/audiopolicy/service/Spatializer.cpp
@@ -714,7 +714,9 @@
             mEngine->setEnabled(false);
             mEngine.clear();
             mPoseController.reset();
+            AudioSystem::removeSupportedLatencyModesCallback(this);
         }
+
         // create FX instance on output
         AttributionSourceState attributionSource = AttributionSourceState();
         mEngine = new AudioEffect(attributionSource);
@@ -730,6 +732,13 @@
         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) {
@@ -759,6 +768,7 @@
         // remove FX instance
         mEngine->setEnabled(false);
         mEngine.clear();
+        AudioSystem::removeSupportedLatencyModesCallback(this);
         output = mOutput;
         mOutput = AUDIO_IO_HANDLE_NONE;
         mPoseController.reset();
@@ -771,6 +781,15 @@
     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) {
@@ -781,17 +800,25 @@
 }
 
 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() {