audio policy: do not route accessibility prompts to compressed output

When a digital output (HDMI or S/PDIF) is configured with
a non linear PCM audio format it is likely that the audio HAL
or HW will not be able to mix other sounds with the main
media stream being played.

In this case, do not condider HDMI or S/PDIF as a valid route for
accessibilty strategy so that accessibility prompts are always audible.

Bug: 18067208.
Change-Id: If20603a1dc1dc470f206f841308bed2b87daf21c

1 files changed, 15 insertions, 0 deletions

diff --git a/services/audiopolicy/AudioPolicyManager.cpp b/services/audiopolicy/AudioPolicyManager.cpp
index 8ca0b96..cd8df2f 100644
--- a/services/audiopolicy/AudioPolicyManager.cpp
+++ b/services/audiopolicy/AudioPolicyManager.cpp
@@ -4355,6 +4355,21 @@ audio_devices_t AudioPolicyManager::getDeviceForStrategy(routing_strategy strate
 
     // FIXME: STRATEGY_ACCESSIBILITY and STRATEGY_REROUTING follow STRATEGY_MEDIA for now
     case STRATEGY_ACCESSIBILITY:
+        if (strategy == STRATEGY_ACCESSIBILITY) {
+            // do not route accessibility prompts to a digital output currently configured with a
+            // compressed format as they would likely not be mixed and dropped.
+            for (size_t i = 0; i < mOutputs.size(); i++) {
+                sp<AudioOutputDescriptor> desc = mOutputs.valueAt(i);
+                audio_devices_t devices = desc->device() &
+                    (AUDIO_DEVICE_OUT_HDMI | AUDIO_DEVICE_OUT_SPDIF | AUDIO_DEVICE_OUT_HDMI_ARC);
+                if (desc->isActive() && !audio_is_linear_pcm(desc->mFormat) &&
+                        devices != AUDIO_DEVICE_NONE) {
+                    availableOutputDeviceTypes = availableOutputDeviceTypes & ~devices;
+                }
+            }
+        }
+        // FALL THROUGH
+
     case STRATEGY_REROUTING:
     case STRATEGY_MEDIA: {
         uint32_t device2 = AUDIO_DEVICE_NONE;