audio policy: fix mute delay when setting output device

The duration of the temporary mute applied on each output
when switching device must be more than twice the actual delay
we wait for the mute to be effective at the output.
Otherwise some outputs with short latencies will be unmuted before the
device switch is actually executed.

This change makes sure that we take the maximum wait time into account
when requesting the delayed unmuting of each output.

Change-Id: Id92c201b47786082a44b6a5c1c8015273835a42e

1 files changed, 25 insertions, 18 deletions

diff --git a/services/audiopolicy/AudioPolicyManager.cpp b/services/audiopolicy/AudioPolicyManager.cpp
index fc9b81a..62a44ee 100644
--- a/services/audiopolicy/AudioPolicyManager.cpp
+++ b/services/audiopolicy/AudioPolicyManager.cpp
@@ -2920,9 +2920,6 @@ uint32_t AudioPolicyManager::checkDeviceMuteStrategies(AudioOutputDescriptor *ou
     uint32_t muteWaitMs = 0;
     audio_devices_t device = outputDesc->device();
     bool shouldMute = outputDesc->isActive() && (popcount(device) >= 2);
-    // temporary mute output if device selection changes to avoid volume bursts due to
-    // different per device volumes
-    bool tempMute = outputDesc->isActive() && (device != prevDevice);
 
     for (size_t i = 0; i < NUM_STRATEGIES; i++) {
         audio_devices_t curDevice = getDeviceForStrategy((routing_strategy)i, false /*fromCache*/);
@@ -2936,7 +2933,7 @@ uint32_t AudioPolicyManager::checkDeviceMuteStrategies(AudioOutputDescriptor *ou
             doMute = true;
             outputDesc->mStrategyMutedByDevice[i] = false;
         }
-        if (doMute || tempMute) {
+        if (doMute) {
             for (size_t j = 0; j < mOutputs.size(); j++) {
                 AudioOutputDescriptor *desc = mOutputs.valueAt(j);
                 // skip output if it does not share any device with current output
@@ -2949,15 +2946,14 @@ uint32_t AudioPolicyManager::checkDeviceMuteStrategies(AudioOutputDescriptor *ou
                       mute ? "muting" : "unmuting", i, curDevice, curOutput);
                 setStrategyMute((routing_strategy)i, mute, curOutput, mute ? 0 : delayMs);
                 if (desc->isStrategyActive((routing_strategy)i)) {
-                    // do tempMute only for current output
-                    if (tempMute && (desc == outputDesc)) {
-                        setStrategyMute((routing_strategy)i, true, curOutput);
-                        setStrategyMute((routing_strategy)i, false, curOutput,
-                                            desc->latency() * 2, device);
-                    }
-                    if ((tempMute && (desc == outputDesc)) || mute) {
-                        if (muteWaitMs < desc->latency()) {
-                            muteWaitMs = desc->latency();
+                    if (mute) {
+                        // FIXME: should not need to double latency if volume could be applied
+                        // immediately by the audioflinger mixer. We must account for the delay
+                        // between now and the next time the audioflinger thread for this output
+                        // will process a buffer (which corresponds to one buffer size,
+                        // usually 1/2 or 1/4 of the latency).
+                        if (muteWaitMs < desc->latency() * 2) {
+                            muteWaitMs = desc->latency() * 2;
                         }
                     }
                 }
@@ -2965,11 +2961,22 @@ uint32_t AudioPolicyManager::checkDeviceMuteStrategies(AudioOutputDescriptor *ou
         }
     }
 
-    // FIXME: should not need to double latency if volume could be applied immediately by the
-    // audioflinger mixer. We must account for the delay between now and the next time
-    // the audioflinger thread for this output will process a buffer (which corresponds to
-    // one buffer size, usually 1/2 or 1/4 of the latency).
-    muteWaitMs *= 2;
+    // temporary mute output if device selection changes to avoid volume bursts due to
+    // different per device volumes
+    if (outputDesc->isActive() && (device != prevDevice)) {
+        if (muteWaitMs < outputDesc->latency() * 2) {
+            muteWaitMs = outputDesc->latency() * 2;
+        }
+        for (size_t i = 0; i < NUM_STRATEGIES; i++) {
+            if (outputDesc->isStrategyActive((routing_strategy)i)) {
+                setStrategyMute((routing_strategy)i, true, outputDesc->mId);
+                // do tempMute unmute after twice the mute wait time
+                setStrategyMute((routing_strategy)i, false, outputDesc->mId,
+                                muteWaitMs *2, device);
+            }
+        }
+    }
+
     // wait for the PCM output buffers to empty before proceeding with the rest of the command
     if (muteWaitMs > delayMs) {
         muteWaitMs -= delayMs;