commit ea04d97050e778e7cefb755b442156310afada05
author Phil Burk <philburk@google.com> Mon Aug 07 12:30:44 2017 -0700
committer Phil Burk <philburk@google.com> Mon Aug 07 14:34:55 2017 -0700
tree bb9a6566e18b07b6a14236713b9e4eb6253c14ba
parent fc32901189f8655d3d51064a0366ec9d8264940d

aaudio: stop buzzing when MMAP stream disconnected

When a stream is disconnected, clear the MMAP memory
buffer to prevent the hardware from looping on stale data
and making a buzzing sound.

Bug: 63342351
Test: play GStomper with AAudio through headphones and then unplug them
Change-Id: I6372b0a031dea242e3830cc2d226a4c043d4467e

media/libaaudio/src/client/AudioEndpoint.cpp

diff --git a/media/libaaudio/src/client/AudioEndpoint.cpp b/media/libaaudio/src/client/AudioEndpoint.cpp
index 6ec285f..6ae5379 100644
--- a/media/libaaudio/src/client/AudioEndpoint.cpp
+++ b/media/libaaudio/src/client/AudioEndpoint.cpp
@@ -254,3 +254,7 @@
     ALOGD("AudioEndpoint: data readCounter  = %lld", (long long) mDataQueue->getReadCounter());
     ALOGD("AudioEndpoint: data writeCounter = %lld", (long long) mDataQueue->getWriteCounter());
 }
+
+void AudioEndpoint::eraseDataMemory() {
+    mDataQueue->eraseMemory();
+}

media/libaaudio/src/client/AudioEndpoint.h

diff --git a/media/libaaudio/src/client/AudioEndpoint.h b/media/libaaudio/src/client/AudioEndpoint.h
index 81a4f7b..f5b67e8 100644
--- a/media/libaaudio/src/client/AudioEndpoint.h
+++ b/media/libaaudio/src/client/AudioEndpoint.h
@@ -86,6 +86,11 @@
 
     int32_t getBufferCapacityInFrames() const;
 
+    /**
+     * Write zeros to the data queue memory.
+     */
+    void eraseDataMemory();
+
     void dump() const;
 
 private:

media/libaaudio/src/client/AudioStreamInternal.cpp

diff --git a/media/libaaudio/src/client/AudioStreamInternal.cpp b/media/libaaudio/src/client/AudioStreamInternal.cpp
index 8c3045a..3f46232 100644
--- a/media/libaaudio/src/client/AudioStreamInternal.cpp
+++ b/media/libaaudio/src/client/AudioStreamInternal.cpp
@@ -436,10 +436,14 @@
             setState(AAUDIO_STREAM_STATE_CLOSED);
             break;
         case AAUDIO_SERVICE_EVENT_DISCONNECTED:
+            // Prevent hardware from looping on old data and making buzzing sounds.
+            if (getDirection() == AAUDIO_DIRECTION_OUTPUT) {
+                mAudioEndpoint.eraseDataMemory();
+            }
             result = AAUDIO_ERROR_DISCONNECTED;
             setState(AAUDIO_STREAM_STATE_DISCONNECTED);
             ALOGW("WARNING - AudioStreamInternal::onEventFromServer()"
-                          " AAUDIO_SERVICE_EVENT_DISCONNECTED");
+                          " AAUDIO_SERVICE_EVENT_DISCONNECTED - FIFO cleared");
             break;
         case AAUDIO_SERVICE_EVENT_VOLUME:
             mStreamVolume = (float)message->event.dataDouble;

media/libaaudio/src/fifo/FifoBuffer.cpp

diff --git a/media/libaaudio/src/fifo/FifoBuffer.cpp b/media/libaaudio/src/fifo/FifoBuffer.cpp
index 8d2c62d..a869886 100644
--- a/media/libaaudio/src/fifo/FifoBuffer.cpp
+++ b/media/libaaudio/src/fifo/FifoBuffer.cpp
@@ -210,3 +210,9 @@
     return mFifo->getCapacity();
 }
 
+void FifoBuffer::eraseMemory() {
+    int32_t numBytes = convertFramesToBytes(getBufferCapacityInFrames());
+    if (numBytes > 0) {
+        memset(mStorage, 0, (size_t) numBytes);
+    }
+}

media/libaaudio/src/fifo/FifoBuffer.h

diff --git a/media/libaaudio/src/fifo/FifoBuffer.h b/media/libaaudio/src/fifo/FifoBuffer.h
index a94e9b0..f5a9e27 100644
--- a/media/libaaudio/src/fifo/FifoBuffer.h
+++ b/media/libaaudio/src/fifo/FifoBuffer.h
@@ -111,6 +111,11 @@
         mFifo->setWriteCounter(n);
     }
 
+    /*
+     * This is generally only called before or after the buffer is used.
+     */
+    void eraseMemory();
+
 private:
 
     void fillWrappingBuffer(WrappingBuffer *wrappingBuffer,