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/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,