aaudio: prevent noise when stopping a stream
The DSP is stopped after the callback is stopped.
If the CPU is slow and the time gap is too large then
the DSP can play past the valid data and play invalid data.
To prevent noise, this new code clears part of the FIFO
beyond the valid data. Then when the DSP has read the valid
data it clears the entire FIFO.
Then it waits for the valid data to reach the speaker,
based on a latency estimation using timestamps.
Bug: 261783315
Test: Use OboeTester with repro steps in the bug.
Change-Id: Ia31df4b21c805b4ae9ca4fb8366068be1cce2c9f
diff --git a/media/libaaudio/src/client/AudioEndpoint.cpp b/media/libaaudio/src/client/AudioEndpoint.cpp
index e780f4f..cd7679c 100644
--- a/media/libaaudio/src/client/AudioEndpoint.cpp
+++ b/media/libaaudio/src/client/AudioEndpoint.cpp
@@ -278,3 +278,9 @@
mDataQueue->eraseMemory();
}
}
+
+void AudioEndpoint::eraseEmptyDataMemory(int32_t numFrames) {
+ if (mDataQueue != nullptr) {
+ mDataQueue->eraseEmptyMemory(numFrames);
+ }
+}
diff --git a/media/libaaudio/src/client/AudioEndpoint.h b/media/libaaudio/src/client/AudioEndpoint.h
index b117572..7e97c6a 100644
--- a/media/libaaudio/src/client/AudioEndpoint.h
+++ b/media/libaaudio/src/client/AudioEndpoint.h
@@ -107,6 +107,8 @@
*/
void eraseDataMemory();
+ void eraseEmptyDataMemory(int32_t numFrames);
+
void freeDataQueue() { mDataQueue.reset(); }
void dump() const;
diff --git a/media/libaaudio/src/client/AudioStreamInternal.cpp b/media/libaaudio/src/client/AudioStreamInternal.cpp
index 7648e25..b2e93f0 100644
--- a/media/libaaudio/src/client/AudioStreamInternal.cpp
+++ b/media/libaaudio/src/client/AudioStreamInternal.cpp
@@ -575,10 +575,20 @@
return AAUDIO_ERROR_INVALID_STATE;
}
+ // For playback, sleep until all the audio data has played.
+ // Then clear the buffer to prevent noise.
+ prepareBuffersForStop();
+
mClockModel.stop(AudioClock::getNanoseconds());
setState(AAUDIO_STREAM_STATE_STOPPING);
mAtomicInternalTimestamp.clear();
+#if 0
+ // Simulate very slow CPU, force race condition where the
+ // DSP keeps playing after we stop writing.
+ AudioClock::sleepForNanos(800 * AAUDIO_NANOS_PER_MILLISECOND);
+#endif
+
result = mServiceInterface.stopStream(mServiceStreamHandleInfo);
if (result == AAUDIO_ERROR_INVALID_HANDLE) {
ALOGD("%s() INVALID_HANDLE, stream was probably stolen", __func__);
diff --git a/media/libaaudio/src/client/AudioStreamInternal.h b/media/libaaudio/src/client/AudioStreamInternal.h
index a5981b1..20d55f9 100644
--- a/media/libaaudio/src/client/AudioStreamInternal.h
+++ b/media/libaaudio/src/client/AudioStreamInternal.h
@@ -123,6 +123,8 @@
virtual void prepareBuffersForStart() {}
+ virtual void prepareBuffersForStop() {}
+
virtual void advanceClientToMatchServerPosition(int32_t serverMargin) = 0;
virtual void onFlushFromServer() {}
diff --git a/media/libaaudio/src/client/AudioStreamInternalPlay.cpp b/media/libaaudio/src/client/AudioStreamInternalPlay.cpp
index 5d4c3d4..0427777 100644
--- a/media/libaaudio/src/client/AudioStreamInternalPlay.cpp
+++ b/media/libaaudio/src/client/AudioStreamInternalPlay.cpp
@@ -19,6 +19,8 @@
#define ATRACE_TAG ATRACE_TAG_AUDIO
+#include <algorithm>
+
#include <media/MediaMetricsItem.h>
#include <utils/Trace.h>
@@ -108,6 +110,61 @@
mAudioEndpoint->eraseDataMemory();
}
+void AudioStreamInternalPlay::prepareBuffersForStop() {
+ // If this is a shared stream and the FIFO is being read by the mixer then
+ // we don't have to worry about the DSP reading past the valid data. We can skip all this.
+ if(!mAudioEndpoint->isFreeRunning()) {
+ return;
+ }
+ // Sleep until the DSP has read all of the data written.
+ int64_t validFramesInBuffer = getFramesWritten() - getFramesRead();
+ if (validFramesInBuffer >= 0) {
+ int64_t emptyFramesInBuffer = ((int64_t) getBufferCapacity()) - validFramesInBuffer;
+
+ // Prevent stale data from being played if the DSP is still running.
+ // Erase some of the FIFO memory in front of the DSP read cursor.
+ // Subtract one burst so we do not accidentally erase data that the DSP might be using.
+ int64_t framesToErase = std::max((int64_t) 0,
+ emptyFramesInBuffer - getFramesPerBurst());
+ mAudioEndpoint->eraseEmptyDataMemory(framesToErase);
+
+ // Sleep until we are confident the DSP has consumed all of the valid data.
+ // Sleep for one extra burst as a safety margin because the IsochronousClockModel
+ // is not perfectly accurate.
+ int64_t positionInEmptyMemory = getFramesWritten() + getFramesPerBurst();
+ int64_t timeAllConsumed = mClockModel.convertPositionToTime(positionInEmptyMemory);
+ int64_t durationAllConsumed = timeAllConsumed - AudioClock::getNanoseconds();
+ // Prevent sleeping for too long.
+ durationAllConsumed = std::min(200 * AAUDIO_NANOS_PER_MILLISECOND, durationAllConsumed);
+ AudioClock::sleepForNanos(durationAllConsumed);
+ }
+
+ // Erase all of the memory in case the DSP keeps going and wraps around.
+ mAudioEndpoint->eraseDataMemory();
+
+ // Wait for the last buffer to reach the DAC.
+ // This is because the expected behavior of stop() is that all data written to the stream
+ // should be played before the hardware actually shuts down.
+ // This is different than pause(), where we just end as soon as possible.
+ // This can be important when, for example, playing car navigation and
+ // you want the user to hear the complete instruction.
+ if (mAtomicInternalTimestamp.isValid()) {
+ // Use timestamps to calculate the latency between the DSP reading
+ // a frame and when it reaches the DAC.
+ // This code assumes that timestamps are accurate.
+ Timestamp timestamp = mAtomicInternalTimestamp.read();
+ int64_t dacPosition = timestamp.getPosition();
+ int64_t hardwareReadTime = mClockModel.convertPositionToTime(dacPosition);
+ int64_t hardwareLatencyNanos = timestamp.getNanoseconds() - hardwareReadTime;
+ ALOGD("%s() hardwareLatencyNanos = %lld", __func__,
+ (long long) hardwareLatencyNanos);
+ // Prevent sleeping for too long.
+ hardwareLatencyNanos = std::min(30 * AAUDIO_NANOS_PER_MILLISECOND,
+ hardwareLatencyNanos);
+ AudioClock::sleepForNanos(hardwareLatencyNanos);
+ }
+}
+
void AudioStreamInternalPlay::advanceClientToMatchServerPosition(int32_t serverMargin) {
int64_t readCounter = mAudioEndpoint->getDataReadCounter() + serverMargin;
int64_t writeCounter = mAudioEndpoint->getDataWriteCounter();
@@ -353,20 +410,26 @@
// Call application using the AAudio callback interface.
callbackResult = maybeCallDataCallback(mCallbackBuffer.get(), mCallbackFrames);
- if (callbackResult == AAUDIO_CALLBACK_RESULT_CONTINUE) {
- // Write audio data to stream. This is a BLOCKING WRITE!
- result = write(mCallbackBuffer.get(), mCallbackFrames, timeoutNanos);
- if ((result != mCallbackFrames)) {
- if (result >= 0) {
- // Only wrote some of the frames requested. The stream can be disconnected
- // or timed out.
- processCommands();
- result = isDisconnected() ? AAUDIO_ERROR_DISCONNECTED : AAUDIO_ERROR_TIMEOUT;
- }
- maybeCallErrorCallback(result);
- break;
+ // Write audio data to stream. This is a BLOCKING WRITE!
+ // Write data regardless of the callbackResult because we assume the data
+ // is valid even when the callback returns AAUDIO_CALLBACK_RESULT_STOP.
+ // Imagine a callback that is playing a large sound in menory.
+ // When it gets to the end of the sound it can partially fill
+ // the last buffer with the end of the sound, then zero pad the buffer, then return STOP.
+ // If the callback has no valid data then it should zero-fill the entire buffer.
+ result = write(mCallbackBuffer.get(), mCallbackFrames, timeoutNanos);
+ if ((result != mCallbackFrames)) {
+ if (result >= 0) {
+ // Only wrote some of the frames requested. The stream can be disconnected
+ // or timed out.
+ processCommands();
+ result = isDisconnected() ? AAUDIO_ERROR_DISCONNECTED : AAUDIO_ERROR_TIMEOUT;
}
- } else if (callbackResult == AAUDIO_CALLBACK_RESULT_STOP) {
+ maybeCallErrorCallback(result);
+ break;
+ }
+
+ if (callbackResult == AAUDIO_CALLBACK_RESULT_STOP) {
ALOGD("%s(): callback returned AAUDIO_CALLBACK_RESULT_STOP", __func__);
result = systemStopInternal();
break;
diff --git a/media/libaaudio/src/client/AudioStreamInternalPlay.h b/media/libaaudio/src/client/AudioStreamInternalPlay.h
index b51b5d0..4e14f18 100644
--- a/media/libaaudio/src/client/AudioStreamInternalPlay.h
+++ b/media/libaaudio/src/client/AudioStreamInternalPlay.h
@@ -66,6 +66,8 @@
void prepareBuffersForStart() override;
+ void prepareBuffersForStop() override;
+
void advanceClientToMatchServerPosition(int32_t serverMargin) override;
void onFlushFromServer() override;
diff --git a/media/libaaudio/src/fifo/FifoBuffer.cpp b/media/libaaudio/src/fifo/FifoBuffer.cpp
index 5c11882..f3e3bbd 100644
--- a/media/libaaudio/src/fifo/FifoBuffer.cpp
+++ b/media/libaaudio/src/fifo/FifoBuffer.cpp
@@ -150,7 +150,7 @@
getEmptyRoomAvailable(&wrappingBuffer);
- // Read data in one or two parts.
+ // Write data in one or two parts.
int partIndex = 0;
while (framesLeft > 0 && partIndex < WrappingBuffer::SIZE) {
fifo_frames_t framesToWrite = framesLeft;
@@ -192,3 +192,29 @@
memset(getStorage(), 0, (size_t) numBytes);
}
}
+
+fifo_frames_t FifoBuffer::eraseEmptyMemory(fifo_frames_t numFrames) {
+ WrappingBuffer wrappingBuffer;
+ fifo_frames_t framesLeft = numFrames;
+
+ getEmptyRoomAvailable(&wrappingBuffer);
+
+ // Erase data in one or two parts.
+ int partIndex = 0;
+ while (framesLeft > 0 && partIndex < WrappingBuffer::SIZE) {
+ fifo_frames_t framesToWrite = framesLeft;
+ fifo_frames_t framesAvailable = wrappingBuffer.numFrames[partIndex];
+ if (framesAvailable > 0) {
+ if (framesToWrite > framesAvailable) {
+ framesToWrite = framesAvailable;
+ }
+ int32_t numBytes = convertFramesToBytes(framesToWrite);
+ memset(wrappingBuffer.data[partIndex], 0, numBytes);
+ framesLeft -= framesToWrite;
+ } else {
+ break;
+ }
+ partIndex++;
+ }
+ return numFrames - framesLeft; // number erased
+}
diff --git a/media/libaaudio/src/fifo/FifoBuffer.h b/media/libaaudio/src/fifo/FifoBuffer.h
index 7b0aca1..860ccad 100644
--- a/media/libaaudio/src/fifo/FifoBuffer.h
+++ b/media/libaaudio/src/fifo/FifoBuffer.h
@@ -115,6 +115,13 @@
*/
void eraseMemory();
+ /**
+ * Clear some memory after the write pointer.
+ * This can be used to prevent the reader from accidentally reading stale data
+ * in case it is reading asynchronously.
+ */
+ fifo_frames_t eraseEmptyMemory(fifo_frames_t numFrames);
+
protected:
virtual uint8_t *getStorage() const = 0;