Fix AudioTrack offloaded timestamp handling.
getTimestamp for offloaded tracks now returns WOULD_BLOCK for
situations where the timestamp is unavailable due to the
previous track still flushing or the timestamp is stale.
It is fixed for normal playback conditions.
Bug: 14659809
Bug: 17428188
Change-Id: Ic9ec07ccabc604236979769db5c4ea2dec252660
diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index ff7da83..762dca5 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -37,6 +37,19 @@
namespace android {
// ---------------------------------------------------------------------------
+static int64_t convertTimespecToUs(const struct timespec &tv)
+{
+ return tv.tv_sec * 1000000ll + tv.tv_nsec / 1000;
+}
+
+// current monotonic time in microseconds.
+static int64_t getNowUs()
+{
+ struct timespec tv;
+ (void) clock_gettime(CLOCK_MONOTONIC, &tv);
+ return convertTimespecToUs(tv);
+}
+
// static
status_t AudioTrack::getMinFrameCount(
size_t* frameCount,
@@ -420,6 +433,7 @@
mServer = 0;
mPosition = 0;
mReleased = 0;
+ mStartUs = 0;
AudioSystem::acquireAudioSessionId(mSessionId, mClientPid);
mSequence = 1;
mObservedSequence = mSequence;
@@ -451,6 +465,12 @@
// reset current position as seen by client to 0
mPosition = 0;
mReleased = 0;
+ // For offloaded tracks, we don't know if the hardware counters are really zero here,
+ // since the flush is asynchronous and stop may not fully drain.
+ // We save the time when the track is started to later verify whether
+ // the counters are realistic (i.e. start from zero after this time).
+ mStartUs = getNowUs();
+
// force refresh of remaining frames by processAudioBuffer() as last
// write before stop could be partial.
mRefreshRemaining = true;
@@ -587,9 +607,18 @@
if (isOffloaded_l()) {
if (mOutput != AUDIO_IO_HANDLE_NONE) {
+ // An offload output can be re-used between two audio tracks having
+ // the same configuration. A timestamp query for a paused track
+ // while the other is running would return an incorrect time.
+ // To fix this, cache the playback position on a pause() and return
+ // this time when requested until the track is resumed.
+
+ // OffloadThread sends HAL pause in its threadLoop. Time saved
+ // here can be slightly off.
+
+ // TODO: check return code for getRenderPosition.
+
uint32_t halFrames;
- // OffloadThread sends HAL pause in its threadLoop.. time saved
- // here can be slightly off
AudioSystem::getRenderPosition(mOutput, &halFrames, &mPausedPosition);
ALOGV("AudioTrack::pause for offload, cache current position %u", mPausedPosition);
}
@@ -825,6 +854,8 @@
uint32_t halFrames;
AudioSystem::getRenderPosition(mOutput, &halFrames, &dspFrames);
}
+ // FIXME: dspFrames may not be zero in (mState == STATE_STOPPED || mState == STATE_FLUSHED)
+ // due to hardware latency. We leave this behavior for now.
*position = dspFrames;
} else {
// IAudioTrack::stop() isn't synchronous; we don't know when presentation completes
@@ -1881,13 +1912,70 @@
if (mFlags & AUDIO_OUTPUT_FLAG_FAST) {
return INVALID_OPERATION;
}
- if (mState != STATE_ACTIVE && mState != STATE_PAUSED) {
- return INVALID_OPERATION;
+
+ switch (mState) {
+ case STATE_ACTIVE:
+ case STATE_PAUSED:
+ break; // handle below
+ case STATE_FLUSHED:
+ case STATE_STOPPED:
+ return WOULD_BLOCK;
+ case STATE_STOPPING:
+ case STATE_PAUSED_STOPPING:
+ if (!isOffloaded_l()) {
+ return INVALID_OPERATION;
+ }
+ break; // offloaded tracks handled below
+ default:
+ LOG_ALWAYS_FATAL("Invalid mState in getTimestamp(): %d", mState);
+ break;
}
+
// The presented frame count must always lag behind the consumed frame count.
// To avoid a race, read the presented frames first. This ensures that presented <= consumed.
status_t status = mAudioTrack->getTimestamp(timestamp);
- if (status == NO_ERROR) {
+ if (status != NO_ERROR) {
+ ALOGW_IF(status != WOULD_BLOCK, "getTimestamp error:%#x", status);
+ return status;
+ }
+ if (isOffloadedOrDirect_l()) {
+ if (isOffloaded_l() && (mState == STATE_PAUSED || mState == STATE_PAUSED_STOPPING)) {
+ // use cached paused position in case another offloaded track is running.
+ timestamp.mPosition = mPausedPosition;
+ clock_gettime(CLOCK_MONOTONIC, ×tamp.mTime);
+ return NO_ERROR;
+ }
+
+ // Check whether a pending flush or stop has completed, as those commands may
+ // be asynchronous or return near finish.
+ if (mStartUs != 0 && mSampleRate != 0) {
+ static const int kTimeJitterUs = 100000; // 100 ms
+ static const int k1SecUs = 1000000;
+
+ const int64_t timeNow = getNowUs();
+
+ if (timeNow < mStartUs + k1SecUs) { // within first second of starting
+ const int64_t timestampTimeUs = convertTimespecToUs(timestamp.mTime);
+ if (timestampTimeUs < mStartUs) {
+ return WOULD_BLOCK; // stale timestamp time, occurs before start.
+ }
+ const int64_t deltaTimeUs = timestampTimeUs - mStartUs;
+ const int64_t deltaPositionByUs = timestamp.mPosition * 1000000LL / mSampleRate;
+
+ if (deltaPositionByUs > deltaTimeUs + kTimeJitterUs) {
+ // Verify that the counter can't count faster than the sample rate
+ // since the start time. If greater, then that means we have failed
+ // to completely flush or stop the previous playing track.
+ ALOGW("incomplete flush or stop:"
+ " deltaTimeUs(%lld) deltaPositionUs(%lld) tsmPosition(%u)",
+ (long long)deltaTimeUs, (long long)deltaPositionByUs,
+ timestamp.mPosition);
+ return WOULD_BLOCK;
+ }
+ }
+ mStartUs = 0; // no need to check again, start timestamp has either expired or unneeded.
+ }
+ } else {
// Update the mapping between local consumed (mPosition) and server consumed (mServer)
(void) updateAndGetPosition_l();
// Server consumed (mServer) and presented both use the same server time base,