Pause faster during audio underrun
Check for advancing timestamps more frequently, limited to every 150ms
so that we can detect stalling faster and pause earlier during underrun
conditions.
Test: atest android.media.decoder.cts.DecoderTest#testTunneledAudioUnderrunAvc
Bug: 234327211
Change-Id: I515b63e4b8fbd885b19b129043ec99636153fabb
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index 56ebb6e..401a19e 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -178,6 +178,11 @@
// Direct output thread minimum sleep time in idle or active(underrun) state
static const nsecs_t kDirectMinSleepTimeUs = 10000;
+// Minimum amount of time between checking to see if the timestamp is advancing
+// for underrun detection. If we check too frequently, we may not detect a
+// timestamp update and will falsely detect underrun.
+static const nsecs_t kMinimumTimeBetweenTimestampChecksNs = 150 /* ms */ * 1000;
+
// The universal constant for ubiquitous 20ms value. The value of 20ms seems to provide a good
// balance between power consumption and latency, and allows threads to be scheduled reliably
// by the CFS scheduler.
@@ -2030,7 +2035,8 @@
mFastTrackAvailMask(((1 << FastMixerState::sMaxFastTracks) - 1) & ~1),
mHwSupportsPause(false), mHwPaused(false), mFlushPending(false),
mLeftVolFloat(-1.0), mRightVolFloat(-1.0),
- mDownStreamPatch{}
+ mDownStreamPatch{},
+ mIsTimestampAdvancing(kMinimumTimeBetweenTimestampChecksNs)
{
snprintf(mThreadName, kThreadNameLength, "AudioOut_%X", id);
mNBLogWriter = audioFlinger->newWriter_l(kLogSize, mThreadName);
@@ -5889,18 +5895,35 @@
return trackCount;
}
-bool AudioFlinger::PlaybackThread::checkRunningTimestamp()
+bool AudioFlinger::PlaybackThread::IsTimestampAdvancing::check(AudioStreamOut * output)
{
+ // Check the timestamp to see if it's advancing once every 150ms. If we check too frequently, we
+ // could falsely detect that the frame position has stalled due to underrun because we haven't
+ // given the Audio HAL enough time to update.
+ const nsecs_t nowNs = systemTime();
+ if (nowNs - mPreviousNs < mMinimumTimeBetweenChecksNs) {
+ return mLatchedValue;
+ }
+ mPreviousNs = nowNs;
+ mLatchedValue = false;
+ // Determine if the presentation position is still advancing.
uint64_t position = 0;
struct timespec unused;
- const status_t ret = mOutput->getPresentationPosition(&position, &unused);
+ const status_t ret = output->getPresentationPosition(&position, &unused);
if (ret == NO_ERROR) {
- if (position != mLastCheckedTimestampPosition) {
- mLastCheckedTimestampPosition = position;
- return true;
+ if (position != mPreviousPosition) {
+ mPreviousPosition = position;
+ mLatchedValue = true;
}
}
- return false;
+ return mLatchedValue;
+}
+
+void AudioFlinger::PlaybackThread::IsTimestampAdvancing::clear()
+{
+ mLatchedValue = true;
+ mPreviousPosition = 0;
+ mPreviousNs = 0;
}
// isTrackAllowed_l() must be called with ThreadBase::mLock held
@@ -6335,9 +6358,9 @@
// No buffers for this track. Give it a few chances to
// fill a buffer, then remove it from active list.
// Only consider last track started for mixer state control
+ bool isTimestampAdvancing = mIsTimestampAdvancing.check(mOutput);
if (--(track->mRetryCount) <= 0) {
- const bool running = checkRunningTimestamp();
- if (running) { // still running, give us more time.
+ if (isTimestampAdvancing) { // HAL is still playing audio, give us more time.
track->mRetryCount = kMaxTrackRetriesOffload;
} else {
ALOGV("BUFFER TIMEOUT: remove track(%d) from active list", trackId);
@@ -6918,9 +6941,9 @@
} else {
// No buffers for this track. Give it a few chances to
// fill a buffer, then remove it from active list.
+ bool isTimestampAdvancing = mIsTimestampAdvancing.check(mOutput);
if (--(track->mRetryCount) <= 0) {
- const bool running = checkRunningTimestamp();
- if (running) { // still running, give us more time.
+ if (isTimestampAdvancing) { // HAL is still playing audio, give us more time.
track->mRetryCount = kMaxTrackRetriesOffload;
} else {
ALOGV("OffloadThread: BUFFER TIMEOUT: remove track(%d) from active list",
diff --git a/services/audioflinger/Threads.h b/services/audioflinger/Threads.h
index b2962ed8..e196e1e 100644
--- a/services/audioflinger/Threads.h
+++ b/services/audioflinger/Threads.h
@@ -1381,13 +1381,38 @@
std::atomic_bool mCheckOutputStageEffects{};
- // A differential check on the timestamps to see if there is a change in the
- // timestamp frame position between the last call to checkRunningTimestamp.
- uint64_t mLastCheckedTimestampPosition = ~0LL;
- bool checkRunningTimestamp();
+ // Provides periodic checking for timestamp advancement for underrun detection.
+ class IsTimestampAdvancing {
+ public:
+ // The timestamp will not be checked any faster than the specified time.
+ IsTimestampAdvancing(nsecs_t minimumTimeBetweenChecksNs)
+ : mMinimumTimeBetweenChecksNs(minimumTimeBetweenChecksNs)
+ {
+ clear();
+ }
+ // Check if the presentation position has advanced in the last periodic time.
+ bool check(AudioStreamOut * output);
+ // Clear the internal state when the playback state changes for the output
+ // stream.
+ void clear();
+ private:
+ // The minimum time between timestamp checks.
+ const nsecs_t mMinimumTimeBetweenChecksNs;
+ // Add differential check on the timestamps to see if there is a change in the
+ // timestamp frame position between the last call to check.
+ uint64_t mPreviousPosition;
+ // The time at which the last check occurred, to ensure we don't check too
+ // frequently, giving the Audio HAL enough time to update its timestamps.
+ nsecs_t mPreviousNs;
+ // The valued is latched so we don't check timestamps too frequently.
+ bool mLatchedValue;
+ };
+ IsTimestampAdvancing mIsTimestampAdvancing;
- virtual void flushHw_l() { mLastCheckedTimestampPosition = ~0LL; }
+ virtual void flushHw_l() {
+ mIsTimestampAdvancing.clear();
+ }
};
class MixerThread : public PlaybackThread {