TrackMetrics: Fix volume computation
Average volume should be weighted based on active time
not total lifetime.
Improve the numerical accuracy of average volume using
West's algorithm.
Remove unneeded variables.
Test: youtube, play/pause, adb shell dumpsys media.metrics
Bug: 233409482
Change-Id: I9fadb7287bd0bccbf5c74aad5a07eab277303d02
diff --git a/services/audioflinger/TrackBase.h b/services/audioflinger/TrackBase.h
index 2677ab3..20bfbb0 100644
--- a/services/audioflinger/TrackBase.h
+++ b/services/audioflinger/TrackBase.h
@@ -397,6 +397,8 @@
int64_t mLogStartFrames = 0; // Timestamp frames at start()
double mLogLatencyMs = 0.; // Track the last log latency
+ bool mLogForceVolumeUpdate = true; // force volume update to TrackMetrics.
+
TrackMetrics mTrackMetrics;
bool mServerLatencySupported = false;
diff --git a/services/audioflinger/TrackMetrics.h b/services/audioflinger/TrackMetrics.h
index 30d69ab..6fc70d6 100644
--- a/services/audioflinger/TrackMetrics.h
+++ b/services/audioflinger/TrackMetrics.h
@@ -64,7 +64,6 @@
AMEDIAMETRICS_PROP_EVENT_VALUE_BEGINAUDIOINTERVALGROUP, devices.c_str());
}
++mIntervalCount;
- mIntervalStartTimeNs = systemTime();
}
void logConstructor(pid_t creatorPid, uid_t creatorUid, int32_t internalTrackId,
@@ -90,11 +89,9 @@
// Called when we are removed from the Thread.
void logEndInterval() {
std::lock_guard l(mLock);
- if (mIntervalStartTimeNs != 0) {
- const int64_t elapsedTimeNs = systemTime() - mIntervalStartTimeNs;
- mIntervalStartTimeNs = 0;
- mCumulativeTimeNs += elapsedTimeNs;
- mDeviceTimeNs += elapsedTimeNs;
+ if (mLastVolumeChangeTimeNs != 0) {
+ logVolume_l(mVolume); // flush out the last volume.
+ mLastVolumeChangeTimeNs = 0;
}
}
@@ -133,20 +130,8 @@
// may be called multiple times during an interval
void logVolume(float volume) {
- const int64_t timeNs = systemTime();
std::lock_guard l(mLock);
- if (mStartVolumeTimeNs == 0) {
- mDeviceVolume = mVolume = volume;
- mLastVolumeChangeTimeNs = mStartVolumeTimeNs = timeNs;
- updateMinMaxVolume(0, mVolume);
- return;
- }
- const int64_t durationNs = timeNs - mLastVolumeChangeTimeNs;
- updateMinMaxVolume(durationNs, mVolume);
- mDeviceVolume = (mDeviceVolume * (mLastVolumeChangeTimeNs - mStartVolumeTimeNs) +
- mVolume * durationNs) / (timeNs - mStartVolumeTimeNs);
- mVolume = volume;
- mLastVolumeChangeTimeNs = timeNs;
+ logVolume_l(volume);
}
// Use absolute numbers returned by AudioTrackShared.
@@ -158,6 +143,7 @@
}
private:
+
// no lock required - all arguments and constants.
void deliverDeviceMetrics(const char *eventName, const char *devices) const {
mediametrics::LogItem(mMetricsId)
@@ -167,6 +153,23 @@
.record();
}
+ void logVolume_l(float volume) REQUIRES(mLock) {
+ const int64_t timeNs = systemTime();
+ const int64_t durationNs = mLastVolumeChangeTimeNs == 0
+ ? 0 : timeNs - mLastVolumeChangeTimeNs;
+ if (durationNs > 0) {
+ // See West's algorithm for weighted averages
+ // https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance
+ mDeviceVolume += (mVolume - mDeviceVolume) * durationNs
+ / (durationNs + mDeviceTimeNs);
+ mDeviceTimeNs += durationNs;
+ mCumulativeTimeNs += durationNs;
+ }
+ updateMinMaxVolume(durationNs, mVolume); // always update.
+ mVolume = volume;
+ mLastVolumeChangeTimeNs = timeNs;
+ }
+
void deliverCumulativeMetrics(const char *eventName) const REQUIRES(mLock) {
if (mIntervalCount > 0) {
mediametrics::LogItem item(mMetricsId);
@@ -199,14 +202,12 @@
// mDevices is not reset by resetIntervalGroupMetrics.
mIntervalCount = 0;
- mIntervalStartTimeNs = 0;
// mCumulativeTimeNs is not reset by resetIntervalGroupMetrics.
mDeviceTimeNs = 0;
mVolume = 0.f;
mDeviceVolume = 0.f;
- mStartVolumeTimeNs = 0;
- mLastVolumeChangeTimeNs = 0;
+ mLastVolumeChangeTimeNs = 0; // last time volume logged, cleared on endInterval
mMinVolume = AMEDIAMETRICS_INITIAL_MIN_VOLUME;
mMaxVolume = AMEDIAMETRICS_INITIAL_MAX_VOLUME;
mMinVolumeDurationNs = 0;
@@ -230,14 +231,12 @@
// Number of intervals and playing time
int32_t mIntervalCount GUARDED_BY(mLock) = 0;
- int64_t mIntervalStartTimeNs GUARDED_BY(mLock) = 0;
- int64_t mCumulativeTimeNs GUARDED_BY(mLock) = 0;
- int64_t mDeviceTimeNs GUARDED_BY(mLock) = 0;
+ int64_t mCumulativeTimeNs GUARDED_BY(mLock) = 0; // total time.
+ int64_t mDeviceTimeNs GUARDED_BY(mLock) = 0; // time on device.
// Average volume
- double mVolume GUARDED_BY(mLock) = 0.f;
- double mDeviceVolume GUARDED_BY(mLock) = 0.f;
- int64_t mStartVolumeTimeNs GUARDED_BY(mLock) = 0;
+ double mVolume GUARDED_BY(mLock) = 0.f; // last set volume.
+ double mDeviceVolume GUARDED_BY(mLock) = 0.f; // running average volume.
int64_t mLastVolumeChangeTimeNs GUARDED_BY(mLock) = 0;
// Min/Max volume
diff --git a/services/audioflinger/Tracks.cpp b/services/audioflinger/Tracks.cpp
index a9720da..30301a8 100644
--- a/services/audioflinger/Tracks.cpp
+++ b/services/audioflinger/Tracks.cpp
@@ -1123,6 +1123,7 @@
.mPosition[ExtendedTimestamp::LOCATION_KERNEL];
mLogLatencyMs = 0.;
}
+ mLogForceVolumeUpdate = true; // at least one volume logged for metrics when starting.
if (status == NO_ERROR || status == ALREADY_EXISTS) {
// for streaming tracks, remove the buffer read stop limit.
@@ -1394,7 +1395,11 @@
if (mFinalVolume != volume) { // Compare to an epsilon if too many meaningless updates
mFinalVolume = volume;
setMetadataHasChanged();
- mTrackMetrics.logVolume(volume);
+ mLogForceVolumeUpdate = true;
+ }
+ if (mLogForceVolumeUpdate) {
+ mLogForceVolumeUpdate = false;
+ mTrackMetrics.logVolume(mFinalVolume);
}
}