AudioFlinger: refine latency computation if track is drained
Use server timestamp if track has no actively presented frames
(i.e. drained). Sometimes track frames may not have reached the HAL.
Test: audioflinger dumpsys with BT audio
Bug: 80447764
Change-Id: Iffc52f4cfcbadd419c6b6ccfa278e0712f3af4af
diff --git a/services/audioflinger/TrackBase.h b/services/audioflinger/TrackBase.h
index 9f17c3c..dafba1e 100644
--- a/services/audioflinger/TrackBase.h
+++ b/services/audioflinger/TrackBase.h
@@ -106,6 +106,86 @@
}
#endif
+ /** returns the buffer contents size converted to time in milliseconds
+ * for PCM Playback or Record streaming tracks. The return value is zero for
+ * PCM static tracks and not defined for non-PCM tracks.
+ *
+ * This may be called without the thread lock.
+ */
+ virtual double bufferLatencyMs() const {
+ return mServerProxy->framesReadySafe() * 1000 / sampleRate();
+ }
+
+ /** returns whether the track supports server latency computation.
+ * This is set in the constructor and constant throughout the track lifetime.
+ */
+
+ bool isServerLatencySupported() const { return mServerLatencySupported; }
+
+ /** computes the server latency for PCM Playback or Record track
+ * to the device sink/source. This is the time for the next frame in the track buffer
+ * written or read from the server thread to the device source or sink.
+ *
+ * This may be called without the thread lock, but latencyMs and fromTrack
+ * may be not be synchronized. For example PatchPanel may not obtain the
+ * thread lock before calling.
+ *
+ * \param latencyMs on success is set to the latency in milliseconds of the
+ * next frame written/read by the server thread to/from the track buffer
+ * from the device source/sink.
+ * \param fromTrack on success is set to true if latency was computed directly
+ * from the track timestamp; otherwise set to false if latency was
+ * estimated from the server timestamp.
+ * fromTrack may be nullptr or omitted if not required.
+ *
+ * \returns OK or INVALID_OPERATION on failure.
+ */
+ status_t getServerLatencyMs(double *latencyMs, bool *fromTrack = nullptr) const {
+ if (!isServerLatencySupported()) {
+ return INVALID_OPERATION;
+ }
+
+ // if no thread lock is acquired, these atomics are not
+ // synchronized with each other, considered a benign race.
+
+ const double serverLatencyMs = mServerLatencyMs.load();
+ if (serverLatencyMs == 0.) {
+ return INVALID_OPERATION;
+ }
+ if (fromTrack != nullptr) {
+ *fromTrack = mServerLatencyFromTrack.load();
+ }
+ *latencyMs = serverLatencyMs;
+ return OK;
+ }
+
+ /** computes the total client latency for PCM Playback or Record tracks
+ * for the next client app access to the device sink/source; i.e. the
+ * server latency plus the buffer latency.
+ *
+ * This may be called without the thread lock, but latencyMs and fromTrack
+ * may be not be synchronized. For example PatchPanel may not obtain the
+ * thread lock before calling.
+ *
+ * \param latencyMs on success is set to the latency in milliseconds of the
+ * next frame written/read by the client app to/from the track buffer
+ * from the device sink/source.
+ * \param fromTrack on success is set to true if latency was computed directly
+ * from the track timestamp; otherwise set to false if latency was
+ * estimated from the server timestamp.
+ * fromTrack may be nullptr or omitted if not required.
+ *
+ * \returns OK or INVALID_OPERATION on failure.
+ */
+ status_t getTrackLatencyMs(double *latencyMs, bool *fromTrack = nullptr) const {
+ double serverLatencyMs;
+ status_t status = getServerLatencyMs(&serverLatencyMs, fromTrack);
+ if (status == OK) {
+ *latencyMs = serverLatencyMs + bufferLatencyMs();
+ }
+ return status;
+ }
+
protected:
DISALLOW_COPY_AND_ASSIGN(TrackBase);
@@ -222,6 +302,10 @@
audio_io_handle_t mThreadIoHandle; // I/O handle of the thread the track is attached to
audio_port_handle_t mPortId; // unique ID for this track used by audio policy
bool mIsInvalid; // non-resettable latch, set by invalidate()
+
+ bool mServerLatencySupported = false;
+ std::atomic<bool> mServerLatencyFromTrack{}; // latency from track or server timestamp.
+ std::atomic<double> mServerLatencyMs{}; // last latency pushed from server thread.
};
// PatchProxyBufferProvider interface is implemented by PatchTrack and PatchRecord.