aaudio: offset MMAP timestamps
This can be used to debug and analyze problems
with the AAudio MMAP IsochronousClockModel.
That is a model of the DSP that is used by AAudio
to predict the read/write timing of the DSP.
If there is an error in the model or in the timestamps
then the DSP and CPU pointers can cross, which causes
an audio glitch.
By changing the offset we can force glitches and indirectly
measure the time distribution of the DSP transfers.
Test: adb shell setprop aaudio.out_mmap_offset_usec
Bug: 123096058
Change-Id: I9a3df345a6820baf20a24d261642b3c8c0c2a27e
diff --git a/media/libaaudio/src/client/AudioStreamInternal.h b/media/libaaudio/src/client/AudioStreamInternal.h
index 86c4698..9395416 100644
--- a/media/libaaudio/src/client/AudioStreamInternal.h
+++ b/media/libaaudio/src/client/AudioStreamInternal.h
@@ -194,6 +194,7 @@
// By delaying slightly we can avoid waking up before other side is ready.
const int32_t mWakeupDelayNanos; // delay past typical wakeup jitter
const int32_t mMinimumSleepNanos; // minimum sleep while polling
+ int32_t mTimeOffsetNanos = 0; // add to time part of an MMAP timestamp
AudioEndpointParcelable mEndPointParcelable; // description of the buffers filled by service
EndpointDescriptor mEndpointDescriptor; // buffer description with resolved addresses