commit 97350f9df7252c881f011a410fcd9e6d766d2bee
author Phil Burk <philburk@google.com> Fri Jul 21 15:59:44 2017 -0700
committer Phil Burk <philburk@google.com> Wed Aug 02 10:57:31 2017 -0700
tree fab6334a25607e03276648611584b8fc23b40463
parent eb1c0658e405e5b7e26f4b16761c5b1ce3f77d46

aaudio: improve accuracy of timestamps

Account for latency added by the AAudio service.
Fix input timestamps.

Bug: 37080396
Test: test_timestamps.cpp input_monitor.cpp
Change-Id: I1053cd21af722bb9b9371df4e5731bf4a0a57b0b

media/libaaudio/src/client/AudioStreamInternal.cpp

diff --git a/media/libaaudio/src/client/AudioStreamInternal.cpp b/media/libaaudio/src/client/AudioStreamInternal.cpp
index 4c7d0f7..259c9b9 100644
--- a/media/libaaudio/src/client/AudioStreamInternal.cpp
+++ b/media/libaaudio/src/client/AudioStreamInternal.cpp
@@ -68,6 +68,7 @@
         , mServiceInterface(serviceInterface)
         , mWakeupDelayNanos(AAudioProperty_getWakeupDelayMicros() * AAUDIO_NANOS_PER_MICROSECOND)
         , mMinimumSleepNanos(AAudioProperty_getMinimumSleepMicros() * AAUDIO_NANOS_PER_MICROSECOND)
+        , mAtomicTimestamp()
         {
     ALOGD("AudioStreamInternal(): mWakeupDelayNanos = %d, mMinimumSleepNanos = %d",
           mWakeupDelayNanos, mMinimumSleepNanos);
@@ -351,12 +352,15 @@
 aaudio_result_t AudioStreamInternal::getTimestamp(clockid_t clockId,
                            int64_t *framePosition,
                            int64_t *timeNanoseconds) {
-    // TODO Generate in server and pass to client. Return latest.
-    int64_t time = AudioClock::getNanoseconds();
-    *framePosition = mClockModel.convertTimeToPosition(time) + mFramesOffsetFromService;
-    // TODO Get a more accurate timestamp from the service. This code just adds a fudge factor.
-    *timeNanoseconds = time + (6 * AAUDIO_NANOS_PER_MILLISECOND);
-    return AAUDIO_OK;
+    // Generated in server and passed to client. Return latest.
+    if (mAtomicTimestamp.isValid()) {
+        Timestamp timestamp = mAtomicTimestamp.read();
+        *framePosition = timestamp.getPosition();
+        *timeNanoseconds = timestamp.getNanoseconds();
+        return AAUDIO_OK;
+    } else {
+        return AAUDIO_ERROR_UNAVAILABLE;
+    }
 }
 
 aaudio_result_t AudioStreamInternal::updateStateWhileWaiting() {
@@ -385,7 +389,7 @@
     oldTime = nanoTime;
 }
 
-aaudio_result_t AudioStreamInternal::onTimestampFromServer(AAudioServiceMessage *message) {
+aaudio_result_t AudioStreamInternal::onTimestampService(AAudioServiceMessage *message) {
 #if LOG_TIMESTAMPS
     logTimestamp(*message);
 #endif
@@ -393,6 +397,12 @@
     return AAUDIO_OK;
 }
 
+aaudio_result_t AudioStreamInternal::onTimestampHardware(AAudioServiceMessage *message) {
+    Timestamp timestamp(message->timestamp.position, message->timestamp.timestamp);
+    mAtomicTimestamp.write(timestamp);
+    return AAUDIO_OK;
+}
+
 aaudio_result_t AudioStreamInternal::onEventFromServer(AAudioServiceMessage *message) {
     aaudio_result_t result = AAUDIO_OK;
     switch (message->event.event) {
@@ -456,8 +466,12 @@
             break; // no command this time, no problem
         }
         switch (message.what) {
-        case AAudioServiceMessage::code::TIMESTAMP:
-            result = onTimestampFromServer(&message);
+        case AAudioServiceMessage::code::TIMESTAMP_SERVICE:
+            result = onTimestampService(&message);
+            break;
+
+        case AAudioServiceMessage::code::TIMESTAMP_HARDWARE:
+            result = onTimestampHardware(&message);
             break;
 
         case AAudioServiceMessage::code::EVENT:

media/libaaudio/src/client/AudioStreamInternal.h

diff --git a/media/libaaudio/src/client/AudioStreamInternal.h b/media/libaaudio/src/client/AudioStreamInternal.h
index 1b991de..607e734 100644
--- a/media/libaaudio/src/client/AudioStreamInternal.h
+++ b/media/libaaudio/src/client/AudioStreamInternal.h
@@ -122,7 +122,9 @@
 
     aaudio_result_t onEventFromServer(AAudioServiceMessage *message);
 
-    aaudio_result_t onTimestampFromServer(AAudioServiceMessage *message);
+    aaudio_result_t onTimestampService(AAudioServiceMessage *message);
+
+    aaudio_result_t onTimestampHardware(AAudioServiceMessage *message);
 
     void logTimestamp(AAudioServiceMessage &message);
 
@@ -181,6 +183,11 @@
 
     AudioEndpointParcelable  mEndPointParcelable; // description of the buffers filled by service
     EndpointDescriptor       mEndpointDescriptor; // buffer description with resolved addresses
+
+    SimpleDoubleBuffer<Timestamp>  mAtomicTimestamp;
+
+    int64_t                  mServiceLatencyNanos = 0;
+
 };
 
 } /* namespace aaudio */