Merge "audio: Implement more accurate timing for the stub stream" into main
diff --git a/audio/aidl/default/include/core-impl/StreamStub.h b/audio/aidl/default/include/core-impl/StreamStub.h
index f4ee566..22b2020 100644
--- a/audio/aidl/default/include/core-impl/StreamStub.h
+++ b/audio/aidl/default/include/core-impl/StreamStub.h
@@ -44,6 +44,10 @@
     const bool mIsInput;
     bool mIsInitialized = false;  // Used for validating the state machine logic.
     bool mIsStandby = true;       // Used for validating the state machine logic.
+
+    // Used by the worker thread.
+    int64_t mStartTimeNs = 0;
+    long mFramesSinceStart = 0;
 };
 
 class StreamInStub final : public StreamIn, public StreamStub {
diff --git a/audio/aidl/default/stub/StreamStub.cpp b/audio/aidl/default/stub/StreamStub.cpp
index 3b6a85a..a3d99a8 100644
--- a/audio/aidl/default/stub/StreamStub.cpp
+++ b/audio/aidl/default/stub/StreamStub.cpp
@@ -83,7 +83,6 @@
     if (!mIsInitialized) {
         LOG(FATAL) << __func__ << ": must not happen for an uninitialized driver";
     }
-    usleep(500);
     mIsStandby = true;
     return ::android::OK;
 }
@@ -92,8 +91,9 @@
     if (!mIsInitialized) {
         LOG(FATAL) << __func__ << ": must not happen for an uninitialized driver";
     }
-    usleep(500);
     mIsStandby = false;
+    mStartTimeNs = ::android::uptimeNanos();
+    mFramesSinceStart = 0;
     return ::android::OK;
 }
 
@@ -105,14 +105,23 @@
     if (mIsStandby) {
         LOG(FATAL) << __func__ << ": must not happen while in standby";
     }
-    static constexpr float kMicrosPerSecond = MICROS_PER_SECOND;
-    static constexpr float kScaleFactor = .8f;
+    *actualFrameCount = frameCount;
     if (mIsAsynchronous) {
         usleep(500);
     } else {
-        const size_t delayUs = static_cast<size_t>(
-                std::roundf(kScaleFactor * frameCount * kMicrosPerSecond / mSampleRate));
-        usleep(delayUs);
+        mFramesSinceStart += *actualFrameCount;
+        const long bufferDurationUs =
+                (*actualFrameCount) * MICROS_PER_SECOND / mContext.getSampleRate();
+        const auto totalDurationUs =
+                (::android::uptimeNanos() - mStartTimeNs) / NANOS_PER_MICROSECOND;
+        const long totalOffsetUs =
+                mFramesSinceStart * MICROS_PER_SECOND / mContext.getSampleRate() - totalDurationUs;
+        LOG(VERBOSE) << __func__ << ": totalOffsetUs " << totalOffsetUs;
+        if (totalOffsetUs > 0) {
+            const long sleepTimeUs = std::min(totalOffsetUs, bufferDurationUs);
+            LOG(VERBOSE) << __func__ << ": sleeping for " << sleepTimeUs << " us";
+            usleep(sleepTimeUs);
+        }
     }
     if (mIsInput) {
         uint8_t* byteBuffer = static_cast<uint8_t*>(buffer);
@@ -120,7 +129,6 @@
             byteBuffer[i] = std::rand() % 255;
         }
     }
-    *actualFrameCount = frameCount;
     return ::android::OK;
 }