Timing is finally good

apps/LoopThroughWithOpenGLCompositing/videoio/decklink/DeckLinkSession.cpp

@@ -12,6 +12,9 @@
 
 namespace
 {
+constexpr int64_t kMinimumHealthyScheduleLeadFrames = 4;
+constexpr int64_t kProactiveScheduleLeadFloorFrames = 1;
+
 class SystemMemoryDeckLinkVideoBuffer : public IDeckLinkVideoBuffer
 {
 public:
@@ -539,6 +542,7 @@ bool DeckLinkSession::ScheduleFrame(IDeckLinkMutableVideoFrame* outputVideoFrame
 	}
 
 	UpdateScheduleLeadTelemetry();
+	MaybeRealignScheduleCursorForLowLead();
 	const VideoIOScheduleTime scheduleTime = mScheduler.NextScheduleTime();
 	const auto scheduleStart = std::chrono::steady_clock::now();
 	const HRESULT result = output->ScheduleVideoFrame(outputVideoFrame, scheduleTime.streamTime, scheduleTime.duration, scheduleTime.timeScale);
@@ -577,6 +581,24 @@ void DeckLinkSession::UpdateScheduleLeadTelemetry()
 	mState.deckLinkScheduleLeadFrames = static_cast<int64_t>(nextScheduleFrameIndex) - static_cast<int64_t>(playbackFrameIndex);
 }
 
+void DeckLinkSession::MaybeRealignScheduleCursorForLowLead()
+{
+	if (!mState.deckLinkScheduleLeadAvailable)
+		return;
+
+	if (mState.deckLinkScheduleLeadFrames >= kMinimumHealthyScheduleLeadFrames)
+	{
+		mProactiveScheduleRealignmentArmed = true;
+		return;
+	}
+
+	if (!mProactiveScheduleRealignmentArmed || mState.deckLinkScheduleLeadFrames > kProactiveScheduleLeadFloorFrames)
+		return;
+
+	RealignScheduleCursorToPlayback();
+	mProactiveScheduleRealignmentArmed = false;
+}
+
 void DeckLinkSession::RealignScheduleCursorToPlayback()
 {
 	if (output == nullptr)

apps/LoopThroughWithOpenGLCompositing/videoio/decklink/DeckLinkSession.h

@@ -76,6 +76,7 @@ private:
 	bool PopulateOutputFrame(IDeckLinkMutableVideoFrame* outputVideoFrame, VideoIOOutputFrame& frame);
 	bool ScheduleFrame(IDeckLinkMutableVideoFrame* outputVideoFrame);
 	void UpdateScheduleLeadTelemetry();
+	void MaybeRealignScheduleCursorForLowLead();
 	void RealignScheduleCursorToPlayback();
 	bool ScheduleSystemMemoryFrame(const VideoIOOutputFrame& frame);
 	bool ScheduleBlackFrame(IDeckLinkMutableVideoFrame* outputVideoFrame);
@@ -95,6 +96,7 @@ private:
 	VideoPlayoutScheduler					mScheduler;
 	bool									mScheduleRealignmentPending = false;
 	bool									mScheduleRealignmentArmed = true;
+	bool									mProactiveScheduleRealignmentArmed = true;
 	InputFrameCallback						mInputFrameCallback;
 	OutputFrameCallback						mOutputFrameCallback;
 };

apps/RenderCadenceCompositor/telemetry/TelemetryHealthMonitor.h

@@ -78,7 +78,13 @@ private:
 			message << "DeckLink reported frame timing issue: lateDelta=" << lateDelta
 				<< " droppedDelta=" << droppedDelta
 				<< " totalLate=" << snapshot.displayedLate
-				<< " totalDropped=" << snapshot.dropped;
+				<< " totalDropped=" << snapshot.dropped
+				<< " scheduleLead=";
+			if (snapshot.deckLinkScheduleLeadAvailable)
+				message << snapshot.deckLinkScheduleLeadFrames;
+			else
+				message << "n/a";
+			message << " realignments=" << snapshot.deckLinkScheduleRealignments;
 			LogWarning("telemetry", message.str());
 		}