From 6a0340d1b428f0fd850768a739a49663e3e2c185 Mon Sep 17 00:00:00 2001
From: Aiden <68633820+awils27@users.noreply.github.com>
Date: Wed, 13 May 2026 00:28:11 +1000
Subject: [PATCH] proactive realignment

---
 .../videoio/decklink/DeckLinkSession.cpp      | 22 +++++++++++++++++++
 .../videoio/decklink/DeckLinkSession.h        |  2 ++
 2 files changed, 24 insertions(+)

diff --git a/apps/LoopThroughWithOpenGLCompositing/videoio/decklink/DeckLinkSession.cpp b/apps/LoopThroughWithOpenGLCompositing/videoio/decklink/DeckLinkSession.cpp
index 91e022c..1d810d8 100644
--- a/apps/LoopThroughWithOpenGLCompositing/videoio/decklink/DeckLinkSession.cpp
+++ b/apps/LoopThroughWithOpenGLCompositing/videoio/decklink/DeckLinkSession.cpp
@@ -12,6 +12,9 @@
 
 namespace
 {
+constexpr int64_t kMinimumHealthyScheduleLeadFrames = 3;
+constexpr int64_t kProactiveScheduleLeadFloorFrames = 2;
+
 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)
diff --git a/apps/LoopThroughWithOpenGLCompositing/videoio/decklink/DeckLinkSession.h b/apps/LoopThroughWithOpenGLCompositing/videoio/decklink/DeckLinkSession.h
index 21aa215..e1442cc 100644
--- a/apps/LoopThroughWithOpenGLCompositing/videoio/decklink/DeckLinkSession.h
+++ b/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;
 };