timing refactor

apps/LoopThroughWithOpenGLCompositing/videoio/VideoPlayoutScheduler.cpp

@@ -32,6 +32,17 @@ VideoIOScheduleTime VideoPlayoutScheduler::NextScheduleTime()
 	return time;
 }
 
+void VideoPlayoutScheduler::AlignNextScheduleTimeToPlayback(int64_t streamTime, uint64_t leadFrames)
+{
+	if (mFrameDuration <= 0 || streamTime < 0)
+		return;
+
+	const uint64_t playbackFrameIndex = static_cast<uint64_t>(streamTime / mFrameDuration);
+	const uint64_t minimumScheduleIndex = playbackFrameIndex + leadFrames;
+	if (minimumScheduleIndex > mScheduledFrameIndex)
+		mScheduledFrameIndex = minimumScheduleIndex;
+}
+
 VideoPlayoutRecoveryDecision VideoPlayoutScheduler::AccountForCompletionResult(VideoIOCompletionResult result, uint64_t readyQueueDepth)
 {
 	++mCompletedFrameIndex;

apps/LoopThroughWithOpenGLCompositing/videoio/VideoPlayoutScheduler.h

@@ -12,6 +12,7 @@ public:
 	void Configure(int64_t frameDuration, int64_t timeScale, const VideoPlayoutPolicy& policy);
 	void Reset();
 	VideoIOScheduleTime NextScheduleTime();
+	void AlignNextScheduleTimeToPlayback(int64_t streamTime, uint64_t leadFrames);
 	VideoPlayoutRecoveryDecision AccountForCompletionResult(VideoIOCompletionResult result, uint64_t readyQueueDepth = 0);
 	double FrameBudgetMilliseconds() const;
 	uint64_t ScheduledFrameIndex() const { return mScheduledFrameIndex; }

apps/LoopThroughWithOpenGLCompositing/videoio/decklink/DeckLinkSession.cpp

@@ -526,13 +526,24 @@ bool DeckLinkSession::PopulateOutputFrame(IDeckLinkMutableVideoFrame* outputVide
 
 bool DeckLinkSession::ScheduleFrame(IDeckLinkMutableVideoFrame* outputVideoFrame)
 {
-	const VideoIOScheduleTime scheduleTime = mScheduler.NextScheduleTime();
 	if (outputVideoFrame == nullptr || output == nullptr)
 	{
 		++mState.deckLinkScheduleFailureCount;
 		return false;
 	}
 
+	BMDTimeValue streamTime = 0;
+	double playbackSpeed = 0.0;
+	if (output->GetScheduledStreamTime(mScheduler.TimeScale(), &streamTime, &playbackSpeed) == S_OK && playbackSpeed > 0.0)
+	{
+		RefreshBufferedVideoFrameCount();
+		const uint64_t leadFrames = mState.actualDeckLinkBufferedFramesAvailable
+			? static_cast<uint64_t>(mState.actualDeckLinkBufferedFrames) + 1
+			: static_cast<uint64_t>(mPlayoutPolicy.targetPrerollFrames);
+		mScheduler.AlignNextScheduleTimeToPlayback(streamTime, leadFrames);
+	}
+
+	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);
 	const auto scheduleEnd = std::chrono::steady_clock::now();

apps/RenderCadenceCompositor/README.md

@@ -11,14 +11,14 @@ Before adding features here, read the guardrails in [Render Cadence Golden Rules
 ```text
 RenderThread
   owns a hidden OpenGL context
-  polls latest input frames without waiting
+  polls the oldest ready input frame without waiting
   uploads input frames into a render-owned GL texture
   renders simple BGRA8 motion at selected cadence
   queues async PBO readback
   publishes completed frames into SystemFrameExchange
 
 InputFrameMailbox
-  owns latest disposable CPU input slots
+  owns bounded FIFO CPU input slots
   keeps a bounded three-ready-frame input buffer for render
   trims frames beyond that bound to avoid runaway input latency
   protects the one frame currently being uploaded by render
@@ -26,7 +26,7 @@ InputFrameMailbox
 
 SystemFrameExchange
   owns Free / Rendering / Completed / Scheduled slots
-  drops old completed unscheduled frames when render needs space
+  preserves completed output frames once they are waiting for playout
   protects scheduled frames until DeckLink completion
 
 DeckLinkOutputThread
@@ -286,8 +286,8 @@ Input telemetry:
 - `renderFrameMaxMs`: maximum observed render-thread draw duration for this process
 - `readbackQueueMs`: time spent queueing the most recent async BGRA8 PBO readback
 - `completedReadbackCopyMs`: time spent mapping/copying the most recent completed readback into system-memory frame storage
-- `completedDrops`: completed unscheduled system-memory frames dropped so render could reuse the slot
-- `acquireMisses`: times render/readback could not acquire a writable system-memory frame slot
+- `completedDrops`: completed unscheduled system-memory frames dropped by latest-N acquire paths; expected to stay flat in the cadence compositor output path
+- `acquireMisses`: times render/readback could not acquire a writable system-memory frame slot; completed frames waiting for playout are preserved instead of being displaced
 - `inputConsumeMisses`: render ticks where no ready input frame was available to upload
 - `inputUploadMisses`: input texture upload attempts that reused the previous GL input texture
 - `inputReadyFrames`: ready input frames currently queued in `InputFrameMailbox`

apps/RenderCadenceCompositor/RenderCadenceCompositor.cpp

@@ -111,14 +111,23 @@ int main(int argc, char** argv)
 	InputFrameMailbox inputMailbox(inputMailboxConfig);
 
 	VideoFormat inputVideoMode;
+	VideoFormat outputVideoMode;
 	std::string inputVideoModeError;
 	const bool inputVideoModeResolved = ResolveConfiguredVideoFormat(appConfig.inputVideoFormat, appConfig.inputFrameRate, inputVideoMode);
+	const bool outputVideoModeResolved = ResolveConfiguredVideoFormat(appConfig.outputVideoFormat, appConfig.outputFrameRate, outputVideoMode);
 	if (!inputVideoModeResolved)
 	{
 		inputVideoModeError = "Unsupported DeckLink inputVideoFormat/inputFrameRate in config/runtime-host.json: " +
 			appConfig.inputVideoFormat + " / " + appConfig.inputFrameRate;
 		RenderCadenceCompositor::LogWarning("app", inputVideoModeError);
 	}
+	if (!outputVideoModeResolved)
+	{
+		RenderCadenceCompositor::LogWarning(
+			"app",
+			"Unsupported DeckLink outputVideoFormat/outputFrameRate in config/runtime-host.json; render cadence will use parsed frame-rate fallback: " +
+				appConfig.outputVideoFormat + " / " + appConfig.outputFrameRate);
+	}
 
 	RenderCadenceCompositor::DeckLinkInput deckLinkInput(inputMailbox);
 	RenderCadenceCompositor::DeckLinkInputThread deckLinkInputThread(deckLinkInput);
@@ -173,7 +182,10 @@ int main(int argc, char** argv)
 	RenderThread::Config renderConfig;
 	renderConfig.width = frameExchangeConfig.width;
 	renderConfig.height = frameExchangeConfig.height;
-	renderConfig.frameDurationMilliseconds = RenderCadenceCompositor::FrameDurationMillisecondsFromRateString(appConfig.outputFrameRate);
+	const double fallbackFrameDurationMilliseconds = RenderCadenceCompositor::FrameDurationMillisecondsFromRateString(appConfig.outputFrameRate);
+	renderConfig.frameDurationMilliseconds = outputVideoModeResolved
+		? RenderCadenceCompositor::FrameDurationMillisecondsFromDisplayMode(outputVideoMode.displayMode, fallbackFrameDurationMilliseconds)
+		: fallbackFrameDurationMilliseconds;
 	renderConfig.pboDepth = 6;
 
 	RenderThread renderThread(frameExchange, &inputMailbox, renderConfig);

apps/RenderCadenceCompositor/app/AppConfigProvider.cpp

@@ -4,6 +4,7 @@
 
 #include <algorithm>
 #include <cctype>
+#include <cstdint>
 #include <cstdlib>
 #include <fstream>
 #include <sstream>
@@ -184,6 +185,50 @@ double FrameDurationMillisecondsFromRateString(const std::string& rateText, doub
 	return 1000.0 / rate;
 }
 
+double FrameDurationMillisecondsFromDisplayMode(BMDDisplayMode displayMode, double fallbackMilliseconds)
+{
+	struct ModeRate
+	{
+		BMDDisplayMode mode;
+		int64_t frameDuration;
+		int64_t timeScale;
+	};
+
+	static const ModeRate rates[] =
+	{
+		{ bmdModeHD720p50, 1, 50 },
+		{ bmdModeHD720p5994, 1001, 60000 },
+		{ bmdModeHD720p60, 1, 60 },
+		{ bmdModeHD1080i50, 1, 25 },
+		{ bmdModeHD1080i5994, 1001, 30000 },
+		{ bmdModeHD1080i6000, 1, 30 },
+		{ bmdModeHD1080p2398, 1001, 24000 },
+		{ bmdModeHD1080p24, 1, 24 },
+		{ bmdModeHD1080p25, 1, 25 },
+		{ bmdModeHD1080p2997, 1001, 30000 },
+		{ bmdModeHD1080p30, 1, 30 },
+		{ bmdModeHD1080p50, 1, 50 },
+		{ bmdModeHD1080p5994, 1001, 60000 },
+		{ bmdModeHD1080p6000, 1, 60 },
+		{ bmdMode4K2160p2398, 1001, 24000 },
+		{ bmdMode4K2160p24, 1, 24 },
+		{ bmdMode4K2160p25, 1, 25 },
+		{ bmdMode4K2160p2997, 1001, 30000 },
+		{ bmdMode4K2160p30, 1, 30 },
+		{ bmdMode4K2160p50, 1, 50 },
+		{ bmdMode4K2160p5994, 1001, 60000 },
+		{ bmdMode4K2160p60, 1, 60 }
+	};
+
+	for (const ModeRate& rate : rates)
+	{
+		if (rate.mode == displayMode && rate.timeScale > 0)
+			return (static_cast<double>(rate.frameDuration) * 1000.0) / static_cast<double>(rate.timeScale);
+	}
+
+	return fallbackMilliseconds;
+}
+
 void VideoFormatDimensions(const std::string& formatName, unsigned& width, unsigned& height)
 {
 	std::string normalized = formatName;

apps/RenderCadenceCompositor/app/AppConfigProvider.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "AppConfig.h"
+#include "DeckLinkDisplayMode.h"
 
 #include <filesystem>
 #include <string>
@@ -27,6 +28,7 @@ private:
 };
 
 double FrameDurationMillisecondsFromRateString(const std::string& rateText, double fallbackRate = 59.94);
+double FrameDurationMillisecondsFromDisplayMode(BMDDisplayMode displayMode, double fallbackMilliseconds);
 void VideoFormatDimensions(const std::string& formatName, unsigned& width, unsigned& height);
 std::filesystem::path FindConfigFile(const std::filesystem::path& relativePath = "config/runtime-host.json");
 std::filesystem::path FindRepoPath(const std::filesystem::path& relativePath);

apps/RenderCadenceCompositor/frames/InputFrameMailbox.cpp

@@ -120,38 +120,6 @@ bool InputFrameMailbox::SubmitFrame(const void* bytes, unsigned rowBytes, uint64
 	return true;
 }
 
-bool InputFrameMailbox::TryAcquireLatest(InputFrame& frame)
-{
-	std::lock_guard<std::mutex> lock(mMutex);
-	while (!mReadyIndices.empty())
-	{
-		const std::size_t index = mReadyIndices.back();
-		mReadyIndices.pop_back();
-		if (index >= mSlots.size() || mSlots[index].state != InputFrameSlotState::Ready)
-			continue;
-
-		while (!mReadyIndices.empty())
-		{
-			const std::size_t olderIndex = mReadyIndices.front();
-			mReadyIndices.pop_front();
-			if (olderIndex >= mSlots.size() || mSlots[olderIndex].state != InputFrameSlotState::Ready)
-				continue;
-			mSlots[olderIndex].state = InputFrameSlotState::Free;
-			++mSlots[olderIndex].generation;
-			++mCounters.droppedReadyFrames;
-		}
-
-		mSlots[index].state = InputFrameSlotState::Reading;
-		FillFrameLocked(index, frame);
-		++mCounters.consumedFrames;
-		return true;
-	}
-
-	frame = InputFrame();
-	++mCounters.consumeMisses;
-	return false;
-}
-
 bool InputFrameMailbox::TryAcquireOldest(InputFrame& frame)
 {
 	std::lock_guard<std::mutex> lock(mMutex);

apps/RenderCadenceCompositor/frames/InputFrameMailbox.h

@@ -64,7 +64,6 @@ public:
 	InputFrameMailboxConfig Config() const;
 
 	bool SubmitFrame(const void* bytes, unsigned rowBytes, uint64_t frameIndex);
-	bool TryAcquireLatest(InputFrame& frame);
 	bool TryAcquireOldest(InputFrame& frame);
 	bool Release(const InputFrame& frame);
 	void Clear();

apps/RenderCadenceCompositor/frames/SystemFrameExchange.cpp

@@ -47,12 +47,9 @@ bool SystemFrameExchange::AcquireForRender(SystemFrame& frame)
 	std::lock_guard<std::mutex> lock(mMutex);
 	if (!AcquireFreeLocked(frame))
 	{
-		if (!DropOldestCompletedLocked() || !AcquireFreeLocked(frame))
-		{
-			frame = SystemFrame();
-			++mCounters.acquireMisses;
-			return false;
-		}
+		frame = SystemFrame();
+		++mCounters.acquireMisses;
+		return false;
 	}
 
 	++mCounters.acquiredFrames;
@@ -234,27 +231,6 @@ bool SystemFrameExchange::AcquireFreeLocked(SystemFrame& frame)
 	return false;
 }
 
-bool SystemFrameExchange::DropOldestCompletedLocked()
-{
-	while (!mCompletedIndices.empty())
-	{
-		const std::size_t index = mCompletedIndices.front();
-		mCompletedIndices.pop_front();
-		if (index >= mSlots.size() || mSlots[index].state != SystemFrameSlotState::Completed)
-			continue;
-
-		Slot& slot = mSlots[index];
-		slot.state = SystemFrameSlotState::Free;
-		slot.frameIndex = 0;
-		++slot.generation;
-		++mCounters.completedDrops;
-		mCondition.notify_all();
-		return true;
-	}
-
-	return false;
-}
-
 bool SystemFrameExchange::IsValidLocked(const SystemFrame& frame) const
 {
 	return frame.index < mSlots.size() && mSlots[frame.index].generation == frame.generation;

apps/RenderCadenceCompositor/frames/SystemFrameExchange.h

@@ -40,7 +40,6 @@ private:
 	};
 
 	bool AcquireFreeLocked(SystemFrame& frame);
-	bool DropOldestCompletedLocked();
 	bool IsValidLocked(const SystemFrame& frame) const;
 	void FillFrameLocked(std::size_t index, SystemFrame& frame);
 	std::size_t CompletedCountLocked() const;

apps/RenderCadenceCompositor/render/runtime/RuntimeRenderSceneRender.cpp

@@ -65,7 +65,7 @@ void RuntimeRenderScene::RenderFrame(uint64_t frameIndex, unsigned width, unsign
 	}
 
 	// Shader source contract:
-	// - gVideoInput is the decoded latest input texture for every layer in the stack.
+	// - gVideoInput is the decoded current input texture for every layer in the stack.
 	// - gLayerInput starts as gVideoInput for the first layer, then becomes the previous layer output.
 	GLuint layerInputTexture = videoInputTexture;
 	std::size_t nextTargetIndex = 0;

apps/RenderCadenceCompositor/video/DeckLinkOutputThread.h

@@ -82,7 +82,6 @@ private:
 				std::this_thread::sleep_for(mConfig.idleSleep);
 				continue;
 			}
-
 			SystemFrame frame;
 			if (!mExchange.ConsumeCompletedForSchedule(frame))
 			{