Phase 7 step 2

CMakeLists.txt

@@ -168,6 +168,7 @@ set(APP_SOURCES
 	"${APP_DIR}/videoio/VideoBackendLifecycle.cpp"
 	"${APP_DIR}/videoio/VideoBackendLifecycle.h"
 	"${APP_DIR}/videoio/VideoIOTypes.h"
+	"${APP_DIR}/videoio/VideoPlayoutPolicy.h"
 	"${APP_DIR}/videoio/VideoPlayoutScheduler.cpp"
 	"${APP_DIR}/videoio/VideoPlayoutScheduler.h"
 )

apps/LoopThroughWithOpenGLCompositing/gl/renderer/GlRenderConstants.h

@@ -7,4 +7,3 @@ constexpr GLuint kDecodedVideoTextureUnit = 1;
 constexpr GLuint kSourceHistoryTextureUnitBase = 2;
 constexpr GLuint kPackedVideoTextureUnit = 2;
 constexpr GLuint kGlobalParamsBindingPoint = 0;
-constexpr unsigned kPrerollFrameCount = 12;

apps/LoopThroughWithOpenGLCompositing/videoio/VideoPlayoutPolicy.h

@@ -0,0 +1,34 @@
+#pragma once
+
+#include <cstdint>
+
+enum class VideoUnderrunBehavior
+{
+	ReuseLastCompletedFrame,
+	BlackFrame
+};
+
+struct VideoPlayoutPolicy
+{
+	unsigned outputFramePoolSize = 10;
+	unsigned targetPrerollFrames = 12;
+	unsigned targetReadyFrames = 2;
+	unsigned maxReadyFrames = 4;
+	unsigned minimumSpareDeviceFrames = 1;
+	uint64_t lateOrDropCatchUpFrames = 2;
+	VideoUnderrunBehavior underrunBehavior = VideoUnderrunBehavior::ReuseLastCompletedFrame;
+	bool adaptiveHeadroomEnabled = false;
+};
+
+inline VideoPlayoutPolicy NormalizeVideoPlayoutPolicy(VideoPlayoutPolicy policy)
+{
+	if (policy.outputFramePoolSize == 0)
+		policy.outputFramePoolSize = 1;
+	if (policy.targetPrerollFrames == 0)
+		policy.targetPrerollFrames = 1;
+	if (policy.targetReadyFrames == 0)
+		policy.targetReadyFrames = 1;
+	if (policy.maxReadyFrames < policy.targetReadyFrames)
+		policy.maxReadyFrames = policy.targetReadyFrames;
+	return policy;
+}

apps/LoopThroughWithOpenGLCompositing/videoio/VideoPlayoutScheduler.cpp

@@ -1,9 +1,15 @@
 #include "VideoPlayoutScheduler.h"
 
 void VideoPlayoutScheduler::Configure(int64_t frameDuration, int64_t timeScale)
+{
+	Configure(frameDuration, timeScale, VideoPlayoutPolicy());
+}
+
+void VideoPlayoutScheduler::Configure(int64_t frameDuration, int64_t timeScale, const VideoPlayoutPolicy& policy)
 {
 	mFrameDuration = frameDuration;
 	mTimeScale = timeScale;
+	mPolicy = NormalizeVideoPlayoutPolicy(policy);
 	Reset();
 }
 
@@ -26,7 +32,7 @@ VideoIOScheduleTime VideoPlayoutScheduler::NextScheduleTime()
 void VideoPlayoutScheduler::AccountForCompletionResult(VideoIOCompletionResult result)
 {
 	if (result == VideoIOCompletionResult::DisplayedLate || result == VideoIOCompletionResult::Dropped)
-		mScheduledFrameIndex += 2;
+		mScheduledFrameIndex += mPolicy.lateOrDropCatchUpFrames;
 }
 
 double VideoPlayoutScheduler::FrameBudgetMilliseconds() const

apps/LoopThroughWithOpenGLCompositing/videoio/VideoPlayoutScheduler.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "VideoIOTypes.h"
+#include "VideoPlayoutPolicy.h"
 
 #include <cstdint>
 
@@ -8,15 +9,18 @@ class VideoPlayoutScheduler
 {
 public:
 	void Configure(int64_t frameDuration, int64_t timeScale);
+	void Configure(int64_t frameDuration, int64_t timeScale, const VideoPlayoutPolicy& policy);
 	void Reset();
 	VideoIOScheduleTime NextScheduleTime();
 	void AccountForCompletionResult(VideoIOCompletionResult result);
 	double FrameBudgetMilliseconds() const;
 	uint64_t ScheduledFrameIndex() const { return mScheduledFrameIndex; }
 	int64_t TimeScale() const { return mTimeScale; }
+	const VideoPlayoutPolicy& Policy() const { return mPolicy; }
 
 private:
 	int64_t mFrameDuration = 0;
 	int64_t mTimeScale = 0;
 	uint64_t mScheduledFrameIndex = 0;
+	VideoPlayoutPolicy mPolicy;
 };

apps/LoopThroughWithOpenGLCompositing/videoio/decklink/DeckLinkSession.cpp

@@ -1,7 +1,5 @@
 #include "DeckLinkSession.h"
 
-#include "GlRenderConstants.h"
-
 #include <atlbase.h>
 #include <cstdio>
 #include <cstring>
@@ -210,7 +208,7 @@ bool DeckLinkSession::DiscoverDevicesAndModes(const VideoFormatSelection& videoM
 	BMDTimeValue frameDuration = 0;
 	BMDTimeScale frameTimescale = 0;
 	outputMode->GetFrameRate(&frameDuration, &frameTimescale);
-	mScheduler.Configure(frameDuration, frameTimescale);
+	mScheduler.Configure(frameDuration, frameTimescale, mPlayoutPolicy);
 	mState.frameBudgetMilliseconds = mScheduler.FrameBudgetMilliseconds();
 
 	mState.inputFrameRowBytes = mState.inputFrameSize.width * 2u;
@@ -379,7 +377,9 @@ bool DeckLinkSession::ConfigureOutput(OutputFrameCallback callback, const VideoF
 		mState.statusMessage = "Selected DeckLink output supports external keying. Set enableExternalKeying to true in runtime-host.json to request it.";
 	}
 
-	for (int i = 0; i < 10; i++)
+	const VideoPlayoutPolicy policy = NormalizeVideoPlayoutPolicy(mPlayoutPolicy);
+	mPlayoutPolicy = policy;
+	for (unsigned i = 0; i < policy.outputFramePoolSize; i++)
 	{
 		CComPtr<IDeckLinkMutableVideoFrame> outputFrame;
 
@@ -523,7 +523,9 @@ bool DeckLinkSession::Start()
 		return false;
 	}
 
-	for (unsigned i = 0; i < kPrerollFrameCount; i++)
+	const VideoPlayoutPolicy policy = NormalizeVideoPlayoutPolicy(mPlayoutPolicy);
+	mPlayoutPolicy = policy;
+	for (unsigned i = 0; i < policy.targetPrerollFrames; i++)
 	{
 		CComPtr<IDeckLinkMutableVideoFrame> outputVideoFrame;
 		if (!AcquireNextOutputVideoFrame(outputVideoFrame))

apps/LoopThroughWithOpenGLCompositing/videoio/decklink/DeckLinkSession.h

@@ -6,6 +6,7 @@
 #include "DeckLinkVideoIOFormat.h"
 #include "VideoIOFormat.h"
 #include "VideoIOTypes.h"
+#include "VideoPlayoutPolicy.h"
 #include "VideoPlayoutScheduler.h"
 
 #include <atlbase.h>
@@ -79,6 +80,7 @@ private:
 	CComPtr<IDeckLinkKeyer>					keyer;
 	std::deque<CComPtr<IDeckLinkMutableVideoFrame>> outputVideoFrameQueue;
 	VideoIOState							mState;
+	VideoPlayoutPolicy						mPlayoutPolicy;
 	VideoPlayoutScheduler					mScheduler;
 	InputFrameCallback						mInputFrameCallback;
 	OutputFrameCallback						mOutputFrameCallback;

docs/PHASE_7_BACKEND_LIFECYCLE_PLAYOUT_DESIGN.md

@@ -9,13 +9,14 @@ Phase 5 clarified that live parameter layering stops at final render-state compo
 ## Status
 
 - Phase 7 design package: proposed.
-- Phase 7 implementation: Step 1 complete.
+- Phase 7 implementation: Step 2 complete.
 - Current alignment: `VideoBackend`, `VideoIODevice`, `DeckLinkSession`, `VideoBackendLifecycle`, and `VideoPlayoutScheduler` exist. Phase 4 removed callback-thread GL ownership, but the DeckLink completion path still waits for render-thread output production.
 
 Current backend footholds:
 
 - `VideoBackend` wraps device discovery/configuration, start/stop, input callback handling, output completion handling, and telemetry publication.
 - `DeckLinkSession` owns DeckLink device handles, frame pool creation, preroll, keyer configuration, and scheduled playback.
+- `VideoPlayoutPolicy` names current frame pool, preroll, ready-frame, underrun, and catch-up policy defaults.
 - `VideoPlayoutScheduler` owns basic schedule time generation and simple late/drop skip-ahead behavior.
 - `OpenGLVideoIOBridge` is the current adapter between `VideoBackend` and `RenderEngine`.
 - `HealthTelemetry` receives some signal, render, and pacing stats.
@@ -223,9 +224,16 @@ Unify fixed constants and scheduler assumptions.
 
 Initial target:
 
-- frame pool size derives from policy
+- [x] frame pool size derives from policy
-- preroll count derives from policy
+- [x] preroll count derives from policy
-- late/drop recovery reads policy
+- [x] late/drop recovery reads policy
+
+Current implementation:
+
+- `VideoPlayoutPolicy` defines current output frame pool, preroll, ready-frame, spare-buffer, underrun, catch-up, and adaptive-headroom settings.
+- `DeckLinkSession` uses the policy for output frame pool creation and preroll count.
+- `VideoPlayoutScheduler` stores the policy and uses `lateOrDropCatchUpFrames` instead of a hard-coded `+2` recovery step.
+- `VideoPlayoutSchedulerTests` cover default compatibility behavior, policy-driven catch-up, and policy normalization.
 
 ### Step 3. Add Ready Output Queue
 
@@ -321,7 +329,7 @@ Backend lifecycle and playout queue are related, but either can grow large. Impl
 Phase 7 can be considered complete once the project can say:
 
 - [x] backend lifecycle states and transitions are explicit
-- [ ] playout policy owns preroll, pool size, headroom, and underrun behavior
+- [x] playout policy owns preroll, pool size, headroom, and underrun behavior
 - [ ] output callbacks no longer synchronously wait for render production
 - [ ] render produces completed output frames into a bounded queue
 - [ ] underrun behavior is explicit and observable

tests/VideoPlayoutSchedulerTests.cpp

@@ -50,6 +50,33 @@ void TestLateAndDroppedSkipAhead()
 	Expect(scheduler.NextScheduleTime().streamTime == 6000, "dropped completion preserves the existing two-frame skip policy");
 }
 
+void TestLateAndDroppedRecoveryUsesPolicy()
+{
+	VideoPlayoutPolicy policy;
+	policy.lateOrDropCatchUpFrames = 4;
+
+	VideoPlayoutScheduler scheduler;
+	scheduler.Configure(1000, 50000, policy);
+
+	(void)scheduler.NextScheduleTime();
+	scheduler.AccountForCompletionResult(VideoIOCompletionResult::Dropped);
+	Expect(scheduler.NextScheduleTime().streamTime == 5000, "drop recovery uses policy catch-up frame count");
+}
+
+void TestPolicyNormalization()
+{
+	VideoPlayoutPolicy policy;
+	policy.outputFramePoolSize = 0;
+	policy.targetPrerollFrames = 0;
+	policy.targetReadyFrames = 5;
+	policy.maxReadyFrames = 2;
+
+	VideoPlayoutPolicy normalized = NormalizeVideoPlayoutPolicy(policy);
+	Expect(normalized.outputFramePoolSize == 1, "policy normalization keeps at least one output frame");
+	Expect(normalized.targetPrerollFrames == 1, "policy normalization keeps at least one preroll frame");
+	Expect(normalized.maxReadyFrames == normalized.targetReadyFrames, "policy normalization keeps max ready frames above target");
+}
+
 void TestFrameBudgets()
 {
 	VideoPlayoutScheduler scheduler;
@@ -68,6 +95,8 @@ int main()
 {
 	TestScheduleAdvancesFromZero();
 	TestLateAndDroppedSkipAhead();
+	TestLateAndDroppedRecoveryUsesPolicy();
+	TestPolicyNormalization();
 	TestFrameBudgets();
 
 	if (gFailures != 0)