Clean

apps/LoopThroughWithOpenGLCompositing/videoio/VideoBackend.cpp

@@ -110,19 +110,42 @@ bool VideoBackend::ConfigureOutput(const VideoFormat& outputVideoMode, bool exte
 bool VideoBackend::Start()
 {
 	ApplyLifecycleTransition(VideoBackendLifecycleState::Prerolling, "Video backend preroll starting.");
+	if (!mVideoIODevice->PrepareOutputSchedule())
+	{
+		ApplyLifecycleFailure(StatusMessage().empty() ? "Video backend output schedule preparation failed." : StatusMessage());
+		return false;
+	}
+
 	StartOutputCompletionWorker();
-	const bool started = mVideoIODevice->Start();
-	if (started)
-	{
-		StartOutputProducerWorker();
-		ApplyLifecycleTransition(VideoBackendLifecycleState::Running, "Video backend started.");
-	}
-	else
+	StartOutputProducerWorker();
+
+	if (!WarmupOutputPreroll())
 	{
+		StopOutputProducerWorker();
 		StopOutputCompletionWorker();
-		ApplyLifecycleFailure(StatusMessage().empty() ? "Video backend start failed." : StatusMessage());
+		ApplyLifecycleFailure(StatusMessage().empty() ? "Video backend preroll warmup failed." : StatusMessage());
+		return false;
 	}
-	return started;
+
+	if (!mVideoIODevice->StartInputStreams())
+	{
+		StopOutputProducerWorker();
+		StopOutputCompletionWorker();
+		ApplyLifecycleFailure(StatusMessage().empty() ? "Video backend input stream start failed." : StatusMessage());
+		return false;
+	}
+
+	if (!mVideoIODevice->StartScheduledPlayback())
+	{
+		StopOutputProducerWorker();
+		mVideoIODevice->Stop();
+		StopOutputCompletionWorker();
+		ApplyLifecycleFailure(StatusMessage().empty() ? "Video backend scheduled playback start failed." : StatusMessage());
+		return false;
+	}
+
+	ApplyLifecycleTransition(VideoBackendLifecycleState::Running, "Video backend started.");
+	return true;
 }
 
 bool VideoBackend::Stop()
@@ -393,6 +416,39 @@ void VideoBackend::NotifyOutputProducer()
 	mOutputProducerCondition.notify_one();
 }
 
+bool VideoBackend::WarmupOutputPreroll()
+{
+	const VideoPlayoutPolicy policy = NormalizeVideoPlayoutPolicy(mPlayoutPolicy);
+	const std::size_t targetPrerollFrames = static_cast<std::size_t>(policy.targetPrerollFrames);
+	if (targetPrerollFrames == 0)
+		return true;
+
+	const double frameBudgetMilliseconds = State().frameBudgetMilliseconds > 0.0 ? State().frameBudgetMilliseconds : 16.0;
+	const auto estimatedCadenceTime = std::chrono::duration_cast<std::chrono::milliseconds>(
+		std::chrono::duration<double, std::milli>(frameBudgetMilliseconds * static_cast<double>(targetPrerollFrames + 2)));
+	const auto timeout = (std::max)(std::chrono::milliseconds(1000), estimatedCadenceTime + std::chrono::milliseconds(500));
+	const auto deadline = std::chrono::steady_clock::now() + timeout;
+
+	while (std::chrono::steady_clock::now() < deadline)
+	{
+		ScheduleReadyOutputFramesToTarget();
+		const SystemOutputFramePoolMetrics metrics = mSystemOutputFramePool.GetMetrics();
+		RecordSystemMemoryPlayoutStats();
+		if (metrics.scheduledCount >= targetPrerollFrames)
+			return true;
+
+		NotifyOutputProducer();
+		const auto waitDuration = (std::min)(OutputProducerWakeInterval(), std::chrono::milliseconds(5));
+		std::unique_lock<std::mutex> lock(mOutputProducerMutex);
+		mOutputProducerCondition.wait_for(lock, waitDuration);
+		if (mOutputProducerWorkerStopping)
+			return false;
+	}
+
+	SetStatusMessage("Timed out warming up DeckLink preroll from rendered system-memory frames.");
+	return false;
+}
+
 void VideoBackend::OutputCompletionWorkerMain()
 {
 	for (;;)