Step 3

apps/LoopThroughWithOpenGLCompositing/videoio/RenderOutputQueue.cpp

@@ -0,0 +1,70 @@
+#include "RenderOutputQueue.h"
+
+RenderOutputQueue::RenderOutputQueue(const VideoPlayoutPolicy& policy) :
+	mPolicy(NormalizeVideoPlayoutPolicy(policy))
+{
+}
+
+void RenderOutputQueue::Configure(const VideoPlayoutPolicy& policy)
+{
+	std::lock_guard<std::mutex> lock(mMutex);
+	mPolicy = NormalizeVideoPlayoutPolicy(policy);
+	while (mReadyFrames.size() > CapacityLocked())
+	{
+		mReadyFrames.pop_front();
+		++mDroppedCount;
+	}
+}
+
+bool RenderOutputQueue::Push(RenderOutputFrame frame)
+{
+	std::lock_guard<std::mutex> lock(mMutex);
+	if (mReadyFrames.size() >= CapacityLocked())
+	{
+		mReadyFrames.pop_front();
+		++mDroppedCount;
+	}
+
+	mReadyFrames.push_back(frame);
+	++mPushedCount;
+	return true;
+}
+
+bool RenderOutputQueue::TryPop(RenderOutputFrame& frame)
+{
+	std::lock_guard<std::mutex> lock(mMutex);
+	if (mReadyFrames.empty())
+	{
+		++mUnderrunCount;
+		return false;
+	}
+
+	frame = mReadyFrames.front();
+	mReadyFrames.pop_front();
+	++mPoppedCount;
+	return true;
+}
+
+void RenderOutputQueue::Clear()
+{
+	std::lock_guard<std::mutex> lock(mMutex);
+	mReadyFrames.clear();
+}
+
+RenderOutputQueueMetrics RenderOutputQueue::GetMetrics() const
+{
+	std::lock_guard<std::mutex> lock(mMutex);
+	RenderOutputQueueMetrics metrics;
+	metrics.depth = mReadyFrames.size();
+	metrics.capacity = CapacityLocked();
+	metrics.pushedCount = mPushedCount;
+	metrics.poppedCount = mPoppedCount;
+	metrics.droppedCount = mDroppedCount;
+	metrics.underrunCount = mUnderrunCount;
+	return metrics;
+}
+
+std::size_t RenderOutputQueue::CapacityLocked() const
+{
+	return static_cast<std::size_t>(mPolicy.maxReadyFrames);
+}

apps/LoopThroughWithOpenGLCompositing/videoio/RenderOutputQueue.h

@@ -0,0 +1,48 @@
+#pragma once
+
+#include "VideoIOTypes.h"
+#include "VideoPlayoutPolicy.h"
+
+#include <cstdint>
+#include <deque>
+#include <mutex>
+
+struct RenderOutputFrame
+{
+	VideoIOOutputFrame frame;
+	uint64_t frameIndex = 0;
+	bool stale = false;
+};
+
+struct RenderOutputQueueMetrics
+{
+	std::size_t depth = 0;
+	std::size_t capacity = 0;
+	uint64_t pushedCount = 0;
+	uint64_t poppedCount = 0;
+	uint64_t droppedCount = 0;
+	uint64_t underrunCount = 0;
+};
+
+class RenderOutputQueue
+{
+public:
+	explicit RenderOutputQueue(const VideoPlayoutPolicy& policy = VideoPlayoutPolicy());
+
+	void Configure(const VideoPlayoutPolicy& policy);
+	bool Push(RenderOutputFrame frame);
+	bool TryPop(RenderOutputFrame& frame);
+	void Clear();
+	RenderOutputQueueMetrics GetMetrics() const;
+
+private:
+	std::size_t CapacityLocked() const;
+
+	mutable std::mutex mMutex;
+	VideoPlayoutPolicy mPolicy;
+	std::deque<RenderOutputFrame> mReadyFrames;
+	uint64_t mPushedCount = 0;
+	uint64_t mPoppedCount = 0;
+	uint64_t mDroppedCount = 0;
+	uint64_t mUnderrunCount = 0;
+};