Move the Vsync logic from VTRenderer into a VsyncSource

app/streaming/video/ffmpeg-renderers/pacer/pacer.h

@@ -0,0 +1,45 @@
+#pragma once
+
+#include "../renderer.h"
+
+#include <QQueue>
+
+class Pacer;
+
+class IVsyncRenderer {
+public:
+    virtual ~IVsyncRenderer() {}
+    virtual void renderFrameAtVsync(AVFrame* frame) = 0;
+};
+
+class IVsyncSource {
+public:
+    virtual ~IVsyncSource() {}
+    virtual bool initialize(SDL_Window* window) = 0;
+};
+
+class Pacer
+{
+public:
+    Pacer(IVsyncRenderer* renderer);
+
+    ~Pacer();
+
+    void submitFrame(AVFrame* frame);
+
+    bool initialize(SDL_Window* window, int maxVideoFps);
+
+    void vsyncCallback();
+
+    void drain();
+
+private:
+    QQueue<AVFrame*> m_FrameQueue;
+    QQueue<int> m_FrameQueueHistory;
+    SDL_SpinLock m_FrameQueueLock;
+
+    IVsyncSource* m_VsyncSource;
+    IVsyncRenderer* m_VsyncRenderer;
+    int m_MaxVideoFps;
+    int m_DisplayFps;
+};