Use Pacer to drive all rendering

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

@@ -36,7 +36,7 @@ public:
                             int height,
                             int maxFps);
     virtual bool prepareDecoderContext(AVCodecContext* context);
-    virtual void renderFrame(AVFrame* frame);
+    virtual void renderFrameAtVsync(AVFrame* frame);
 
 private:
     int m_WindowSystem;