Separate FFmpeg decoder from the Session class (#4)

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

@@ -0,0 +1,34 @@
+#pragma once
+
+#include <SDL.h>
+
+extern "C" {
+#include <libavcodec/avcodec.h>
+}
+
+class IFFmpegRenderer {
+public:
+    virtual ~IFFmpegRenderer() {}
+    virtual bool initialize(SDL_Window* window,
+                            int videoFormat,
+                            int width,
+                            int height) = 0;
+    virtual bool prepareDecoderContext(AVCodecContext* context) = 0;
+    virtual void renderFrame(AVFrame* frame) = 0;
+};
+
+class SdlRenderer : public IFFmpegRenderer {
+public:
+    SdlRenderer();
+    virtual ~SdlRenderer();
+    virtual bool initialize(SDL_Window* window,
+                            int videoFormat,
+                            int width,
+                            int height);
+    virtual bool prepareDecoderContext(AVCodecContext* context);
+    virtual void renderFrame(AVFrame* frame);
+
+private:
+    SDL_Renderer* m_Renderer;
+    SDL_Texture* m_Texture;
+};