Add initial project files and implement basic audio-visual recording functionality

Source/AudioVideoRecord/SimpleRecorder.h

@@ -96,6 +96,9 @@ private:
 	/** Called every frame on the render thread when the back buffer is ready. */
 	void OnBackBufferReady(SWindow& SlateWindow, const FTextureRHIRef& BackBuffer);
 
+	/** Launches the FFmpeg video pipe with the actual back-buffer dimensions. */
+	bool LaunchFFmpegVideoPipe();
+
 	/** Writes the captured audio buffer to a .wav file. */
 	void SaveAudioToWav();
 
@@ -108,6 +111,7 @@ private:
 	// Video
 	FDelegateHandle            BackBufferDelegateHandle;
 	FILE*                      FFmpegVideoPipe = nullptr;
+	bool                       bFFmpegStarted = false;
 
 	// Audio — accumulated raw PCM data
 	TArray<float>              AudioBuffer;          // interleaved float samples