This code continuously reads frames from a video file using OpenCV’s VideoCapture class in a loop. If the frame is not empty, it is displayed in a window using imshow() and then converted to an AVFrame that can be used by FFmpeg. The converted frame is then encoded using avcodec_encode_video2() function and written to an output file using av_interleaved_write_frame(). If there are any errors during encoding, the loop breaks and the program exits.
The loop also checks for user input to quit the program by checking if the ‘q’ key has been pressed using waitKey(). If the key has been pressed, the loop breaks and the program exits.
