opencv combine video

To combine videos using the OpenCV library in C++, you can follow the steps below:

  1. Import the necessary libraries:

  2. #include <opencv2/opencv.hpp>: This includes the OpenCV library.

  3. Create a VideoCapture object for each video file you want to combine:

  4. cv::VideoCapture video1("path/to/video1.mp4");: This creates a VideoCapture object named video1 and opens the first video file.

  5. cv::VideoCapture video2("path/to/video2.mp4");: This creates a VideoCapture object named video2 and opens the second video file.

  6. Check if the videos were successfully opened:

  7. if (!video1.isOpened() || !video2.isOpened()): This condition checks if either video1 or video2 failed to open. If any of them failed, it means there was an error opening the video files.

  8. Get the properties of the videos:

  9. double fps = video1.get(cv::CAP_PROP_FPS);: This retrieves the frames per second (FPS) of the first video.
  10. cv::Size frameSize(video1.get(cv::CAP_PROP_FRAME_WIDTH), video1.get(cv::CAP_PROP_FRAME_HEIGHT));: This gets the frame size (width and height) of the first video.

  11. int fourcc = cv::VideoWriter::fourcc('M', 'J', 'P', 'G');: This specifies the codec to be used for the output video.

  12. Create a VideoWriter object to save the combined video:

  13. cv::VideoWriter output("path/to/output.mp4", fourcc, fps, frameSize);: This creates a VideoWriter object named output and specifies the output video file path, codec, FPS, and frame size.

  14. Read frames from each video and write them to the output video:

  15. cv::Mat frame1, frame2;: This creates Mat objects to store the frames of video1 and video2.
  16. while (video1.read(frame1) && video2.read(frame2)): This loop reads frames from both videos until there are no more frames to read.
  17. cv::Mat combinedFrame(frameSize.height, frameSize.width * 2, frame1.type());: This creates a new Mat object with a width twice the size of the individual frames to accommodate both videos side by side.
  18. frame1.copyTo(combinedFrame(cv::Rect(0, 0, frameSize.width, frameSize.height)));: This copies the frame from video1 to the left side of the combined frame.
  19. frame2.copyTo(combinedFrame(cv::Rect(frameSize.width, 0, frameSize.width, frameSize.height)));: This copies the frame from video2 to the right side of the combined frame.

  20. output.write(combinedFrame);: This writes the combined frame to the output video.

  21. Release the resources:

  22. video1.release();: This releases the resources used by video1.
  23. video2.release();: This releases the resources used by video2.
  24. output.release();: This releases the resources used by the output video.

That's it! Following these steps will allow you to combine two videos using OpenCV in C++.