How can I save the video file from matlab videoPlayer

How can I save the video file from matlab videoPlayer? I want to export the processed video https://kr.mathworks.com/help/vision/examples/detecting-cars-using-gaussian-mixture-models.html Or how can I change the videoPlayer to videoWriter command?

foregroundDetector = vision.ForegroundDetector('NumGaussians', 3, ...
    'NumTrainingFrames', 50);

videoReader = vision.VideoFileReader('visiontraffic.avi');
for i = 1:150
    frame = step(videoReader); % read the next video frame
    foreground = step(foregroundDetector, frame);
end
figure; imshow(frame); title('Video Frame');
figure; imshow(foreground); title('Foreground');
se = strel('square', 3);
filteredForeground = imopen(foreground, se);
figure; imshow(filteredForeground); title('Clean Foreground');
blobAnalysis = vision.BlobAnalysis('BoundingBoxOutputPort', true, ...
    'AreaOutputPort', false, 'CentroidOutputPort', false, ...
    'MinimumBlobArea', 150);
bbox = step(blobAnalysis, filteredForeground);
result = insertShape(frame, 'Rectangle', bbox, 'Color', 'green');
numCars = size(bbox, 1);
result = insertText(result, [10 10], numCars, 'BoxOpacity', 1, ...
    'FontSize', 14);
figure; imshow(result); title('Detected Cars');
videoPlayer = vision.VideoPlayer('Name', 'Detected Cars');
videoPlayer.Position(3:4) = [650,400];  % window size: [width, height]
se = strel('square', 3); % morphological filter for noise removal

while ~isDone(videoReader)

      frame = step(videoReader); % read the next video frame

      % Detect the foreground in the current video frame
      foreground = step(foregroundDetector, frame);

      % Use morphological opening to remove noise in the foreground
      filteredForeground = imopen(foreground, se);

      % Detect the connected components with the specified minimum area, and
      % compute their bounding boxes
      bbox = step(blobAnalysis, filteredForeground);

      % Draw bounding boxes around the detected cars
      result = insertShape(frame, 'Rectangle', bbox, 'Color', 'green');

      % Display the number of cars found in the video frame
      numCars = size(bbox, 1);
      result = insertText(result, [10 10], numCars, 'BoxOpacity', 1, ...
          'FontSize', 14);

      step(videoPlayer, result);  % display the results
  end

release(videoReader); % close the video file

[KD IS]

videoReader = vision.VideoFileReader('visiontraffic.avi');

videoFWriter=vision.VideoFileWriter('result.avi',...

'FrameRate',videoReader.info.VideoFrameRate);

...

...

step(videoPlayer, result); % display the results

step(videoFWriter,result); % saves video

...

...

release(videoReader); % close the videoReader

release(videoFWriter); % close the videoWriter

Answer 1

[Harish Ramachandran]

In the piece of code you attached above, you are using a VideoReader in order to get the individual frames and implement the car detection algorithm.

In a similar manner, you need to create a VideoWriter object in order to write the frames and process/save them into a video.

(Think of it as 'fread' and 'fwrite' but for video files)

Start a 'for' loop and use the 'open' command. Inside the loop, you will need to use the method 'writeVideo'. Then close the file after the loop.

video_object = VideoWriter('getframes');
open(video_object);
for i = 1:number of input frames
   writeVideo(video_object, format, other options);
end
close(video_object );

Reference:

https://www.mathworks.com/help/matlab/ref/videowriter.html https://www.mathworks.com/matlabcentral/answers/268883-how-do-you-save-the-output-of-a-processed-video

[Thomas Dixon]

The second link seems to have expired

Answer 2

[Vemana]

Create a video reader named turtleVideo for the video file turtles.avi.