can someone tell me why cant i use any other video as an example in this code : https://in​.mathworks​.com/help/​vision/exa​mples/dete​cting-cars​-using-gau​ssian-mixt​ure-models​.html

foregroundDetector = vision.ForegroundDetector('NumGaussians', 3, ...
    'NumTrainingFrames',80 );

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

Answer 1

[Steven Lord]

You didn't say what happens when you try using a different video in the example.

• Do you have Computer Vision System Toolbox installed? That example uses many functions from that toolbox, so if you don't have it installed you won't be able to run the example. Check the ver function output to determine if you have it installed.

• Which release of MATLAB are you using? The online documentation is for the most recent release (currently release R2018b.) I'm not sure how much (if any) that example has changed in recent releases, but if you're using a sufficiently old release you may need to use the version of that example included in the documentation for the release you're using. If you're using a really old version (one that predates the introduction of some of the functions/objects used in the example) that example may not exist or may be significantly different.

• Do you receive an error? If so, what is the full text of the error message (everything displayed in red text) that you receive when you try running the code?

• Do you receive a different result than you expected? If so, what result do you receive and what result did you expect to receive? Be specific about the differences between the actual results and your expected results.

• Did something else happen? if so, describe in detail what happened.

[Y.Rahul Kumar]

sorry maybe i just framed the question in a wrong way,actually the code is running perfectly but i dont understand why iam unable to use any other video other than the one which is already in that .

[Steven Lord]

What exactly happens when you change this line of the example to use a different video file?

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

[Y.Rahul Kumar]

i don't know exactly whether im doing it in a correct way or not but instead of using this visiontraffic.avi i tryed randomvideo.avi (randomvideo=some video that i had downloaded)