How to read a video file and save it to multiple frames in numerical order? Because I keep getting back random frames not in order of the video progression

Question

Manuella Juwita 2020-4-23

0
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评论： Manuella Juwita 2020-4-23

My current code is

vid = VideoReader('vid.mp4');
numrames = vid.NumberofFrames;
n = numFrames;
for i = 1:1:n
    frames = read(vid,i);
    imwrite(frames,['mydirectory\'int2str(i),'.jpg']);
    im(i) = image(frames);
end

I know that we can use natsortfiles to read a folder of images in numerical order, but how do you do it with a video file?

Thanks in advance

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Answer 1

Geoff Hayes 2020-4-23

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Manuella - does the because I keep getting back random frames not in order of video propression refer to the files that you have created or the images you see in your figure? If the former, try padding some zeros to the integer file name as

imwrite(frames,sprintf('mydirectory\%05d.jpg', i));

so that the file names are like 00001.jpg, 00002.jpg, etc.

If the latter (images you see are in random order) you may need to pause after displaying the image. The pause should be the inverse of the frame rate

vid = VideoReader('vid.mp4');
numFrames = vid.NumberofFrames;
frameRate = vid.FrameRate;
n = numFrames;
for i = 1:1:n
    frames = read(vid,i);
    imwrite(frames,sprintf('mydirectory\%05d.jpg', i));
    im(i) = image(frames);
    pause(1/frameRate);
end