Reading in an Entire Video

Question

Kevin Castell 2019-5-20

0
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https://ww2.mathworks.cn/matlabcentral/answers/463171-reading-in-an-entire-video

关闭： MATLAB Answer Bot 2021-8-20

I would like to read in an entire video as a matrix if possible. I know this runs into the memory usage problem. My main concern is that I would like to analyze the video frame by frame, in a faster manner than literally looping through the data. Ideally, I could plot the data from a region of interst to see if there has been a change in that region at any point during the video. I am currently using the CurrentTime function from the VideoReader class to just check in intervals. I also tried using memmapfile but I do not really understand how the function works.

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Answer 1

KSSV 2019-5-21

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/463171-reading-in-an-entire-video#answer_375930

在 MATLAB Online 中打开

vidObj = VideoReader('C:\Users\Public\Videos\Sample Videos\Wildlife.wmv');
numFrames = 0;
iwant = cell([],1) ; 
while hasFrame(vidObj)
    F = readFrame(vidObj);    
    numFrames = numFrames + 1;   
    imagesc(F)
    drawnow
    iwant{numFrames} = F ;
end
numFrames

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Kevin Castell 2019-5-21

I have already tried this strategy and the problem is say I have a video that is 2 hours long at 60fps, if we assume that any processing i do on the frames is performed just as fast as they are played, and the loop is as fast or slightly faster than the fps, it will take at least 2 hours to process the video. I want to process the video in under 2 minutes.