How to read video file stored in structure?
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I am trying to process a video file,i am able to read and store it in a structure.But i am not able to read values from structure to process and play it. My code is like this:
vid = Video Reader('sample.avi');
nframes= vid.NumberOfFrames;
vidHeight = vid.Height;
vidWidth = vid.Width;
halfframes=round(nframes/2);
mov(1:halfframes) = struct('cdata',zeros(vidHeight, vidWidth, 3, 'uint8'),'colormap', []);
%to read the frames and store it in structure
for k = 1:halfframes
mov(k).cdata = read(vid,( 2*k -1));
end
%till here its working fine
%if i try to read values by using a loop its not working
for k = 1:halfframes
frame= mov(k).cdata
imshow(frame);
end
this loop is not working and i am not getting all images/frames please help me with this
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Answers (2)
Walter Roberson
on 11 Feb 2012
A) There have been some reports that VideoReader is skipping frames and repeating frames, with the incidence of that perhaps higher for variable frame-rate files.
B) put a drawnow() after the imshow().
C) If you have the image processing toolkit, you may wish to consider using implay rather than looping displaying the frames yourself.
2 Comments
Walter Roberson
on 11 Feb 2012
Note by the way that NumberOfFrames is not meaningful for a variable-frame-rate video until after the video has been read to the last frame.
Side note: you do not need to initialize the zeros for mov(k).cdata. The read() you are doing will construct new storage and will use that storage, discarding any storage already allocated for mov(k).cdata . Might as well just initialize it to a single 0.
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