I just want the matlab code for converting a video into fewer frames .

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Disha 2013-12-19

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https://ww2.mathworks.cn/matlabcentral/answers/110176-i-just-want-the-matlab-code-for-converting-a-video-into-fewer-frames

回答： Walter Roberson 2013-12-19

is that possible for someone to help me with the code for converting the video into few number of frames?

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Answer 1

Walter Roberson 2013-12-19

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https://ww2.mathworks.cn/matlabcentral/answers/110176-i-just-want-the-matlab-code-for-converting-a-video-into-fewer-frames#answer_118810

在 MATLAB Online 中打开

Combining examples from the VideoWriter and VideoReader documentation pages:

http://www.mathworks.com/help/matlab/ref/videoreaderclass.html

%this part is straight from the VideoReader documentation
xyloObj = VideoReader('xylophone.mp4');
nFrames = xyloObj.NumberOfFrames;
vidHeight = xyloObj.Height;
vidWidth = xyloObj.Width;
% Preallocate movie structure.
mov(1:nFrames) = ...
    struct('cdata', zeros(vidHeight, vidWidth, 3, 'uint8'),...
           'colormap', []);
% Read one frame at a time.
for k = 1 : nFrames
    mov(k).cdata = read(xyloObj, k);
end

start making it smaller

%now a change to write in fewer frames:
frame_keep_fraction = 1/3;   %for example
discard_frame = rand(1,nFrames) > frame_keep_fraction;
mov(discard_frame) = [];   %throw away those frames because we want a smaller video

done making it smaller

%now we can write. Adapting now from the VideoWriter documentation
writerObj = VideoWriter('peaks.avi');
open(writerObj);
writeVideo(writerObj, mov);    %we already have all the data so do not need to go frame by frame
close(writerObj);