downsample from image 360*640 to 180*320

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Andrea Gusmara
Andrea Gusmara 2020-5-22
评论： Ameer Hamza 2020-5-22
hi to everyone , I would to ask two question . the first is place in the title , and i know that i'm going to lose data , but i need to. the image in question i frame in the code under
. the second is that i'm trying to execute this code , but somthing wrong append .
video1=VideoReader('Francesca-Michielin---No-Degree-Of-Separation-Italy-Live-at-Semi-Final-2.mp4');
video2=VideoReader('Jamala---1944-Ukraine-Live-at-Semi-Final-2-of-the-2016-Eurovision-Song-Contest.mp4');
videoOut=VideoWriter('provaMix.avi');
videoOut.FrameRate=video1.FrameRate;
open(videoOut)
frames=read(video1,[1 2316]);
for frame=frames
% eventualmente resize (downsampling) del frame
writeVideo(videoOut,frame);
end
thank so much

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采纳的回答

Ameer Hamza
Ameer Hamza 2020-5-22
See imresize(): https://www.mathworks.com/help/releases/R2020a/matlab/ref/imresize.html. Use it with a scaling factor of 0.5;
frame_small = imresize(frame, 0.5)
For videoReader object, use readFrame() function to read a frame at a time, as shown in this example:: https://www.mathworks.com/help/releases/R2020a/matlab/ref/videoreader.html#busqe2j-1_1

更多回答（1 个）

Andrea Gusmara
Andrea Gusmara 2020-5-22
Thanks you for your answer. For the second question, is there any function that permits to read more frames? I have seen the functions readFrame and read. I have read the documentation about the latter function but I couldn't use it very well. The documentation said that a frame range could be recovered
  3 个评论
显示 1更早的评论
Andrea Gusmara
Andrea Gusmara 2020-5-22
No errors, the function returned only a value
Ameer Hamza
Ameer Hamza 2020-5-22
Your for loop is wrong. Write it like this
frames=read(video1,[1 2316]);
for idx=1:2316
% eventualmente resize (downsampling) del frame
writeVideo(videoOut,frames(:,:,:,i));
end

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