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Create a video from a 4D array

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Alber
Alber 2020-4-17
评论： Ameer Hamza 2020-4-18
Hello, I have a problem in this code.
function [] = writeBufferToFinalVideo(buffer)
video = VideoWriter('example','MPEG-4');
video.FrameRate = 25;
open(video)
for i = 1:size(buffer,4)
img = buffer(i);
img(img>1) = 1;
img(img<0) = 0;
writeVideo(video,img);
end
close(video);
end
My buffer is a 4-dimensional array that has frames inside. It is composed of: (height, width, numChannels, framesPerSymbol). The latter is the number of frames that are in a symbol, that is, the size of my buffer.
In my opinion, I think the code is correct, but I always get an empty video without the frames in my buffer.
  2 个评论
Alber
Alber 2020-4-17
编辑：Alber 2020-4-17
I made the buffer with an array buffer = zeros(height, width, numChannels, framesPerSymbol) and with other function I put the frames of the original video input the buffer.

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采纳的回答

Ameer Hamza
Ameer Hamza 2020-4-17
If buffer is a 4D-array, then you will need to index it like this
img = buffer(:,:,:,i);
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Alber
Alber 2020-4-18
Yes!!! This is the solution, Thank you!!
Ameer Hamza
Ameer Hamza 2020-4-18
I am glad to be of help.
Reason: if the datatype of the matrix is double, MATLAB considers the RGB color values between 0 and 1. Whereas, for your matrix, the values were given in an 8-bit format from 0 to 255. MATLAB takes all value over one as white (that is why you saw white video frames) Dividing by 255, normalizes the value between 0 and 1. I guess, the following will also work for your original code
writeBufferToFinalVideo(uint8(encodedBuffer));

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更多回答（1 个）

Image Analyst
Image Analyst 2020-4-18
Make sure buffer is uint8.
buffer = zeros(height, width, numChannels, framesPerSymbol, 'uint8')

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