How can we merge two separate video files into one?

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Parham Babakhani Dehkordi
评论： Sven Beckhuis 2021-12-8
Hello,
I have two separate video .avi files named as 'first' and 'second'. The first video contains 13 frames, and second video includes 18 frames. I need to combine these two video into one single file so that the first video comes first, followed by the second one with frame rate of 0.4.
I use the following code, however, the error said that 'Dimensions of arrays being concatenated are not consistent', which emphasize that two input files do not have the same dimensions, any help would be appreciated.
vid1 = VideoReader('first.avi');
vid2 = VideoReader('second.avi');
videoPlayer = vision.VideoPlayer;
% new video
outputVideo = VideoWriter('newvideo.avi');
outputVideo.FrameRate = vid1.FrameRate;
open(outputVideo);
while hasFrame(vid1) && hasFrame(vid2)
img1 = readFrame(vid1);
img2 = readFrame(vid2);
imgt = horzcat(img1, img2);
% play video
step(videoPlayer, imgt);
% record new video
writeVideo(outputVideo, imgt);
end
release(videoPlayer);
close(outputVideo);

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采纳的回答

Image Analyst
Image Analyst 2020-9-12
Try calling imresize() to make them the same size:
img1 = readFrame(vid1);
[rows1, columns1, numColors1] = size(img1);
img2 = readFrame(vid2);
[rows2, columns2, numColors2] = size(img1);
img2 = imresize(img2, [rows1, rows2]);
imgt = horzcat(img1, img2);
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Walter Roberson
Walter Roberson 2021-12-8
You need the Computer Vision Toolbox in order to write combined audio and video.
https://www.mathworks.com/help/vision/ref/vision.videofilewriter-system-object.html for the writing
https://www.mathworks.com/help/vision/ref/vision.videofilereader-system-object.html for the reading.
You cannot switch audio rates in the middle of a file, so you would need to examine the audio rates of both files in advance and decide which rate you are going to convert the samples to.
You should also be interpolating video frame rates since you cannot change frame rates in the middle of writing. At the moment I am not sure what a good video frame rate conversion method is.
Sven Beckhuis
Sven Beckhuis 2021-12-8
Thank you for your answer Walter! I will give it a try! :)

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更多回答（1 个）

Walter Roberson
Walter Roberson 2020-9-12
You cannot change the size of the frame in the middle of a video.
You will need to do one of the following:
  • pad the smaller frames to be the same size as the larger
  • crop the larger frames to be the same size as the smaller
  • imresize the smaller frames to be the same size as the larger
  • imresize the larger frames to be the same size as the smaller
  • imresize() all frames to be a fixed size
Note that imresize() distorts proportions unless the scalling factor happens to be the same horizontally and vertically (same aspect ratio).
If you pad you probably want to center the image rather than padding only on one edge. https://www.mathworks.com/help/images/ref/padarray.html

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