Setting frames from mid video

Question

Daevin 2014-8-19

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/151447-setting-frames-from-mid-video

编辑： Geoff Hayes 2014-8-21

I need to take 300 frames from the middle of a huge video (20000 frames) to do further manipulation. I got the following from the xylophone example but it only takes frames from the start of the video; I need to set a smaller video from frames 3701:4000:

Clip1 = VideoReader('C:\Users\(username)\Videos\Day3.4.avi');   %xylophone.mp4');
nFrames = 500;  %Clip1.NumberOfFrames;
vidHeight = Clip1.Height;
vidWidth = Clip1.Width;
%%Movie Structure
mov(1:nFrames) = ...
    struct('cdata',zeros(vidHeight,vidWidth, 3,'uint8'),...
           'colormap',[]);
%%Reading frames
for k = 1 : nFrames
    mov(k).cdata = read(Clip1,k);
end
hf = figure;
set(hf, 'position', [150 150 vidWidth vidHeight])

Any help would be greatly appriciated.

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Geoff Hayes 2014-8-20

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/151447-setting-frames-from-mid-video#answer_149192

编辑：Geoff Hayes 2014-8-21

在 MATLAB Online 中打开

Daevin - according to videoreader.read, it is possible to read in whichever frame that you wish

video = read(obj,index) reads only the specified frames. index can be a single number or a two-element array representing an index range of the video stream.

If you are interested only in the 300 frames starting at 3701, then your above code could be modified as

 nFrames   = 300;  %Clip1.NumberOfFrames;
 vidHeight = Clip1.Height;
 vidWidth  = Clip1.Width;
 %%Movie Structure
 mov(1:nFrames) = ...
    struct('cdata',zeros(vidHeight,vidWidth, 3,'uint8'),'colormap',[]);
 %%Reading frames
 for k = 1:nFrames
    mov(k).cdata = read(Clip1,3700+k);
 end