obj=VideoReader（‘F:\matlabwork\viptrain.avi‘）;
nframes=obj.NumberOfframes;
vid=VideoWriter（‘F:\new.avi‘）;
tmp=read（obj1）;
[mn]=size（tmp）;
open（vid）;
for?k=1:nframes
????tmp=read（objnframes-k+1）;
????tmp