finding the compression ratio

I have a code below

writerObj = VideoWriter('ne1.mpg');

     open(writerObj)                 

    for k = 1:nFrames
     image = ((imread(fullfile(path,files(k).name))));

      writeVideo(writerObj,image);
    end 

close(writerObj);    

xyloObj = VideoReader('ne1.avi');

i have some frames when i use mpg format i get error as file not found in matlab path,if i use avi it works fine,plz help

another thing how to find the compression ratio for video

original is ne.avi and compressed is ne1.avi

[Jan]

The questions are not clear. Please do not describe the error like "as file not found", but copy the error message and explain in which line it occurs. What exactly is the "compression ratio"? Would the relation between the file sizes matchs your needs already?