VideoCompressionWithQuantization

url = 'C:\Users\pawan\Desktop\shuttle_out.avi';
%implay(url);
frames = 'C:\Users\pawan\Desktop\frames';
mkdir(frames);
mkdir(frames,'collections');
vr = VideoReader(url);
n = vr.NumberOfFrames;
for i = 1:1:n; 
    %img = rgb2ycbcr(read(vr,i))
    img = read(vr,i);
    imwrite(img , fullfile(frames,'collections',sprintf('img%d.jpg',i)));
end;
imgName = dir(fullfile(frames,'collections','*.jpg'));
imgName = {imgName.name};
%disp(imgName(1:10));
imgString = regexp([imgName{:}],'(\d*)','match');
imgNumbers = str2double(imgString);
[ ~ ,sortedIndex] = sort(imgNumbers);
sortedImgNames = imgName(sortedIndex);
%disp(sortedImgNames(1:10));
outputVideo = VideoWriter(fullfile(frames,'shuttle_out.avi'));
outputVideo.FrameRate = 5;
open(outputVideo);
quality = 50;
for ii = 1:length(sortedImgNames)
    Q50 = [16 11 10 16 24 40 51 61;12 12 14 19 26 58 60 55;14 13 16 24 40 57 64 56;14 17 22 29 51 87 80 82;18 22 37 56 68 109 103 77;24 35 55 64 81 104 113 92;49 64 78 87 103 121 120 171;72 92 95  98 112 100 103 99]
    if quality > 50
         QX = round (Q50.*(ones(8)*((100-quality)/50)));
         %QX = unit8(QX);
     elseif quality <50
         QX= round(Q50.*(ones(8)*(50/quality)));
         %QX=unit8(QX);
     elseif quality ==50
         QX=Q50;
     end
    img = imread(fullfile(frames,'collections',sortedImgNames{ii}));
    %writeVideo(outputVideo,img);
    g=img;
    %[l,m] = size(g);
    k=rgb2gray(g);
    I1 = double(k);
    [m,n] = size(I1);
    for i = 1:8:m
        for j = 1:8:n
            block = I1(i:i+7,j:j+7);
            dctt = dctmtx(8);
            dctmult = dctt * double(block)*dctt';
            mult = round(dctmult./QX);
            dctmult1 = dctt'* mult *dctt;
            dctmult2 = dctt'* dctmult *dctt;
            %img1(i:i+7,j:j+7)= mult;
            img1(i:i+7,j:j+7)= dctmult2; %Without quantization
            img2(i:i+7,j:j+7)= dctmult1; %with quantization
        end
    end
    a=mat2gray(img1);
    b=mat2gray(img2);

    writeVideo(outputVideo,b);
end
close(outputVideo);