Loading and reading yuv files into matlab for video processing

Can somebody explain how this code works? What are the output variables, such as mov here. This code basically loads the avi file, originally a yuv file, into Matlab for processing. But I don't know the details in this code.

    %f1: anchor frame; f2: target frame, fp: predicted image;
    %mvx,mvy: store the MV image
    %widthxheight: image size; N: block size, R: search range

    clear; clc;
    %load sample_avi; 
    %x = sample_avi;

    %for k = 1:150   % 150 frames
        %c{k} = struct2cell(x(k));
        %xx = c{k};
        %Ximg{k} = xx{1};    % cell array of 150 frames 144x176x3
    %end

    %# Get the video data:

    vidObj = mmreader('foreman_qcif.avi');  %# Create a video file object
    nFrames = vidObj.NumberOfFrames;   %# Get the number of frames
    vidHeight = vidObj.Height;         %# Get the image height
    vidWidth = vidObj.Width;           %# Get the image width

    %# Preallocate the structure array of movie frames:

    mov(1:nFrames) = struct('cdata',zeros(vidHeight,vidWidth,3,'uint8'),...
                        'colormap',[]);  %# Note that colormap is empty!

    %# Read each video frame into the structure array:

    for k = 1:nFrames
      mov(k).cdata = read(vidObj,k)  %# Place frame k in the cdata field of mov(k)
    end

Can this code be used for my main program below? This code is used for predicting the second frame from the first frame through motion estimation and compensation. Can somebody again help me out on the details of this code?

    f1 = mov(1).cdata %first frame
    f2 = mov(2).cdata %seconde frame
    R = input('search range = ');

    % convert images to grayscale
    %f1 = 0.2989*f1(:,:,1) + 0.5870*f1(:,:,2) + 0.1140*f1(:,:,3);
    %f2 = 0.2989*f2(:,:,1) + 0.5870*f2(:,:,2) + 0.1140*f2(:,:,3);

    [height width] = size(f1); %size of first frame
    N = 16;  % blocksize

    mvx=[]; mvy=[]; ii = 1; fp = uint8(zeros(height,width));
    for i = 1:N:height
        jj = 1;
        for j = 1:N:width %for every block in the anchor frame
            MAD_min = 256*N*N
            MAD = MAD_min
            dx = 0
            dy = 0 
            for k = -R:1:R  % defines search range
                for l = -R:1:R %defines search range, for every search candidate
                    if ~(i+k<=0 | j+l<=0 | i+k+N-1>height | j+l+N-1>width) % if inside boundary
                        MAD = sum(sum(abs(f1(i:i+N-1,j:j+N-1)-f2(i+k:i+k+N-1,j+l:j+l+N-1))))
                        if MAD < MAD_min
                            MAD_min = MAD
                            dy = k
                            dx = l
                        else
                            MAD = MAD_min
                            dx = dx
                            dy = dy
                        end
                    else
                        MAD = MAD_min
                        dx = dx
                        dy = dy
                    end
                    % calculate MAD for this candidate
                end
            end
            %put the best matching block in the predicted image
            fp(i:i+N-1,j:j+N-1) = f2(i+dy:i+dy+N-1,j+dx:j+dx+N-1);
            mvx(ii,jj) = dx;
            mvy(ii,jj) = dy; %record the estimated MV
            jj = jj + 1
        end
        ii = ii + 1
    end
    figure; imshow(f1); title('anchor image');
    figure; imshow(f2); title('target image');
    figure; imshow(fp); title('predicted image');
    figure; imshow(f1-fp); title('prediction image error');
    figure; quiver(mvx,mvy); axis ij;

    f11 = double(f1); fpp = double(fp);
    err = 0;
    for c1 = 1:height
        for c2 = 1:width
            err = err + (f11(c1,c2) - fpp(c1,c2))^2;
        end
    end
    mse = err/(height*width);
    psnr = 10*log10((pk^2)/mse);
    pk = 255; %double(max(max(f1)));

    fprintf('PSNR = %f dB\n',psnr);

What is the output of this code?

Answer 1

[Ching-Huang Hsieh]

 %f1: anchor frame; f2: target frame, fp: predicted image;

 f2?