MATLAB function (mp4 to jpg frames)

parse_video.m

function parse_video(resizeOption, cropOption)
% 
% Parsing video (*.mp4/*.avi) file(s) into image (*.jpg) files
% 
% Written by Hio-Been Han, hiobeen.han@kaist.ac.kr
%
% 2020-09-30
%
if nargin < 1, resizeOption = false; end
if nargin < 2, cropOption = false; end

%% (1) Get file info & set save directory
[file_list, vid_directory] = uigetfile('*.*','MultiSelect','on');
if ischar(file_list),  file_list = {file_list}; end
resize_size = [448,448];
img_directory = [vid_directory 'frames/'];
if ~isdir(img_directory), mkdir(img_directory); end
cropOption = false;
convert_resolution = sprintf( '%dx%d', resize_size(1),resize_size(2));
save_format = '.jpg';

%% (2) Parse video into JPEG files
for fileIdx = 1:length(file_list)
    
    % Set save directory
    fname = file_list{fileIdx};
    uniqname = fname(1:end-4);
    fileformat = fname(end-3:end);
    vidname = [vid_directory uniqname];
    save_directory = [img_directory uniqname '/'];
    if ~isdir(save_directory), mkdir(save_directory); end
    
    % Read frames
    v = VideoReader( [ vidname fileformat ]);
    nFrames = v.Duration * v.FrameRate;
    for frameIdx = 1:nFrames
        if v.hasFrame
            frame = v.readFrame();
            
            % Set ROI
            if frameIdx == 1
                if cropOption
                    mask = image_ROI_selection(frame, ['Select ROI to save' ...
                        ' [Occlusion => Right Click]']);
                else
                    mask = logical(ones([size(frame,1), size(frame,2)]));
                end
                idx_x = find( nanmean(mask,2) );
                idx_y = find( nanmean(mask,1) );
                original_resolution = sprintf( '%dx%d', size(frame,1), size(frame,2));
            end
            
            % Save frame
            frame_valid = rgb2gray( frame(idx_x,idx_y,:) );
            imgname_write = [num2str(sprintf('frame-%06d',frameIdx))...
                '-' uniqname '-from' original_resolution '-to' convert_resolution save_format];
            imwrite( imresize( frame_valid, resize_size ), [ save_directory imgname_write ] )
        end
    end
end

%% Subfunc
function mask = image_ROI_selection(I, textInput)
if nargin == 1, textInput = ''; end
figure(1), set(gcf, 'Color', [1 1 1]);
colormap(gray);
imshow(uint8(I), 'DisplayRange', [], 'InitialMagnification',600/max(size(I))*100 );
title( textInput )

%%-- Display instructions to user
%title('click points to make an initial contour, right click to close contour and finish');
disp('click points to make an initial contour,');
disp('right click to close contour and finish');

%%-- begin getting points
[y1 x1 b] = ginput(1);
xi = x1;
yi = y1;
if(b ~= 1) return; end

[ny nx c] = size(I);
mask = zeros(ny,nx);

while(1)
    x2 = x1;  y2 = y1;
    [y1 x1 b] = ginput(1);
    if(b ~= 1),  x1 = xi;  y1 = yi;   end
    lx = x2-x1;  ly = y2-y1;
    len = ceil((lx^2+ly^2)^(1/2))+1;
    x = round(x1:(lx)/(len-1):x2);    y = round(y1:(ly)/(len-1):y2); %make another one for y
    if(length(x) == 0),  x = round(x1) * ones(1,len); end
    if(length(y) == 0)
        y = round(y1) * ones(1,len);
    end
    
    this_index2 = sub2ind(size(mask),x, y);
    if size(this_index2) == [1 1]
        title('Try Again!', 'FontSize', 18)
        sprintf Try_Again!
    end
    
    try    mask(this_index2) = 1; end
    idx = find(mask==1);
    backup_mask = mask;
    %%-- draw the users line in the image (color or grayscale)
    if(c-1)
        Ir = I(:,:,1); Ig = I(:,:,2); Ib = I(:,:,3);
        Ir(idx) = 0;
        Ig(idx) = 255;
        Ib(idx) = 0;
        I(:,:,1) = Ir; I(:,:,2) = Ig; I(:,:,3) = Ib;
    else
        I(idx) = 255;
    end
    imshow(uint8(I),'DisplayRange', [], 'InitialMagnification', 600/max(size(I))*100);
    title( textInput )
    if(b ~= 1) break; end
end

mask = bwfill(mask, 'holes');
% mask = ~mask;