📄 aviread.m
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function output = AviRead(filename,option,option2,option3)
%--------------------------------------------------------------------
% result = AviRead (filename,
% number of frames to process,
% first frame to display,
% last frame to display)
%
% Result = last image displayed (depending on color depth of AVI:
% 8 Bits per Pixel: Matrix[Lines, Rows] of uint8
% 16 Bits per Pixel: Matrix[Lines, Rows] of uint16
% 24 Bits per Pixel: Matrix[Lines, Rows, 3] of uint8
%
% Example: AviRead('sample.avi',30,10,12)
% reads and processes the first 30 frames of the file
% 'sample.avi', and displays frame 10, 11 and 12 each
% in its own figure.
%
% NOTE: supports only uncompressed plain avi(RIFF) files
% (8, 16, 24, 32 Bit per Pixel)
%
% (c) by Rainer Rawer (using Matlab 5.3)
% http://www.rawer.de/rainer/software/
% rrawer@gmx.de
% 18/12/2000 %--------------------------------------------------------------------
% default declarations:
JUNK = [74 85 78 75]; % <JUNK>
RIFF = [82 73 70 70]; % <RIFF>
AVI = [65 86 73 32]; % <AVI >
MOVI = [109 111 118 105]; % <movi>
ValidFrameID = [48 48 100 98]; % <00db>
AVIH = [97 118 105 104]; % <avih>
STRF = [115 116 114 102]; % <strf>
version = '1.12';
lines = 240; % default lines per frame
columns = 320; % default colons per frame
bytes = 1; % default bytes per pixel
no_of_frames = 1; % no of frames to read
%-------------------------------------------------------------------------
%-------------------------------------------------------------------------
% checking if files is existing and a valid RIFF/AVI file
%-------------------------------------------------------------------------
if nargin == 0;
disp(['-------------------------------']);
disp([' AviRead V',version, ' by R.Rawer `99-`00'])
disp(['-------------------------------']);
disp([' usage: AviRead(filename,'])
disp([' number of frames to process,'])
disp([' first frame to display,'])
disp([' last frame to display)'])
error(['### no parameters']);
end
if nargin < 4; option3=option2 ; end
if nargin < 3; option2 = 0, option3= 0 ; end
if nargin < 2; option = 0; option2 = 0, option3= 0 ; end
fid = fopen(filename, 'r'); if fid < 3; error(['### AviRead: ', filename, ' NOT found.']); end
xx = uint8(fread(fid, 5000, 'uint8')); if max(xx(1:4)'==RIFF==0); %check for: 'RIFF'
error(['### AviRead: ', filename, ... ' is not a valid RIFF file.']);
elseif max(xx(9:12)'==AVI==0); %check for: 'AVI '
error(['### AviRead: ', filename, ... ' is not a valid AVI file.']);
end fclose(fid);
%-------------------------------------------------------------------------
% Extracting AVI header information
%-------------------------------------------------------------------------
h=1;i=0;h2=0;e=1;
while e==1;
h=h+1;
if min(xx(h:(h+3))'== AVIH); %check for ID: 'avih'
h2=h;
e=0;
end
end
time_per_frame = double(xx(h2+8))+double(xx(h2+9))*256+double(xx(h2+10))*256*256+double(xx(h2+11))*256*256*256;
no_of_frames = double(xx(h2+24))+double(xx(h2+25))*256+double(xx(h2+26))*256*256+double(xx(h2+27))*256*256*256;
columns = double(xx(h2+40))+double(xx(h2+41))*256+double(xx(h2+42))*256*256+double(xx(h2+43))*256*256*256;
lines = double(xx(h2+44))+double(xx(h2+45))*256+double(xx(h2+46))*256*256+double(xx(h2+47))*256*256*256;
i=0;h3=0;e=1;
while e==1;
h=h+1;
if min(xx(h:(h+3))'==STRF); %check for ID: 'strf'
h3=h;
e=0;
end
end
color_depth=double(xx(h3+22))+double(xx(h3+23))*256;
switch color_depth
case 8
bytes=1;
case 16
bytes=2;
case 24
bytes=3;
otherwise bytes=4;
end
e=1;
while e==1;
h=h+1;
if min(xx(h:(h+3))'==MOVI); %check for ID: 'movi'
e=0;
h1=h;
end
end
frame_length=double(xx(h1+8))+double(xx(h1+9))*256+double(xx(h1+10))*256*256+double(xx(h1+11))*256*256*256;
frame_ID=xx(h1+4:h1+7);
% re-open file to check foer actual framelength:
fid = fopen(filename, 'r');if fid < 3; error(['### AviRead: ', filename, ' NOT found.']); end
% seek to place where 2nd frame should be:
fseek(fid,h1+4+frame_length,-1);
xx = uint8(fread(fid, 5000, 'uint8')); h=0;i=0;h5=0;e=1;
while e==1;
h=h+1;
if min(xx(h:(h+3))'==frame_ID'); %check for ID: frame_ID
h5=h;
e=0;
end
end
frame_offset=h5;
% check for compressed AVIs:
if ((lines*columns)~=(frame_length/bytes));
error('### no compressed AVI supported !');
end;
% check if fra,mes to read exeeds number of frames in file:
if (option > no_of_frames)
option = no_of_frames;
disp(sprintf('Warning: No of frames to read adjusted to %d!',option));
end;
%display header information:
frame_ID=double(frame_ID);
disp('---------------------------------------------------------');
disp(['AviRead V',version,' by R.Rawer `99']);
disp(sprintf(' filename : "%s"',filename));
disp(sprintf(' number of frames to read : %d',option));
disp(sprintf(' display frame : #%d to #%d',option2,option3));
disp('---------------------------------------------------------');
disp(sprintf(' number of data blocks : %d',no_of_frames));
disp(sprintf(' frames per second : %5.2f',1000000*1/time_per_frame));
disp(sprintf(' frame size : %d x %d',columns,lines));
disp(sprintf(' colour depth : %d (%dbyte)',color_depth,bytes));
disp(sprintf(' frame length : %d (0x%x)',frame_length,frame_length));
disp(sprintf(' frame ID : %c%c%c%c',frame_ID(1),frame_ID(2),frame_ID(3),frame_ID(4)));
disp(sprintf(' frame offset : %d',frame_offset));
disp('---------------------------------------------------------');
%-------------------------------------------------------------------------
% start reading single frames
%-------------------------------------------------------------------------
% re-open file for actual reading of data:
fid = fopen(filename, 'r');if fid < 3; error(['### AviRead: ', filename, ' NOT found.']); end
fseek(fid,h1+3,-1);
% read frames
frames=0;
if option>0; no_of_frames=option;end
while (i<no_of_frames);
frames=frames+1;
i=i+1;
%disp(sprintf('processing frame %d of %d ',i,no_of_frames));
frame_header = uint8(fread(fid, 8, 'uint8')');
f_length=double(frame_header(5))+double(frame_header(6))*256+double(frame_header(7))*256*256+double(frame_header(8))*256*256*256;
% seek for next valid pixture dataset:
e=0;
while e==0;
if (frame_header(1:4)==JUNK );
%found a JUNK frame and skipping it...
disp('reading JUNK frame...');
xx=uint8(fread(fid, f_length, 'uint8')');
frame_header = uint8(fread(fid, 8, 'uint8')');
f_length=double(frame_header(5))+double(frame_header(6))*256+double(frame_header(7))*256*256+double(frame_header(8))*256*256*256;
elseif f_length==0;
%found empty frame and skipping it...
disp('reading empty frame...');
frame_header = uint8(fread(fid, 8, 'uint8')');
i=i+1;
f_length=double(frame_header(5))+double(frame_header(6))*256+double(frame_header(7))*256*256+double(frame_header(8))*256*256*256;
elseif (frame_header(1:4)== frame_ID')
%found valid frame....
%disp('found valid movi-frame...');
e=1;
else
%found non-movi media frame
%disp('skipping non-movi frame...');
%disp('flength');f_length
xx=uint8(fread(fid, f_length, 'uint8')');
frame_header = uint8(fread(fid, 8, 'uint8')');
f_length=double(frame_header(5))+double(frame_header(6))*256+double(frame_header(7))*256*256+double(frame_header(8))*256*256*256;
end
end
%==================================================================
% (*1*) =
% =
% Reading Image Data (depening on number of bytes per pixel) =
% and rearrange it to image-matrix =
%==================================================================
switch bytes
case 1
% read 8bit per Pixel (greyscale) Data:
xx = uint8(fread(fid, frame_length/bytes, 'uint8'));
% reshape data as 2-dimentional image array:
im = reshape(xx(1,:),columns,lines);
case 2
% read 16bit per Pixel Data:
xx = uint16(fread(fid, frame_length/bytes, 'uint16'));
% reshape data as 2-dimentional image array:
im = reshape(xx(1,:),columns,lines);
case 3
% read 24bit per Pixel (truecolor) Data:
xx = uint8(fread(fid, frame_length, 'uint8'));
xx = reshape(xx,3,frame_length/3)';
% reshape data as 3-dimentional truecolor image array
% ([rows,lines,3], three color planes RGB):
im(:,:,3) = rot90(reshape(xx(:,1),columns,lines));
im(:,:,2) = rot90(reshape(xx(:,2),columns,lines));
im(:,:,1) = rot90(reshape(xx(:,3),columns,lines));
otherwise
% read 32bit per Pixel Data:
xx = uint32(fread(fid, frame_length/bytes, 'uint32'));
% reshape data as 2-dimentional image array:
im = double(reshape(xx,columns,lines));
end
%=================================================================
% (*2*) =
% =
% processing data of each frame starts here =
% if you don't want to display any of the frames simply =
% delete the folowing lines... (cut to cut) =
%=================================================================
%---cut---
% display image data if needed:
if option2>0;
if ((i>=option2)&(i<=option3));
figure('name',sprintf('Frame #%d',i));
switch bytes
case 1
imshow(im');colormap(gray);
case 2
imshow(im');colormap(gray);
case 3
image(im);
otherwise
imshow(im);
end
end
end
%---cut---
% your code comes here ....
%-----------------------------------------------------------------
% Use the following varibles:
%
% no_of_frames: number of frames to be read
% time_per_frame: time to display each frame [ms] (reverse of Frames
% per 0.001 second)
% frames: number of this frame
% columns: number of pixels per line
% lines: number of lines per image
% bytes: number of bytes per pixel
% im: image data:
% 8bit/pixel: uint8-Matrix[columns,lines]
% 16bit/pixel: uint16-Matrix[columns,lines]
% 24bit/pixel: uint8-Matrix[columns,lines,3]
% (3 Color Planes R,G,B)
% 32bit/pixel: uint32-Matrix[columns,lines]
% xx: raw image data:
% 8bit/pixel: uint8-Matrix[columns*lines]
% (1-dimentional)
% 16bit/pixel: uint16-Matrix[columns*lines]
% (1-dimentional)
% 24bit/pixel: uint8-Matrix[3,columns*lines]
% (1-dimentional, 3 Color Planes R,G,B)
% 32bit/pixel: uint32-Matrix[columns*lines]
% (1-dimentional)
%
% Note: if you prefer another byte-arangement in order to speed up
% your image processing refere to section (*1*) and modify
% the reshape commands in order to speed up the rearanging
% process
%
%-----------------------------------------------------------------
end % end reading single frames -----------------------------------
% output read statistics:
disp('---------------------------------------------------------');
disp(sprintf('Read %d Blocks, %d valid Frames',i,frames));
disp('---------------------------------------------------------');
% plot results of maximum positions
output=im;
disp (['script done !']);
disp(' ');
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