domultifullreadtest.m

Video IO toolbox for matlab. 用directshow做的

function doMultiFullReadTest(varargin)
%DOMULTIFULLREADTEST(...)
%  First we read the entire specified file into memory.  Then we attempt to
%  simultaneously read the same file in using two videoReader objects.
%  This tests thread and video handle management issues.
%
%  Any arguments given are passed directly to the videoReader constructor.
%
%Examples:
%  doMultiFullReadTest
%  doMultiFullReadTest ffmpegPopen2  % linux & similar
%  doMultiFullReadTest ffmpegDirect  % ...if system's gcc is compatible w/ Matlab's
%  doMultiFullReadTest DirectShow    % Windows
%
%Copyright (c) 2006 Gerald Dalley
%See "MIT.txt" in the installation directory for licensing details (especially
%when using this library on GNU/Linux).

ienter('>>> doMultiFullReadTest(''%s'',...)', varargin{1});
images = doFullRead(varargin{:});
if (size(images,3) > 1) % skip single-frame videos
  % make sure first two frames have different data (makes sure next is
  % working)
  vrassert any(images(:,:,1) ~= images(:,:,2));

  % read from multiple videos at the same time
  vr1 = videoReader(varargin{:});
  vr2 = videoReader(varargin{:});
  i = 1;
  while (next(vr1) && next(vr2))
    i1 = getframe(vr1); i1 = i1(:,:,1);
    i2 = getframe(vr2); i2 = i2(:,:,1);
    
    % Ideally, we'd test 
    %   all(all(i1 == i2))
    %   all(all(images(:,:,i) == i1))
    % but it turns out that some decoders (namely ffdshow-tryout's) 
    % will produce slightly different output when reading a video
    % file multiple times.  This may be a decoder bug, or it may be
    % an optimization where it does a higher-quality decode after
    % the first pass.  If you know the real answer, feel free to
    % contact the videoIO authors and let us know.
    vrassert all(abs(double(i1(:)) - double(i2(:))) < 35);
    vrassert mean(abs(double(i1(:)) - double(i2(:)))) < 4;
    
    vrassert all(all(abs(double(images(:,:,i)) - double(i1)) < 35));
    vrassert mean(mean(abs(double(images(:,:,i)) - double(i1)))) < 4;
    
    % since the error bounds are quite high for the above tests,
    % we'll also make sure that the frames are more like each other than
    % the previous/next frame
    errThisFrame = err(mydiff(ilookup(images,i),   i1));
    errNextFrame = err(mydiff(ilookup(images,i+1), i1));
    errPrevFrame = err(mydiff(ilookup(images,i-1), i1));
    vrassert errThisFrame < errNextFrame;
    vrassert errThisFrame < errPrevFrame;
    
    errThisFrame = err(mydiff(ilookup(images,i),   i2));
    errNextFrame = err(mydiff(ilookup(images,i+1), i2));
    errPrevFrame = err(mydiff(ilookup(images,i-1), i2));
    vrassert errThisFrame < errNextFrame;
    vrassert errThisFrame < errPrevFrame;
    
    i = i + 1;
  end
  vr1 = close(vr1);
  vr2 = close(vr2);
end
iexit('<<< doMultiFullReadTest(''%s'',...)', varargin{1});

%------------------------------------------------------
function out = mydiff(a,b) 
out = abs(double(a(:)) - double(b(:)));

function out = clipper(d) 
dontCareErrThresh = 2;
out = d(d>dontCareErrThresh);

function out = err(d) 
out = sum(clipper(d).^2);

function out = ilookup(images,i) 
out = images(:,:,mod(i-1,size(images,3))+1);