videoreader_imread.m

Video IO toolbox for matlab. 用directshow做的

function [out,out2] = videoReader_imread(cmd, handle, varargin)
%[...] = videoReader_imread(cmd, handle, varargin)
%  videoReader plugin for reading videos stored as individual images on
%  disk.  This plugin uses Matlab's IMREAD function to read the frames and
%  is implemented as M-code instead of as a MEX function.  Users should not
%  call this function directly.  Instead they should use the videoReader
%  constructor and specify the 'imread' plugin.
%
%  Type 'help videoReader' for usage documentation.
%
%Example:
%  % make a few video frames -- a rotating gradient
%  for i=1:10
%    frame = repmat(mod([0:99]/99 + (i-1)/10, 1), [75,1]);
%    imwrite(frame, sprintf('%04d.jpg', i));
%  end
%  % read in the video and show it as a movie
%  vr = videoReader('%04d.jpg', 'plugin','imread');
%  for i=1:10
%    seek(vr,i);
%    imshow(getframe(vr));
%    title(sprintf('frame %d', i));
%    pause(1);
%  end
%  vr = close(vr);
%
%Copyright (c) 2008 Gerald Dalley
%See "MIT.txt" in the installation directory for licensing details (especially
%when using this library on GNU/Linux). 

% Registry of reader data.  The videoIO architecture calls for plugins to
% keep all the data for a videoReader/videoWriter object stored in the
% plugin and accessible through objects identified by handles.  This allows
% videoIO to work well with MEX functions.  Here we store the data for each
% open object as well as some bookkeeping information.
persistent nextHandle handles dirnames filenames currFrames infos;
if isempty(nextHandle)
  nextHandle = int32(now);           % handle to use for the next open command
  handles    = int32(zeros(0,0));    % list of currently-active handles
  dirnames   = {};                   % image files directory for each handle
  filenames  = {};                   % for each handle, a list of image files
  currFrames = [];                   % for each handle, the current frame num
  infos      = {};                   % for each handle, what getinfo returns
end

% Get the handle for this instance
i = validateHandle(cmd,handle,handles);

if strcmp(cmd, 'close'),
  %........................................................................
  % CLOSE COMMAND
  if ~isempty(varargin)
    error('The "close" command does not take any optional arguments');
  end
  handles    = handles([1:i-1, i+1:end]);
  dirnames   = {dirnames{[1:i-1, i+1:end]}};
  filenames  = {filenames{[1:i-1, i+1:end]}};
  currFrames = currFrames([1:i-1, i+1:end]);
  infos      = {infos{[1:i-1, i+1:end]}};
  
elseif strcmp(cmd, 'getframe')
  %........................................................................
  % GETFRAME COMMAND
  if ~isempty(varargin)
    error('The "getframe" command does not take any optional arguments');
  end
  dirname = dirnames{i};
  fname   = filenames{i}{currFrames(i)+1};
  out     = imread(fullfile(dirname, fname));
  
elseif strcmp(cmd, 'getinfo')
  %........................................................................
  % GETINFO COMMAND
  if ~isempty(varargin)
    error('The "getinfo" command does not take any optional arguments');
  end
  out  = fieldnames(infos{i});
  out2 = struct2cell(infos{i});
  
elseif strcmp(cmd, 'next')
  %........................................................................
  % NEXT COMMAND
  if ~isempty(varargin)
    error('The "next" command does not take any optional arguments');
  end
  currFrames(i) = currFrames(i) + 1;
  if currFrames(i) < infos{i}.numFrames
    out = int32(1);
  else
    out = int32(0);
  end
  
elseif strcmp(cmd, 'open')
  %........................................................................
  % OPEN COMMAND
  %   videoReader_imread('open',-1, filepattern)
  %     filepattern may use wildcards, e.g. 'mydir/*.png', or it may use
  %     an sprintf-like '%d' string, e.g. 'mydir/%04d.png'.  The wildcard
  %     or sprintf substitution must be in the filename, not in a directory
  %     name (e.g. neither 'mydir/%04d/pic.png' nor 'mydir/*/pic.png' is
  %     allowed).
  %
  %     For sprintf strings, we assume that the substituted number is the
  %     frame number.  Currently, only non-negative numbers are supported.
  %     Only frames that are found when the open command is executed can 
  %     be read.
  %
  %     For wildcard strings, all files matching the pattern are examined
  %     and they are sorted in alphabetic order.  The alphabetically-first
  %     frame is used as frame 0.  Only frames that are found when the
  %     open command is executed can be read.
  %
  %     Both the percent character (%) and wildcards (?,*) cannot appear 
  %     in the same file pattern at the present time (e.g. 
  %     'mydir/*/%04d.png' is not allowed).  The percent character may
  %     appear at most once (e.g. 'mydir/%04d_%04d.png' is not allowed). 
  i          = length(handles)+1;
  handles(i) = nextHandle;
  out        = nextHandle;
  nextHandle = int32(double(nextHandle)+1);
  
  if length(varargin)>1
    error('No optional arguments are supported for the "open" command are supported for the imread plugin');
  end
  
  filepattern = varargin{1};
  [dirnames{i}, filenames{i}] = getFileList(filepattern);
  
  img = imread(fullfile(dirnames{i}, filenames{i}{end}));
  currFrames(i) = -1;
  infos{i}      = struct(...
    'url',                varargin{1}, ...
    'fps',               -1, ...
    'height',             size(img,1), ...
    'width',              size(img,2), ...
    'numFrames',          length(filenames{i}), ...
    'fourcc',             '',...
    'nHiddenFinalFrames', 0);
  
elseif strcmp(cmd, 'seek')
  %........................................................................
  % SEEK COMMAND
  if length(varargin) ~= 1
    error('The "seek" command takes exactly one argument');
  end
  currFrames(i) = varargin{1};
  if currFrames(i) < infos{i}.numFrames && currFrames(i) >= 0
    out = int32(1);
  else
    out = int32(0);
  end
  
  
elseif strcmp(cmd, 'step')
  %........................................................................
  % STEP COMMAND
  if length(varargin) ~= 1
    error('The "step" command takes exactly one argument');
  end
  currFrames(i) = currFrames(i) + varargin{1};
  if currFrames(i) < infos{i}.numFrames && currFrames(i) >= 0
    out = int32(1);
  else
    out = int32(0);
  end
  
else
  error(['Unrecognized command: "' cmd '"']);
end

%--------------------------------------------
function i = validateHandle(cmd,handle,handles)
if strcmp(cmd, 'open')
  if (handle ~= int32(-1))
    % This is a slightly pedantic check to detect if someone has been
    % messing with the constructor or is trying to call us directly.
    error('Unexpected handle for the "open" command');
  end
  i = int32(-1);
else
  [tst,i] = ismember(handle,handles);
  if ~tst
    error('Invalid load plugin handle');
  end
end