How to save a stabilized video to hard disk?

Hi, I used the demo script (run file below) to learn about video stabilization.

%  Input video file which needs to be stabilized.
filename = 'shaky_car.avi';
% filename = 'TEST.avi';

hVideoSource = vision.VideoFileReader(filename, ...
                                      'ImageColorSpace', 'Intensity',...
                                      'VideoOutputDataType', 'double');

hTranslate = vision.GeometricTranslator( ...
                              'OutputSize', 'Same as input image', ...
                              'OffsetSource', 'Input port');

hTM = vision.TemplateMatcher('ROIInputPort', true, ...
                            'BestMatchNeighborhoodOutputPort', true);

hShapeInserter = vision.ShapeInserter('BorderColor', 'White');

hTextInserter = vision.TextInserter('(%+05.1f,%+05.1f)', ...
                                   'Location', [191 215], ...
                                   'Color', 1, ...
                                   'FontSize', 16);

hVideoOut = vision.VideoPlayer('Name', 'Video Stabilization');
hVideoOut.Position(1) = round(0.4*hVideoOut.Position(1));
hVideoOut.Position(2) = round(1.5*(hVideoOut.Position(2)));
hVideoOut.Position(3:4) = [650 350];

pos.template_orig = [109 100]; % [x y] upper left corner
pos.template_size = [22 18];   % [width height]
pos.search_border = [15 10];   % max horizontal and vertical displacement
pos.template_center = floor((pos.template_size-1)/2);
pos.template_center_pos = (pos.template_orig + pos.template_center - 1);
fileInfo = info(hVideoSource);
W = fileInfo.VideoSize(1); % Width in pixels
H = fileInfo.VideoSize(2); % Height in pixels
BorderCols = [1:pos.search_border(1)+4 W-pos.search_border(1)+4:W];
BorderRows = [1:pos.search_border(2)+4 H-pos.search_border(2)+4:H];
sz = fileInfo.VideoSize;
TargetRowIndices = ...
  pos.template_orig(2)-1:pos.template_orig(2)+pos.template_size(2)-2;
TargetColIndices = ...
  pos.template_orig(1)-1:pos.template_orig(1)+pos.template_size(1)-2;
SearchRegion = pos.template_orig - pos.search_border - 1;
Offset = [0 0];
Target = zeros(18,22);
firstTime = true;

while ~isDone(hVideoSource)
    input = step(hVideoSource);

      % Find location of Target in the input video frame
      if firstTime
        Idx = int32(pos.template_center_pos);
        MotionVector = [0 0];
        firstTime = false;
      else
        IdxPrev = Idx;

        ROI = [SearchRegion, pos.template_size+2*pos.search_border];
        Idx = step(hTM, input, Target, ROI);

        MotionVector = double(Idx-IdxPrev);
      end

      [Offset, SearchRegion] = updatesearch(sz, MotionVector, ...
          SearchRegion, Offset, pos);

      % Translate video frame to offset the camera motion
      Stabilized = step(hTranslate, input, fliplr(Offset));

      Target = Stabilized(TargetRowIndices, TargetColIndices);

      % Add black border for display
      Stabilized(:, BorderCols) = 0;
      Stabilized(BorderRows, :) = 0;

      TargetRect = [pos.template_orig-Offset, pos.template_size];
      SearchRegionRect = [SearchRegion, pos.template_size + 2*pos.search_border];

      % Draw rectangles on input to show target and search region
      input = step(hShapeInserter, input, [TargetRect; SearchRegionRect]);

      % Display the offset values on the input image
      input = step(hTextInserter, input, Offset);

      % Display video
      step(hVideoOut, [input Stabilized]);
  end;

QUESTIONS:

1) I wonder if someone could suggest me how to write a command line to write the stabilized video into a local folder in the computer.

2) Why the file does not run when I substitute shaky_car.avi by TEST.avi. For example,I copied TEST.avi into the same folder as shaky_car.avi and changed the first line of the script accordingly but it generate the following errors:

Error using dspmmfileinfo>getFileInfo (line 82)
Could not add the data source to the filter graph : The specified file was not found.

Error in dspmmfileinfo (line 46)
        fileInfo = getFileInfo(filename);

I thank you in advance for your attention and help

Emerson

Answer 1

[Image Analyst]

1) You can use VideoWriter to write out your video.

2) Try writing robust code like this:

folder = 'd:\my videos'; % Wherever...
baseFileName = 'shaky_car.avi';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
  % File doesn't exist -- didn't find it there.  Check the search path for it.
  fullFileName = baseFileName; % No path this time.
  if ~exist(fullFileName, 'file')
    % Still didn't find it.  Alert user.
    errorMessage = sprintf('Error: %s does not exist in the search path folders.', fullFileName);
    uiwait(warndlg(errorMessage));
    return;
  end
end

[Wenting Xie]

Hi,

I have the same problems. And I have tried to add the code you write.

However, it just inform me the 'error message' and the video is not saved at the required site.

Is there anything I can try to save the stabilized video.

Thanks a lot.