%% This script is used to correct video files for lens distortion using
% camera parameters found using matlabs camera calibrator application it
% reads in the the camera parameters variable "cameraParams" from a loaded
% matlab workspace "CameraParameters.mat" then uses a loop that reads in
% the video file and corrects the frames one at a time, then saves them to
% a new video file. 


%% setup

% Pass in the camera parameters varibale from a saved work space
load CameraParameters.mat 

% opens up user interface to select video file
filename = uigetfile('', 'select video file');

% gets input file name
fileVideoUNDIST = filename; 

% prompts the user to name the new video file
NewFileName = uiputfile; 

% **********************NOTE***********************************************
% you MUST use the .mp4 extension when you enter the name of the new file
% to be saved i.e. " newfile.mp4 "
% *************************************************************************

% Video file reader variable 
videoFileReaderUNDIST = vision.VideoFileReader(fileVideoUNDIST);

% Player window
videoPlayerUNDIST = vision.VideoPlayer('Position', [100, 100, 1280, 720]);

% reads in the first frame of the video file
objectFrameUNDIST = step(videoFileReaderUNDIST);

% sets up the video file writer variable and its parameters
videoFileWriterUNDIST = vision.VideoFileWriter(NewFileName, 'FrameRate',...
videoFileReaderUNDIST.info.VideoFrameRate, 'FileFormat', 'MPEG4');

%% loop to read in video frame, pass it into the undistort function, and 
% save as a new video file

while ~isDone(videoFileReaderUNDIST)
    
    % reads in frame from video file
    framePRE_UNDIST = step(videoFileReaderUNDIST);
    
    % uses the camera paramters to undistort the image
    framePOST_UNDIST = undistortImage(framePRE_UNDIST, cameraParams); 
    
    % writes to video file
    step(videoFileWriterUNDIST, framePOST_UNDIST);
    
end

%% release video reader/player

release(videoPlayerUNDIST);
release(videoFileReaderUNDIST);
release(videoFileWriterUNDIST);


%% finish

msgbox('conversion Complete')