I don't know why I can't run this LSB Stego code..

Hello,

I'm new to Matlab and while trying to execute this code it gives an error like

''function varargout = audiostegano(varargin)
 |
Error: Function definitions are not permitted in this context.''

I dont know why it is happening. Can anybody please tell me what is wrong with this code?

    function varargout = audiostegano(varargin)

%file with easy implimentation of steganography.
% AUDIOSTEGANO M-file for audiostegano.fig
%      AUDIOSTEGANO, by itself, creates a new AUDIOSTEGANO or raises the existing
%      singleton*.
%
%      H = AUDIOSTEGANO returns the handle to a new AUDIOSTEGANO or the handle to
%      the existing singleton*.
%
%      AUDIOSTEGANO('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in AUDIOSTEGANO.M with the given input arguments.
%
%      AUDIOSTEGANO('Property','Value',...) creates a new AUDIOSTEGANO or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before audiostegano_OpeningFunction gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to audiostegano_OpeningFcn via varargin.
%
%      *See GUI Options on GUIDE's Tools menu.  Choose "GUI allows only one
%      instance to run (singleton)".
%
% See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text to modify the response to help audiostegano

% Last Modified by GUIDE v2.5 29-Aug-2009 20:51:38

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @audiostegano_OpeningFcn, ...
                   'gui_OutputFcn',  @audiostegano_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
if nargin && ischar(varargin{1})
    gui_State.gui_Callback = str2func(varargin{1});
end

if nargout
    [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
    gui_mainfcn(gui_State, varargin{:});
end
% End initialization code - DO NOT EDIT

% --- Executes just before audiostegano is made visible.
function audiostegano_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% varargin   command line arguments to audiostegano (see VARARGIN)

% Choose default command line output for audiostegano
handles.output = hObject;
handles.fname='';
handles.pname='';
set(handles.pushbutton2,'enable','off');
set(handles.text2,'string','Select a wav file in which you want to hide text');
% Update handles structure
guidata(hObject, handles);

% UIWAIT makes audiostegano wait for user response (see UIRESUME)
% uiwait(handles.figure1);

% --- Outputs from this function are returned to the command line.
function varargout = audiostegano_OutputFcn(hObject, eventdata, handles) 
% varargout  cell array for returning output args (see VARARGOUT);
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure
varargout{1} = handles.output;

function edit1_Callback(hObject, eventdata, handles)
% hObject    handle to edit1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of edit1 as text
%        str2double(get(hObject,'String')) returns contents of edit1 as a double

% --- Executes during object creation, after setting all properties.
function edit1_CreateFcn(hObject, eventdata, handles)
% hObject    handle to edit1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
value1=get(handles.radiobutton1,'value');
value2=get(handles.radiobutton2,'value');
if value1==1

      [handles.fname, handles.pname] = uigetfile('*.wav','Select a file');        
      set(handles.pushbutton2,'enable','on'); 
      guidata(hObject, handles); %update handle structure

end
if value2==1
     set(handles.pushbutton2,'enable','off'); 
     [filename, pathname] = uigetfile('*.wav','Select a file');        
     [y,fs,nbits,opts]=wavread([pathname filename],[1 2]);
     %open the file with hidden text
     fid1=fopen([pathname filename],'r'); 
     header=fread(fid1,40,'uint8=>char');
     data_size=fread(fid1,1,'uint32');
     %read the wave data samples
     [dta,count]=fread(fid1,inf,'uint16');
     %close the file,only wav data samples are sufficient for extracting the text
     fclose(fid1);

       lsb=1;

       identity=bitget(dta(1:8),lsb)';
       if identity==[1 0 1 0 1 0 1 0]
         %extract the length of text from first 9th to 28th wav data samples 
         len_bin=zeros(20,1);
         m_bin=zeros(10,1);
         n_bin=zeros(10,1);

         m_bin(1:10)=bitget(dta(9:18),lsb);
         n_bin(1:10)=bitget(dta(19:28),lsb);
         %convert the length to decimal
         %len=bi2de((len_bin)');
         m=bi2de(m_bin');
         n=bi2de(n_bin');
         len=m*n*8;

         secmsg_bin=zeros(len,1);
         %extract the lsb from wave data sample
         secmsg_bin(1:len)=bitget(dta(29:28+len),lsb);
         secmsg_bin_re=reshape(secmsg_bin,len/8,8);

         secmsg_double=bi2de(secmsg_bin_re); %convert it to decimal

         secmsg=char(reshape(secmsg_double,m,n));  %convert to char(ASCII)
         %size(secmsg)
         %secmsg=reshape(secmsg,m,n/8);
         set(handles.edit1,'string',secmsg);

       else
       msgbox('File has no hidden text','Empty');
       end
  end
  % --- Executes on button press in pushbutton2.
  function pushbutton2_Callback(hObject, eventdata, handles)
  % hObject    handle to pushbutton2 (see GCBO)
  % eventdata  reserved - to be defined in a future version of MATLAB
  % handles    structure with handles and user data (see GUIDATA)
  msg=get(handles.edit1,'string');

if length(msg)==0
     msgbox('Please type some text','Empty');
else
    [y,fs,nbits,opts]=wavread([handles.pname handles.fname],[1 2]);
    %open a wav file for hidding text
    fid1=fopen([handles.pname handles.fname],'r');

      %first 40 bytes make wav header,store the header
      header=fread(fid1,40,'uint8=>char'); 

      %41st byte to 43rd byte,length of wav data samples 
      data_size=fread(fid1,1,'uint32');

      %copy the 16 bit wav data samples starting from 44th byte
      [dta,count]=fread(fid1,inf,'uint16');   

      %close the file, only wav data samples are sufficient to hide the text 
      fclose(fid1);

      lsb=1;

      msg=get(handles.edit1,'string');    %get text message from editbox
      [ro,co]=size(msg);
      if ( (ro*co*8+28) > count )
        msgbox('Message too big, select small message','Empty');
      else
          [m_msg,n_msg]=size(msg);
          msg_double=double(msg);             %convert it to double

          msg_bin=de2bi(msg_double,8);        %then convert message to binary
          [m,n]=size(msg_bin);                %size of message binary
          msg_bin_re=reshape(msg_bin,m*n,1);  %reshape the message binary in a column vector   
          m_bin=de2bi(m_msg,10)';          %
          n_bin=de2bi(n_msg,10)';          %
          len=length(msg_bin_re);       %length of message binary 

          len_bin=de2bi(len,20)';       %convert the length to binary

          %hide identity in first 8 wav data samples.
          identity=[1 0 1 0 1 0 1 0]';
          dta(1:8)=bitset(dta(1:8),lsb,identity(1:8));

          %hide binary length of message from 9th to 28 th sample 
          dta(9:18)=bitset(dta(9:18),lsb,m_bin(1:10));
          dta(19:28)=bitset(dta(19:28),lsb,n_bin(1:10));                              
          %hide the message binary starting from 29th position of wave data samples
          dta(29:28+len)=bitset(dta(29:28+len),lsb,msg_bin(1:len)');

          randname=num2str(randint(1,1,[1 2000]));

          %open a new wav file in write mode
          fid2=fopen(['new' randname '.wav'],'w');

          %copy the header of original wave file
          fwrite(fid2,header,'uint8');
          fwrite(fid2,data_size,'uint32');

          %copy the wav data samples with hidden text in new file
          fwrite(fid2,dta,'uint16');
          fclose(fid2);

          msgbox(['Your text is hidden in  new' randname '.wav file'],'');
          set(hObject,'enable','off');
      end
  end

% --- Executes on button press in radiobutton2.
function radiobutton2_Callback(hObject, eventdata, handles)
% hObject    handle to radiobutton2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% Hint: get(hObject,'Value') returns toggle state of radiobutton2
set(hObject,'value',1);
set(handles.text2,'string','Select a wav file in which text is already hidden');
set(handles.pushbutton2,'enable','off'); 

% --- Executes on button press in radiobutton1.
function radiobutton1_Callback(hObject, eventdata, handles)
% hObject    handle to radiobutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hint: get(hObject,'Value') returns toggle state of radiobutton1
set(hObject,'value',1);
set(handles.text2,'string','Select a wav file in which you want to hide text');

[Rena Berman]

(Answers Dev) Restored edit

Answer 1

[Walter Roberson]

You need to write all of that code to audiostegano.m . In that file, the only thing that may be before the "function" like is comments and empty lines: "function" must be the first executable line.

It is not permitted to have a "function" line in a script file, and it is not permitted to define a function at the MATLAB command line.

Answer 2

[Chandra shekar]

create function definition in separate file and call it in main or remove the function in this code