Spectrogram plotting (giving me errors) using GUI (guide)

Hello, i am trying to plot spectrogram of audio signal from microphone at real time, here is the code:

    function varargout = sp(varargin)
    % Last Modified by GUIDE v2.5 15-Jul-2011 12:49:33

    % Begin initialization code - DO NOT EDIT
    gui_Singleton = 1;
    gui_State = struct('gui_Name',       mfilename, ...
                       'gui_Singleton',  gui_Singleton, ...
                       'gui_OpeningFcn', @sp_OpeningFcn, ...
                       'gui_OutputFcn',  @sp_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 sp is made visible.
    function sp_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 sp (see VARARGIN)

    % Choose default command line output for sp
    handles.output = hObject;

    % Update handles structure
    guidata(hObject, handles);

    % My coded part
    daq_object = analoginput('winsound');
    chan = addchannel(daq_object,[1 2]);

    num_samples=1000;
    axes(handles.axes1);
    phandle= spectrogram(zeros(num_samples,1));

    handles.daq_object=daq_object;
    handles.phandle=phandle;
    handles.num_samples=num_samples;
    guidata(hObject,handles);

set(daq_object,'SamplesPerTrigger',inf,'SamplesAcquiredFcnCount',num_samples,...
  'SamplesAcquiredFcn',{@update_plot,handles});

     % End of my coded part (more in the start call back and      
     % update_plot function.

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

    % --- Outputs from this function are returned to the command line.
    function varargout = sp_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;

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

    % My coded part
    if(strcmp(handles.daq_object.running,'On'))
        return;
    else
        start(handles.daq_object);
    end
    % My coded end

    % My coded part 
    function update_plot(hObject, eventdata, handles)
    data=getdata(handles.daq_object,handles.num_samples);
    for i=1:length(handles.phandle)
        set(handles.phandle(i),'YData',data(:));
    end
    % My coded part

but i am getting this error: ??? Error using ==> set There is no 'YData' property in the 'root' class.

    Error in ==> sp>update_plot at 107
        set(handles.phandle(i),'YData',data(:));

    Warning: The SamplesAcquiredFcn callback is being disabled.
    To enable the callback, set the SamplesAcquiredFcn property.

basically i am trying to read input from microphone and plot it at real time. I been trying to do this for a while and kind of struggling, if you can help it would be great.

if its hard to read that: in the function sp_OpeningFcn, i added this code: (right after:guidata(hObject, handles);) daq_object = analoginput('winsound'); chan = addchannel(daq_object,[1 2]);

    num_samples=1000;
    axes(handles.axes1);
    phandle= spectrogram(zeros(num_samples,1));

    handles.daq_object=daq_object;
    handles.phandle=phandle;
    handles.num_samples=num_samples;
    guidata(hObject,handles);

    set(daq_object,'SamplesPerTrigger',inf,'SamplesAcquiredFcnCount',num_samples,...
    'SamplesAcquiredFcn',{@update_plot,handles});

and in the start call back function: if(strcmp(handles.daq_object.running,'On')) return; else start(handles.daq_object); end

and at the end update_plot function. function update_plot(hObject, eventdata, handles) data=getdata(handles.daq_object,handles.num_samples); for i=1:length(handles.phandle) set(handles.phandle(i),'YData',data(:)); end

In the GUI i have two this an axis1 and an start button called start

Answer 1

[Walter Roberson]

If you are using the signal processing spectrogram then note that when you ask to return an output argument from spectrogram(), no plot will be created and instead the fft of the data will be returned. The fft happens to include at least one 0, and attempting to access the YData property of the handle 0 fails.

The above-referenced documentation shows an example of how to return values from the spectrogram and plot them.