Creating a microphone GUI

Hi, I am an almost completely new matlab user, and I'm trying to create a very simple microphone GUI that has three buttons: a record button to stop recording, a stop button to stop recording, and a playback button to playback the recorded audio. I cobbled this code together from another similar question. First, I created handles for the fs and the recorder

function recorderTest_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 recorderTest (see VARARGIN)
% Choose default command line output for recorderTest
handles.output = hObject;
%setting sample rate
handles.fs=8192;
%creating the recorder
handles.recorder=audiorecorder(handles.fs,8,1);

% Update handles structure
guidata(hObject, handles);

Then, I programmed each button

% --- Outputs from this function are returned to the command line.
function varargout = recorderTest_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 record.
function record_Callback(hObject, eventdata, handles)
% hObject    handle to record (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
recorder=handles.recorder
record(recorder)
guidata(hObject,handles)
% --- Executes on button press in stop.
function stop_Callback(hObject, eventdata, handles)
% hObject    handle to stop (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
recorder=handles.recorder
stop(recorder)
guidata(hObject,handles)
% --- Executes on button press in playback.
function playback_Callback(hObject, eventdata, handles)
% hObject    handle to playback (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
recorder=handles.recorder
play(recorder)
guidata(hObject,handles)
end

When I run it, and hit record, pause, and play in that order, the audioplayer properties popup, but I don't hear anything when I press play. I would actually prefer an error because then I would know what to look for! Any help would be appreciated.

Answer 1

[Geoff Hayes]

Austin - I suspect that the audio is being played but then terminated immediately when the playback_Callback returns. You could add a pause call after you have called play so that the function does not return until the playback completes, but then you would have to determine how long to pause.

A better solution would be to use an audioplayer for the playback since it has a playblocking function to hold control until audio playback has completed. Your code would then become

 function playback_Callback(hObject, eventdata, handles)

 myAudioPlayer = audioplayer(getaudiodata(handles.recorder),handles.fs);
 playblocking(myAudioPlayer);

Try the above and see what happens! Note that there is no need call guidata in any of your pushbutton callback functions since there is no code that modifies the handles object. You only need to call

 guidata(hObject,handles)

if you update the handles structure.