problem with play, not stopping @ 10 seconds

Hi, im having an issue with the play not stopping after 10 seconds.

I have created a GUI which has x2 play, pause, resume, stop. Named as A/B

here is a snippet of my code

Load A

% --- Executes on button press in load_sound.
function load_a_Callback(hObject, eventdata, handles)
global signal;
global FS;
% hObject    handle to load_sound (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
[filename, pathname] = uigetfile('*.wav','select a wave file to load');
  if filename== 0
        return;
  end

    set(handles.txt_sound_one,'String',[pathname filename]);
  % check file is selected

   [signal,FS] = wavread([pathname filename]);
   signal = 0.99*signal/max(abs(signal));
   % plot to sound_one axes
   axes(handles.sound_one);
   plot_sig(signal);

Play A

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

global signal;
global FS;
global player;

player=audioplayer(signal,FS);

play(player);
pause(10);

Load B

% --- Executes on button press in load_b.
function load_b_Callback(hObject, eventdata, handles)
global signal1
global FS1;
% hObject    handle to load_b (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

[filename, pathname] = uigetfile('*.wav','select a wave file to load');
  if filename== 0
        return;
  end 

    set(handles.txt_sound_two,'String',[pathname filename]);    
  % check file is selected

   [file,FS1] = wavread([pathname filename]);
   signal1 = 0.99*file/max(abs(file));
   % plot to sound_one axes
   axes(handles.sound_two);
   plot_sig(signal1);

play B

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

global signal1;
global FS1;
global player;

player=audioplayer(signal1,FS1);

play(player);
pause(10);

Answer 1

[Geoff Hayes]

James - the reason that the audio isn't stopping after ten seconds is because your player has been declared as a global variable. So even though the function exits after ten seconds, the audio continues.

You could try the replacing the play and pause with playblocking which will allow you to play a certain number of samples of audio before releasing control (and allow the processing to continue). For example, you could replace

 player=audioplayer(signal,FS);
 play(player);
 pause(10);

with

 player=audioplayer(signal,FS);
 playblocking(player,[1 10*FS]);

Since there are FS samples per second, then we want to play (and block) from the first sample to 10*FS.

Of course, you may not need to declare the player as a global variable and so that would be another way to fix the problem. In fact, you don't have to use global variables at all, but make use of the handles structure which is also intended to manage user-defined data which you can use to store the signal and FS data (and signal1 and FS1) variables. In your load_a_Callback function, you could do

 function load_a_Callback(hObject, eventdata, handles)

 [filename, pathname] = uigetfile('*.wav','select a wave file to load');
 if filename== 0
     return;
 end

 set(handles.txt_sound_one,'String',[pathname filename]);

 % check file is selected
 [signal,FS] = wavread([pathname filename]);
 signal = 0.99*signal/max(abs(signal));

 % plot to sound_one axes
 axes(handles.sound_one);
 plot_sig(signal);

 % save the data to handles
 handles.signal = signal;
 handles.FS     = FS;
 guidata(hObject,handles);

The last three lines of code are important - we add the data to the two new fields within handles, and then call guidata to save the updated handles structure.

In the play_a function, we then access this data through handles as

 function play_a_Callback(hObject, eventdata, handles)

 if isfield(handles,'signal')
     player=audioplayer(handles.signal,handles.FS);
     playblocking(player,[1 10*handles.FS]);
 end

Try the above and see what happens!

[Geoff Hayes]

James' answer moved here

So I dont quite understand if im going the right direction for my other buttons(pause, resume, stop). As the complexity of the code above is a huge jump for me.

Im basically storing the data of signal and FS into a handles struct but to call do I use another isfield function?

As before I just used global variable e.g.

global player;

stop(player);

or

global player;

resume(player);

[Geoff Hayes]

James - you could store the player in the handles structure too. In the (for example) pause button callback, you could do something like

 if isfield(handles,'player')
     if strcmpi(get(handles.player,'Running'),'on')
         % player is running so pause it
         pause(handles.player);
     end
 end

[James Wayne]

I have used your code but the pause dosent work. I look at a video about handles but still unsure what your snippet of code is doing.

http://blogs.mathworks.com/videos/2008/04/17/advanced-matlab-handles-and-other-inputs-to-guide-callbacks/

this part is confusing part

if isfield(handles,'player')
     if strcmpi(get(handles.player,'Running'),'on')

[Geoff Hayes]

James - you will either have to post the code or describe what you mean by the pause doesn't work. Are you stepping through the code in the debugger and verifying that this code is not executing? Have you added the recorder to the handles structure in playa_Callback as

 function play_a_Callback(hObject, eventdata, handles)

 if isfield(handles,'signal')
     handles.player=audioplayer(handles.signal,handles.FS);
     guidata(handles,hObject);
     playblocking(handles.player,[1 10*handles.FS]);
 end

If you are going to retrieve the player from handles, then you have to set it too...

[James Wayne]

what I meant was when I click on button function pause_a_Callback it dosent pause the audio.

I have not stepped through the debugger to verify the code is executing or not, however when I click on Pause A no error shows up in the command window. Also I have not added a recorder to my handle as I dont know where to start.

[James Wayne]

just tried the debugged - I set my debugger to start @ line 105 which is

if isfield(handles,'signal')

in the compiler it displays

105 if isfield(handles,'signal')

and dosent go any further if I click step.

[Geoff Hayes]

Also I have not added a recorder to my handle as I dont know where to start.

Add the recorder to the handle at the point where you have instantiated/created the recorder which will be the point where the audio starts/plays. That would be in the play_a_Callback and the play_b_Callback.

That being said, if you only play ten seconds of audio which is play blocking, how do you expect to pause it as the audio will already be finished? Are you wanting to pause it during the ten seconds or at some other time?

[James Wayne]

Right, what I doing before I got into this was playing the music x amount of seconds using the global variable and can pause/resume where it was left off, which worked, but this in depth coding has got me scratching my head. As you said I can increase the duration e.g. 1 40*handles.FS]), but I doubt that will help. What I really want is to play/pause/resume within the x seconds.

[Geoff Hayes]

Then try replacing the

 playblocking(player,[1 10*handles.FS]);

with just

 play(player,[1 10*handles.FS]);

Since you are no longer blocking, then any other "event" such as pressing the pause button can occur and should allow the player to be paused.

The idea with the playblocking was to prevent any other action from occurring i.e. all other push button events or whatever would have had to wait until the audio had finished.

[James Wayne]

ive removed playblocking and used the play(player,[1 10*handles.FS]); however when I click play the sound dosent play, I ran it through the debugger

   if isfield(handles,'signal')
       player=audioplayer(handles.signal,handles.FS);
       play(player,[1 10*handles.FS]);
   end

at line 93 - if isfield(handles,'signal') is shown on the debugger but it skips line 94 and 95, and when the debugger hits end the music plays for 10 second but not when im actually pressing the button on the GUI.

[Geoff Hayes]

Are you sure that you have saved your changes to the GUI before putting the breakpoint and pressing run? It isn't clear to me why the debugger would skip the lines and then play the audio. Can you attach your code?

[James Wayne]

I have fixed the issue and the play,pause,resume and stop works on A/B buttons , thanks for your feedback. The only issue I have now is joining the 2 audio files together.

I created something like this:

handles.signal_mix = [handles.signal;handles.signal1]; guidata(hObject,handles);

**

in here I dont know what to type.

**

In my previous attempt i got an audio to play but it only played A.

[Geoff Hayes]

So you have joined the two audio signals together. Have you verified that they have the same sample rate? If so, then you should be able to just play this combined audio signal in a manner similar to what you have done for A or B. But if the two signals don't have the same sample rate, then you will have to resample. If you have access to the Signal Processing Toolbox, you could use its resample function.

[Image Analyst]

James's Answers moved here:

Thanks for the help, I was thinking about moving the global variables away but werent too sure which option to take. This has help me a lot, Thank you.

So I dont quite understand if im going the right direction for my other buttons(pause, resume, stop). As the complexity of the code above is a huge jump for me.

Im basically storing the data of signal and FS into a handles struct but to call do I use another isfield function?

As before I just used global variable e.g.

global player;

stop(player);

or

global player;

resume(player);

[James Wayne]

Forgot to reply back, ive fixed my issue.

[James Wayne]

I'm trying to incorporate the audio duration onto a static text box, I've tried this code but it dosent show up the duration.

   nSamples = signal();
   fileTime = nSamples / FS;

   % compute file time (minutes, seconds, dseconds):
  fileHours = floor(fileTime/3600);
  fileMinutes = floor(fileTime/60);
  fileSeconds = mod(fileTime, 60);
  fileDecSeconds = round(10*(fileSeconds - floor(fileSeconds)));
  fileSeconds = floor(fileSeconds);

   set(handles.info2, 'String', sprintf('%.2d:%.2d:%.2d.%d',fileHours,fileMinutes, fileSeconds, fileDecSeconds));

I have got the FS to show up in a static box but have no idea how to get the duration to work properly

[Geoff Hayes]

James - put a breakpoint at the line

 fileTime = nSamples / FS;

and then run your GUI and follow whatever steps are needed to get to this point where the above code will fire (not sure which callback this is from). Then when the debugger pauses at the line with the breakpoint, start stepping through the code and use the Command Window to type in these variables

 nSamples
 FS
 fileTime
 fileHours
 etc.

Do you observe values for each? When you get to the line that sets the string, paste the line

 sprintf('%.2d:%.2d:%.2d.%d',fileHours,fileMinutes, fileSeconds, fileDecSeconds)

in the Command Window. What do you see? With dummy data, I have verified that the above works and produces a string, so there must be something going wrong in the code that prevents the set from happening.

[James Wayne]

I fixed my issue with this:

End=length(signal);
 nSamples = End;
 fileTime = nSamples / FS;

   % compute file time (minutes, seconds, dseconds):
  fileMinutes = floor(fileTime/60);
  fileSeconds = mod(fileTime, 60);
  fileDecSeconds = round(10*(fileSeconds - floor(fileSeconds)));
  fileSeconds = floor(fileSeconds);

   %display file info:
    set(handles.info1, 'String', sprintf('%d Hz',FS));
    set(handles.info2, 'String', sprintf('%.2d:%.2d.%d',fileMinutes, fileSeconds, fileDecSeconds));

[Geoff Hayes]

James - what do you mean by my next issue is trying to get the audio input seconds to work? You need to describe the problem that you are facing in more detail. Have you tried stepping through the code in the debugger?