Extracting samples at the same time of recording

hi i am using this code to record audio from microphone and extract audio samples at the same time but am getting following error

Warning: Error occurred while executing the listener callback for event Executing defined for class
internal.IntervalTimer:
Error using tryaudio>audioTimer (line 35)
Undefined function or variable 'lastSampleIdx'. 
> In internal.IntervalTimer/onCustomEvent (line 154)
  In internal.IntervalTimer>@(source,data)obj.onCustomEvent(data.Type,data.Data) (line 115)
  In asyncio.Channel/onCustomEvent (line 473)
  In asyncio.Channel>@(source,data)obj.onCustomEvent(data.Type,data.Data) (line 405) 

please help me in this i dont know how to solve it or where i am doing it wrong

Fs=8000;
if ~exist('durationSecs','var')
        % default to five minutes of recording
        durationSecs = 5;
    end
    
    if ~exist('N','var')
        % default to the sampling rate
        N = Fs;
    end
    % add an extra half-second so that we get the full duration in our
    % processing
    durationSecs = durationSecs + 0.5;
     % index of the last sample obtained from our recording
    lastSampleIdx = 0;
    
    % start time of the recording
    atTimSecs     = 0;
    
    % create the audio recorder
    recorder = audiorecorder(Fs,8,1);
     % assign a timer function to the recorder
    set(recorder,'TimerPeriod',1,'TimerFcn',{@audioTimer});
    % start the recording
    record(recorder,durationSecs);
    
    % define the timer callback
    function audioTimer(hObject,~)
        
        % get the sample data
        samples  = getaudiodata(hObject);
        
        % skip if not enough data
        if length(samples)<lastSampleIdx+1+Fs
            return;
        end
        
        % extract the samples that we have not performed an FFT on
        X = samples(lastSampleIdx+1:lastSampleIdx+Fs);
    end

[dpb]

The variables lastSampleIdx and Fs aren't visible to the callback function...you need to follow the example in the doc for the callback function that passes additional arguments.

[Hamza Ashraf]

oki but in that example i can not reuse the samples X in my code can you help me how can i use these X samples somewhere else in the code

% extract the samples that we have not performed an FFT on
        X = samples(lastSampleIdx+1:lastSampleIdx+Fs);

[Geoff Hayes]

Hamza - you perhaps should show all of the relevant code and/or clarify how the above is used (via GUI, command line, etc.).