plotting the recorded sound while recording

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Huseyin 2014-11-26

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https://ww2.mathworks.cn/matlabcentral/answers/164435-plotting-the-recorded-sound-while-recording

评论： Walter Roberson 2018-6-13

采纳的回答： Geoff Hayes

Hi,

Is it possible to record speech from microphone and plot it continuously?

I tried to use "audiorecorder" but, it plots the results after recording. What I want to do is, for instance I want to record for 5 sec. While recording I want to see what is recorded in every sec. X-axis (time) should be between 0 and 5 at the end of the recording and the whole record must be shown on one plot.

Thanks...

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Geoff Hayes 2014-11-26

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https://ww2.mathworks.cn/matlabcentral/answers/164435-plotting-the-recorded-sound-while-recording#answer_160365

编辑：Geoff Hayes 2014-11-26

Huseyin - yes, you can do what you want using the audiorecorder and a timer function that could fire every one second and process/plot the data captured in that last one second. See How to record and analyze audio in real-time for an idea of how to proceed.

See also How to trigger the microphone to record via a GUI pushbutton for an example that provides information.

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Geoff Hayes 2014-11-27

在 MATLAB Online 中打开

myAudioRecording.m

Huseyin - perhaps the attached will be more useful as it doesn't rely on a GUI (since you might not have been using one). It is a simple function that you call as

myAudioRecording(Fs,durationSecs,N)

where Fs is the sample rate (Hz), durationSecs is the duration of the recording (seconds), and N is the FFT block size. So you may call the function as

myAudioRecording(5000,5,5000)

The code does the following - it creates some local variables and the recorder as

    % 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',@audioTimerCallback);

We are going to nest our callback within the main function, myAudioRecording, so that the callback has access to the above local variables. The audio recorder is created with the sample rate Fs and a timer callback is assigned to it so that it fires every one second.

We then create the figure with two subplots, and start the recording for durationSecs

    % create a figure with two subplots
    hFig   = figure;
    hAxes1 = subplot(2,1,1);
    hAxes2 = subplot(2,1,2);
    % create the graphics handles to the data that will be plotted on each
    % axes
    hPlot1 = plot(hAxes1,NaN,NaN);
    hPlot2 = plot(hAxes2,NaN,NaN);
    drawnow;
    % start the recording
    record(recorder,durationSecs);

We will be using the handles to the plot graphics objects, hPlot1 and hPlot2, to update the plot data whenever we get a new second of data (rather than repotting the data).

The callback looks like

    % define the timer callback
    function audioTimerCallback(hObject,eventdata)
        % 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);
        % compute the FFT
        Y = fft(X,N);
        % plot the data
        t = linspace(0,1-1/Fs,Fs) + atTimSecs;
        set(hPlot1,'XData',t,'YData',X);
        f = 0:Fs/N:(Fs/N)*(N-1);
        set(hPlot2,'XData',f,'YData',abs(Y));
        % increment the last sample index
        lastSampleIdx = lastSampleIdx + Fs;
        % increment the time in seconds "counter"
        atTimSecs     = atTimSecs + 1; 
    end

Every one second, it grabs all of the samples collected so far, and checks to make sure that we have a new second's worth of data. If we do, then we extract those new samples and compute the FFT, and then plots the data on the time domain data and the frequency domain data on the two subplots. On the next call to this function, the data is replaced with the next one second's worth of data. This isn't quite what you want, as you want to display all 5 seconds worth of data, so you can modify the code as you see fit.

The final line is

waitfor(hFig);

which prevents the function from exiting until the user has deleted/closed the figure that is displaying the two plots.

hoda kazemzadeh 2018-5-30

编辑：Walter Roberson 2018-5-30

在 MATLAB Online 中打开

Thank you for your answer. I am using GUIDE. My code is as following: the start button does not work, if it works I can edit the part for stop button.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function demo6_OpeningFcn(hObject, ~, handles, varargin)
handles.output = hObject;
handles.Fs=48000;
handles.recorder = audiorecorder(handles.Fs,24,1);
set(handles.recorder,'TimerPeriod',1,'TimerFcn',{@audioTimer,hObject});
guidata(hObject, handles);
function varargout = demo6_OutputFcn(hObject, ~, handles) 
varargout{1} = handles.output;
function pushbutton1_Callback(hObject, ~, handles)
record(handles.recorder)
handles.lastSampleIdx = 0;
handles.atTimSecs     = 0;
function audioTimer(hObject,varargin)
hFigure = varargin{2}; 
handles = guidata(hFigure);
samples  = getaudiodata(hObject);
X = samples(handles.lastSampleIdx+1:handles.lastSampleIdx+(handles.Fs),1);
t1 = linspace(0,1-1/handles.Fs,handles.Fs) + handles.atTimSecs;
       set(hPlot1,'XData',t1,'YData',X);
       title(hAxes1,'Audio Signal');
handles.lastSampleIdx = handles.lastSampleIdx + handles.Fs;
handles.atTimSecs = handles.atTimSecs + 1; 
% --- Executes on button press in stopbutton.
function stopbutton_Callback(hObject, eventdata, handles)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

hoda kazemzadeh 2018-6-13

在 MATLAB Online 中打开

Geoff- I have an important issue, I posted new question but I ask you again here because my code is always this one that we disscused in this post. I want to continue recording for long time (one hour for example), but the data accumulates in samples and after a while I need to remove data from memory otherwise Matlab would end because of memory problem. How is it possible to flush data of samples sometimes?

samples=getaudiodata(hObject)

Walter Roberson 2018-6-13

(Answered at https://www.mathworks.com/matlabcentral/answers/405548-how-to-remove-the-data-output-of-the-function-getaudiodata-from-the-memory-buffer-when-i-record#answer_324581)

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