Audio Recording tool for MATLAB/Octave

arayuru.m

%ARAYURU(vargin)
%  This is very simple audio recording tool. You can extract short audio
%  segment by mouse clicking (right-click, then select 'save' menu).
%<OPTIONS>
%  varname       : Variable name for segments (DEFAULT: 'arayuru_segments')
%  sampling_rate : Sampling rate of audio (DEFAULT: 16000 [Hz])
%  record_len    : Length of recording window (DEFAULT: 2.0 [sec])
%  segment_len   : Length of segmentation window (DEFAULT: 0.6 [sec])
%<USAGE>
%  arayuru('varname', 'mydata');
%  arayuru('sampling_rate', 8000, 'record_len', 10.0);
%
%  Sunao Hara, Okayama University, 2020.
%  <sunao.hara@gmail.com>
%
function arayuru(varargin)
    %% Argument parsing
    arg = inputParser;
    addParameter(arg, 'varname', 'arayuru_segments');
    addParameter(arg, 'sampling_rate', 16000, @(x)isnumeric(x)&&isscalar(x));
    addParameter(arg, 'record_len', 2.0, @(x)isnumeric(x)&&isscalar(x));
    addParameter(arg, 'segment_len', 0.6, @(x)isnumeric(x)&&isscalar(x));
    parse(arg, varargin{:});
    
    %% Debug output
    disp('*** Arguments ***');
    disp(arg.Results);
 
    %% Prepare parameters
    ud.output_varname = arg.Results.varname;
    ud.sampling_rate = arg.Results.sampling_rate;
    ud.max_length = arg.Results.record_len * ud.sampling_rate;
    ud.segment_length = arg.Results.segment_len * ud.sampling_rate;

    ud.audio_obj = [];
    ud.timer_obj = [];
    ud.signals = zeros(ud.max_length, 1);
    ud.segments = {};
    ud.curX = 0;
    ud.curLine = [];

    %% Construct UI
    ud.f = figure;
    ud.ax = axes('Position', [0.1 0.2 0.8 0.7], 'Box', 'on', ...
        'Tag', 'AXES_WAVEFORM', 'XLim', [0 ud.max_length], 'YLim', [-1 1]);

    ud.waveplot = plot(ud.ax, ud.signals);
    setup_waveform_figure(ud.ax, ud.max_length);
    
    c = uicontextmenu;
    uimenu(c, 'Label', 'save', 'Callback', @save_segment);
    set(gca, 'UIContextMenu', c);

    ud.btn_start = uicontrol('Style', 'pushbutton', 'Tag', 'BTN_START', ...
        'String', 'START',...
        'Position', [20 20 100 40], ...
        'Callback', @click_button_start);  
    ud.btn_stop = uicontrol('Style', 'pushbutton', 'Tag', 'BTN_STOP', ...
        'String', 'STOP',...
        'Position', [140 20 100 40], ...
        'Callback', @click_button_stop); 

    if ~isOctave()
        set(gcf, 'WindowButtonMotionFcn', @mouse_move);  % Avoid tracing mousemoves on Octave.
    else
        set(gcf, 'WindowButtonDownFcn', @mouse_move);
    end

    %% Save variables for another GUI threads
    guidata(gcf, ud);
end

function save_segment(source, event)
    ud = guidata(source);
    varname = ud.output_varname;
    ud.segments{end+1} = ud.signals(ud.curX:ud.curX+ud.segment_length-1, 1);
    guidata(source, ud);
    % Attach variables in 'global' workspaces
    assignin('base', 'TMP_segment', ud.segments);
    evalin('base', [varname ' = TMP_segment; clear TMP_segment;']);

    % Display message
    Fs = ud.sampling_rate; pt_b = ud.curX; pt_e = ud.curX+ud.segment_length-1;
    str_1 = ['save samples in "' varname '{' num2str(length(ud.segments)) '}"']
    str_2 = ['  [Time: ' num2str(double(pt_b)/Fs, '%.3f') '-' num2str(double(pt_e)/Fs, '%.3f') ' s' ];
    str_3 = [' (' num2str(pt_b) '-' num2str(pt_e) ' pt)]' ];
    disp([str_1 str_2 str_3]);
end

function mouse_move(source, event)
    % Ignore right click: ('alt' == right click)
    if strcmp('alt', get(gcf, 'SelectionType'))
      return;
    end

    ud = guidata(source);
    C = get (ud.ax, 'CurrentPoint');

    % Calculate line that position the mouse cursor as center of the lines
    x1 = int32(C(1,1)-0.5*ud.segment_length);    % cf. y = C(1,2)
    x1 = min(max(x1, 0), ud.max_length-ud.segment_length);
    x2 = x1 + ud.segment_length - 1;

    % Delete current(old) line
    if ~isempty(ud.curLine)
        delete(ud.curLine);
    end
    % Append new line
    X = [x1 x1; x2 x2]';
    Y = [-1 1; -1 1]';
    h = line(X, Y, 'LineWidth', 2);
    title(ud.ax, ['X = (', num2str(x1), ', ',num2str(x2), ')'])
    drawnow expose;

    ud.curX = x1;
    ud.curLine = h;
    guidata(source, ud);
end

function click_button_start(source, event)
    ud = guidata(source);
    Fs = ud.sampling_rate;
    nBits = 16;
    nChannels = 1;
    
    audio_obj = audiorecorder(Fs, nBits, nChannels);
    
     if ~isOctave()
         audio_obj.TimerFcn = {@callback_audiorecorded, source.Parent};
     end
    
    record(audio_obj);
    ud.audio_obj = audio_obj;

    guidata(source, ud);

     if isOctave()
        OCTAVE_audio_loop(source);
     end
end

function OCTAVE_audio_loop(source)
    ud = guidata(source);

    while isrecording(ud.audio_obj)
        callback_audiorecorded(ud.audio_obj, [], source);
        pause(0.2);
        drawnow;
    end
end

function click_button_stop(source, event)
    ud = guidata(source);
    stop(ud.audio_obj);
end

function callback_audiorecorded(src_audiorec, event, hFigure)
    % Fetch audio samples
    % If there are no samples, `getaudiodata` will raise error.
    try
        x = getaudiodata(src_audiorec);
    catch
        pause(0.01);
        return ;
    end

    % Update waveform samples
    ud = guidata(hFigure);
    if length(x) < ud.max_length
        ud.signals = x;
    else
        ud.signals = x((end-ud.max_length):end, 1);
    end
    guidata(hFigure, ud);
    
    % Update waveform plot
    set(ud.waveplot, 'YData', ud.signals);
    drawnow expose;

end

function setup_waveform_figure(hAxes, max_length)
    lower_level_indicator = 0.4;
    upper_level_indicator = 0.8;
    xlim(hAxes, [0 max_length]);
    ylim(hAxes, [-1 1]);  % The signal is normalized.
    ylabel('Signal value');
    xlabel('Time index');
    line(hAxes, [0 max_length], [lower_level_indicator lower_level_indicator], 'Color', 'blue', 'LineWidth', 1, 'LineStyle', ':');
    line(hAxes, [0 max_length], [-lower_level_indicator -lower_level_indicator], 'Color', 'blue', 'LineWidth', 1, 'LineStyle', ':');
    line(hAxes, [0 max_length], [upper_level_indicator upper_level_indicator], 'Color', 'red', 'LineWidth', 1, 'LineStyle', '--');
    line(hAxes, [0 max_length], [-upper_level_indicator -upper_level_indicator], 'Color', 'red', 'LineWidth', 1, 'LineStyle', '--');
    grid(hAxes, 'on');
end

function isOctave = isOctave()
    isOctave = exist('OCTAVE_VERSION', 'builtin') > 0;
end