clear;
clc;
%% MATLAB
%% read file
%_________________________________________
[y,fs]=audioread('UnchainMyHeart.wav');
% audioread = read wav -file
% y = contains the audio signal
% fs = 44100
% 'UnchainMyHeart' = name of the wav-file
%_________________________________________
%% PARAMETER FOR STFT
%_________________________________________
t_seg=0.03; % length of segment in ms
fftlen = 4096; %FFT-Points

% Defining size of frequency bands
f_low= 1:200;    %lower frequencies
f_medium= 201:600;  %medium frequencies
f_high= 601:1000; %higher frequencies
%__________________________________________
%% CODE

segl =floor(t_seg*fs);
windowshift=segl/2;
% defining the size of the window shift
window=hann(segl);
% apply hann function on segment length (30 ms)
window=window.';
% transpose vector
si=1;
% defining start index
ei=segl;
% defining end index

N=floor( length(y)/windowshift - 1);
% Calculates the number, how often the window has to shift
% until to length of the audio signal

f1=figure;
    % Generating new window

    f=0:1:fftlen-1;
    f=f/fftlen*fs;
    % defining frequency vector

    Ya=zeros(1,fftlen);

    ValuesOfYc = NaN(1,N);
    ValuesOfYd = NaN(1,N);
    ValuesOfYe = NaN(1,N);

    x =(1:N)*windowshift/fs;
    % defining x-axis

for m= 1:1:N

    y_a = y(si:ei);
    % a segment is taken out from audio signal length(30ms)
    y_a= y_a.*window;
    % multiplying segment with window (hanning)
    Ya=fft(y_a, fftlen);
    % Applying fft on segment
    Yb=abs(Ya(1:end/2)).^2;
    % Squaring the magnitudes from one-sided spectrum

        drawnow; % Updating the graphical values

    figure(f1);
    % Showing the power values

    %% frequency bands

    y_low = Yb(f_low);  % LOW frequency spectrum
    y_medium = Yb(f_medium); % MEDIUM frequency spectrum
    y_high = Yb(f_high); % HIGH frequency spectrum

    Yc=sum(y_low);
    Yd=sum(y_medium);
    Ye=sum(y_high);
    % Summing all the power values from one frequency spectrum together
    % so you get one power value from one spectrum
    ValuesOfYc(m) = Yc;
    ValuesOfYd(m) = Yd;
    ValuesOfYe(m) = Ye;
    %Output values are being saved here, which are generated from the for
    %loop
    % m = start variable from for loop

    subplot(2,1,1)
    p=plot(x,ValuesOfYc,'r-');%,x, ValuesOfYd,'g-', x, ValuesOfYe,'b-' );
    p(1).LineWidth =0.5;
    xlabel('time (Audio length)')
    ylabel('Power')
    grid on

    subplot(2,1,2)
    p=plot(x, ValuesOfYd,'g-', x, ValuesOfYe,'b-' );
    p(1).LineWidth =0.5;
    xlabel('time (Audio length)')
    ylabel('Power')
    grid on

    si=si+windowshift;
    % Updating start index
    ei=ei+windowshift;
    % Updating end index


end