clear all; close all;

filename='portique_bas.wav';

% read the sound sample and plot the frequency diagram
info=audioinfo(filename);
[y,Fs] = audioread(filename);
if info.NumChannels==2 % stereo case
    y=y(:,1);
end

% figure : sound sample
subplot(1,2,1);
t=[0:length(y)-1]/Fs;
plot(t,y);
title('Original sound signal'); xlabel('Time (s)')

% select the region of interest
t_min=input('Beginning time ?');
hold on ; line([t_min t_min],[min(y) max(y)],'color','r')
t_max=input('Finishing time ?');
hold on ; line([t_max t_max],[min(y) max(y)],'color','r')

y(find(t>t_max))=[];y(find(t<t_min))=[];

% frequency space
[py,f]=periodogram(y,[],length(y),Fs);

% frequence range
freq_range=[0 200];
py(find(f>max(freq_range)))=[];
py(find(f<min(freq_range)))=[];
f(find(f>max(freq_range)))=[];
f(find(f<min(freq_range)))=[];

% filtering and normalizing
py=smooth(py,10,'lowess');py=py/max(py);

% figure : frequencies
subplot(1,2,2);plot(f,py);
title('Frequencies diagram'); xlabel('Frequency (Hz)'); ylim([-0.1 1])

% %find peaks
% height=0.03;
% distance=10;
% [pks,locs]=findpeaks(py,'minPeakHeight',height,'MinPeakDistance',distance);
% fprintf(['main frequencies = ',num2str(f(locs)')])
% hold on ; line([f(locs)'; f(locs)'],[-1 1],'color','r')