% ================================
% Example Signal Analysis
% ================================
% Script: Victor M. Espinoza
% ================================




clc
close all
clear all

[y, fs] = audioread('C:\Users\Victor\Downloads\A_S1_03.wav');


len = length(y);
n = 0:(len-1);
t = n/fs;

figure(1)
%plot(t,y,'linewidth',2)

plot(t,20*log10(abs(y)+1e-6),'linewidth',2)
ylabel('dBFS')


% Análisis de frecuencia
[H, f] = pwelch(y,hann(4096),2048,4096,fs,'ms');


figure(2)
semilogx(f,10*log10(H),'linewidth',2)


[b, a] = butter(2,[80 400]/(fs/2));

y_filt = filter(b,a,y);

% Análisis de frecuencia
[H_fil, f] = pwelch(y_filt,hann(4096),2048,4096,fs,'ms');
hold on
semilogx(f,10*log10(H_fil),'linewidth',2,'color',[1 0 0])
hold off
grid


figure(1)
hold on
plot(t,20*log10(abs(y_filt)+1e-6),'linewidth',2,'color',[1 0 0])
hold off

figure(3)
plot(t,y,'linewidth',2)
hold on
plot(t,y_filt,'linewidth',2,'color',[1 0 0])
hold off

y_env = envelope(y,600,'rms');


figure
plot(t,y_env)


[y_peaks, I_peaks] = findpeaks(y_env);

hold on
plot(t(I_peaks),y_peaks,'o')
hold off