% Script 2 for Week 11 

audioinfo('SoundCheck.wav')

S=audioread('SoundCheck.wav');


figure(1)
plot(S)
xlabel('Sample Number');
ylabel('Amplitude');


SS=S([1:40000]);
csvwrite('SS.txt',SS);

audiowrite('SS.wav',SS,44100);


figure(2)
plot([1:length(SS)],SS)
xlabel('Sample Number');
ylabel('Amplitude');


SF=S([32769:55536]);
csvwrite('SF.txt',SF);


audiowrite('SF.wav',SF,44100);


figure(3)
plot([1:length(SF)],SF)
xlabel('Sample Number');
ylabel('Amplitude');


FSF = fft(SF);
csvwrite('FSF.txt',FSF);


IFSF=ifft(FSF);
csvwrite('invfftSF.txt',IFSF);


figure(4)
plot(FSF,'ro')
title('Fourier Coefficients in the Complex Plane');
xlabel('Real Axis');
ylabel('Imaginary Axis');


N=length(FSF);
power = abs(FSF(1:(N/2))).^2;
freq = (1:N/2)/N;


figure(5)
plot(freq,power)
xlabel('Cycles/Sample Interval')
ylabel('Power');
title('Periodogram')


figure(6)
plot(freq(1:400),power(1:400))
xlabel('Cycles/Sample Interval')
ylabel('Power');
title('Periodogram')


figure(7)
index=find(power==max(power))
period=1./freq;
Herz=44100/period(index)


plot(freq((index-50):(index+50)),power((index-50):(index+50)))
xlabel('Cycles/Sample Interval')
ylabel('Power');
title('Periodogram')
hold on;


mainFreqStr=num2str(freq(index)*44100);
plot(freq(index),power(index),'r.', 'MarkerSize',25);
text(freq(index)+0.01*freq(index),power(index),['Main Frequency = ',mainFreqStr]);
hold off;


figure(8)
plot(period((index-50):(index+50)),power((index-50):(index+50)))
ylabel('Power');
xlabel('Period (Sample Intervals/Cycle)');
hold on;


mainPeriodStr=num2str(period(index));
plot(period(index),power(index),'r.', 'MarkerSize',25);
text(period(index)+0.01*period(index),power(index),['Period = ',mainPeriodStr]);
hold off;