MATLAB Code
mlab_music.m
% HAIL PURUDE in MATLAB
% Written by: Jeffrey Kubascik
clear;
% Sampling period
delta = 1/10000;
% Duration of the notes (beats)
Wn = 4;
Hn = 2;
Qn = 1;
dQn = 1.5 * Qn;
En = 1/2;
Sn = 1/4;
% Frequency of the notes (Hz)
C4 = 264; % Base to calculate all other frequencies
B5 = C4 * 15/8 * 2;
A5 = C4 * 5/3 * 2;
G5 = C4 * 3/2 * 2;
F5 = C4 * 4/3 * 2;
E5 = C4 * 5/4 * 2;
D5 = C4 * 9/8 * 2;
C5 = C4 * 2;
B4 = C4 * 15/8;
A4 = C4 * 5/3;
G4 = C4 * 3/2;
F4 = C4 * 4/3;
E4 = C4 * 5/4;
D4 = C4 * 9/8;
C4 = C4;
R = 0; % A rest (frequency=0 => sin(0)=0 => no sound, since it is constant)
% Song data
hail_purdue = [Hn,E4, Qn,F4, Qn,G4, dQn,A4, En,B4, Qn,C5, Qn,C5, ...
Qn,D5, En,D5, En,D5, Qn,A4, En,B4, En,B4, Hn,C5, Qn,C5, Qn,R, ...
Hn,C5, Qn,C5, Qn,B4, dQn,A4, En,B4, Qn,C5, Qn,C5, Qn,B4, En,F4, En,G4, ...
Qn,A4, En,G4, En,E4, Hn,B4, Qn,B4, Qn,R, dQn,E4, En,E4, ...
Qn,F4, Qn,G4, dQn,A4, En,B4, Qn,C5, En,C5, En,C5, Qn,D5, Qn,D5, Qn,A4, Qn,B4, ...
Hn,C5, Qn,C5, Qn,R, dQn,F4, En,G4, Qn,A4, Qn,F4, Qn,E4, Qn,A4, ...
Qn,C5, Qn,E4, dQn,F4, En,C5, dQn,B4, En,A4, Hn,A4, Qn,A4, Qn,R];
% Generate the music waveform
y = generate_waveform(hail_purdue, 160, delta, 1);
% Create a wav file from the music waveform
wavwrite(y, 1/delta, 'hail_purdue.wav');
% Place the tune 2x faster (2x tempo)
y = generate_waveform(hail_purdue, 2*160, delta, 1);
% Create a wav file from the music waveform
wavwrite(y, 1/delta, 'hail_purdue_2xfast.wav');
% Scale the frequency by 2
y = generate_waveform(hail_purdue, 1*160, delta, 2);
% Create a wav file from the music waveform
wavwrite(y, 1/delta, 'hail_purdue_2xfreq.wav');
generate_waveform.m
function waveform = generate_waveform(song, tempo, delta, freq_scale)
% Generate the music waveform
y = [];
length = size(song) / 2; % Number of notes in the array
for index = 1:length(2);
duration = 60 / tempo * song(index*2 - 1); % Duration of the note
frequency = song(index*2); % Frequency of the note
% Create a time vector
t = 0:delta:duration;
% Create the sound wave form
% Here, I have modified the sin wave to decay linearly. This helps
% distinguish each note, and also prevents any "jumps" in the waveform
% i.e. the end of note ends with a non-zero value, and the next note
% starts at zero. This creats a "tick" noise.
x = sin(2*pi*frequency*t*freq_scale) .* (1 - t/duration);
% Append the note to our music waveform
y = [y x];
end
waveform = y;
