%Charles W. Peak
%ECE 301
%Homework 1
%Prof. Mimi Boutin
%Play the following using Matlab
%Part 1
%1.The main melody of the song "Smoke On The Water" by Deep Purple.
%You have to play the melody at its original tempo (112 beats per minute).
%2.The tune of a) played 2 times faster.
%3.Take the signal x(t) corresponding to the tune of a) and rescale it according to the transformation y(t) = x(2t).
%Part 2
%1.What is the forward repeated phrase.
%2.Write a Matlab routine to extract the subliminal message by playing the extract backwards.
%Part 1
%G Bf C G Bf Df C G Bf C Bf G
%Q Q DQ Q Q E H Q Q DQ Q Q
%Tempo 110 BPM
%f = 2 ^ (n / 12) * Fa
clc;
clear;
delta = 0.0005;
for part = 1:3 %loop to determine if the song is to be played at regular speed, twice as fast of rescaled.
if part == 2
tempo = 224; % for a song twice as fast the tempo must be doubled.
else
tempo = 112; % the normal tempo for "Smoke on the Water"
end
%calculation of note lengths in seconds
Q = 0:delta: (1 * 60/tempo);
E = 0:delta: (0.5 * 60/tempo);
H = 0:delta: (2 * 60/tempo);
DQ = 0:delta: (1.5 * 60/tempo);
%Frequencies of pitches used in Smoke On The Water
if part == 3
fa = 880; %Rescaling the pitch of A4 for part 3 to be y(t) = x(2t)
else
fa = 440; %Pitch for A440
end
%Frequencies of remaining dependent pitches. These pitches are dependent
%on the frequency of A4
fG = 2 ^ (-2/12) * fa;
fBf = 2 ^ (1/12) * fa;
fC = 2 ^ (3/12) * fa;
fDf = 2 ^ (4/12) * fa;
%Calculation of Actual note lengths based on the formula presented.
GQ = sin(2 * pi * fG * Q);
BfQ = sin(2 * pi * fBf * Q);
CH = sin(2 * pi * fC * H);
CDQ = sin(2 * pi * fC * DQ);
DfE = sin(2 * pi * fDf * E);
%To play the song
smoke_on_the_water = [GQ, BfQ, CDQ, GQ, BfQ, DfE, CH, GQ, BfQ CDQ, BfQ, GQ];
sound(smoke_on_the_water, 1/delta);
%Write the song
if part == 1
wavwrite(smoke_on_the_water,1/delta,32,'Normal_Speed')
elseif part == 2
wavwrite(smoke_on_the_water,1/delta,32,'Double_Speed')
else
wavwrite(smoke_on_the_water,1/delta,32,'Rescale')
end
end
%Part 2
clear clc
%Read the Beatles song and stores it in an array for Matlab to use
[song,Fs] = wavread('Beatles.wav');
%Flipud reverses the song and stores it again as an array
Reveresed_song = flipud(song);
%Playing of the reversed Beatles song
sound(Reveresed_song,Fs);
%When the song is played forward, it say "number nine"
%The reversed message is difficult to interpret though resembles "Turn me
%on dead man"
