-
-
Save elijahrockers/1e9f1ece4fcc546d756b to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
% Tabber | |
% Elijah Rockers - 2013 | |
% Autocorrelation | |
% E2 = 82.41Hz | |
% E6 = 1318.510Hz | |
% Variables | |
sample_rate = 48000; | |
window_size = 3000; | |
min_lag = 25; | |
max_lag = 800; | |
energy_threshold = 0; | |
f_tone = 170; | |
%x = wavread('G Major.wav'); | |
t=0:1/sample_rate:3; | |
tone = sin(f_tone*2*pi*t); | |
x = transpose(tone); | |
% Roughly calculates how many iterations are needed to cover all data | |
j=(size(x,1)/(max_lag)); | |
j=floor(j); | |
for i=1:j | |
% Makes sure 'x1' does not exceed valid size | |
if ((size(x,1)) < ((max_lag*i)+window_size-max_lag)) | |
break | |
else | |
x1 = x(((max_lag*i)+1-max_lag):((max_lag*i)+window_size-max_lag)); | |
% May need to 'fade window' x1 here | |
% This for-loop autocorrelates | |
for k=min_lag:max_lag | |
% Make sure 'x2' doesn't exceed valid size | |
if ((size(x,1)) < ((max_lag*i)+window_size-max_lag+k)) | |
break | |
else | |
x2 = x(((max_lag*i)+1-max_lag+k):((max_lag*i)+window_size-max_lag+k)); | |
r(i,k)=dot(x1,x2); | |
end | |
end | |
% 'n' keeps track of which sample each window started on | |
n(i) = (max_lag*i)+1-max_lag; | |
max_i(i)=0; | |
% THIS NEEDS TO FIND PERIOD... DOESN'T REALLY | |
for k=2:(size(r,2)-1) | |
if (size(r,1) < i) | |
break | |
else | |
if ((r(i,k) > r(i,k-1))&&(r(i,k) > r(i,k+1))) | |
max_i(i)=k; | |
end | |
end | |
end | |
if (r(i,min_lag) >= energy_threshold) | |
freq_i(i)=(1/(max_i(i)/sample_rate)); | |
else | |
freq_i(i)=0; | |
end | |
end | |
end | |
for i=1:size(freq_i,2) | |
if freq_i(i) > 1320 | |
freq_i(i)=0; | |
end | |
end | |
figure(1); | |
subplot(2,1,1), plot(1:size(x),x(1:size(x))); | |
xlabel('samples'); | |
ylabel('audio'); | |
subplot(2,1,2), plot(n,freq_i(1:size(freq_i,2))); | |
xlabel('samples'); | |
ylabel('frequency'); |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment