% MP3 vs. CD-quality blind A/B comparison across different genres of music
% Follow on-screen instructions. Saves .csv file to working directory
%
% AUTHOR: Evan Ruzanski, UCSB, 2/23/2003
clear all
clc
format short g
% Build track selection matrix (5 X 6*(7)) of genre and bitrate strings as follows:
%----------------------------------------------------------------------------------------------
% Genre 1.4Mbps 192kbps 128kbps 96kbps 64kbps 32kbps
%----------------------------------------------------------------------------------------------
% Classical (Nocturne) CH0 CH1 CH2 CH3 CH4 CH5
% Classical (Capriccio) BA0 BA1 BA2 BA3 BA4 BA5
% Soft Rock BJ0 BJ1 BJ2 BJ3 BJ4 BJ5
% Hard Rock KO0 KO1 KO2 KO3 KO4 KO5
% Rap BI0 BI1 BI2 BI3 BI4 BI5
%----------------------------------------------------------------------------------------------
S=[1:7]; % Choose storage array for string lengths = file name lengths
M(1,S) = 'CH0.wav'; % <- CHANGE THESE FILE NAMES TO THE NAMES OF THE DESIRED FILES TO TEST
M(1,1*length(S)+S) = 'CH1.wav'; % KEEP FILENAME LENGTHS THE SAME AS THESE
M(1,2*length(S)+S) = 'CH2.wav';
M(1,3*length(S)+S) = 'CH3.wav';
M(1,4*length(S)+S) = 'CH4.wav';
M(1,5*length(S)+S) = 'CH5.wav';
M(2,S) = 'BA0.wav';
M(2,1*length(S)+S) = 'BA1.wav';
M(2,2*length(S)+S) = 'BA2.wav';
M(2,3*length(S)+S) = 'BA3.wav';
M(2,4*length(S)+S) = 'BA4.wav';
M(2,5*length(S)+S) = 'BA5.wav';
M(3,S) = 'BJ0.wav';
M(3,1*length(S)+S) = 'BJ1.wav';
M(3,2*length(S)+S) = 'BJ2.wav';
M(3,3*length(S)+S) = 'BJ3.wav';
M(3,4*length(S)+S) = 'BJ4.wav';
M(3,5*length(S)+S) = 'BJ5.wav';
M(4,S) = 'KO0.wav';
M(4,1*length(S)+S) = 'KO1.wav';
M(4,2*length(S)+S) = 'KO2.wav';
M(4,3*length(S)+S) = 'KO3.wav';
M(4,4*length(S)+S) = 'KO4.wav';
M(4,5*length(S)+S) = 'KO5.wav';
M(5,S) = 'BI0.wav';
M(5,1*length(S)+S) = 'BI1.wav';
M(5,2*length(S)+S) = 'BI2.wav';
M(5,3*length(S)+S) = 'BI3.wav';
M(5,4*length(S)+S) = 'BI4.wav';
M(5,5*length(S)+S) = 'BI5.wav';
% Create actual play vs. choice play(ed) matrices
Q(5,6) = 0; % "In CD vs. <this bitrate (col)>, in which position was the CD played?"
P(5,6) = 0; % "In CD vs. <this bitrate (col)>, the CD was chosen to be in this position."
%Display instructions to user
disp('Listen carefully to the following 25 pairs of music segments. After each segment is complete, you will ');
disp('be asked to press ENTER to continue. After the second selection, you will be asked to choose which segment ');
disp('played was the CD file and which was the MP3 file. Select your choice by entering a "1" or "2", with ');
disp('a "1" selection stating the first segment played was the CD track and a "2" stating the second track was the ');
disp('CD track. Assume the CD file to be of higher quality. Press ENTER after your choice. Have fun! ');
disp(' ');
disp('Press ENTER to begin');
pause
% Begin experiment
for k = 1:25
g = 1; % Create matrix test variable
while g == 1,
c = ceil(5*rand(1)); % Generate random number between 1 and 5 for row (genre) selection
d = ceil(5*rand(1))+1; % Generate random number between 2 and 6 for column (bitrate) selection
if P(c,d) == 0 % Avoid repetition
[x,fsx] = wavread(char(M(c,S))); % CD track
[y,fsy] = wavread(char(M(c,(d-1)*length(S)+S))); % MP3 track
z = rand(1)-0.5; % Generate random number for CD position
if z >= 0
Q(c,d) = 1;
wavplay(x,fsx);
disp('Press ENTER to hear the second segment')
pause
wavplay(y,fsy);
else
Q(c,d) = 2;
wavplay(y,fsy);
disp('Press ENTER to hear the second segment')
pause
wavplay(x,fsx);
end % END IF
while (P(c,d) ~= 1) & (P(c,d) ~= 2) % Ensure valid user input
P(c,d) = input('Which segment was the CD track? ');
end % END WHILE
g=0;
end % END IF
end % END WHILE
disp(' ');
disp('Press ENTER to continue')
pause
disp(' ');
end
disp('This concludes the test. Thank you.')
pause
% LOAD saved array of previous results (NB: ensure file is not currently in use)
R = csvread('results.csv');
index = 1;
for u = 1:5 % Append column array via recursion
for v = 1:6
R(index,1) = R(index,1) + abs(Q(u,v)-P(u,v));
index = index + 1;
end
end
R(31,1) = R(31,1) + 1; % Update experiment iteration numbe
% SAVE array of updated results (column array), keeps R variable active in current workspace
save('results.csv','R','-ASCII')
% Get accumulated P(E) matrix
PofE = R./R(31,1);
% OPTIONAL (comment or modify as necessary): Plot updated results
br = [192 128 96 64 32];
figure(1)
stem(br,R(2:6))
eval(['title(''Experimental Results for Classical (Nocturne) for ', num2str(R(31,1)),' runs'')'])
xlabel('kbps');ylabel('Accumulated # of incorrect selections');grid;
axis([0 200 0 R(31,1)])
figure(2)
stem(br,R(8:12))
eval(['title(''Experimental Results for Classical (Capriccio) for ', num2str(R(31,1)),' runs'')'])
xlabel('kbps');ylabel('Accumulated # of incorrect selections');grid;
axis([0 200 0 R(31,1)])
figure(3)
stem(br,R(14:18))
eval(['title(''Experimental Results for Soft Rock for ', num2str(R(31,1)),' runs'')'])
xlabel('kbps');ylabel('Accumulated # of incorrect selections');grid;
axis([0 200 0 R(31,1)])
figure(4)
stem(br,R(20:24))
eval(['title(''Experimental Results for Heavy Metal for ', num2str(R(31,1)),' runs'')'])
xlabel('kbps');ylabel('Accumulated # of incorrect selections');grid;
axis([0 200 0 R(31,1)])
figure(5)
stem(br,R(26:30))
eval(['title(''Experimental Results for Rap for ', num2str(R(31,1)),' runs'')'])
xlabel('kbps');ylabel('Accumulated # of incorrect selections');grid;
axis([0 200 0 R(31,1)])
% EOF "comparison.m"
