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%  
% CSC 790  Fall 2009  Pluf  
% Homework 1  Questions 6 and 7  
%  
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clear f f1 e e1 en;

f = wavread('python.wav');      % original signal  
e = linspace(0, 0, length(f));  % error  

f1 = f;                         % decoded signal  

k = 0.001;     % value per level  
nLevels = 100; % number of levels on one side of zero
for i = 2:length(f)
    % achtung! must use f1 (the encoded and decoded signal) for the difference
    diff(i) = f(i) - f1(i-1);
    e(i) = sign(diff(i))*min(floor(abs(diff(i))/k), nLevels);  
    if(e(i) == 0)
       e(i) = 1;
    end;
    e(i) = e(i)*k;
    f1(i) = f1(i-1) + e(i); 
end


plot(f, 'b');
hold
plot(f1, 'r');