%Program 11.1 Audio codec
%input: number of quantization bits; 1 is there is windowing, 0 if there is
%no windowing
%output: vector out of output signal
%Example usage: out=simplecodec(cos((1:2^(12))*2*pi*256/2^(13)));
%               example signal is 1/2 sec. pure tone of frequency f = 256
function audioComp5(qBits,windowing)
[x,Fs] = audioread('Tristram.mp3');
len=length(x);
n=32;                                 % length of window
nw=floor(len/n);                      % number of length n windows in x
x=x(1:n*nw);                          % cut x to integer number of n windows
xshort = x(n+1: end-n);                       % cut for the original signal
xshort = 0.3*xshort/max(abs(xshort));         % normalize signal to max amplitude = 0.3
% Fs=2^(13);                          % Fs=sampling rate
b=qBits; L=0.3;                       % b = quantization bits, [-L,L] amplitude range
q=2*L/(2^b-1);                        % q used for b bits on interval [-L, L]
for i=1:n                             % form the MDCT matrix
  for j=1:2*n
    M(i,j)= cos((i-1+1/2)*(j-1+1/2+n/2)*pi/n);
  end
end
M=sqrt(2/n)*M;
N=M';                                 % inverse MDCT
%if there is windowing, then h(j) will be created, if not, h will stay as 1
h=1;
if (windowing == 1)
    for j = 1:2*n                     % creates h(j), addition for windowing function
        h(j) = sqrt(2)*sin((j-.5)*pi/(2*n));
    end
    h = h';
end

x=0.3*x/max(abs(x));                  % normalize signal to max amplitude = 0.3
out=[];
for k=1:nw-1                          % loop over length 2n windows
  x0=(x(1+(k-1)*n:2*n+(k-1)*n)').*h;
  y0=M*x0;
  y1=round(y0/q);                     % transform components quantized
% Storage/transmission of file occurs here
  y2=y1*q;                            % transform components dequantized
  w(:,k)=(N*y2).*h;                  % invert the MDCT
  if(k>1)
      w2=w(n+1:2*n,k-1);w3=w(1:n,k);
      out=[out;(w2+w3)/2];            % collect the reconstructed signal
  end                                 % (of length 2n less than length of x)
end

RMSE = sqrt(mean((xshort(:) - out(:)).^2))

%audiowrite('TristramCompressed.wav', out, Fs);

Not enough input arguments.
Error in audioComp5 (line 16)
b=qBits; L=0.3;                       % b = quantization bits, [-L,L] amplitude range

Published with MATLAB® R2017a