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perform_quantization.m
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perform_quantization.m
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function [y, y_quant] = perform_quantization(x, T, dir)
% perform_quantization - perform a quantization of the signal with double zero bin.
%
% If x is a double array (or a cell collection of arrays)
% to be quantized, use
% [y, y_quant] = perform_quantization(x, T, 1);
% y is the quantified value (real value)
% y_quant is the signed token representing each entry of y
% (this is an integer).
% If y_quant is an int32
% x = perform_quantization(y_quant, T, -1);
%
% The quantizer is defined by y=Q_T(x) where:
% Q_T(x) = 0 if |x|<T
% Q_T(x) = sign(x) * ([x/T]+0.5)*T where [.]=floor
% (i.e. a nearly uniform quantizer with twice larger zero bin).
%
% Copyright (c) 2004 Gabriel Peyré
if iscell(x)
if nargin<3
if isinteger(x{1})
dir = -1;
else
dir = 1;
end
end
% recurse on each entry of the cell array
y = {}; y_quant = {};
for i=1:length(x)
[y{i}, y_quant{i}] = perform_quantization(x{i}, T, dir);
end
return;
end
if nargin<3
dir = 1;
end
if dir==-1
% perform un-transformation
x = double(x);
y = sign(x) .* (abs(x)+0.5) * T;
return;
end
% perform quantization
I = find(abs(x)<T);
q = floor(abs(x)/T);
y_quant = sign(x).*q;
y = sign(x).*(q+0.5)*T;
y(I) = 0;