test_1_lin.m

audio compression matlab code

clc; clear; clf;
% linear transforms 

%the numbar of the inputs bits...
nbits_in = 15; 
nbits_out = 7;

% define the range
x_min = - 2^nbits_in  ;
x_max = + 2^nbits_in -1;
in_range =  x_max - x_min;

step = 100;
x = x_min:step:x_max;
y_min = - 2^nbits_out  ;
y_max = + 2^nbits_out -1;
out_range =  y_max - y_min;

y = (out_range / in_range) .* x;

xb = (in_range / out_range) * y;

subplot(221), stairs(x,y); title('Compression'); 
axis([x_min x_max 5*y_min 5*y_max]);

subplot(222), stairs(y,xb); title('Expanding')
axis([5*y_min 5*y_max x_min x_max]);

subplot(223), plot(x, xb)
title('transfer characteristic');

subplot(224),  stairs(x, (xb -x) ./ x .* 100); 
axis([x_min x_max x_min x_max]);
title('Reconstruction Error [%]');