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1636
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1 function y = lin2mu (x) |
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2 |
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3 # usage: y = lin2mu (x) |
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4 # |
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5 # x is a vector of an 8- or 16-bit linearly encoded audio sample, |
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6 # This is transformed into a mu-law encoded vector. |
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7 |
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8 # Written by AW (Andreas.Weingessel@ci.tuwien.ac.at) on Oct 17, 1994 |
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9 # Copyright Department of Probability Theory and Statistics TU Wien |
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10 |
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11 if (nargin != 1) |
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12 usage ("y = lin2mu (x)"); |
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13 endif |
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14 |
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15 if (! is_vector (x)) |
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16 error ("lin2mu: x must be a vector"); |
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17 endif |
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18 |
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19 # transform 8-bit format to 16-bit |
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20 if (max (abs (x)) <= 128) |
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21 x = 256 .* x; |
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22 endif |
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23 |
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24 # determine sign of x, set sign(0) = 1. |
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25 sig = sign(x) + (x == 0); |
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26 |
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27 # take absolute value of x, but force it to be smaller than 32636; |
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28 # add bias |
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29 x = min (abs (x), 32635 * ones (size (x))) + 132; |
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30 |
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31 # find exponent and fraction of bineary representation |
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32 [f, e] = log2 (x); |
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33 |
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34 y = 64 * sig - 16 * e - fix (32 * f) + 335; |
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35 |
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36 endfunction |
