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EQ: Handle edge case in peaking filter 

Handle div by 0 case for gui

Signed-off-by: Curtis Malainey <cujomalainey@google.com>
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Curtis Malainey 2019-03-13 12:54:15 -07:00 committed by Liam Girdwood
parent 30bbfb49bb
commit fe2d9c197f
1 changed files with 11 additions and 0 deletions
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11
tools/tune/eq/eq_define_parametric_eq.m
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@ -126,6 +126,17 @@ function [b, a] = peak_2nd(fhz, gdb, Q, fs)
% Reference http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt
A = 10^(gdb/40); % Square root of linear gain
wc = 2*pi*fhz/fs;
if Q <= 0
% To fix gui edge cases, comment from CRAS code:
% When Q = 0, the above formulas have problems. If we
% look at the z-transform, we can see that the limit
% as Q->0 is A^2, so set the filter that way.
b = [A * A, 0, 0]
a = [1, 0, 0];
return;
endif
alpha = sin(wc)/(2*Q);
b0 = 1 + alpha * A;
b1 = -2 * cos(wc);