130 lines
4.3 KiB
Matlab
130 lines
4.3 KiB
Matlab
function [b_t, a_t] = eq_define_parametric_eq(peq, fs)
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%%
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% Copyright (c) 2016, Intel Corporation
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% All rights reserved.
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%
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% Redistribution and use in source and binary forms, with or without
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% modification, are permitted provided that the following conditions are met:
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% * Redistributions of source code must retain the above copyright
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% notice, this list of conditions and the following disclaimer.
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% * Redistributions in binary form must reproduce the above copyright
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% notice, this list of conditions and the following disclaimer in the
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% documentation and/or other materials provided with the distribution.
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% * Neither the name of the Intel Corporation nor the
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% names of its contributors may be used to endorse or promote products
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% derived from this software without specific prior written permission.
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%
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% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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% AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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% IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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% ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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% LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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% CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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% SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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% INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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% CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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% ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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% POSSIBILITY OF SUCH DAMAGE.
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%
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% Author: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>
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%
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% Parametric types
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PEQ_HP1 = 1; PEQ_HP2 = 2; PEQ_LP1 = 3; PEQ_LP2 = 4;
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PEQ_LS1 = 5; PEQ_LS2 = 6; PEQ_HS1 = 7; PEQ_HS2 = 8;
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PEQ_PN2 = 9; PEQ_LP4 = 10; PEQ_HP4 = 11;
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sp = size(peq);
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b_t = 1; a_t = 1;
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for i=1:sp(1)
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type = peq(i,1);
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f = peq(i,2);
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g = peq(i,3);
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Q = peq(i,4);
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if f < fs/2
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switch peq(i,1)
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case PEQ_HP1, [b0, a0] = butter(1, 2*f/fs, 'high');
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case PEQ_HP2, [b0, a0] = butter(2, 2*f/fs, 'high');
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case PEQ_HP4, [b0, a0] = butter(4, 2*f/fs, 'high');
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case PEQ_LP1, [b0, a0] = butter(1, 2*f/fs);
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case PEQ_LP2, [b0, a0] = butter(2, 2*f/fs);
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case PEQ_LP4, [b0, a0] = butter(4, 2*f/fs);
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case PEQ_LS1, [b0, a0] = low_shelf_1st(f, g, fs);
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case PEQ_LS2, [b0, a0] = low_shelf_2nd(f, g, fs);
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case PEQ_HS1, [b0, a0] = high_shelf_1st(f, g, fs);
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case PEQ_HS2, [b0, a0] = high_shelf_2nd(f, g, fs);
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case PEQ_PN2, [b0, a0] = peak_2nd(f, g, Q, fs);
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otherwise
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error('Unknown parametric EQ type');
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end
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b_t=conv(b_t, b0); a_t = conv(a_t, a0);
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end
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end
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end
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function [b, a] = low_shelf_1st(fhz, gdb, fs)
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zw = 2*pi*fhz;
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w = wmap(zw, fs);
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glin = 10^(gdb/20);
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bs = [1 glin*w];
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as = [1 w];
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[b, a] = my_bilinear(bs, as, fs);
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end
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function [b, a] = low_shelf_2nd(fhz, gdb, fs)
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zw = 2*pi*fhz;
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w = wmap(zw, fs);
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glin = 10^(gdb/20);
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bs = [1 w*sqrt(2*glin) glin*w^2];
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as = [1 w*sqrt(2) w^2];
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[b, a] = my_bilinear(bs, as, fs);
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end
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function [b, a] = high_shelf_1st(fhz, gdb, fs)
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zw = 2*pi*fhz;
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w = wmap(zw, fs);
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glin = 10^(gdb/20);
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bs = [glin w];
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as = [1 w];
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[b, a] = my_bilinear(bs, as, fs);
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end
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function [b, a] = high_shelf_2nd(fhz, gdb, fs)
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zw = 2*pi*fhz;
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w = wmap(zw, fs);
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glin = 10^(gdb/20);
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bs = [glin w*sqrt(2*glin) w^2];
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as = [1 w*sqrt(2) w^2];
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[b, a] = my_bilinear(bs, as, fs);
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end
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function [b, a] = peak_2nd(fhz, gdb, Q, fs)
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% Reference http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt
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A = 10^(gdb/40); % Square root of linear gain
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wc = 2*pi*fhz/fs;
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alpha = sin(wc)/(2*Q);
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b0 = 1 + alpha * A;
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b1 = -2 * cos(wc);
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b2 = 1 - alpha * A;
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a0 = 1 + alpha / A;
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a1 = -2 * cos(wc);
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a2 = 1 - alpha / A;
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b = [b0 / a0 b1 / a0 b2 / a0];
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a = [1 a1 / a0 a2 / a0];
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end
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function [b, a] = my_bilinear(sb, sa, fs)
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if exist('OCTAVE_VERSION', 'builtin')
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[b, a] = bilinear(sb, sa, 1/fs);
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else
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[b, a] = bilinear(sb, sa, fs);
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end
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end
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function sw = wmap(w, fs)
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t = 1/fs;
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sw = 2/t*tan(w*t/2);
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end
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