115 lines
4.0 KiB
Matlab
115 lines
4.0 KiB
Matlab
function eq = eq_norm(eq)
|
|
|
|
%%
|
|
% Copyright (c) 2016, Intel Corporation
|
|
% All rights reserved.
|
|
%
|
|
% Redistribution and use in source and binary forms, with or without
|
|
% modification, are permitted provided that the following conditions are met:
|
|
% * Redistributions of source code must retain the above copyright
|
|
% notice, this list of conditions and the following disclaimer.
|
|
% * Redistributions in binary form must reproduce the above copyright
|
|
% notice, this list of conditions and the following disclaimer in the
|
|
% documentation and/or other materials provided with the distribution.
|
|
% * Neither the name of the Intel Corporation nor the
|
|
% names of its contributors may be used to endorse or promote products
|
|
% derived from this software without specific prior written permission.
|
|
%
|
|
% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
% AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
% IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
% ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
|
% LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
% CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
% SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
% INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
% CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
% ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
% POSSIBILITY OF SUCH DAMAGE.
|
|
%
|
|
% Author: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>
|
|
%
|
|
|
|
%% Normalize loudness of EQ by computing weighted average of linear
|
|
% response. Find scale need to make the average one.
|
|
w_lin = level_norm_fweight(eq.f);
|
|
m_lin_fir = 10.^(eq.fir_eq_db/20);
|
|
m_lin_iir = 10.^(eq.iir_eq_db/20);
|
|
i1k = find(eq.f > 1e3, 1, 'first') - 1;
|
|
m_max_fir = max(eq.fir_eq_db);
|
|
m_max_iir = max(eq.iir_eq_db);
|
|
sens_fir = sum(m_lin_fir.*w_lin)/sum(w_lin);
|
|
sens_iir = sum(m_lin_iir.*w_lin)/sum(w_lin);
|
|
g_offs = 10^(eq.norm_offs_db/20);
|
|
|
|
%% Determine scaling gain
|
|
switch lower(eq.norm_type)
|
|
case 'loudness'
|
|
g_fir = 1/sens_fir;
|
|
g_iir = 1/sens_iir;
|
|
case '1k'
|
|
g_fir = 1/m_lin_fir(i1k);
|
|
g_iir = 1/m_lin_iir(i1k);
|
|
|
|
case 'peak'
|
|
g_fir = 10^(-m_max_fir/20);
|
|
g_iir = 10^(-m_max_iir/20);
|
|
otherwise
|
|
error('Requested normalization is not supported');
|
|
end
|
|
|
|
%% Adjust FIR and IIR gains if enabled
|
|
if eq.enable_fir && eq.enable_iir
|
|
eq.b_fir = eq.b_fir * g_fir * g_offs;
|
|
eq.b_p = eq.b_p * g_iir * g_offs;
|
|
end
|
|
if eq.enable_fir && eq.enable_iir == 0
|
|
eq.b_fir = eq.b_fir * g_fir * g_offs;
|
|
end
|
|
if eq.enable_fir == 0 && eq.enable_iir
|
|
eq.b_p = eq.b_p * g_iir * g_offs;
|
|
end
|
|
|
|
%% Re-compute response after adjusting gain
|
|
eq = eq_compute_tot_response(eq);
|
|
|
|
end
|
|
|
|
function m_lin = level_norm_fweight(f)
|
|
|
|
%% w_lin = level_norm_fweight(f)
|
|
%
|
|
% Provides frequency weight that is useful in normalization of
|
|
% loudness of effect like equalizers. The weight consists of pink noise
|
|
% like spectral shape that attenuates higher frequencies 3 dB per
|
|
% octave. The low frequencies are shaped by 2nd order high-pass
|
|
% response at 20 Hz and higher frequencies by 3rd order low-pass at 20
|
|
% kHz.
|
|
%
|
|
% Note: This weight may have similarity with a standard defined test signal
|
|
% characteristic for evaluating music player output levels but this is not
|
|
% an implementation of it. This weight may help in avoiding a designed EQ to
|
|
% exceed safe playback levels in othervise compliant device.
|
|
%
|
|
% Input f - frequencies vector in Hz
|
|
%
|
|
% Output w_lin - weight curve, aligned to peak of 1.0 in the requested f
|
|
%
|
|
|
|
[z_hp, p_hp] = butter(2, 22.4,'high','s');
|
|
[z_lp, p_lp] = butter(3, 22.4e3,'s');
|
|
z_bp = conv(z_hp, z_lp);
|
|
p_bp = conv(p_hp, p_lp);
|
|
h = freqs(z_bp, p_bp, f);
|
|
m0 = 20*log10(abs(h));
|
|
noct = log(max(f)/min(f))/log(2);
|
|
att = 3*noct;
|
|
nf = length(f);
|
|
w = zeros(1,nf);
|
|
w = w - linspace(0,att,nf);
|
|
m = m0 + w;
|
|
m = m-max(m);
|
|
m_lin = 10.^(m/20);
|
|
|
|
end
|