mirror of https://github.com/thesofproject/sof.git
115 lines
4.0 KiB
Matlab
115 lines
4.0 KiB
Matlab
function eq = eq_norm(eq)
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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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%% Normalize loudness of EQ by computing weighted average of linear
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% response. Find scale need to make the average one.
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w_lin = level_norm_fweight(eq.f);
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m_lin_fir = 10.^(eq.fir_eq_db/20);
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m_lin_iir = 10.^(eq.iir_eq_db/20);
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i1k = find(eq.f > 1e3, 1, 'first') - 1;
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m_max_fir = max(eq.fir_eq_db);
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m_max_iir = max(eq.iir_eq_db);
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sens_fir = sum(m_lin_fir.*w_lin)/sum(w_lin);
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sens_iir = sum(m_lin_iir.*w_lin)/sum(w_lin);
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g_offs = 10^(eq.norm_offs_db/20);
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%% Determine scaling gain
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switch lower(eq.norm_type)
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case 'loudness'
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g_fir = 1/sens_fir;
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g_iir = 1/sens_iir;
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case '1k'
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g_fir = 1/m_lin_fir(i1k);
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g_iir = 1/m_lin_iir(i1k);
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case 'peak'
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g_fir = 10^(-m_max_fir/20);
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g_iir = 10^(-m_max_iir/20);
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otherwise
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error('Requested normalization is not supported');
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end
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%% Adjust FIR and IIR gains if enabled
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if eq.enable_fir && eq.enable_iir
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eq.b_fir = eq.b_fir * g_fir * g_offs;
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eq.p_k = eq.p_k * g_iir * g_offs;
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end
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if eq.enable_fir && eq.enable_iir == 0
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eq.b_fir = eq.b_fir * g_fir * g_offs;
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end
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if eq.enable_fir == 0 && eq.enable_iir
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eq.p_k = eq.p_k * g_iir * g_offs;
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end
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%% Re-compute response after adjusting gain
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eq = eq_compute_tot_response(eq);
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end
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function m_lin = level_norm_fweight(f)
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%% w_lin = level_norm_fweight(f)
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%
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% Provides frequency weight that is useful in normalization of
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% loudness of effect like equalizers. The weight consists of pink noise
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% like spectral shape that attenuates higher frequencies 3 dB per
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% octave. The low frequencies are shaped by 2nd order high-pass
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% response at 20 Hz and higher frequencies by 3rd order low-pass at 20
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% kHz.
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%
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% Note: This weight may have similarity with a standard defined test signal
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% characteristic for evaluating music player output levels but this is not
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% an implementation of it. This weight may help in avoiding a designed EQ to
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% exceed safe playback levels in othervise compliant device.
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%
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% Input f - frequencies vector in Hz
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%
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% Output w_lin - weight curve, aligned to peak of 1.0 in the requested f
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%
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[z_hp, p_hp] = butter(2, 22.4,'high','s');
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[z_lp, p_lp] = butter(3, 22.4e3,'s');
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z_bp = conv(z_hp, z_lp);
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p_bp = conv(p_hp, p_lp);
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h = freqs(z_bp, p_bp, f);
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m0 = 20*log10(abs(h));
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noct = log(max(f)/min(f))/log(2);
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att = 3*noct;
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nf = length(f);
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w = zeros(1,nf);
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w = w - linspace(0,att,nf);
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m = m0 + w;
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m = m-max(m);
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m_lin = 10.^(m/20);
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end
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