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lfe-filter: Import code from the Chrome OS audio server
The chrome OS audio server has some already existing code, which has been made available under a BSD-style license, which should be safe to import by us. Signed-off-by: David Henningsson <david.henningsson@canonical.com>
This commit is contained in:
David Henningsson
parent
ff329cdabb
commit
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6 changed files with 713 additions and 0 deletions
3
LICENSE
3
LICENSE
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@ -29,6 +29,9 @@ considered too small and stable to be considered as an external library) use the
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more permissive MIT license. This include the device reservation DBus protocol
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more permissive MIT license. This include the device reservation DBus protocol
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and realtime kit implementations.
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and realtime kit implementations.
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A more permissive BSD-style license is used for LFE filters, see
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src/pulsecore/filter/LICENSE.WEBKIT for details.
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Additionally, a more permissive Sun license is used for code that performs
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Additionally, a more permissive Sun license is used for code that performs
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u-law, A-law and linear PCM conversions.
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u-law, A-law and linear PCM conversions.
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27
src/pulsecore/filter/LICENSE.WEBKIT
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27
src/pulsecore/filter/LICENSE.WEBKIT
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@ -0,0 +1,27 @@
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/*
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* Copyright (C) 2010 Google Inc. 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
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* are met:
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*
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* 1. 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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* 2. 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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* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
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* its contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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368
src/pulsecore/filter/biquad.c
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368
src/pulsecore/filter/biquad.c
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/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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/* Copyright (C) 2010 Google Inc. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE.WEBKIT file.
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*/
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#include <math.h>
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#include "biquad.h"
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#ifndef max
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#define max(a, b) ({ __typeof__(a) _a = (a); \
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__typeof__(b) _b = (b); \
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_a > _b ? _a : _b; })
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#endif
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#ifndef min
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#define min(a, b) ({ __typeof__(a) _a = (a); \
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__typeof__(b) _b = (b); \
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_a < _b ? _a : _b; })
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#endif
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#ifndef M_PI
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#define M_PI 3.14159265358979323846
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#endif
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static void set_coefficient(struct biquad *bq, double b0, double b1, double b2,
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double a0, double a1, double a2)
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{
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double a0_inv = 1 / a0;
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bq->b0 = b0 * a0_inv;
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bq->b1 = b1 * a0_inv;
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bq->b2 = b2 * a0_inv;
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bq->a1 = a1 * a0_inv;
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bq->a2 = a2 * a0_inv;
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}
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static void biquad_lowpass(struct biquad *bq, double cutoff, double resonance)
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{
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/* Limit cutoff to 0 to 1. */
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cutoff = max(0.0, min(cutoff, 1.0));
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if (cutoff == 1) {
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/* When cutoff is 1, the z-transform is 1. */
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set_coefficient(bq, 1, 0, 0, 1, 0, 0);
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} else if (cutoff > 0) {
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/* Compute biquad coefficients for lowpass filter */
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resonance = max(0.0, resonance); /* can't go negative */
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double g = pow(10.0, 0.05 * resonance);
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double d = sqrt((4 - sqrt(16 - 16 / (g * g))) / 2);
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double theta = M_PI * cutoff;
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double sn = 0.5 * d * sin(theta);
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double beta = 0.5 * (1 - sn) / (1 + sn);
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double gamma = (0.5 + beta) * cos(theta);
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double alpha = 0.25 * (0.5 + beta - gamma);
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double b0 = 2 * alpha;
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double b1 = 2 * 2 * alpha;
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double b2 = 2 * alpha;
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double a1 = 2 * -gamma;
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double a2 = 2 * beta;
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set_coefficient(bq, b0, b1, b2, 1, a1, a2);
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} else {
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/* When cutoff is zero, nothing gets through the filter, so set
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* coefficients up correctly.
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*/
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set_coefficient(bq, 0, 0, 0, 1, 0, 0);
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}
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}
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static void biquad_highpass(struct biquad *bq, double cutoff, double resonance)
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{
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/* Limit cutoff to 0 to 1. */
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cutoff = max(0.0, min(cutoff, 1.0));
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if (cutoff == 1) {
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/* The z-transform is 0. */
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set_coefficient(bq, 0, 0, 0, 1, 0, 0);
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} else if (cutoff > 0) {
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/* Compute biquad coefficients for highpass filter */
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resonance = max(0.0, resonance); /* can't go negative */
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double g = pow(10.0, 0.05 * resonance);
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double d = sqrt((4 - sqrt(16 - 16 / (g * g))) / 2);
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double theta = M_PI * cutoff;
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double sn = 0.5 * d * sin(theta);
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double beta = 0.5 * (1 - sn) / (1 + sn);
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double gamma = (0.5 + beta) * cos(theta);
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double alpha = 0.25 * (0.5 + beta + gamma);
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double b0 = 2 * alpha;
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double b1 = 2 * -2 * alpha;
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double b2 = 2 * alpha;
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double a1 = 2 * -gamma;
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double a2 = 2 * beta;
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set_coefficient(bq, b0, b1, b2, 1, a1, a2);
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} else {
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/* When cutoff is zero, we need to be careful because the above
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* gives a quadratic divided by the same quadratic, with poles
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* and zeros on the unit circle in the same place. When cutoff
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* is zero, the z-transform is 1.
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*/
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set_coefficient(bq, 1, 0, 0, 1, 0, 0);
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}
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}
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static void biquad_bandpass(struct biquad *bq, double frequency, double Q)
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{
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/* No negative frequencies allowed. */
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frequency = max(0.0, frequency);
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/* Don't let Q go negative, which causes an unstable filter. */
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Q = max(0.0, Q);
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if (frequency > 0 && frequency < 1) {
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double w0 = M_PI * frequency;
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if (Q > 0) {
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double alpha = sin(w0) / (2 * Q);
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double k = cos(w0);
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double b0 = alpha;
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double b1 = 0;
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double b2 = -alpha;
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double a0 = 1 + alpha;
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double a1 = -2 * k;
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double a2 = 1 - alpha;
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set_coefficient(bq, b0, b1, b2, a0, a1, a2);
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} else {
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/* When Q = 0, the above formulas have problems. If we
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* look at the z-transform, we can see that the limit
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* as Q->0 is 1, so set the filter that way.
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*/
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set_coefficient(bq, 1, 0, 0, 1, 0, 0);
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}
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} else {
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/* When the cutoff is zero, the z-transform approaches 0, if Q
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* > 0. When both Q and cutoff are zero, the z-transform is
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* pretty much undefined. What should we do in this case?
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* For now, just make the filter 0. When the cutoff is 1, the
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* z-transform also approaches 0.
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*/
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set_coefficient(bq, 0, 0, 0, 1, 0, 0);
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}
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}
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static void biquad_lowshelf(struct biquad *bq, double frequency, double db_gain)
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{
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/* Clip frequencies to between 0 and 1, inclusive. */
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frequency = max(0.0, min(frequency, 1.0));
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double A = pow(10.0, db_gain / 40);
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if (frequency == 1) {
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/* The z-transform is a constant gain. */
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set_coefficient(bq, A * A, 0, 0, 1, 0, 0);
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} else if (frequency > 0) {
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double w0 = M_PI * frequency;
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double S = 1; /* filter slope (1 is max value) */
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double alpha = 0.5 * sin(w0) *
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sqrt((A + 1 / A) * (1 / S - 1) + 2);
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double k = cos(w0);
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double k2 = 2 * sqrt(A) * alpha;
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double a_plus_one = A + 1;
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double a_minus_one = A - 1;
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double b0 = A * (a_plus_one - a_minus_one * k + k2);
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double b1 = 2 * A * (a_minus_one - a_plus_one * k);
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double b2 = A * (a_plus_one - a_minus_one * k - k2);
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double a0 = a_plus_one + a_minus_one * k + k2;
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double a1 = -2 * (a_minus_one + a_plus_one * k);
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double a2 = a_plus_one + a_minus_one * k - k2;
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set_coefficient(bq, b0, b1, b2, a0, a1, a2);
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} else {
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/* When frequency is 0, the z-transform is 1. */
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set_coefficient(bq, 1, 0, 0, 1, 0, 0);
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}
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}
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static void biquad_highshelf(struct biquad *bq, double frequency,
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double db_gain)
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{
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/* Clip frequencies to between 0 and 1, inclusive. */
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frequency = max(0.0, min(frequency, 1.0));
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double A = pow(10.0, db_gain / 40);
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if (frequency == 1) {
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/* The z-transform is 1. */
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set_coefficient(bq, 1, 0, 0, 1, 0, 0);
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} else if (frequency > 0) {
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double w0 = M_PI * frequency;
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double S = 1; /* filter slope (1 is max value) */
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double alpha = 0.5 * sin(w0) *
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sqrt((A + 1 / A) * (1 / S - 1) + 2);
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double k = cos(w0);
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double k2 = 2 * sqrt(A) * alpha;
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double a_plus_one = A + 1;
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double a_minus_one = A - 1;
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double b0 = A * (a_plus_one + a_minus_one * k + k2);
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double b1 = -2 * A * (a_minus_one + a_plus_one * k);
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double b2 = A * (a_plus_one + a_minus_one * k - k2);
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double a0 = a_plus_one - a_minus_one * k + k2;
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double a1 = 2 * (a_minus_one - a_plus_one * k);
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double a2 = a_plus_one - a_minus_one * k - k2;
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set_coefficient(bq, b0, b1, b2, a0, a1, a2);
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} else {
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/* When frequency = 0, the filter is just a gain, A^2. */
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set_coefficient(bq, A * A, 0, 0, 1, 0, 0);
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}
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}
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static void biquad_peaking(struct biquad *bq, double frequency, double Q,
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double db_gain)
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{
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/* Clip frequencies to between 0 and 1, inclusive. */
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frequency = max(0.0, min(frequency, 1.0));
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/* Don't let Q go negative, which causes an unstable filter. */
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Q = max(0.0, Q);
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double A = pow(10.0, db_gain / 40);
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if (frequency > 0 && frequency < 1) {
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if (Q > 0) {
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double w0 = M_PI * frequency;
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double alpha = sin(w0) / (2 * Q);
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double k = cos(w0);
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double b0 = 1 + alpha * A;
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double b1 = -2 * k;
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double b2 = 1 - alpha * A;
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double a0 = 1 + alpha / A;
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double a1 = -2 * k;
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double a2 = 1 - alpha / A;
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set_coefficient(bq, b0, b1, b2, a0, a1, a2);
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} else {
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/* When Q = 0, the above formulas have problems. If we
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* look at the z-transform, we can see that the limit
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* as Q->0 is A^2, so set the filter that way.
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*/
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set_coefficient(bq, A * A, 0, 0, 1, 0, 0);
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}
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} else {
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/* When frequency is 0 or 1, the z-transform is 1. */
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set_coefficient(bq, 1, 0, 0, 1, 0, 0);
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}
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}
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static void biquad_notch(struct biquad *bq, double frequency, double Q)
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{
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/* Clip frequencies to between 0 and 1, inclusive. */
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frequency = max(0.0, min(frequency, 1.0));
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/* Don't let Q go negative, which causes an unstable filter. */
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Q = max(0.0, Q);
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if (frequency > 0 && frequency < 1) {
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if (Q > 0) {
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double w0 = M_PI * frequency;
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double alpha = sin(w0) / (2 * Q);
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double k = cos(w0);
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double b0 = 1;
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double b1 = -2 * k;
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double b2 = 1;
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double a0 = 1 + alpha;
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double a1 = -2 * k;
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double a2 = 1 - alpha;
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set_coefficient(bq, b0, b1, b2, a0, a1, a2);
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} else {
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/* When Q = 0, the above formulas have problems. If we
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* look at the z-transform, we can see that the limit
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* as Q->0 is 0, so set the filter that way.
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*/
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set_coefficient(bq, 0, 0, 0, 1, 0, 0);
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}
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} else {
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/* When frequency is 0 or 1, the z-transform is 1. */
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set_coefficient(bq, 1, 0, 0, 1, 0, 0);
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}
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}
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static void biquad_allpass(struct biquad *bq, double frequency, double Q)
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{
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/* Clip frequencies to between 0 and 1, inclusive. */
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frequency = max(0.0, min(frequency, 1.0));
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/* Don't let Q go negative, which causes an unstable filter. */
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Q = max(0.0, Q);
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if (frequency > 0 && frequency < 1) {
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if (Q > 0) {
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double w0 = M_PI * frequency;
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|
double alpha = sin(w0) / (2 * Q);
|
||||||
|
double k = cos(w0);
|
||||||
|
|
||||||
|
double b0 = 1 - alpha;
|
||||||
|
double b1 = -2 * k;
|
||||||
|
double b2 = 1 + alpha;
|
||||||
|
double a0 = 1 + alpha;
|
||||||
|
double a1 = -2 * k;
|
||||||
|
double a2 = 1 - alpha;
|
||||||
|
|
||||||
|
set_coefficient(bq, b0, b1, b2, a0, a1, a2);
|
||||||
|
} else {
|
||||||
|
/* 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 -1, so set the filter that way.
|
||||||
|
*/
|
||||||
|
set_coefficient(bq, -1, 0, 0, 1, 0, 0);
|
||||||
|
}
|
||||||
|
} else {
|
||||||
|
/* When frequency is 0 or 1, the z-transform is 1. */
|
||||||
|
set_coefficient(bq, 1, 0, 0, 1, 0, 0);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
void biquad_set(struct biquad *bq, enum biquad_type type, double freq, double Q,
|
||||||
|
double gain)
|
||||||
|
{
|
||||||
|
/* Default is an identity filter. Also clear history values. */
|
||||||
|
set_coefficient(bq, 1, 0, 0, 1, 0, 0);
|
||||||
|
bq->x1 = 0;
|
||||||
|
bq->x2 = 0;
|
||||||
|
bq->y1 = 0;
|
||||||
|
bq->y2 = 0;
|
||||||
|
|
||||||
|
switch (type) {
|
||||||
|
case BQ_LOWPASS:
|
||||||
|
biquad_lowpass(bq, freq, Q);
|
||||||
|
break;
|
||||||
|
case BQ_HIGHPASS:
|
||||||
|
biquad_highpass(bq, freq, Q);
|
||||||
|
break;
|
||||||
|
case BQ_BANDPASS:
|
||||||
|
biquad_bandpass(bq, freq, Q);
|
||||||
|
break;
|
||||||
|
case BQ_LOWSHELF:
|
||||||
|
biquad_lowshelf(bq, freq, gain);
|
||||||
|
break;
|
||||||
|
case BQ_HIGHSHELF:
|
||||||
|
biquad_highshelf(bq, freq, gain);
|
||||||
|
break;
|
||||||
|
case BQ_PEAKING:
|
||||||
|
biquad_peaking(bq, freq, Q, gain);
|
||||||
|
break;
|
||||||
|
case BQ_NOTCH:
|
||||||
|
biquad_notch(bq, freq, Q);
|
||||||
|
break;
|
||||||
|
case BQ_ALLPASS:
|
||||||
|
biquad_allpass(bq, freq, Q);
|
||||||
|
break;
|
||||||
|
case BQ_NONE:
|
||||||
|
break;
|
||||||
|
}
|
||||||
|
}
|
||||||
57
src/pulsecore/filter/biquad.h
Normal file
57
src/pulsecore/filter/biquad.h
Normal file
|
|
@ -0,0 +1,57 @@
|
||||||
|
/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
|
||||||
|
* Use of this source code is governed by a BSD-style license that can be
|
||||||
|
* found in the LICENSE file.
|
||||||
|
*/
|
||||||
|
|
||||||
|
#ifndef BIQUAD_H_
|
||||||
|
#define BIQUAD_H_
|
||||||
|
|
||||||
|
#ifdef __cplusplus
|
||||||
|
extern "C" {
|
||||||
|
#endif
|
||||||
|
|
||||||
|
/* The biquad filter parameters. The transfer function H(z) is (b0 + b1 * z^(-1)
|
||||||
|
* + b2 * z^(-2)) / (1 + a1 * z^(-1) + a2 * z^(-2)). The previous two inputs
|
||||||
|
* are stored in x1 and x2, and the previous two outputs are stored in y1 and
|
||||||
|
* y2.
|
||||||
|
*
|
||||||
|
* We use double during the coefficients calculation for better accurary, but
|
||||||
|
* float is used during the actual filtering for faster computation.
|
||||||
|
*/
|
||||||
|
struct biquad {
|
||||||
|
float b0, b1, b2;
|
||||||
|
float a1, a2;
|
||||||
|
float x1, x2;
|
||||||
|
float y1, y2;
|
||||||
|
};
|
||||||
|
|
||||||
|
/* The type of the biquad filters */
|
||||||
|
enum biquad_type {
|
||||||
|
BQ_NONE,
|
||||||
|
BQ_LOWPASS,
|
||||||
|
BQ_HIGHPASS,
|
||||||
|
BQ_BANDPASS,
|
||||||
|
BQ_LOWSHELF,
|
||||||
|
BQ_HIGHSHELF,
|
||||||
|
BQ_PEAKING,
|
||||||
|
BQ_NOTCH,
|
||||||
|
BQ_ALLPASS
|
||||||
|
};
|
||||||
|
|
||||||
|
/* Initialize a biquad filter parameters from its type and parameters.
|
||||||
|
* Args:
|
||||||
|
* bq - The biquad filter we want to set.
|
||||||
|
* type - The type of the biquad filter.
|
||||||
|
* frequency - The value should be in the range [0, 1]. It is relative to
|
||||||
|
* half of the sampling rate.
|
||||||
|
* Q - Quality factor. See Web Audio API for details.
|
||||||
|
* gain - The value is in dB. See Web Audio API for details.
|
||||||
|
*/
|
||||||
|
void biquad_set(struct biquad *bq, enum biquad_type type, double freq, double Q,
|
||||||
|
double gain);
|
||||||
|
|
||||||
|
#ifdef __cplusplus
|
||||||
|
} /* extern "C" */
|
||||||
|
#endif
|
||||||
|
|
||||||
|
#endif /* BIQUAD_H_ */
|
||||||
188
src/pulsecore/filter/crossover.c
Normal file
188
src/pulsecore/filter/crossover.c
Normal file
|
|
@ -0,0 +1,188 @@
|
||||||
|
/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
|
||||||
|
* Use of this source code is governed by a BSD-style license that can be
|
||||||
|
* found in the LICENSE file.
|
||||||
|
*/
|
||||||
|
|
||||||
|
#include "crossover.h"
|
||||||
|
#include "biquad.h"
|
||||||
|
|
||||||
|
static void lr4_set(struct lr4 *lr4, enum biquad_type type, float freq)
|
||||||
|
{
|
||||||
|
struct biquad q;
|
||||||
|
biquad_set(&q, type, freq, 0, 0);
|
||||||
|
lr4->b0 = q.b0;
|
||||||
|
lr4->b1 = q.b1;
|
||||||
|
lr4->b2 = q.b2;
|
||||||
|
lr4->a1 = q.a1;
|
||||||
|
lr4->a2 = q.a2;
|
||||||
|
lr4->x1 = 0;
|
||||||
|
lr4->x2 = 0;
|
||||||
|
lr4->y1 = 0;
|
||||||
|
lr4->y2 = 0;
|
||||||
|
lr4->z1 = 0;
|
||||||
|
lr4->z2 = 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
/* Split input data using two LR4 filters, put the result into the input array
|
||||||
|
* and another array.
|
||||||
|
*
|
||||||
|
* data0 --+-- lp --> data0
|
||||||
|
* |
|
||||||
|
* \-- hp --> data1
|
||||||
|
*/
|
||||||
|
static void lr4_split(struct lr4 *lp, struct lr4 *hp, int count, float *data0,
|
||||||
|
float *data1)
|
||||||
|
{
|
||||||
|
float lx1 = lp->x1;
|
||||||
|
float lx2 = lp->x2;
|
||||||
|
float ly1 = lp->y1;
|
||||||
|
float ly2 = lp->y2;
|
||||||
|
float lz1 = lp->z1;
|
||||||
|
float lz2 = lp->z2;
|
||||||
|
float lb0 = lp->b0;
|
||||||
|
float lb1 = lp->b1;
|
||||||
|
float lb2 = lp->b2;
|
||||||
|
float la1 = lp->a1;
|
||||||
|
float la2 = lp->a2;
|
||||||
|
|
||||||
|
float hx1 = hp->x1;
|
||||||
|
float hx2 = hp->x2;
|
||||||
|
float hy1 = hp->y1;
|
||||||
|
float hy2 = hp->y2;
|
||||||
|
float hz1 = hp->z1;
|
||||||
|
float hz2 = hp->z2;
|
||||||
|
float hb0 = hp->b0;
|
||||||
|
float hb1 = hp->b1;
|
||||||
|
float hb2 = hp->b2;
|
||||||
|
float ha1 = hp->a1;
|
||||||
|
float ha2 = hp->a2;
|
||||||
|
|
||||||
|
int i;
|
||||||
|
for (i = 0; i < count; i++) {
|
||||||
|
float x, y, z;
|
||||||
|
x = data0[i];
|
||||||
|
y = lb0*x + lb1*lx1 + lb2*lx2 - la1*ly1 - la2*ly2;
|
||||||
|
z = lb0*y + lb1*ly1 + lb2*ly2 - la1*lz1 - la2*lz2;
|
||||||
|
lx2 = lx1;
|
||||||
|
lx1 = x;
|
||||||
|
ly2 = ly1;
|
||||||
|
ly1 = y;
|
||||||
|
lz2 = lz1;
|
||||||
|
lz1 = z;
|
||||||
|
data0[i] = z;
|
||||||
|
|
||||||
|
y = hb0*x + hb1*hx1 + hb2*hx2 - ha1*hy1 - ha2*hy2;
|
||||||
|
z = hb0*y + hb1*hy1 + hb2*hy2 - ha1*hz1 - ha2*hz2;
|
||||||
|
hx2 = hx1;
|
||||||
|
hx1 = x;
|
||||||
|
hy2 = hy1;
|
||||||
|
hy1 = y;
|
||||||
|
hz2 = hz1;
|
||||||
|
hz1 = z;
|
||||||
|
data1[i] = z;
|
||||||
|
}
|
||||||
|
|
||||||
|
lp->x1 = lx1;
|
||||||
|
lp->x2 = lx2;
|
||||||
|
lp->y1 = ly1;
|
||||||
|
lp->y2 = ly2;
|
||||||
|
lp->z1 = lz1;
|
||||||
|
lp->z2 = lz2;
|
||||||
|
|
||||||
|
hp->x1 = hx1;
|
||||||
|
hp->x2 = hx2;
|
||||||
|
hp->y1 = hy1;
|
||||||
|
hp->y2 = hy2;
|
||||||
|
hp->z1 = hz1;
|
||||||
|
hp->z2 = hz2;
|
||||||
|
}
|
||||||
|
|
||||||
|
/* Split input data using two LR4 filters and sum them back to the original
|
||||||
|
* data array.
|
||||||
|
*
|
||||||
|
* data --+-- lp --+--> data
|
||||||
|
* | |
|
||||||
|
* \-- hp --/
|
||||||
|
*/
|
||||||
|
static void lr4_merge(struct lr4 *lp, struct lr4 *hp, int count, float *data)
|
||||||
|
{
|
||||||
|
float lx1 = lp->x1;
|
||||||
|
float lx2 = lp->x2;
|
||||||
|
float ly1 = lp->y1;
|
||||||
|
float ly2 = lp->y2;
|
||||||
|
float lz1 = lp->z1;
|
||||||
|
float lz2 = lp->z2;
|
||||||
|
float lb0 = lp->b0;
|
||||||
|
float lb1 = lp->b1;
|
||||||
|
float lb2 = lp->b2;
|
||||||
|
float la1 = lp->a1;
|
||||||
|
float la2 = lp->a2;
|
||||||
|
|
||||||
|
float hx1 = hp->x1;
|
||||||
|
float hx2 = hp->x2;
|
||||||
|
float hy1 = hp->y1;
|
||||||
|
float hy2 = hp->y2;
|
||||||
|
float hz1 = hp->z1;
|
||||||
|
float hz2 = hp->z2;
|
||||||
|
float hb0 = hp->b0;
|
||||||
|
float hb1 = hp->b1;
|
||||||
|
float hb2 = hp->b2;
|
||||||
|
float ha1 = hp->a1;
|
||||||
|
float ha2 = hp->a2;
|
||||||
|
|
||||||
|
int i;
|
||||||
|
for (i = 0; i < count; i++) {
|
||||||
|
float x, y, z;
|
||||||
|
x = data[i];
|
||||||
|
y = lb0*x + lb1*lx1 + lb2*lx2 - la1*ly1 - la2*ly2;
|
||||||
|
z = lb0*y + lb1*ly1 + lb2*ly2 - la1*lz1 - la2*lz2;
|
||||||
|
lx2 = lx1;
|
||||||
|
lx1 = x;
|
||||||
|
ly2 = ly1;
|
||||||
|
ly1 = y;
|
||||||
|
lz2 = lz1;
|
||||||
|
lz1 = z;
|
||||||
|
|
||||||
|
y = hb0*x + hb1*hx1 + hb2*hx2 - ha1*hy1 - ha2*hy2;
|
||||||
|
z = hb0*y + hb1*hy1 + hb2*hy2 - ha1*hz1 - ha2*hz2;
|
||||||
|
hx2 = hx1;
|
||||||
|
hx1 = x;
|
||||||
|
hy2 = hy1;
|
||||||
|
hy1 = y;
|
||||||
|
hz2 = hz1;
|
||||||
|
hz1 = z;
|
||||||
|
data[i] = z + lz1;
|
||||||
|
}
|
||||||
|
|
||||||
|
lp->x1 = lx1;
|
||||||
|
lp->x2 = lx2;
|
||||||
|
lp->y1 = ly1;
|
||||||
|
lp->y2 = ly2;
|
||||||
|
lp->z1 = lz1;
|
||||||
|
lp->z2 = lz2;
|
||||||
|
|
||||||
|
hp->x1 = hx1;
|
||||||
|
hp->x2 = hx2;
|
||||||
|
hp->y1 = hy1;
|
||||||
|
hp->y2 = hy2;
|
||||||
|
hp->z1 = hz1;
|
||||||
|
hp->z2 = hz2;
|
||||||
|
}
|
||||||
|
|
||||||
|
void crossover_init(struct crossover *xo, float freq1, float freq2)
|
||||||
|
{
|
||||||
|
int i;
|
||||||
|
for (i = 0; i < 3; i++) {
|
||||||
|
float f = (i == 0) ? freq1 : freq2;
|
||||||
|
lr4_set(&xo->lp[i], BQ_LOWPASS, f);
|
||||||
|
lr4_set(&xo->hp[i], BQ_HIGHPASS, f);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
void crossover_process(struct crossover *xo, int count, float *data0,
|
||||||
|
float *data1, float *data2)
|
||||||
|
{
|
||||||
|
lr4_split(&xo->lp[0], &xo->hp[0], count, data0, data1);
|
||||||
|
lr4_merge(&xo->lp[1], &xo->hp[1], count, data0);
|
||||||
|
lr4_split(&xo->lp[2], &xo->hp[2], count, data1, data2);
|
||||||
|
}
|
||||||
70
src/pulsecore/filter/crossover.h
Normal file
70
src/pulsecore/filter/crossover.h
Normal file
|
|
@ -0,0 +1,70 @@
|
||||||
|
/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
|
||||||
|
* Use of this source code is governed by a BSD-style license that can be
|
||||||
|
* found in the LICENSE file.
|
||||||
|
*/
|
||||||
|
|
||||||
|
#ifndef CROSSOVER_H_
|
||||||
|
#define CROSSOVER_H_
|
||||||
|
|
||||||
|
#ifdef __cplusplus
|
||||||
|
extern "C" {
|
||||||
|
#endif
|
||||||
|
|
||||||
|
/* An LR4 filter is two biquads with the same parameters connected in series:
|
||||||
|
*
|
||||||
|
* x -- [BIQUAD] -- y -- [BIQUAD] -- z
|
||||||
|
*
|
||||||
|
* Both biquad filter has the same parameter b[012] and a[12],
|
||||||
|
* The variable [xyz][12] keep the history values.
|
||||||
|
*/
|
||||||
|
struct lr4 {
|
||||||
|
float b0, b1, b2;
|
||||||
|
float a1, a2;
|
||||||
|
float x1, x2;
|
||||||
|
float y1, y2;
|
||||||
|
float z1, z2;
|
||||||
|
};
|
||||||
|
|
||||||
|
/* Three bands crossover filter:
|
||||||
|
*
|
||||||
|
* INPUT --+-- lp0 --+-- lp1 --+---> LOW (0)
|
||||||
|
* | | |
|
||||||
|
* | \-- hp1 --/
|
||||||
|
* |
|
||||||
|
* \-- hp0 --+-- lp2 ------> MID (1)
|
||||||
|
* |
|
||||||
|
* \-- hp2 ------> HIGH (2)
|
||||||
|
*
|
||||||
|
* [f0] [f1]
|
||||||
|
*
|
||||||
|
* Each lp or hp is an LR4 filter, which consists of two second-order
|
||||||
|
* lowpass or highpass butterworth filters.
|
||||||
|
*/
|
||||||
|
struct crossover {
|
||||||
|
struct lr4 lp[3], hp[3];
|
||||||
|
};
|
||||||
|
|
||||||
|
/* Initializes a crossover filter
|
||||||
|
* Args:
|
||||||
|
* xo - The crossover filter we want to initialize.
|
||||||
|
* freq1 - The normalized frequency splits low and mid band.
|
||||||
|
* freq2 - The normalized frequency splits mid and high band.
|
||||||
|
*/
|
||||||
|
void crossover_init(struct crossover *xo, float freq1, float freq2);
|
||||||
|
|
||||||
|
/* Splits input samples to three bands.
|
||||||
|
* Args:
|
||||||
|
* xo - The crossover filter to use.
|
||||||
|
* count - The number of input samples.
|
||||||
|
* data0 - The input samples, also the place to store low band output.
|
||||||
|
* data1 - The place to store mid band output.
|
||||||
|
* data2 - The place to store high band output.
|
||||||
|
*/
|
||||||
|
void crossover_process(struct crossover *xo, int count, float *data0,
|
||||||
|
float *data1, float *data2);
|
||||||
|
|
||||||
|
#ifdef __cplusplus
|
||||||
|
} /* extern "C" */
|
||||||
|
#endif
|
||||||
|
|
||||||
|
#endif /* CROSSOVER_H_ */
|
||||||
Loading…
Add table
Add a link
Reference in a new issue