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-rw-r--r--cras/src/dsp/biquad.c381
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diff --git a/cras/src/dsp/biquad.c b/cras/src/dsp/biquad.c
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--- a/cras/src/dsp/biquad.c
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@@ -1,381 +0,0 @@
-/* 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.
- */
-
-/* Copyright (C) 2010 Google Inc. All rights reserved.
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE.WEBKIT file.
- */
-
-#include <math.h>
-#include "biquad.h"
-
-#ifndef max
-#define max(a, b) \
- ({ \
- __typeof__(a) _a = (a); \
- __typeof__(b) _b = (b); \
- _a > _b ? _a : _b; \
- })
-#endif
-
-#ifndef min
-#define min(a, b) \
- ({ \
- __typeof__(a) _a = (a); \
- __typeof__(b) _b = (b); \
- _a < _b ? _a : _b; \
- })
-#endif
-
-#ifndef M_PI
-#define M_PI 3.14159265358979323846
-#endif
-
-static void set_coefficient(struct biquad *bq, double b0, double b1, double b2,
- double a0, double a1, double a2)
-{
- double a0_inv = 1 / a0;
- bq->b0 = b0 * a0_inv;
- bq->b1 = b1 * a0_inv;
- bq->b2 = b2 * a0_inv;
- bq->a1 = a1 * a0_inv;
- bq->a2 = a2 * a0_inv;
-}
-
-static void biquad_lowpass(struct biquad *bq, double cutoff, double resonance)
-{
- /* Limit cutoff to 0 to 1. */
- cutoff = max(0.0, min(cutoff, 1.0));
-
- if (cutoff == 1 || cutoff == 0) {
- /* When cutoff is 1, the z-transform is 1.
- * When cutoff is zero, nothing gets through the filter, so set
- * coefficients up correctly.
- */
- set_coefficient(bq, cutoff, 0, 0, 1, 0, 0);
- return;
- }
-
- /* Compute biquad coefficients for lowpass filter */
- resonance = max(0.0, resonance); /* can't go negative */
- double g = pow(10.0, 0.05 * resonance);
- double d = sqrt((4 - sqrt(16 - 16 / (g * g))) / 2);
-
- double theta = M_PI * cutoff;
- double sn = 0.5 * d * sin(theta);
- double beta = 0.5 * (1 - sn) / (1 + sn);
- double gamma = (0.5 + beta) * cos(theta);
- double alpha = 0.25 * (0.5 + beta - gamma);
-
- double b0 = 2 * alpha;
- double b1 = 2 * 2 * alpha;
- double b2 = 2 * alpha;
- double a1 = 2 * -gamma;
- double a2 = 2 * beta;
-
- set_coefficient(bq, b0, b1, b2, 1, a1, a2);
-}
-
-static void biquad_highpass(struct biquad *bq, double cutoff, double resonance)
-{
- /* Limit cutoff to 0 to 1. */
- cutoff = max(0.0, min(cutoff, 1.0));
-
- if (cutoff == 1 || cutoff == 0) {
- /* When cutoff is one, the z-transform is 0. */
- /* When cutoff is zero, we need to be careful because the above
- * gives a quadratic divided by the same quadratic, with poles
- * and zeros on the unit circle in the same place. When cutoff
- * is zero, the z-transform is 1.
- */
- set_coefficient(bq, 1 - cutoff, 0, 0, 1, 0, 0);
- return;
- }
-
- /* Compute biquad coefficients for highpass filter */
- resonance = max(0.0, resonance); /* can't go negative */
- double g = pow(10.0, 0.05 * resonance);
- double d = sqrt((4 - sqrt(16 - 16 / (g * g))) / 2);
-
- double theta = M_PI * cutoff;
- double sn = 0.5 * d * sin(theta);
- double beta = 0.5 * (1 - sn) / (1 + sn);
- double gamma = (0.5 + beta) * cos(theta);
- double alpha = 0.25 * (0.5 + beta + gamma);
-
- double b0 = 2 * alpha;
- double b1 = 2 * -2 * alpha;
- double b2 = 2 * alpha;
- double a1 = 2 * -gamma;
- double a2 = 2 * beta;
-
- set_coefficient(bq, b0, b1, b2, 1, a1, a2);
-}
-
-static void biquad_bandpass(struct biquad *bq, double frequency, double Q)
-{
- /* No negative frequencies allowed. */
- frequency = max(0.0, frequency);
-
- /* Don't let Q go negative, which causes an unstable filter. */
- Q = max(0.0, Q);
-
- if (frequency <= 0 || frequency >= 1) {
- /* When the cutoff is zero, the z-transform approaches 0, if Q
- * > 0. When both Q and cutoff are zero, the z-transform is
- * pretty much undefined. What should we do in this case?
- * For now, just make the filter 0. When the cutoff is 1, the
- * z-transform also approaches 0.
- */
- set_coefficient(bq, 0, 0, 0, 1, 0, 0);
- return;
- }
- if (Q <= 0) {
- /* 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);
- return;
- }
-
- double w0 = M_PI * frequency;
- double alpha = sin(w0) / (2 * Q);
- double k = cos(w0);
-
- double b0 = alpha;
- double b1 = 0;
- double b2 = -alpha;
- double a0 = 1 + alpha;
- double a1 = -2 * k;
- double a2 = 1 - alpha;
-
- set_coefficient(bq, b0, b1, b2, a0, a1, a2);
-}
-
-static void biquad_lowshelf(struct biquad *bq, double frequency, double db_gain)
-{
- /* Clip frequencies to between 0 and 1, inclusive. */
- frequency = max(0.0, min(frequency, 1.0));
-
- double A = pow(10.0, db_gain / 40);
-
- if (frequency == 1) {
- /* The z-transform is a constant gain. */
- set_coefficient(bq, A * A, 0, 0, 1, 0, 0);
- return;
- }
- if (frequency <= 0) {
- /* When frequency is 0, the z-transform is 1. */
- set_coefficient(bq, 1, 0, 0, 1, 0, 0);
- return;
- }
-
- double w0 = M_PI * frequency;
- double S = 1; /* filter slope (1 is max value) */
- double alpha = 0.5 * sin(w0) * sqrt((A + 1 / A) * (1 / S - 1) + 2);
- double k = cos(w0);
- double k2 = 2 * sqrt(A) * alpha;
- double a_plus_one = A + 1;
- double a_minus_one = A - 1;
-
- double b0 = A * (a_plus_one - a_minus_one * k + k2);
- double b1 = 2 * A * (a_minus_one - a_plus_one * k);
- double b2 = A * (a_plus_one - a_minus_one * k - k2);
- double a0 = a_plus_one + a_minus_one * k + k2;
- double a1 = -2 * (a_minus_one + a_plus_one * k);
- double a2 = a_plus_one + a_minus_one * k - k2;
-
- set_coefficient(bq, b0, b1, b2, a0, a1, a2);
-}
-
-static void biquad_highshelf(struct biquad *bq, double frequency,
- double db_gain)
-{
- /* Clip frequencies to between 0 and 1, inclusive. */
- frequency = max(0.0, min(frequency, 1.0));
-
- double A = pow(10.0, db_gain / 40);
-
- if (frequency == 1) {
- /* The z-transform is 1. */
- set_coefficient(bq, 1, 0, 0, 1, 0, 0);
- return;
- }
- if (frequency <= 0) {
- /* When frequency = 0, the filter is just a gain, A^2. */
- set_coefficient(bq, A * A, 0, 0, 1, 0, 0);
- return;
- }
-
- double w0 = M_PI * frequency;
- double S = 1; /* filter slope (1 is max value) */
- double alpha = 0.5 * sin(w0) * sqrt((A + 1 / A) * (1 / S - 1) + 2);
- double k = cos(w0);
- double k2 = 2 * sqrt(A) * alpha;
- double a_plus_one = A + 1;
- double a_minus_one = A - 1;
-
- double b0 = A * (a_plus_one + a_minus_one * k + k2);
- double b1 = -2 * A * (a_minus_one + a_plus_one * k);
- double b2 = A * (a_plus_one + a_minus_one * k - k2);
- double a0 = a_plus_one - a_minus_one * k + k2;
- double a1 = 2 * (a_minus_one - a_plus_one * k);
- double a2 = a_plus_one - a_minus_one * k - k2;
-
- set_coefficient(bq, b0, b1, b2, a0, a1, a2);
-}
-
-static void biquad_peaking(struct biquad *bq, double frequency, double Q,
- double db_gain)
-{
- /* Clip frequencies to between 0 and 1, inclusive. */
- frequency = max(0.0, min(frequency, 1.0));
-
- /* Don't let Q go negative, which causes an unstable filter. */
- Q = max(0.0, Q);
-
- double A = pow(10.0, db_gain / 40);
-
- if (frequency <= 0 || frequency >= 1) {
- /* When frequency is 0 or 1, the z-transform is 1. */
- set_coefficient(bq, 1, 0, 0, 1, 0, 0);
- return;
- }
- if (Q <= 0) {
- /* 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.
- */
- set_coefficient(bq, A * A, 0, 0, 1, 0, 0);
- return;
- }
-
- double w0 = M_PI * frequency;
- double alpha = sin(w0) / (2 * Q);
- double k = cos(w0);
-
- double b0 = 1 + alpha * A;
- double b1 = -2 * k;
- double b2 = 1 - alpha * A;
- double a0 = 1 + alpha / A;
- double a1 = -2 * k;
- double a2 = 1 - alpha / A;
-
- set_coefficient(bq, b0, b1, b2, a0, a1, a2);
-}
-
-static void biquad_notch(struct biquad *bq, double frequency, double Q)
-{
- /* Clip frequencies to between 0 and 1, inclusive. */
- frequency = max(0.0, min(frequency, 1.0));
-
- /* Don't let Q go negative, which causes an unstable filter. */
- Q = max(0.0, Q);
-
- if (frequency <= 0 || frequency >= 1) {
- /* When frequency is 0 or 1, the z-transform is 1. */
- set_coefficient(bq, 1, 0, 0, 1, 0, 0);
- return;
- }
- if (Q <= 0) {
- /* 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 0, so set the filter that way.
- */
- set_coefficient(bq, 0, 0, 0, 1, 0, 0);
- return;
- }
-
- double w0 = M_PI * frequency;
- double alpha = sin(w0) / (2 * Q);
- double k = cos(w0);
-
- double b0 = 1;
- double b1 = -2 * k;
- double b2 = 1;
- double a0 = 1 + alpha;
- double a1 = -2 * k;
- double a2 = 1 - alpha;
-
- set_coefficient(bq, b0, b1, b2, a0, a1, a2);
-}
-
-static void biquad_allpass(struct biquad *bq, double frequency, double Q)
-{
- /* Clip frequencies to between 0 and 1, inclusive. */
- frequency = max(0.0, min(frequency, 1.0));
-
- /* Don't let Q go negative, which causes an unstable filter. */
- Q = max(0.0, Q);
-
- if (frequency <= 0 || frequency >= 1) {
- /* When frequency is 0 or 1, the z-transform is 1. */
- set_coefficient(bq, 1, 0, 0, 1, 0, 0);
- return;
- }
-
- if (Q <= 0) {
- /* 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);
- return;
- }
-
- double w0 = M_PI * frequency;
- 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);
-}
-
-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;
- }
-}
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