1/*
2 * Copyright (C) 2010 Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of Apple Inc. ("Apple") nor the names of
14 * its contributors may be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#ifndef Biquad_h
30#define Biquad_h
31
32#include "AudioArray.h"
33#include <complex>
34#include <sys/types.h>
35
36namespace WebCore {
37
38// A basic biquad (two-zero / two-pole digital filter)
39//
40// It can be configured to a number of common and very useful filters:
41// lowpass, highpass, shelving, parameteric, notch, allpass, ...
42
43class Biquad final {
44public:
45 Biquad();
46 ~Biquad();
47
48 void process(const float* sourceP, float* destP, size_t framesToProcess);
49
50 // frequency is 0 - 1 normalized, resonance and dbGain are in decibels.
51 // Q is a unitless quality factor.
52 void setLowpassParams(double frequency, double resonance);
53 void setHighpassParams(double frequency, double resonance);
54 void setBandpassParams(double frequency, double Q);
55 void setLowShelfParams(double frequency, double dbGain);
56 void setHighShelfParams(double frequency, double dbGain);
57 void setPeakingParams(double frequency, double Q, double dbGain);
58 void setAllpassParams(double frequency, double Q);
59 void setNotchParams(double frequency, double Q);
60
61 // Set the biquad coefficients given a single zero (other zero will be conjugate)
62 // and a single pole (other pole will be conjugate)
63 void setZeroPolePairs(std::complex<double> zero, std::complex<double> pole);
64
65 // Set the biquad coefficients given a single pole (other pole will be conjugate)
66 // (The zeroes will be the inverse of the poles)
67 void setAllpassPole(std::complex<double>);
68
69 // Resets filter state
70 void reset();
71
72 // Filter response at a set of n frequencies. The magnitude and
73 // phase response are returned in magResponse and phaseResponse.
74 // The phase response is in radians.
75 void getFrequencyResponse(int nFrequencies,
76 const float* frequency,
77 float* magResponse,
78 float* phaseResponse);
79private:
80 void setNormalizedCoefficients(double b0, double b1, double b2, double a0, double a1, double a2);
81
82 // Filter coefficients. The filter is defined as
83 //
84 // y[n] + m_a1*y[n-1] + m_a2*y[n-2] = m_b0*x[n] + m_b1*x[n-1] + m_b2*x[n-2].
85 double m_b0;
86 double m_b1;
87 double m_b2;
88 double m_a1;
89 double m_a2;
90
91#if USE(ACCELERATE)
92 void processFast(const float* sourceP, float* destP, size_t framesToProcess);
93 void processSliceFast(double* sourceP, double* destP, double* coefficientsP, size_t framesToProcess);
94
95 AudioDoubleArray m_inputBuffer;
96 AudioDoubleArray m_outputBuffer;
97
98#else
99 // Filter memory
100 double m_x1; // input delayed by 1 sample
101 double m_x2; // input delayed by 2 samples
102 double m_y1; // output delayed by 1 sample
103 double m_y2; // output delayed by 2 samples
104#endif
105};
106
107} // namespace WebCore
108
109#endif // Biquad_h
110