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 Computer, 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 <sys/types.h>
34#include <wtf/Complex.h>
35#include <wtf/Platform.h>
36
37namespace WebCore {
38
39// A basic biquad (two-zero / two-pole digital filter)
40//
41// It can be configured to a number of common and very useful filters:
42//    lowpass, highpass, shelving, parameteric, notch, allpass, ...
43
44class Biquad {
45public:
46    Biquad();
47    virtual ~Biquad() { }
48
49    void process(const float* sourceP, float* destP, size_t framesToProcess);
50
51    // cutoff is 0-1 normalized, resonance is in dB >= 0.0
52    void setLowpassParams(double cutoff, double resonance);
53    void setHighpassParams(double cutoff, double resonance);
54
55    void setLowShelfParams(double cutoff, double dbGain);
56
57    // FIXME: need to implement a few more common filters
58    // void setHighShelfParams(double cutoff, double dbGain);
59    // void setParametricEQParams(double cutoff, double resonance);
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(const Complex& zero, const Complex& 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(const Complex& pole);
68
69    // Resets filter state
70    void reset();
71
72private:
73    // Filter coefficients
74    double m_a0;
75    double m_a1;
76    double m_a2;
77    double m_b1;
78    double m_b2;
79
80    double m_g;
81
82    // Filter memory
83    double m_x1; // input delayed by 1 sample
84    double m_x2; // input delayed by 2 samples
85    double m_y1; // output delayed by 1 sample
86    double m_y2; // output delayed by 2 samples
87
88#if OS(DARWIN)
89    void processFast(const float* sourceP, float* destP, size_t framesToProcess);
90    void processSliceFast(double* sourceP, double* destP, double* coefficientsP, size_t framesToProcess);
91
92    AudioDoubleArray m_inputBuffer;
93    AudioDoubleArray m_outputBuffer;
94#endif
95};
96
97} // namespace WebCore
98
99#endif // Biquad_h
100