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 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
16 * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
17 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
18 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
19 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
20 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
22 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 */
24
25#include "config.h"
26
27#if ENABLE(WEB_AUDIO)
28
29#include "BiquadDSPKernel.h"
30
31#include "BiquadProcessor.h"
32#include "FloatConversion.h"
33#include <limits.h>
34#include <wtf/Vector.h>
35
36namespace WebCore {
37
38// FIXME: As a recursive linear filter, depending on its parameters, a biquad filter can have
39// an infinite tailTime. In practice, Biquad filters do not usually (except for very high resonance values)
40// have a tailTime of longer than approx. 200ms. This value could possibly be calculated based on the
41// settings of the Biquad.
42static const double MaxBiquadDelayTime = 0.2;
43
44void BiquadDSPKernel::updateCoefficientsIfNecessary(bool useSmoothing, bool forceUpdate)
45{
46 if (forceUpdate || biquadProcessor()->filterCoefficientsDirty()) {
47 double value1;
48 double value2;
49 double gain;
50 double detune; // in Cents
51
52 if (biquadProcessor()->hasSampleAccurateValues()) {
53 value1 = biquadProcessor()->parameter1()->finalValue();
54 value2 = biquadProcessor()->parameter2()->finalValue();
55 gain = biquadProcessor()->parameter3()->finalValue();
56 detune = biquadProcessor()->parameter4()->finalValue();
57 } else if (useSmoothing) {
58 value1 = biquadProcessor()->parameter1()->smoothedValue();
59 value2 = biquadProcessor()->parameter2()->smoothedValue();
60 gain = biquadProcessor()->parameter3()->smoothedValue();
61 detune = biquadProcessor()->parameter4()->smoothedValue();
62 } else {
63 value1 = biquadProcessor()->parameter1()->value();
64 value2 = biquadProcessor()->parameter2()->value();
65 gain = biquadProcessor()->parameter3()->value();
66 detune = biquadProcessor()->parameter4()->value();
67 }
68
69 // Convert from Hertz to normalized frequency 0 -> 1.
70 double nyquist = this->nyquist();
71 double normalizedFrequency = value1 / nyquist;
72
73 // Offset frequency by detune.
74 if (detune)
75 normalizedFrequency *= pow(2, detune / 1200);
76
77 // Configure the biquad with the new filter parameters for the appropriate type of filter.
78 switch (biquadProcessor()->type()) {
79 case BiquadFilterType::Lowpass:
80 m_biquad.setLowpassParams(normalizedFrequency, value2);
81 break;
82
83 case BiquadFilterType::Highpass:
84 m_biquad.setHighpassParams(normalizedFrequency, value2);
85 break;
86
87 case BiquadFilterType::Bandpass:
88 m_biquad.setBandpassParams(normalizedFrequency, value2);
89 break;
90
91 case BiquadFilterType::Lowshelf:
92 m_biquad.setLowShelfParams(normalizedFrequency, gain);
93 break;
94
95 case BiquadFilterType::Highshelf:
96 m_biquad.setHighShelfParams(normalizedFrequency, gain);
97 break;
98
99 case BiquadFilterType::Peaking:
100 m_biquad.setPeakingParams(normalizedFrequency, value2, gain);
101 break;
102
103 case BiquadFilterType::Notch:
104 m_biquad.setNotchParams(normalizedFrequency, value2);
105 break;
106
107 case BiquadFilterType::Allpass:
108 m_biquad.setAllpassParams(normalizedFrequency, value2);
109 break;
110 }
111 }
112}
113
114void BiquadDSPKernel::process(const float* source, float* destination, size_t framesToProcess)
115{
116 ASSERT(source && destination && biquadProcessor());
117
118 // Recompute filter coefficients if any of the parameters have changed.
119 // FIXME: as an optimization, implement a way that a Biquad object can simply copy its internal filter coefficients from another Biquad object.
120 // Then re-factor this code to only run for the first BiquadDSPKernel of each BiquadProcessor.
121
122 updateCoefficientsIfNecessary(true, false);
123
124 m_biquad.process(source, destination, framesToProcess);
125}
126
127void BiquadDSPKernel::getFrequencyResponse(int nFrequencies,
128 const float* frequencyHz,
129 float* magResponse,
130 float* phaseResponse)
131{
132 bool isGood = nFrequencies > 0 && frequencyHz && magResponse && phaseResponse;
133 ASSERT(isGood);
134 if (!isGood)
135 return;
136
137 Vector<float> frequency(nFrequencies);
138
139 double nyquist = this->nyquist();
140
141 // Convert from frequency in Hz to normalized frequency (0 -> 1),
142 // with 1 equal to the Nyquist frequency.
143 for (int k = 0; k < nFrequencies; ++k)
144 frequency[k] = narrowPrecisionToFloat(frequencyHz[k] / nyquist);
145
146 // We want to get the final values of the coefficients and compute
147 // the response from that instead of some intermediate smoothed
148 // set. Forcefully update the coefficients even if they are not
149 // dirty.
150
151 updateCoefficientsIfNecessary(false, true);
152
153 m_biquad.getFrequencyResponse(nFrequencies, frequency.data(), magResponse, phaseResponse);
154}
155
156double BiquadDSPKernel::tailTime() const
157{
158 return MaxBiquadDelayTime;
159}
160
161double BiquadDSPKernel::latencyTime() const
162{
163 return 0;
164}
165
166} // namespace WebCore
167
168#endif // ENABLE(WEB_AUDIO)
169