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 "modules/webaudio/BiquadDSPKernel.h"
30
31 #include "platform/FloatConversion.h"
32 #include <limits.h>
33 #include "wtf/Vector.h"
34
35 namespace WebCore {
36
37 // FIXME: As a recursive linear filter, depending on its parameters, a biquad filter can have
38 // an infinite tailTime. In practice, Biquad filters do not usually (except for very high resonance values)
39 // have a tailTime of longer than approx. 200ms. This value could possibly be calculated based on the
40 // settings of the Biquad.
41 static const double MaxBiquadDelayTime = 0.2;
42
updateCoefficientsIfNecessary(bool useSmoothing,bool forceUpdate)43 void BiquadDSPKernel::updateCoefficientsIfNecessary(bool useSmoothing, bool forceUpdate)
44 {
45 if (forceUpdate || biquadProcessor()->filterCoefficientsDirty()) {
46 double value1;
47 double value2;
48 double gain;
49 double detune; // in Cents
50
51 if (biquadProcessor()->hasSampleAccurateValues()) {
52 value1 = biquadProcessor()->parameter1()->finalValue();
53 value2 = biquadProcessor()->parameter2()->finalValue();
54 gain = biquadProcessor()->parameter3()->finalValue();
55 detune = biquadProcessor()->parameter4()->finalValue();
56 } else if (useSmoothing) {
57 value1 = biquadProcessor()->parameter1()->smoothedValue();
58 value2 = biquadProcessor()->parameter2()->smoothedValue();
59 gain = biquadProcessor()->parameter3()->smoothedValue();
60 detune = biquadProcessor()->parameter4()->smoothedValue();
61 } else {
62 value1 = biquadProcessor()->parameter1()->value();
63 value2 = biquadProcessor()->parameter2()->value();
64 gain = biquadProcessor()->parameter3()->value();
65 detune = biquadProcessor()->parameter4()->value();
66 }
67
68 // Convert from Hertz to normalized frequency 0 -> 1.
69 double nyquist = this->nyquist();
70 double normalizedFrequency = value1 / nyquist;
71
72 // Offset frequency by detune.
73 if (detune)
74 normalizedFrequency *= pow(2, detune / 1200);
75
76 // Configure the biquad with the new filter parameters for the appropriate type of filter.
77 switch (biquadProcessor()->type()) {
78 case BiquadProcessor::LowPass:
79 m_biquad.setLowpassParams(normalizedFrequency, value2);
80 break;
81
82 case BiquadProcessor::HighPass:
83 m_biquad.setHighpassParams(normalizedFrequency, value2);
84 break;
85
86 case BiquadProcessor::BandPass:
87 m_biquad.setBandpassParams(normalizedFrequency, value2);
88 break;
89
90 case BiquadProcessor::LowShelf:
91 m_biquad.setLowShelfParams(normalizedFrequency, gain);
92 break;
93
94 case BiquadProcessor::HighShelf:
95 m_biquad.setHighShelfParams(normalizedFrequency, gain);
96 break;
97
98 case BiquadProcessor::Peaking:
99 m_biquad.setPeakingParams(normalizedFrequency, value2, gain);
100 break;
101
102 case BiquadProcessor::Notch:
103 m_biquad.setNotchParams(normalizedFrequency, value2);
104 break;
105
106 case BiquadProcessor::Allpass:
107 m_biquad.setAllpassParams(normalizedFrequency, value2);
108 break;
109 }
110 }
111 }
112
process(const float * source,float * destination,size_t framesToProcess)113 void BiquadDSPKernel::process(const float* source, float* destination, size_t framesToProcess)
114 {
115 ASSERT(source && destination && biquadProcessor());
116
117 // Recompute filter coefficients if any of the parameters have changed.
118 // FIXME: as an optimization, implement a way that a Biquad object can simply copy its internal filter coefficients from another Biquad object.
119 // Then re-factor this code to only run for the first BiquadDSPKernel of each BiquadProcessor.
120
121 updateCoefficientsIfNecessary(true, false);
122
123 m_biquad.process(source, destination, framesToProcess);
124 }
125
getFrequencyResponse(int nFrequencies,const float * frequencyHz,float * magResponse,float * phaseResponse)126 void BiquadDSPKernel::getFrequencyResponse(int nFrequencies,
127 const float* frequencyHz,
128 float* magResponse,
129 float* phaseResponse)
130 {
131 bool isGood = nFrequencies > 0 && frequencyHz && magResponse && phaseResponse;
132 ASSERT(isGood);
133 if (!isGood)
134 return;
135
136 Vector<float> frequency(nFrequencies);
137
138 double nyquist = this->nyquist();
139
140 // Convert from frequency in Hz to normalized frequency (0 -> 1),
141 // with 1 equal to the Nyquist frequency.
142 for (int k = 0; k < nFrequencies; ++k)
143 frequency[k] = narrowPrecisionToFloat(frequencyHz[k] / nyquist);
144
145 // We want to get the final values of the coefficients and compute
146 // the response from that instead of some intermediate smoothed
147 // set. Forcefully update the coefficients even if they are not
148 // dirty.
149
150 updateCoefficientsIfNecessary(false, true);
151
152 m_biquad.getFrequencyResponse(nFrequencies, frequency.data(), magResponse, phaseResponse);
153 }
154
tailTime() const155 double BiquadDSPKernel::tailTime() const
156 {
157 return MaxBiquadDelayTime;
158 }
159
latencyTime() const160 double BiquadDSPKernel::latencyTime() const
161 {
162 return 0;
163 }
164
165 } // namespace WebCore
166
167 #endif // ENABLE(WEB_AUDIO)
168