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 BiquadProcessor::LowPass:
80            m_biquad.setLowpassParams(normalizedFrequency, value2);
81            break;
82
83        case BiquadProcessor::HighPass:
84            m_biquad.setHighpassParams(normalizedFrequency, value2);
85            break;
86
87        case BiquadProcessor::BandPass:
88            m_biquad.setBandpassParams(normalizedFrequency, value2);
89            break;
90
91        case BiquadProcessor::LowShelf:
92            m_biquad.setLowShelfParams(normalizedFrequency, gain);
93            break;
94
95        case BiquadProcessor::HighShelf:
96            m_biquad.setHighShelfParams(normalizedFrequency, gain);
97            break;
98
99        case BiquadProcessor::Peaking:
100            m_biquad.setPeakingParams(normalizedFrequency, value2, gain);
101            break;
102
103        case BiquadProcessor::Notch:
104            m_biquad.setNotchParams(normalizedFrequency, value2);
105            break;
106
107        case BiquadProcessor::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