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#ifndef BiquadDSPKernel_h
26#define BiquadDSPKernel_h
27
28#include "platform/audio/AudioDSPKernel.h"
29#include "platform/audio/Biquad.h"
30#include "modules/webaudio/BiquadProcessor.h"
31
32namespace blink {
33
34class BiquadProcessor;
35
36// BiquadDSPKernel is an AudioDSPKernel and is responsible for filtering one channel of a BiquadProcessor using a Biquad object.
37
38class BiquadDSPKernel FINAL : public AudioDSPKernel {
39public:
40    explicit BiquadDSPKernel(BiquadProcessor* processor)
41    : AudioDSPKernel(processor)
42    {
43    }
44
45    // AudioDSPKernel
46    virtual void process(const float* source, float* dest, size_t framesToProcess) OVERRIDE;
47    virtual void reset() OVERRIDE { m_biquad.reset(); }
48
49    // Get the magnitude and phase response of the filter at the given
50    // set of frequencies (in Hz). The phase response is in radians.
51    void getFrequencyResponse(int nFrequencies,
52                              const float* frequencyHz,
53                              float* magResponse,
54                              float* phaseResponse);
55
56    virtual double tailTime() const OVERRIDE;
57    virtual double latencyTime() const OVERRIDE;
58
59protected:
60    Biquad m_biquad;
61    BiquadProcessor* biquadProcessor() { return static_cast<BiquadProcessor*>(processor()); }
62
63    // To prevent audio glitches when parameters are changed,
64    // dezippering is used to slowly change the parameters.
65    void updateCoefficientsIfNecessary();
66    // Update the biquad cofficients with the given parameters
67    void updateCoefficients(double frequency, double Q, double gain, double detune);
68
69private:
70    // Synchronize process() with getting and setting the filter coefficients.
71    mutable Mutex m_processLock;
72};
73
74} // namespace blink
75
76#endif // BiquadDSPKernel_h
77