content/media/webaudio/blink/Biquad.h@b8a032363ba2 (annotated)
content/media/webaudio/blink/Biquad.h
Thu, 22 Jan 2015 13:21:57 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Thu, 22 Jan 2015 13:21:57 +0100
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
- permissions
- -rw-r--r--
Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6
| michael@0 | 1 | /* |
| michael@0 | 2 | * Copyright (C) 2010 Google Inc. All rights reserved. |
| michael@0 | 3 | * |
| michael@0 | 4 | * Redistribution and use in source and binary forms, with or without |
| michael@0 | 5 | * modification, are permitted provided that the following conditions |
| michael@0 | 6 | * are met: |
| michael@0 | 7 | * |
| michael@0 | 8 | * 1. Redistributions of source code must retain the above copyright |
| michael@0 | 9 | * notice, this list of conditions and the following disclaimer. |
| michael@0 | 10 | * 2. Redistributions in binary form must reproduce the above copyright |
| michael@0 | 11 | * notice, this list of conditions and the following disclaimer in the |
| michael@0 | 12 | * documentation and/or other materials provided with the distribution. |
| michael@0 | 13 | * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of |
| michael@0 | 14 | * its contributors may be used to endorse or promote products derived |
| michael@0 | 15 | * from this software without specific prior written permission. |
| michael@0 | 16 | * |
| michael@0 | 17 | * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY |
| michael@0 | 18 | * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
| michael@0 | 19 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
| michael@0 | 20 | * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY |
| michael@0 | 21 | * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
| michael@0 | 22 | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| michael@0 | 23 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
| michael@0 | 24 | * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| michael@0 | 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| michael@0 | 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| michael@0 | 27 | */ |
| michael@0 | 28 | |
| michael@0 | 29 | #ifndef Biquad_h |
| michael@0 | 30 | #define Biquad_h |
| michael@0 | 31 | |
| michael@0 | 32 | #include <complex> |
| michael@0 | 33 | |
| michael@0 | 34 | namespace WebCore { |
| michael@0 | 35 | |
| michael@0 | 36 | typedef std::complex<double> Complex; |
| michael@0 | 37 | |
| michael@0 | 38 | // A basic biquad (two-zero / two-pole digital filter) |
| michael@0 | 39 | // |
| michael@0 | 40 | // It can be configured to a number of common and very useful filters: |
| michael@0 | 41 | // lowpass, highpass, shelving, parameteric, notch, allpass, ... |
| michael@0 | 42 | |
| michael@0 | 43 | class Biquad { |
| michael@0 | 44 | public: |
| michael@0 | 45 | Biquad(); |
| michael@0 | 46 | ~Biquad(); |
| michael@0 | 47 | |
| michael@0 | 48 | void process(const float* sourceP, float* destP, size_t framesToProcess); |
| michael@0 | 49 | |
| michael@0 | 50 | // frequency is 0 - 1 normalized, resonance and dbGain are in decibels. |
| michael@0 | 51 | // Q is a unitless quality factor. |
| michael@0 | 52 | void setLowpassParams(double frequency, double resonance); |
| michael@0 | 53 | void setHighpassParams(double frequency, double resonance); |
| michael@0 | 54 | void setBandpassParams(double frequency, double Q); |
| michael@0 | 55 | void setLowShelfParams(double frequency, double dbGain); |
| michael@0 | 56 | void setHighShelfParams(double frequency, double dbGain); |
| michael@0 | 57 | void setPeakingParams(double frequency, double Q, double dbGain); |
| michael@0 | 58 | void setAllpassParams(double frequency, double Q); |
| michael@0 | 59 | void setNotchParams(double frequency, double Q); |
| michael@0 | 60 | |
| michael@0 | 61 | // Set the biquad coefficients given a single zero (other zero will be conjugate) |
| michael@0 | 62 | // and a single pole (other pole will be conjugate) |
| michael@0 | 63 | void setZeroPolePairs(const Complex& zero, const Complex& pole); |
| michael@0 | 64 | |
| michael@0 | 65 | // Set the biquad coefficients given a single pole (other pole will be conjugate) |
| michael@0 | 66 | // (The zeroes will be the inverse of the poles) |
| michael@0 | 67 | void setAllpassPole(const Complex& pole); |
| michael@0 | 68 | |
| michael@0 | 69 | // Return true iff the next output block will contain sound even with |
| michael@0 | 70 | // silent input. |
| michael@0 | 71 | bool hasTail() const { return m_y1 || m_y2 || m_x1 || m_x2; } |
| michael@0 | 72 | |
| michael@0 | 73 | // Resets filter state |
| michael@0 | 74 | void reset(); |
| michael@0 | 75 | |
| michael@0 | 76 | // Filter response at a set of n frequencies. The magnitude and |
| michael@0 | 77 | // phase response are returned in magResponse and phaseResponse. |
| michael@0 | 78 | // The phase response is in radians. |
| michael@0 | 79 | void getFrequencyResponse(int nFrequencies, |
| michael@0 | 80 | const float* frequency, |
| michael@0 | 81 | float* magResponse, |
| michael@0 | 82 | float* phaseResponse); |
| michael@0 | 83 | private: |
| michael@0 | 84 | void setNormalizedCoefficients(double b0, double b1, double b2, double a0, double a1, double a2); |
| michael@0 | 85 | |
| michael@0 | 86 | // Filter coefficients. The filter is defined as |
| michael@0 | 87 | // |
| michael@0 | 88 | // y[n] + m_a1*y[n-1] + m_a2*y[n-2] = m_b0*x[n] + m_b1*x[n-1] + m_b2*x[n-2]. |
| michael@0 | 89 | double m_b0; |
| michael@0 | 90 | double m_b1; |
| michael@0 | 91 | double m_b2; |
| michael@0 | 92 | double m_a1; |
| michael@0 | 93 | double m_a2; |
| michael@0 | 94 | |
| michael@0 | 95 | // Filter memory |
| michael@0 | 96 | // |
| michael@0 | 97 | // Double precision for the output values is valuable because errors can |
| michael@0 | 98 | // accumulate. Input values are also stored as double so they need not be |
| michael@0 | 99 | // converted again for computation. |
| michael@0 | 100 | double m_x1; // input delayed by 1 sample |
| michael@0 | 101 | double m_x2; // input delayed by 2 samples |
| michael@0 | 102 | double m_y1; // output delayed by 1 sample |
| michael@0 | 103 | double m_y2; // output delayed by 2 samples |
| michael@0 | 104 | }; |
| michael@0 | 105 | |
| michael@0 | 106 | } // namespace WebCore |
| michael@0 | 107 | |
| michael@0 | 108 | #endif // Biquad_h |
