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1 // Copyright 2016 The Chromium Authors. All rights reserved. | 1 // Copyright 2016 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "modules/webaudio/IIRProcessor.h" | 5 #include "modules/webaudio/IIRProcessor.h" |
6 | 6 |
7 #include "modules/webaudio/IIRDSPKernel.h" | 7 #include "modules/webaudio/IIRDSPKernel.h" |
8 #include "wtf/PtrUtil.h" | 8 #include "wtf/PtrUtil.h" |
9 #include <memory> | 9 #include <memory> |
10 | 10 |
11 namespace blink { | 11 namespace blink { |
12 | 12 |
13 IIRProcessor::IIRProcessor(float sampleRate, | 13 IIRProcessor::IIRProcessor(float sampleRate, |
14 size_t numberOfChannels, | 14 size_t numberOfChannels, |
15 const Vector<double>& feedforwardCoef, | 15 const Vector<double>& feedforwardCoef, |
16 const Vector<double>& feedbackCoef) | 16 const Vector<double>& feedbackCoef) |
17 : AudioDSPKernelProcessor(sampleRate, numberOfChannels) { | 17 : AudioDSPKernelProcessor(sampleRate, numberOfChannels) { |
18 unsigned feedbackLength = feedbackCoef.size(); | 18 unsigned feedbackLength = feedbackCoef.size(); |
19 unsigned feedforwardLength = feedforwardCoef.size(); | 19 unsigned feedforwardLength = feedforwardCoef.size(); |
20 DCHECK_GT(feedbackLength, 0u); | 20 DCHECK_GT(feedbackLength, 0u); |
21 DCHECK_GT(feedforwardLength, 0u); | 21 DCHECK_GT(feedforwardLength, 0u); |
22 | 22 |
23 m_feedforward.allocate(feedforwardLength); | 23 m_feedforward.allocate(feedforwardLength); |
24 m_feedback.allocate(feedbackLength); | 24 m_feedback.allocate(feedbackLength); |
25 m_feedforward.copyToRange(feedforwardCoef.data(), 0, feedforwardLength); | 25 m_feedforward.copyToRange(feedforwardCoef.data(), 0, feedforwardLength); |
26 m_feedback.copyToRange(feedbackCoef.data(), 0, feedbackLength); | 26 m_feedback.copyToRange(feedbackCoef.data(), 0, feedbackLength); |
27 | 27 |
28 // Need to scale the feedback and feedforward coefficients appropriately. (It'
s up to the caller | 28 // Need to scale the feedback and feedforward coefficients appropriately. |
29 // to ensure feedbackCoef[0] is not 0!) | 29 // (It's up to the caller to ensure feedbackCoef[0] is not 0.) |
30 DCHECK_NE(feedbackCoef[0], 0); | 30 DCHECK_NE(feedbackCoef[0], 0); |
31 | 31 |
32 if (feedbackCoef[0] != 1) { | 32 if (feedbackCoef[0] != 1) { |
33 // The provided filter is: | 33 // The provided filter is: |
34 // | 34 // |
35 // a[0]*y(n) + a[1]*y(n-1) + ... = b[0]*x(n) + b[1]*x(n-1) + ... | 35 // a[0]*y(n) + a[1]*y(n-1) + ... = b[0]*x(n) + b[1]*x(n-1) + ... |
36 // | 36 // |
37 // We want the leading coefficient of y(n) to be 1: | 37 // We want the leading coefficient of y(n) to be 1: |
38 // | 38 // |
39 // y(n) + a[1]/a[0]*y(n-1) + ... = b[0]/a[0]*x(n) + b[1]/a[0]*x(n-1) + ... | 39 // y(n) + a[1]/a[0]*y(n-1) + ... = b[0]/a[0]*x(n) + b[1]/a[0]*x(n-1) + ... |
40 // | 40 // |
41 // Thus, the feedback and feedforward coefficients need to be scaled by 1/a[
0]. | 41 // Thus, the feedback and feedforward coefficients need to be scaled by |
| 42 // 1/a[0]. |
42 float scale = feedbackCoef[0]; | 43 float scale = feedbackCoef[0]; |
43 for (unsigned k = 1; k < feedbackLength; ++k) | 44 for (unsigned k = 1; k < feedbackLength; ++k) |
44 m_feedback[k] /= scale; | 45 m_feedback[k] /= scale; |
45 | 46 |
46 for (unsigned k = 0; k < feedforwardLength; ++k) | 47 for (unsigned k = 0; k < feedforwardLength; ++k) |
47 m_feedforward[k] /= scale; | 48 m_feedforward[k] /= scale; |
48 | 49 |
49 // The IIRFilter checks to make sure this coefficient is 1, so make it so. | 50 // The IIRFilter checks to make sure this coefficient is 1, so make it so. |
50 m_feedback[0] = 1; | 51 m_feedback[0] = 1; |
51 } | 52 } |
(...skipping 11 matching lines...) Expand all Loading... |
63 } | 64 } |
64 | 65 |
65 void IIRProcessor::process(const AudioBus* source, | 66 void IIRProcessor::process(const AudioBus* source, |
66 AudioBus* destination, | 67 AudioBus* destination, |
67 size_t framesToProcess) { | 68 size_t framesToProcess) { |
68 if (!isInitialized()) { | 69 if (!isInitialized()) { |
69 destination->zero(); | 70 destination->zero(); |
70 return; | 71 return; |
71 } | 72 } |
72 | 73 |
73 // For each channel of our input, process using the corresponding IIRDSPKernel
into the output | 74 // For each channel of our input, process using the corresponding IIRDSPKernel |
74 // channel. | 75 // into the output channel. |
75 for (unsigned i = 0; i < m_kernels.size(); ++i) | 76 for (unsigned i = 0; i < m_kernels.size(); ++i) |
76 m_kernels[i]->process(source->channel(i)->data(), | 77 m_kernels[i]->process(source->channel(i)->data(), |
77 destination->channel(i)->mutableData(), | 78 destination->channel(i)->mutableData(), |
78 framesToProcess); | 79 framesToProcess); |
79 } | 80 } |
80 | 81 |
81 void IIRProcessor::getFrequencyResponse(int nFrequencies, | 82 void IIRProcessor::getFrequencyResponse(int nFrequencies, |
82 const float* frequencyHz, | 83 const float* frequencyHz, |
83 float* magResponse, | 84 float* magResponse, |
84 float* phaseResponse) { | 85 float* phaseResponse) { |
85 m_responseKernel->getFrequencyResponse(nFrequencies, frequencyHz, magResponse, | 86 m_responseKernel->getFrequencyResponse(nFrequencies, frequencyHz, magResponse, |
86 phaseResponse); | 87 phaseResponse); |
87 } | 88 } |
88 | 89 |
89 } // namespace blink | 90 } // namespace blink |
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