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Side by Side Diff: third_party/WebKit/Source/modules/webaudio/IIRProcessor.cpp

Issue 2389253002: reflow comments in modules/{webaudio,vr} (Closed)
Patch Set: . Created 4 years, 2 months ago
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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
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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