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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 #ifndef IIRFilter_h | 5 #ifndef IIRFilter_h |
6 #define IIRFilter_h | 6 #define IIRFilter_h |
7 | 7 |
8 #include "platform/PlatformExport.h" | 8 #include "platform/PlatformExport.h" |
9 #include "platform/audio/AudioArray.h" | 9 #include "platform/audio/AudioArray.h" |
10 #include "platform/wtf/Vector.h" | 10 #include "platform/wtf/Vector.h" |
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23 | 23 |
24 void Process(const float* source_p, float* dest_p, size_t frames_to_process); | 24 void Process(const float* source_p, float* dest_p, size_t frames_to_process); |
25 | 25 |
26 void Reset(); | 26 void Reset(); |
27 | 27 |
28 void GetFrequencyResponse(int n_frequencies, | 28 void GetFrequencyResponse(int n_frequencies, |
29 const float* frequency, | 29 const float* frequency, |
30 float* mag_response, | 30 float* mag_response, |
31 float* phase_response); | 31 float* phase_response); |
32 | 32 |
33 // Compute the tail time of the IIR filter | |
34 double TailTime(double sample_rate); | |
hongchan
2017/05/12 16:24:05
What's the frequency of this computation?
On a re
Raymond Toy
2017/05/12 17:33:18
I don't quite understand this question? The TailT
hongchan
2017/05/12 17:36:45
You answered this above. We compute just once.
| |
35 | |
36 // Reset the internal state of the IIR filter to the initial state. | |
37 void ResetState(); | |
38 | |
33 private: | 39 private: |
34 // Filter memory | 40 // Filter memory |
35 // | 41 // |
36 // For simplicity, we assume |m_xBuffer| and |m_yBuffer| have the same length, | 42 // For simplicity, we assume |m_xBuffer| and |m_yBuffer| have the same length, |
37 // and the length is a power of two. Since the number of coefficients has a | 43 // and the length is a power of two. Since the number of coefficients has a |
38 // fixed upper length, the size of xBuffer and yBuffer is fixed. |m_xBuffer| | 44 // fixed upper length, the size of xBuffer and yBuffer is fixed. |m_xBuffer| |
39 // holds the old input values and |m_yBuffer| holds the old output values | 45 // holds the old input values and |m_yBuffer| holds the old output values |
40 // needed to compute the new output value. | 46 // needed to compute the new output value. |
41 // | 47 // |
42 // m_yBuffer[m_bufferIndex] holds the most recent output value, say, y[n]. | 48 // m_yBuffer[m_bufferIndex] holds the most recent output value, say, y[n]. |
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54 | 60 |
55 // Coefficients of the IIR filter. To minimize storage, these point to the | 61 // Coefficients of the IIR filter. To minimize storage, these point to the |
56 // arrays given in the constructor. | 62 // arrays given in the constructor. |
57 const AudioDoubleArray* feedback_; | 63 const AudioDoubleArray* feedback_; |
58 const AudioDoubleArray* feedforward_; | 64 const AudioDoubleArray* feedforward_; |
59 }; | 65 }; |
60 | 66 |
61 } // namespace blink | 67 } // namespace blink |
62 | 68 |
63 #endif // IIRFilter_h | 69 #endif // IIRFilter_h |
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