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1 /* | 1 /* |
2 * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. | 2 * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. |
3 * | 3 * |
4 * Use of this source code is governed by a BSD-style license | 4 * Use of this source code is governed by a BSD-style license |
5 * that can be found in the LICENSE file in the root of the source | 5 * that can be found in the LICENSE file in the root of the source |
6 * tree. An additional intellectual property rights grant can be found | 6 * tree. An additional intellectual property rights grant can be found |
7 * in the file PATENTS. All contributing project authors may | 7 * in the file PATENTS. All contributing project authors may |
8 * be found in the AUTHORS file in the root of the source tree. | 8 * be found in the AUTHORS file in the root of the source tree. |
9 */ | 9 */ |
10 | 10 |
11 #ifndef WEBRTC_BASE_ANALYTICS_EXP_FILTER_H_ | 11 #ifndef WEBRTC_BASE_NUMERICS_EXP_FILTER_H_ |
12 #define WEBRTC_BASE_ANALYTICS_EXP_FILTER_H_ | 12 #define WEBRTC_BASE_NUMERICS_EXP_FILTER_H_ |
13 | 13 |
14 namespace rtc { | 14 namespace rtc { |
15 | 15 |
16 // This class can be used, for example, for smoothing the result of bandwidth | 16 // This class can be used, for example, for smoothing the result of bandwidth |
17 // estimation and packet loss estimation. | 17 // estimation and packet loss estimation. |
18 | 18 |
19 class ExpFilter { | 19 class ExpFilter { |
20 public: | 20 public: |
21 static const float kValueUndefined; | 21 static const float kValueUndefined; |
22 | 22 |
23 explicit ExpFilter(float alpha, float max = kValueUndefined) | 23 explicit ExpFilter(float alpha, float max = kValueUndefined) : max_(max) { |
24 : max_(max) { | |
25 Reset(alpha); | 24 Reset(alpha); |
26 } | 25 } |
27 | 26 |
28 // Resets the filter to its initial state, and resets filter factor base to | 27 // Resets the filter to its initial state, and resets filter factor base to |
29 // the given value |alpha|. | 28 // the given value |alpha|. |
30 void Reset(float alpha); | 29 void Reset(float alpha); |
31 | 30 |
32 // Applies the filter with a given exponent on the provided sample: | 31 // Applies the filter with a given exponent on the provided sample: |
33 // y(k) = min(alpha_^ exp * y(k-1) + (1 - alpha_^ exp) * sample, max_). | 32 // y(k) = min(alpha_^ exp * y(k-1) + (1 - alpha_^ exp) * sample, max_). |
34 float Apply(float exp, float sample); | 33 float Apply(float exp, float sample); |
35 | 34 |
36 // Returns current filtered value. | 35 // Returns current filtered value. |
37 float filtered() const { return filtered_; } | 36 float filtered() const { return filtered_; } |
38 | 37 |
39 // Changes the filter factor base to the given value |alpha|. | 38 // Changes the filter factor base to the given value |alpha|. |
40 void UpdateBase(float alpha); | 39 void UpdateBase(float alpha); |
41 | 40 |
42 private: | 41 private: |
43 float alpha_; // Filter factor base. | 42 float alpha_; // Filter factor base. |
44 float filtered_; // Current filter output. | 43 float filtered_; // Current filter output. |
45 const float max_; | 44 const float max_; |
46 }; | 45 }; |
47 } // namespace rtc | 46 } // namespace rtc |
48 | 47 |
49 #endif // WEBRTC_BASE_ANALYTICS_EXP_FILTER_H_ | 48 #endif // WEBRTC_BASE_NUMERICS_EXP_FILTER_H_ |
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