minyue@webrtc.org | 74aaf29 | 2014-07-16 21:28:26 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. |
| 3 | * |
| 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 |
| 6 | * tree. An additional intellectual property rights grant can be found |
| 7 | * in the file PATENTS. All contributing project authors may |
| 8 | * be found in the AUTHORS file in the root of the source tree. |
| 9 | */ |
| 10 | |
Mirko Bonadei | 92ea95e | 2017-09-15 06:47:31 +0200 | [diff] [blame] | 11 | #ifndef RTC_BASE_NUMERICS_EXP_FILTER_H_ |
| 12 | #define RTC_BASE_NUMERICS_EXP_FILTER_H_ |
minyue@webrtc.org | 74aaf29 | 2014-07-16 21:28:26 +0000 | [diff] [blame] | 13 | |
Henrik Kjellander | ec78f1c | 2017-06-29 07:52:50 +0200 | [diff] [blame] | 14 | namespace rtc { |
minyue@webrtc.org | 74aaf29 | 2014-07-16 21:28:26 +0000 | [diff] [blame] | 15 | |
Henrik Kjellander | ec78f1c | 2017-06-29 07:52:50 +0200 | [diff] [blame] | 16 | // This class can be used, for example, for smoothing the result of bandwidth |
| 17 | // estimation and packet loss estimation. |
| 18 | |
| 19 | class ExpFilter { |
| 20 | public: |
| 21 | static const float kValueUndefined; |
| 22 | |
| 23 | explicit ExpFilter(float alpha, float max = kValueUndefined) : max_(max) { |
| 24 | Reset(alpha); |
| 25 | } |
| 26 | |
| 27 | // Resets the filter to its initial state, and resets filter factor base to |
| 28 | // the given value |alpha|. |
| 29 | void Reset(float alpha); |
| 30 | |
| 31 | // Applies the filter with a given exponent on the provided sample: |
| 32 | // y(k) = min(alpha_^ exp * y(k-1) + (1 - alpha_^ exp) * sample, max_). |
| 33 | float Apply(float exp, float sample); |
| 34 | |
| 35 | // Returns current filtered value. |
| 36 | float filtered() const { return filtered_; } |
| 37 | |
| 38 | // Changes the filter factor base to the given value |alpha|. |
| 39 | void UpdateBase(float alpha); |
| 40 | |
| 41 | private: |
| 42 | float alpha_; // Filter factor base. |
| 43 | float filtered_; // Current filter output. |
| 44 | const float max_; |
| 45 | }; |
| 46 | } // namespace rtc |
minyue@webrtc.org | 74aaf29 | 2014-07-16 21:28:26 +0000 | [diff] [blame] | 47 | |
Mirko Bonadei | 92ea95e | 2017-09-15 06:47:31 +0200 | [diff] [blame] | 48 | #endif // RTC_BASE_NUMERICS_EXP_FILTER_H_ |