| /* |
| * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. |
| * |
| * Use of this source code is governed by a BSD-style license |
| * that can be found in the LICENSE file in the root of the source |
| * tree. An additional intellectual property rights grant can be found |
| * in the file PATENTS. All contributing project authors may |
| * be found in the AUTHORS file in the root of the source tree. |
| */ |
| |
| #ifndef WEBRTC_BASE_EXP_FILTER_H_ |
| #define WEBRTC_BASE_EXP_FILTER_H_ |
| |
| namespace rtc { |
| |
| // This class can be used, for example, for smoothing the result of bandwidth |
| // estimation and packet loss estimation. |
| |
| class ExpFilter { |
| public: |
| static const float kValueUndefined; |
| |
| explicit ExpFilter(float alpha, float max = kValueUndefined) |
| : max_(max) { |
| Reset(alpha); |
| } |
| |
| // Resets the filter to its initial state, and resets filter factor base to |
| // the given value |alpha|. |
| void Reset(float alpha); |
| |
| // Applies the filter with a given exponent on the provided sample: |
| // y(k) = min(alpha_^ exp * y(k-1) + (1 - alpha_^ exp) * sample, max_). |
| float Apply(float exp, float sample); |
| |
| // Returns current filtered value. |
| float filtered() const { return filtered_; } |
| |
| // Changes the filter factor base to the given value |alpha|. |
| void UpdateBase(float alpha); |
| |
| private: |
| float alpha_; // Filter factor base. |
| float filtered_; // Current filter output. |
| const float max_; |
| }; |
| } // namespace rtc |
| |
| #endif // WEBRTC_BASE_EXP_FILTER_H_ |