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 | #include "rtc_base/numerics/exp_filter.h" |
minyue@webrtc.org | 74aaf29 | 2014-07-16 21:28:26 +0000 | [diff] [blame] | 12 | |
Mirko Bonadei | b5dd6b6 | 2019-03-20 07:09:48 +0100 | [diff] [blame] | 13 | #include <cmath> |
minyue@webrtc.org | 74aaf29 | 2014-07-16 21:28:26 +0000 | [diff] [blame] | 14 | |
| 15 | namespace rtc { |
| 16 | |
| 17 | const float ExpFilter::kValueUndefined = -1.0f; |
| 18 | |
| 19 | void ExpFilter::Reset(float alpha) { |
| 20 | alpha_ = alpha; |
| 21 | filtered_ = kValueUndefined; |
| 22 | } |
| 23 | |
| 24 | float ExpFilter::Apply(float exp, float sample) { |
| 25 | if (filtered_ == kValueUndefined) { |
| 26 | // Initialize filtered value. |
| 27 | filtered_ = sample; |
| 28 | } else if (exp == 1.0) { |
| 29 | filtered_ = alpha_ * filtered_ + (1 - alpha_) * sample; |
| 30 | } else { |
Mirko Bonadei | b5dd6b6 | 2019-03-20 07:09:48 +0100 | [diff] [blame] | 31 | float alpha = std::pow(alpha_, exp); |
minyue@webrtc.org | 74aaf29 | 2014-07-16 21:28:26 +0000 | [diff] [blame] | 32 | filtered_ = alpha * filtered_ + (1 - alpha) * sample; |
| 33 | } |
| 34 | if (max_ != kValueUndefined && filtered_ > max_) { |
| 35 | filtered_ = max_; |
| 36 | } |
| 37 | return filtered_; |
| 38 | } |
| 39 | |
| 40 | void ExpFilter::UpdateBase(float alpha) { |
| 41 | alpha_ = alpha; |
| 42 | } |
| 43 | } // namespace rtc |