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| 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 |
| 11 #include "webrtc/base/exp_filter.h" |
| 12 |
| 13 #include <math.h> |
| 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 { |
| 31 float alpha = pow(alpha_, exp); |
| 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 |
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