| /* |
| * 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. |
| */ |
| |
| #include "webrtc/base/exp_filter.h" |
| |
| #include <math.h> |
| |
| namespace rtc { |
| |
| const float ExpFilter::kValueUndefined = -1.0f; |
| |
| void ExpFilter::Reset(float alpha) { |
| alpha_ = alpha; |
| filtered_ = kValueUndefined; |
| } |
| |
| float ExpFilter::Apply(float exp, float sample) { |
| if (filtered_ == kValueUndefined) { |
| // Initialize filtered value. |
| filtered_ = sample; |
| } else if (exp == 1.0) { |
| filtered_ = alpha_ * filtered_ + (1 - alpha_) * sample; |
| } else { |
| float alpha = pow(alpha_, exp); |
| filtered_ = alpha * filtered_ + (1 - alpha) * sample; |
| } |
| if (max_ != kValueUndefined && filtered_ > max_) { |
| filtered_ = max_; |
| } |
| return filtered_; |
| } |
| |
| void ExpFilter::UpdateBase(float alpha) { |
| alpha_ = alpha; |
| } |
| } // namespace rtc |