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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/numerics/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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