OLD | NEW |
| (Empty) |
1 /* | |
2 * Copyright (c) 2016 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 #ifndef WEBRTC_COMMON_AUDIO_SMOOTHING_FILTER_H_ | |
12 #define WEBRTC_COMMON_AUDIO_SMOOTHING_FILTER_H_ | |
13 | |
14 #include "webrtc/base/analytics/exp_filter.h" | |
15 #include "webrtc/base/constructormagic.h" | |
16 #include "webrtc/base/optional.h" | |
17 #include "webrtc/system_wrappers/include/clock.h" | |
18 | |
19 namespace webrtc { | |
20 | |
21 class SmoothingFilter { | |
22 public: | |
23 virtual ~SmoothingFilter() = default; | |
24 virtual void AddSample(float sample) = 0; | |
25 virtual rtc::Optional<float> GetAverage() const = 0; | |
26 }; | |
27 | |
28 // SmoothingFilterImpl applies an exponential filter | |
29 // alpha = exp(-sample_interval / time_constant); | |
30 // y[t] = alpha * y[t-1] + (1 - alpha) * sample; | |
31 class SmoothingFilterImpl final : public SmoothingFilter { | |
32 public: | |
33 // |time_constant_ms| is the time constant for the exponential filter. | |
34 SmoothingFilterImpl(int time_constant_ms, const Clock* clock); | |
35 | |
36 void AddSample(float sample) override; | |
37 rtc::Optional<float> GetAverage() const override; | |
38 | |
39 private: | |
40 const int time_constant_ms_; | |
41 const Clock* const clock_; | |
42 | |
43 bool first_sample_received_; | |
44 bool initialized_; | |
45 int64_t first_sample_time_ms_; | |
46 int64_t last_sample_time_ms_; | |
47 rtc::ExpFilter filter_; | |
48 | |
49 RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(SmoothingFilterImpl); | |
50 }; | |
51 | |
52 } // namespace webrtc | |
53 | |
54 #endif // WEBRTC_COMMON_AUDIO_SMOOTHING_FILTER_H_ | |
OLD | NEW |