blob: c4de7b5da5a5dc7f85b2f5e258505fb5025cb7b1 [file] [log] [blame]
* Copyright (c) 2016 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/constructormagic.h"
#include "webrtc/base/exp_filter.h"
#include "webrtc/base/optional.h"
#include "webrtc/system_wrappers/include/clock.h"
namespace webrtc {
class SmoothingFilter {
virtual ~SmoothingFilter() = default;
virtual void AddSample(float sample) = 0;
virtual rtc::Optional<float> GetAverage() const = 0;
// SmoothingFilterImpl applies an exponential filter
// alpha = exp(-sample_interval / time_constant);
// y[t] = alpha * y[t-1] + (1 - alpha) * sample;
class SmoothingFilterImpl final : public SmoothingFilter {
// |time_constant_ms| is the time constant for the exponential filter.
SmoothingFilterImpl(int time_constant_ms, const Clock* clock);
void AddSample(float sample) override;
rtc::Optional<float> GetAverage() const override;
const int time_constant_ms_;
const Clock* const clock_;
bool first_sample_received_;
bool initialized_;
int64_t first_sample_time_ms_;
int64_t last_sample_time_ms_;
rtc::ExpFilter filter_;
} // namespace webrtc