61 lines
2.2 KiB
C
61 lines
2.2 KiB
C
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/*
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* Copyright 2011 The WebRTC Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef WEBRTC_BASE_BANDWIDTHSMOOTHER_H_
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#define WEBRTC_BASE_BANDWIDTHSMOOTHER_H_
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#include "webrtc/base/rollingaccumulator.h"
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#include "webrtc/base/timeutils.h"
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namespace rtc {
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// The purpose of BandwidthSmoother is to smooth out bandwidth
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// estimations so that 'trstate' messages can be triggered when we
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// are "sure" there is sufficient bandwidth. To avoid frequent fluctuations,
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// we take a slightly pessimistic view of our bandwidth. We only increase
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// our estimation when we have sampled bandwidth measurements of values
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// at least as large as the current estimation * percent_increase
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// for at least time_between_increase time. If a sampled bandwidth
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// is less than our current estimation we immediately decrease our estimation
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// to that sampled value.
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// We retain the initial bandwidth guess as our current bandwidth estimation
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// until we have received (min_sample_count_percent * samples_count_to_average)
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// number of samples. Min_sample_count_percent must be in range [0, 1].
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class BandwidthSmoother {
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public:
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BandwidthSmoother(int initial_bandwidth_guess,
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uint32_t time_between_increase,
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double percent_increase,
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size_t samples_count_to_average,
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double min_sample_count_percent);
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~BandwidthSmoother();
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// Samples a new bandwidth measurement.
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// bandwidth is expected to be non-negative.
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// returns true if the bandwidth estimation changed
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bool Sample(uint32_t sample_time, int bandwidth);
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int get_bandwidth_estimation() const {
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return bandwidth_estimation_;
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}
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private:
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uint32_t time_between_increase_;
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double percent_increase_;
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uint32_t time_at_last_change_;
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int bandwidth_estimation_;
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RollingAccumulator<int> accumulator_;
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double min_sample_count_percent_;
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};
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} // namespace rtc
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#endif // WEBRTC_BASE_BANDWIDTHSMOOTHER_H_
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