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* Copyright 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/rollingaccumulator.h"
#include "webrtc/base/timeutils.h"
namespace rtc {
// The purpose of BandwidthSmoother is to smooth out bandwidth
// estimations so that 'trstate' messages can be triggered when we
// are "sure" there is sufficient bandwidth. To avoid frequent fluctuations,
// we take a slightly pessimistic view of our bandwidth. We only increase
// our estimation when we have sampled bandwidth measurements of values
// at least as large as the current estimation * percent_increase
// for at least time_between_increase time. If a sampled bandwidth
// is less than our current estimation we immediately decrease our estimation
// to that sampled value.
// We retain the initial bandwidth guess as our current bandwidth estimation
// until we have received (min_sample_count_percent * samples_count_to_average)
// number of samples. Min_sample_count_percent must be in range [0, 1].
class BandwidthSmoother {
BandwidthSmoother(int initial_bandwidth_guess,
uint32_t time_between_increase,
double percent_increase,
size_t samples_count_to_average,
double min_sample_count_percent);
// Samples a new bandwidth measurement.
// bandwidth is expected to be non-negative.
// returns true if the bandwidth estimation changed
bool Sample(uint32_t sample_time, int bandwidth);
int get_bandwidth_estimation() const {
return bandwidth_estimation_;
uint32_t time_between_increase_;
double percent_increase_;
uint32_t time_at_last_change_;
int bandwidth_estimation_;
RollingAccumulator<int> accumulator_;
double min_sample_count_percent_;
} // namespace rtc