28e2075280
trunk/talk git-svn-id: http://webrtc.googlecode.com/svn/trunk@4318 4adac7df-926f-26a2-2b94-8c16560cd09d
77 lines
3.2 KiB
C++
77 lines
3.2 KiB
C++
/*
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* libjingle
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* Copyright 2011, Google Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef TALK_BASE_BANDWIDTHSMOOTHER_H_
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#define TALK_BASE_BANDWIDTHSMOOTHER_H_
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#include "talk/base/rollingaccumulator.h"
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#include "talk/base/timeutils.h"
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namespace talk_base {
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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 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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// 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 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 time_between_increase_;
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double percent_increase_;
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uint32 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 talk_base
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#endif // TALK_BASE_BANDWIDTHSMOOTHER_H_
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