henrike@webrtc.org | 0e118e7 | 2013-07-10 00:45:36 +0000 | [diff] [blame] | 1 | /* |
| 2 | * libjingle |
| 3 | * Copyright 2011, Google Inc. |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms, with or without |
| 6 | * modification, are permitted provided that the following conditions are met: |
| 7 | * |
| 8 | * 1. Redistributions of source code must retain the above copyright notice, |
| 9 | * this list of conditions and the following disclaimer. |
| 10 | * 2. Redistributions in binary form must reproduce the above copyright notice, |
| 11 | * this list of conditions and the following disclaimer in the documentation |
| 12 | * and/or other materials provided with the distribution. |
| 13 | * 3. The name of the author may not be used to endorse or promote products |
| 14 | * derived from this software without specific prior written permission. |
| 15 | * |
| 16 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| 17 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF |
| 18 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO |
| 19 | * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 20 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| 21 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; |
| 22 | * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
| 23 | * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR |
| 24 | * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
| 25 | * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 26 | */ |
| 27 | |
| 28 | #include "talk/base/bandwidthsmoother.h" |
| 29 | |
| 30 | #include <limits.h> |
| 31 | |
| 32 | namespace talk_base { |
| 33 | |
| 34 | BandwidthSmoother::BandwidthSmoother(int initial_bandwidth_guess, |
| 35 | uint32 time_between_increase, |
| 36 | double percent_increase, |
| 37 | size_t samples_count_to_average, |
| 38 | double min_sample_count_percent) |
| 39 | : time_between_increase_(time_between_increase), |
| 40 | percent_increase_(talk_base::_max(1.0, percent_increase)), |
| 41 | time_at_last_change_(0), |
| 42 | bandwidth_estimation_(initial_bandwidth_guess), |
| 43 | accumulator_(samples_count_to_average), |
| 44 | min_sample_count_percent_( |
| 45 | talk_base::_min(1.0, |
| 46 | talk_base::_max(0.0, min_sample_count_percent))) { |
| 47 | } |
| 48 | |
| 49 | // Samples a new bandwidth measurement |
| 50 | // returns true if the bandwidth estimation changed |
| 51 | bool BandwidthSmoother::Sample(uint32 sample_time, int bandwidth) { |
| 52 | if (bandwidth < 0) { |
| 53 | return false; |
| 54 | } |
| 55 | |
| 56 | accumulator_.AddSample(bandwidth); |
| 57 | |
| 58 | if (accumulator_.count() < static_cast<size_t>( |
| 59 | accumulator_.max_count() * min_sample_count_percent_)) { |
| 60 | // We have not collected enough samples yet. |
| 61 | return false; |
| 62 | } |
| 63 | |
| 64 | // Replace bandwidth with the mean of sampled bandwidths. |
henrike@webrtc.org | 7587c5e | 2014-02-27 17:52:04 +0000 | [diff] [blame] | 65 | const int mean_bandwidth = static_cast<int>(accumulator_.ComputeMean()); |
henrike@webrtc.org | 0e118e7 | 2013-07-10 00:45:36 +0000 | [diff] [blame] | 66 | |
| 67 | if (mean_bandwidth < bandwidth_estimation_) { |
| 68 | time_at_last_change_ = sample_time; |
| 69 | bandwidth_estimation_ = mean_bandwidth; |
| 70 | return true; |
| 71 | } |
| 72 | |
| 73 | const int old_bandwidth_estimation = bandwidth_estimation_; |
| 74 | const double increase_threshold_d = percent_increase_ * bandwidth_estimation_; |
| 75 | if (increase_threshold_d > INT_MAX) { |
| 76 | // If bandwidth goes any higher we would overflow. |
| 77 | return false; |
| 78 | } |
| 79 | |
| 80 | const int increase_threshold = static_cast<int>(increase_threshold_d); |
| 81 | if (mean_bandwidth < increase_threshold) { |
| 82 | time_at_last_change_ = sample_time; |
| 83 | // The value of bandwidth_estimation remains the same if we don't exceed |
| 84 | // percent_increase_ * bandwidth_estimation_ for at least |
| 85 | // time_between_increase_ time. |
| 86 | } else if (sample_time >= time_at_last_change_ + time_between_increase_) { |
| 87 | time_at_last_change_ = sample_time; |
| 88 | if (increase_threshold == 0) { |
| 89 | // Bandwidth_estimation_ must be zero. Assume a jump from zero to a |
| 90 | // positive bandwidth means we have regained connectivity. |
| 91 | bandwidth_estimation_ = mean_bandwidth; |
| 92 | } else { |
| 93 | bandwidth_estimation_ = increase_threshold; |
| 94 | } |
| 95 | } |
| 96 | // Else don't make a change. |
| 97 | |
| 98 | return old_bandwidth_estimation != bandwidth_estimation_; |
| 99 | } |
| 100 | |
| 101 | } // namespace talk_base |