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92ea95e34a
In https://webrtc-review.googlesource.com/c/src/+/1560 we moved WebRTC from src/webrtc to src/ (in order to preserve an healthy git history). This CL takes care of fixing header guards, #include paths, etc... NOPRESUBMIT=true NOTREECHECKS=true NOTRY=true TBR=tommi@webrtc.org Bug: chromium:611808 Change-Id: Iea91618212bee0af16aa3f05071eab8f93706578 Reviewed-on: https://webrtc-review.googlesource.com/1561 Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Reviewed-by: Henrik Kjellander <kjellander@webrtc.org> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org> Cr-Commit-Position: refs/heads/master@{#19846}
107 lines
3.7 KiB
C++
107 lines
3.7 KiB
C++
/*
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* Copyright (c) 2017 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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#include "modules/congestion_controller/bitrate_estimator.h"
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#include <cmath>
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#include "modules/remote_bitrate_estimator/test/bwe_test_logging.h"
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#include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
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namespace webrtc {
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namespace {
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constexpr int kInitialRateWindowMs = 500;
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constexpr int kRateWindowMs = 150;
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} // namespace
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BitrateEstimator::BitrateEstimator()
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: sum_(0),
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current_win_ms_(0),
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prev_time_ms_(-1),
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bitrate_estimate_(-1.0f),
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bitrate_estimate_var_(50.0f) {}
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BitrateEstimator::~BitrateEstimator() = default;
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void BitrateEstimator::Update(int64_t now_ms, int bytes) {
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int rate_window_ms = kRateWindowMs;
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// We use a larger window at the beginning to get a more stable sample that
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// we can use to initialize the estimate.
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if (bitrate_estimate_ < 0.f)
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rate_window_ms = kInitialRateWindowMs;
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float bitrate_sample = UpdateWindow(now_ms, bytes, rate_window_ms);
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if (bitrate_sample < 0.0f)
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return;
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if (bitrate_estimate_ < 0.0f) {
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// This is the very first sample we get. Use it to initialize the estimate.
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bitrate_estimate_ = bitrate_sample;
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return;
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}
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// Define the sample uncertainty as a function of how far away it is from the
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// current estimate.
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float sample_uncertainty =
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10.0f * std::abs(bitrate_estimate_ - bitrate_sample) / bitrate_estimate_;
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float sample_var = sample_uncertainty * sample_uncertainty;
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// Update a bayesian estimate of the rate, weighting it lower if the sample
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// uncertainty is large.
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// The bitrate estimate uncertainty is increased with each update to model
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// that the bitrate changes over time.
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float pred_bitrate_estimate_var = bitrate_estimate_var_ + 5.f;
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bitrate_estimate_ = (sample_var * bitrate_estimate_ +
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pred_bitrate_estimate_var * bitrate_sample) /
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(sample_var + pred_bitrate_estimate_var);
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bitrate_estimate_var_ = sample_var * pred_bitrate_estimate_var /
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(sample_var + pred_bitrate_estimate_var);
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BWE_TEST_LOGGING_PLOT(1, "acknowledged_bitrate", now_ms,
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bitrate_estimate_ * 1000);
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}
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float BitrateEstimator::UpdateWindow(int64_t now_ms,
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int bytes,
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int rate_window_ms) {
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// Reset if time moves backwards.
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if (now_ms < prev_time_ms_) {
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prev_time_ms_ = -1;
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sum_ = 0;
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current_win_ms_ = 0;
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}
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if (prev_time_ms_ >= 0) {
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current_win_ms_ += now_ms - prev_time_ms_;
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// Reset if nothing has been received for more than a full window.
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if (now_ms - prev_time_ms_ > rate_window_ms) {
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sum_ = 0;
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current_win_ms_ %= rate_window_ms;
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}
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}
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prev_time_ms_ = now_ms;
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float bitrate_sample = -1.0f;
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if (current_win_ms_ >= rate_window_ms) {
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bitrate_sample = 8.0f * sum_ / static_cast<float>(rate_window_ms);
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current_win_ms_ -= rate_window_ms;
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sum_ = 0;
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}
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sum_ += bytes;
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return bitrate_sample;
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}
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rtc::Optional<uint32_t> BitrateEstimator::bitrate_bps() const {
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if (bitrate_estimate_ < 0.f)
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return rtc::Optional<uint32_t>();
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return rtc::Optional<uint32_t>(bitrate_estimate_ * 1000);
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}
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void BitrateEstimator::ExpectFastRateChange() {
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// By setting the bitrate-estimate variance to a higher value we allow the
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// bitrate to change fast for the next few samples.
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bitrate_estimate_var_ += 200;
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}
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} // namespace webrtc
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