blob: daa51bddd30977992d8ad0e9f8529377be6d3ae4 [file] [log] [blame]
/*
* Copyright (c) 2018 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 <string>
#include <algorithm>
#include "modules/congestion_controller/congestion_window_pushback_controller.h"
#include "system_wrappers/include/field_trial.h"
namespace webrtc {
// When CongestionWindowPushback is enabled, the pacer is oblivious to
// the congestion window. The relation between outstanding data and
// the congestion window affects encoder allocations directly.
// This experiment is build on top of congestion window experiment.
const char kCongestionPushbackExperiment[] = "WebRTC-CongestionWindowPushback";
const uint32_t kDefaultMinPushbackTargetBitrateBps = 30000;
bool ReadCongestionWindowPushbackExperimentParameter(
uint32_t* min_pushback_target_bitrate_bps) {
RTC_DCHECK(min_pushback_target_bitrate_bps);
std::string experiment_string =
webrtc::field_trial::FindFullName(kCongestionPushbackExperiment);
int parsed_values = sscanf(experiment_string.c_str(), "Enabled-%" PRIu32,
min_pushback_target_bitrate_bps);
if (parsed_values == 1) {
RTC_CHECK_GE(*min_pushback_target_bitrate_bps, 0)
<< "Min pushback target bitrate must be greater than or equal to 0.";
return true;
}
return false;
}
CongestionWindowPushbackController::CongestionWindowPushbackController() {
if (!ReadCongestionWindowPushbackExperimentParameter(
&min_pushback_target_bitrate_bps_)) {
min_pushback_target_bitrate_bps_ = kDefaultMinPushbackTargetBitrateBps;
}
}
void CongestionWindowPushbackController::UpdateOutstandingData(
size_t outstanding_bytes) {
outstanding_bytes_ = outstanding_bytes;
}
void CongestionWindowPushbackController::UpdateMaxOutstandingData(
size_t max_outstanding_bytes) {
DataSize data_window = DataSize::bytes(max_outstanding_bytes);
if (current_data_window_) {
data_window = (data_window + current_data_window_.value()) / 2;
}
current_data_window_ = data_window;
}
void CongestionWindowPushbackController::SetDataWindow(DataSize data_window) {
current_data_window_ = data_window;
}
uint32_t CongestionWindowPushbackController::UpdateTargetBitrate(
uint32_t bitrate_bps) {
if (!current_data_window_ || current_data_window_->IsZero())
return bitrate_bps;
double fill_ratio =
outstanding_bytes_ / static_cast<double>(current_data_window_->bytes());
if (fill_ratio > 1.5) {
encoding_rate_ratio_ *= 0.9;
} else if (fill_ratio > 1) {
encoding_rate_ratio_ *= 0.95;
} else if (fill_ratio < 0.1) {
encoding_rate_ratio_ = 1.0;
} else {
encoding_rate_ratio_ *= 1.05;
encoding_rate_ratio_ = std::min(encoding_rate_ratio_, 1.0);
}
uint32_t adjusted_target_bitrate_bps =
static_cast<uint32_t>(bitrate_bps * encoding_rate_ratio_);
// Do not adjust below the minimum pushback bitrate but do obey if the
// original estimate is below it.
bitrate_bps = adjusted_target_bitrate_bps < min_pushback_target_bitrate_bps_
? std::min(bitrate_bps, min_pushback_target_bitrate_bps_)
: adjusted_target_bitrate_bps;
return bitrate_bps;
}
} // namespace webrtc