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/*
* Copyright (c) 2012 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 "modules/remote_bitrate_estimator/remote_bitrate_estimator_single_stream.h"
#include <cstdint>
#include <utility>
#include "absl/types/optional.h"
#include "modules/remote_bitrate_estimator/aimd_rate_control.h"
#include "modules/remote_bitrate_estimator/include/bwe_defines.h"
#include "modules/remote_bitrate_estimator/inter_arrival.h"
#include "modules/remote_bitrate_estimator/overuse_detector.h"
#include "modules/remote_bitrate_estimator/overuse_estimator.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "system_wrappers/include/clock.h"
#include "system_wrappers/include/metrics.h"
namespace webrtc {
namespace {
absl::optional<DataRate> OptionalRateFromOptionalBps(
absl::optional<int> bitrate_bps) {
if (bitrate_bps) {
return DataRate::BitsPerSec(*bitrate_bps);
} else {
return absl::nullopt;
}
}
} // namespace
enum { kTimestampGroupLengthMs = 5 };
static const double kTimestampToMs = 1.0 / 90.0;
struct RemoteBitrateEstimatorSingleStream::Detector {
explicit Detector(int64_t last_packet_time_ms,
const OverUseDetectorOptions& options,
bool enable_burst_grouping,
const FieldTrialsView* key_value_config)
: last_packet_time_ms(last_packet_time_ms),
inter_arrival(90 * kTimestampGroupLengthMs,
kTimestampToMs,
enable_burst_grouping),
estimator(options),
detector(key_value_config) {}
int64_t last_packet_time_ms;
InterArrival inter_arrival;
OveruseEstimator estimator;
OveruseDetector detector;
};
RemoteBitrateEstimatorSingleStream::RemoteBitrateEstimatorSingleStream(
RemoteBitrateObserver* observer,
Clock* clock)
: clock_(clock),
incoming_bitrate_(kBitrateWindowMs, 8000),
last_valid_incoming_bitrate_(0),
remote_rate_(new AimdRateControl(&field_trials_)),
observer_(observer),
last_process_time_(-1),
process_interval_ms_(kProcessIntervalMs),
uma_recorded_(false) {
RTC_LOG(LS_INFO) << "RemoteBitrateEstimatorSingleStream: Instantiating.";
}
RemoteBitrateEstimatorSingleStream::~RemoteBitrateEstimatorSingleStream() {
while (!overuse_detectors_.empty()) {
SsrcOveruseEstimatorMap::iterator it = overuse_detectors_.begin();
delete it->second;
overuse_detectors_.erase(it);
}
}
void RemoteBitrateEstimatorSingleStream::IncomingPacket(
int64_t arrival_time_ms,
size_t payload_size,
const RTPHeader& header) {
if (!uma_recorded_) {
BweNames type = BweNames::kReceiverTOffset;
if (!header.extension.hasTransmissionTimeOffset)
type = BweNames::kReceiverNoExtension;
RTC_HISTOGRAM_ENUMERATION(kBweTypeHistogram, type, BweNames::kBweNamesMax);
uma_recorded_ = true;
}
uint32_t ssrc = header.ssrc;
uint32_t rtp_timestamp =
header.timestamp + header.extension.transmissionTimeOffset;
int64_t now_ms = clock_->TimeInMilliseconds();
MutexLock lock(&mutex_);
SsrcOveruseEstimatorMap::iterator it = overuse_detectors_.find(ssrc);
if (it == overuse_detectors_.end()) {
// This is a new SSRC. Adding to map.
// TODO(holmer): If the channel changes SSRC the old SSRC will still be
// around in this map until the channel is deleted. This is OK since the
// callback will no longer be called for the old SSRC. This will be
// automatically cleaned up when we have one RemoteBitrateEstimator per REMB
// group.
std::pair<SsrcOveruseEstimatorMap::iterator, bool> insert_result =
overuse_detectors_.insert(
std::make_pair(ssrc, new Detector(now_ms, OverUseDetectorOptions(),
true, &field_trials_)));
it = insert_result.first;
}
Detector* estimator = it->second;
estimator->last_packet_time_ms = now_ms;
// Check if incoming bitrate estimate is valid, and if it needs to be reset.
absl::optional<uint32_t> incoming_bitrate = incoming_bitrate_.Rate(now_ms);
if (incoming_bitrate) {
last_valid_incoming_bitrate_ = *incoming_bitrate;
} else if (last_valid_incoming_bitrate_ > 0) {
// Incoming bitrate had a previous valid value, but now not enough data
// point are left within the current window. Reset incoming bitrate
// estimator so that the window size will only contain new data points.
incoming_bitrate_.Reset();
last_valid_incoming_bitrate_ = 0;
}
incoming_bitrate_.Update(payload_size, now_ms);
const BandwidthUsage prior_state = estimator->detector.State();
uint32_t timestamp_delta = 0;
int64_t time_delta = 0;
int size_delta = 0;
if (estimator->inter_arrival.ComputeDeltas(
rtp_timestamp, arrival_time_ms, now_ms, payload_size,
&timestamp_delta, &time_delta, &size_delta)) {
double timestamp_delta_ms = timestamp_delta * kTimestampToMs;
estimator->estimator.Update(time_delta, timestamp_delta_ms, size_delta,
estimator->detector.State(), now_ms);
estimator->detector.Detect(estimator->estimator.offset(),
timestamp_delta_ms,
estimator->estimator.num_of_deltas(), now_ms);
}
if (estimator->detector.State() == BandwidthUsage::kBwOverusing) {
absl::optional<uint32_t> incoming_bitrate_bps =
incoming_bitrate_.Rate(now_ms);
if (incoming_bitrate_bps &&
(prior_state != BandwidthUsage::kBwOverusing ||
GetRemoteRate()->TimeToReduceFurther(
Timestamp::Millis(now_ms),
DataRate::BitsPerSec(*incoming_bitrate_bps)))) {
// The first overuse should immediately trigger a new estimate.
// We also have to update the estimate immediately if we are overusing
// and the target bitrate is too high compared to what we are receiving.
UpdateEstimate(now_ms);
}
}
}
TimeDelta RemoteBitrateEstimatorSingleStream::Process() {
MutexLock lock(&mutex_);
int64_t now_ms = clock_->TimeInMilliseconds();
int64_t next_process_time_ms = last_process_time_ + process_interval_ms_;
if (last_process_time_ == -1 || now_ms >= next_process_time_ms) {
UpdateEstimate(now_ms);
last_process_time_ = now_ms;
return TimeDelta::Millis(process_interval_ms_);
}
return TimeDelta::Millis(next_process_time_ms - now_ms);
}
void RemoteBitrateEstimatorSingleStream::UpdateEstimate(int64_t now_ms) {
BandwidthUsage bw_state = BandwidthUsage::kBwNormal;
SsrcOveruseEstimatorMap::iterator it = overuse_detectors_.begin();
while (it != overuse_detectors_.end()) {
const int64_t time_of_last_received_packet =
it->second->last_packet_time_ms;
if (time_of_last_received_packet >= 0 &&
now_ms - time_of_last_received_packet > kStreamTimeOutMs) {
// This over-use detector hasn't received packets for `kStreamTimeOutMs`
// milliseconds and is considered stale.
delete it->second;
overuse_detectors_.erase(it++);
} else {
// Make sure that we trigger an over-use if any of the over-use detectors
// is detecting over-use.
if (it->second->detector.State() > bw_state) {
bw_state = it->second->detector.State();
}
++it;
}
}
// We can't update the estimate if we don't have any active streams.
if (overuse_detectors_.empty()) {
return;
}
AimdRateControl* remote_rate = GetRemoteRate();
const RateControlInput input(
bw_state, OptionalRateFromOptionalBps(incoming_bitrate_.Rate(now_ms)));
uint32_t target_bitrate =
remote_rate->Update(&input, Timestamp::Millis(now_ms)).bps<uint32_t>();
if (remote_rate->ValidEstimate()) {
process_interval_ms_ = remote_rate->GetFeedbackInterval().ms();
RTC_DCHECK_GT(process_interval_ms_, 0);
std::vector<uint32_t> ssrcs;
GetSsrcs(&ssrcs);
if (observer_)
observer_->OnReceiveBitrateChanged(ssrcs, target_bitrate);
}
}
void RemoteBitrateEstimatorSingleStream::OnRttUpdate(int64_t avg_rtt_ms,
int64_t max_rtt_ms) {
MutexLock lock(&mutex_);
GetRemoteRate()->SetRtt(TimeDelta::Millis(avg_rtt_ms));
}
void RemoteBitrateEstimatorSingleStream::RemoveStream(unsigned int ssrc) {
MutexLock lock(&mutex_);
SsrcOveruseEstimatorMap::iterator it = overuse_detectors_.find(ssrc);
if (it != overuse_detectors_.end()) {
delete it->second;
overuse_detectors_.erase(it);
}
}
DataRate RemoteBitrateEstimatorSingleStream::LatestEstimate() const {
MutexLock lock(&mutex_);
if (!remote_rate_->ValidEstimate() || overuse_detectors_.empty()) {
return DataRate::Zero();
}
return remote_rate_->LatestEstimate();
}
void RemoteBitrateEstimatorSingleStream::GetSsrcs(
std::vector<uint32_t>* ssrcs) const {
RTC_DCHECK(ssrcs);
ssrcs->resize(overuse_detectors_.size());
int i = 0;
for (SsrcOveruseEstimatorMap::const_iterator it = overuse_detectors_.begin();
it != overuse_detectors_.end(); ++it, ++i) {
(*ssrcs)[i] = it->first;
}
}
AimdRateControl* RemoteBitrateEstimatorSingleStream::GetRemoteRate() {
if (!remote_rate_)
remote_rate_.reset(new AimdRateControl(&field_trials_));
return remote_rate_.get();
}
} // namespace webrtc