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/*
* Copyright (c) 2015 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/pacing/packet_router.h"
#include <algorithm>
#include <cstdint>
#include <limits>
#include <memory>
#include <utility>
#include "absl/types/optional.h"
#include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
#include "modules/rtp_rtcp/source/rtcp_packet.h"
#include "modules/rtp_rtcp/source/rtcp_packet/transport_feedback.h"
#include "modules/rtp_rtcp/source/rtp_rtcp_interface.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/time_utils.h"
#include "rtc_base/trace_event.h"
namespace webrtc {
namespace {
constexpr int kRembSendIntervalMs = 200;
} // namespace
PacketRouter::PacketRouter() : PacketRouter(0) {}
PacketRouter::PacketRouter(uint16_t start_transport_seq)
: last_send_module_(nullptr),
last_remb_time_ms_(rtc::TimeMillis()),
last_send_bitrate_bps_(0),
bitrate_bps_(0),
max_bitrate_bps_(std::numeric_limits<decltype(max_bitrate_bps_)>::max()),
active_remb_module_(nullptr),
transport_seq_(start_transport_seq) {}
PacketRouter::~PacketRouter() {
RTC_DCHECK(send_modules_map_.empty());
RTC_DCHECK(send_modules_list_.empty());
RTC_DCHECK(rtcp_feedback_senders_.empty());
RTC_DCHECK(sender_remb_candidates_.empty());
RTC_DCHECK(receiver_remb_candidates_.empty());
RTC_DCHECK(active_remb_module_ == nullptr);
}
void PacketRouter::AddSendRtpModule(RtpRtcpInterface* rtp_module,
bool remb_candidate) {
MutexLock lock(&modules_mutex_);
AddSendRtpModuleToMap(rtp_module, rtp_module->SSRC());
if (absl::optional<uint32_t> rtx_ssrc = rtp_module->RtxSsrc()) {
AddSendRtpModuleToMap(rtp_module, *rtx_ssrc);
}
if (absl::optional<uint32_t> flexfec_ssrc = rtp_module->FlexfecSsrc()) {
AddSendRtpModuleToMap(rtp_module, *flexfec_ssrc);
}
if (rtp_module->SupportsRtxPayloadPadding()) {
last_send_module_ = rtp_module;
}
if (remb_candidate) {
AddRembModuleCandidate(rtp_module, /* media_sender = */ true);
}
}
void PacketRouter::AddSendRtpModuleToMap(RtpRtcpInterface* rtp_module,
uint32_t ssrc) {
RTC_DCHECK(send_modules_map_.find(ssrc) == send_modules_map_.end());
// Always keep the audio modules at the back of the list, so that when we
// iterate over the modules in order to find one that can send padding we
// will prioritize video. This is important to make sure they are counted
// into the bandwidth estimate properly.
if (rtp_module->IsAudioConfigured()) {
send_modules_list_.push_back(rtp_module);
} else {
send_modules_list_.push_front(rtp_module);
}
send_modules_map_[ssrc] = rtp_module;
}
void PacketRouter::RemoveSendRtpModuleFromMap(uint32_t ssrc) {
auto kv = send_modules_map_.find(ssrc);
RTC_DCHECK(kv != send_modules_map_.end());
send_modules_list_.remove(kv->second);
send_modules_map_.erase(kv);
}
void PacketRouter::RemoveSendRtpModule(RtpRtcpInterface* rtp_module) {
MutexLock lock(&modules_mutex_);
MaybeRemoveRembModuleCandidate(rtp_module, /* media_sender = */ true);
RemoveSendRtpModuleFromMap(rtp_module->SSRC());
if (absl::optional<uint32_t> rtx_ssrc = rtp_module->RtxSsrc()) {
RemoveSendRtpModuleFromMap(*rtx_ssrc);
}
if (absl::optional<uint32_t> flexfec_ssrc = rtp_module->FlexfecSsrc()) {
RemoveSendRtpModuleFromMap(*flexfec_ssrc);
}
if (last_send_module_ == rtp_module) {
last_send_module_ = nullptr;
}
}
void PacketRouter::AddReceiveRtpModule(RtcpFeedbackSenderInterface* rtcp_sender,
bool remb_candidate) {
MutexLock lock(&modules_mutex_);
RTC_DCHECK(std::find(rtcp_feedback_senders_.begin(),
rtcp_feedback_senders_.end(),
rtcp_sender) == rtcp_feedback_senders_.end());
rtcp_feedback_senders_.push_back(rtcp_sender);
if (remb_candidate) {
AddRembModuleCandidate(rtcp_sender, /* media_sender = */ false);
}
}
void PacketRouter::RemoveReceiveRtpModule(
RtcpFeedbackSenderInterface* rtcp_sender) {
MutexLock lock(&modules_mutex_);
MaybeRemoveRembModuleCandidate(rtcp_sender, /* media_sender = */ false);
auto it = std::find(rtcp_feedback_senders_.begin(),
rtcp_feedback_senders_.end(), rtcp_sender);
RTC_DCHECK(it != rtcp_feedback_senders_.end());
rtcp_feedback_senders_.erase(it);
}
void PacketRouter::SendPacket(std::unique_ptr<RtpPacketToSend> packet,
const PacedPacketInfo& cluster_info) {
TRACE_EVENT2(TRACE_DISABLED_BY_DEFAULT("webrtc"), "PacketRouter::SendPacket",
"sequence_number", packet->SequenceNumber(), "rtp_timestamp",
packet->Timestamp());
MutexLock lock(&modules_mutex_);
// With the new pacer code path, transport sequence numbers are only set here,
// on the pacer thread. Therefore we don't need atomics/synchronization.
if (packet->HasExtension<TransportSequenceNumber>()) {
packet->SetExtension<TransportSequenceNumber>((++transport_seq_) & 0xFFFF);
}
uint32_t ssrc = packet->Ssrc();
auto kv = send_modules_map_.find(ssrc);
if (kv == send_modules_map_.end()) {
RTC_LOG(LS_WARNING)
<< "Failed to send packet, matching RTP module not found "
"or transport error. SSRC = "
<< packet->Ssrc() << ", sequence number " << packet->SequenceNumber();
return;
}
RtpRtcpInterface* rtp_module = kv->second;
if (!rtp_module->TrySendPacket(packet.get(), cluster_info)) {
RTC_LOG(LS_WARNING) << "Failed to send packet, rejected by RTP module.";
return;
}
if (rtp_module->SupportsRtxPayloadPadding()) {
// This is now the last module to send media, and has the desired
// properties needed for payload based padding. Cache it for later use.
last_send_module_ = rtp_module;
}
for (auto& packet : rtp_module->FetchFecPackets()) {
pending_fec_packets_.push_back(std::move(packet));
}
}
std::vector<std::unique_ptr<RtpPacketToSend>> PacketRouter::FetchFec() {
MutexLock lock(&modules_mutex_);
std::vector<std::unique_ptr<RtpPacketToSend>> fec_packets =
std::move(pending_fec_packets_);
pending_fec_packets_.clear();
return fec_packets;
}
std::vector<std::unique_ptr<RtpPacketToSend>> PacketRouter::GeneratePadding(
DataSize size) {
TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("webrtc"),
"PacketRouter::GeneratePadding", "bytes", size.bytes());
MutexLock lock(&modules_mutex_);
// First try on the last rtp module to have sent media. This increases the
// the chance that any payload based padding will be useful as it will be
// somewhat distributed over modules according the packet rate, even if it
// will be more skewed towards the highest bitrate stream. At the very least
// this prevents sending payload padding on a disabled stream where it's
// guaranteed not to be useful.
std::vector<std::unique_ptr<RtpPacketToSend>> padding_packets;
if (last_send_module_ != nullptr &&
last_send_module_->SupportsRtxPayloadPadding()) {
padding_packets = last_send_module_->GeneratePadding(size.bytes());
}
if (padding_packets.empty()) {
// Iterate over all modules send module. Video modules will be at the front
// and so will be prioritized. This is important since audio packets may not
// be taken into account by the bandwidth estimator, e.g. in FF.
for (RtpRtcpInterface* rtp_module : send_modules_list_) {
if (rtp_module->SupportsPadding()) {
padding_packets = rtp_module->GeneratePadding(size.bytes());
if (!padding_packets.empty()) {
last_send_module_ = rtp_module;
break;
}
}
}
}
#if RTC_TRACE_EVENTS_ENABLED
for (auto& packet : padding_packets) {
TRACE_EVENT2(TRACE_DISABLED_BY_DEFAULT("webrtc"),
"PacketRouter::GeneratePadding::Loop", "sequence_number",
packet->SequenceNumber(), "rtp_timestamp",
packet->Timestamp());
}
#endif
return padding_packets;
}
uint16_t PacketRouter::CurrentTransportSequenceNumber() const {
MutexLock lock(&modules_mutex_);
return transport_seq_ & 0xFFFF;
}
void PacketRouter::OnReceiveBitrateChanged(const std::vector<uint32_t>& ssrcs,
uint32_t bitrate_bps) {
// % threshold for if we should send a new REMB asap.
const int64_t kSendThresholdPercent = 97;
// TODO(danilchap): Remove receive_bitrate_bps variable and the cast
// when OnReceiveBitrateChanged takes bitrate as int64_t.
int64_t receive_bitrate_bps = static_cast<int64_t>(bitrate_bps);
int64_t now_ms = rtc::TimeMillis();
{
MutexLock lock(&remb_mutex_);
// If we already have an estimate, check if the new total estimate is below
// kSendThresholdPercent of the previous estimate.
if (last_send_bitrate_bps_ > 0) {
int64_t new_remb_bitrate_bps =
last_send_bitrate_bps_ - bitrate_bps_ + receive_bitrate_bps;
if (new_remb_bitrate_bps <
kSendThresholdPercent * last_send_bitrate_bps_ / 100) {
// The new bitrate estimate is less than kSendThresholdPercent % of the
// last report. Send a REMB asap.
last_remb_time_ms_ = now_ms - kRembSendIntervalMs;
}
}
bitrate_bps_ = receive_bitrate_bps;
if (now_ms - last_remb_time_ms_ < kRembSendIntervalMs) {
return;
}
// NOTE: Updated if we intend to send the data; we might not have
// a module to actually send it.
last_remb_time_ms_ = now_ms;
last_send_bitrate_bps_ = receive_bitrate_bps;
// Cap the value to send in remb with configured value.
receive_bitrate_bps = std::min(receive_bitrate_bps, max_bitrate_bps_);
}
SendRemb(receive_bitrate_bps, ssrcs);
}
void PacketRouter::SetMaxDesiredReceiveBitrate(int64_t bitrate_bps) {
RTC_DCHECK_GE(bitrate_bps, 0);
{
MutexLock lock(&remb_mutex_);
max_bitrate_bps_ = bitrate_bps;
if (rtc::TimeMillis() - last_remb_time_ms_ < kRembSendIntervalMs &&
last_send_bitrate_bps_ > 0 &&
last_send_bitrate_bps_ <= max_bitrate_bps_) {
// Recent measured bitrate is already below the cap.
return;
}
}
SendRemb(bitrate_bps, /*ssrcs=*/{});
}
bool PacketRouter::SendRemb(int64_t bitrate_bps,
const std::vector<uint32_t>& ssrcs) {
MutexLock lock(&modules_mutex_);
if (!active_remb_module_) {
return false;
}
// The Add* and Remove* methods above ensure that REMB is disabled on all
// other modules, because otherwise, they will send REMB with stale info.
active_remb_module_->SetRemb(bitrate_bps, ssrcs);
return true;
}
bool PacketRouter::SendCombinedRtcpPacket(
std::vector<std::unique_ptr<rtcp::RtcpPacket>> packets) {
MutexLock lock(&modules_mutex_);
// Prefer send modules.
for (RtpRtcpInterface* rtp_module : send_modules_list_) {
if (rtp_module->RTCP() == RtcpMode::kOff) {
continue;
}
rtp_module->SendCombinedRtcpPacket(std::move(packets));
return true;
}
if (rtcp_feedback_senders_.empty()) {
return false;
}
auto* rtcp_sender = rtcp_feedback_senders_[0];
rtcp_sender->SendCombinedRtcpPacket(std::move(packets));
return true;
}
void PacketRouter::AddRembModuleCandidate(
RtcpFeedbackSenderInterface* candidate_module,
bool media_sender) {
RTC_DCHECK(candidate_module);
std::vector<RtcpFeedbackSenderInterface*>& candidates =
media_sender ? sender_remb_candidates_ : receiver_remb_candidates_;
RTC_DCHECK(std::find(candidates.cbegin(), candidates.cend(),
candidate_module) == candidates.cend());
candidates.push_back(candidate_module);
DetermineActiveRembModule();
}
void PacketRouter::MaybeRemoveRembModuleCandidate(
RtcpFeedbackSenderInterface* candidate_module,
bool media_sender) {
RTC_DCHECK(candidate_module);
std::vector<RtcpFeedbackSenderInterface*>& candidates =
media_sender ? sender_remb_candidates_ : receiver_remb_candidates_;
auto it = std::find(candidates.begin(), candidates.end(), candidate_module);
if (it == candidates.end()) {
return; // Function called due to removal of non-REMB-candidate module.
}
if (*it == active_remb_module_) {
UnsetActiveRembModule();
}
candidates.erase(it);
DetermineActiveRembModule();
}
void PacketRouter::UnsetActiveRembModule() {
RTC_CHECK(active_remb_module_);
active_remb_module_->UnsetRemb();
active_remb_module_ = nullptr;
}
void PacketRouter::DetermineActiveRembModule() {
// Sender modules take precedence over receiver modules, because SRs (sender
// reports) are sent more frequently than RR (receiver reports).
// When adding the first sender module, we should change the active REMB
// module to be that. Otherwise, we remain with the current active module.
RtcpFeedbackSenderInterface* new_active_remb_module;
if (!sender_remb_candidates_.empty()) {
new_active_remb_module = sender_remb_candidates_.front();
} else if (!receiver_remb_candidates_.empty()) {
new_active_remb_module = receiver_remb_candidates_.front();
} else {
new_active_remb_module = nullptr;
}
if (new_active_remb_module != active_remb_module_ && active_remb_module_) {
UnsetActiveRembModule();
}
active_remb_module_ = new_active_remb_module;
}
} // namespace webrtc