/*
 *  Copyright (c) 2013 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 "video/video_send_stream.h"

#include <algorithm>
#include <cmath>
#include <set>
#include <sstream>
#include <string>
#include <utility>
#include <vector>

#include "call/rtp_transport_controller_send_interface.h"
#include "call/video_send_stream.h"
#include "common_types.h"  // NOLINT(build/include)
#include "common_video/include/video_bitrate_allocator.h"
#include "modules/bitrate_controller/include/bitrate_controller.h"
#include "modules/congestion_controller/include/send_side_congestion_controller.h"
#include "modules/pacing/packet_router.h"
#include "modules/rtp_rtcp/include/rtp_rtcp.h"
#include "modules/rtp_rtcp/source/rtp_sender.h"
#include "modules/utility/include/process_thread.h"
#include "modules/video_coding/fec_controller_default.h"
#include "modules/video_coding/utility/ivf_file_writer.h"
#include "rtc_base/checks.h"
#include "rtc_base/experiments/alr_experiment.h"
#include "rtc_base/file.h"
#include "rtc_base/location.h"
#include "rtc_base/logging.h"
#include "rtc_base/trace_event.h"
#include "rtc_base/weak_ptr.h"
#include "system_wrappers/include/field_trial.h"
#include "video/call_stats.h"
#include "video/payload_router.h"

namespace webrtc {

static const int kMinSendSidePacketHistorySize = 600;
static const int kSendSideSeqNumSetMaxSize = 15000;

namespace {

// We don't do MTU discovery, so assume that we have the standard ethernet MTU.
const size_t kPathMTU = 1500;

std::vector<RtpRtcp*> CreateRtpRtcpModules(
    Transport* outgoing_transport,
    RtcpIntraFrameObserver* intra_frame_callback,
    RtcpBandwidthObserver* bandwidth_callback,
    RtpTransportControllerSendInterface* transport,
    RtcpRttStats* rtt_stats,
    FlexfecSender* flexfec_sender,
    SendStatisticsProxy* stats_proxy,
    SendDelayStats* send_delay_stats,
    RtcEventLog* event_log,
    RateLimiter* retransmission_rate_limiter,
    OverheadObserver* overhead_observer,
    size_t num_modules,
    RtpKeepAliveConfig keepalive_config,
    RtcpIntervalConfig rtc_interval_config) {
  RTC_DCHECK_GT(num_modules, 0);
  RtpRtcp::Configuration configuration;
  configuration.audio = false;
  configuration.receiver_only = false;
  configuration.flexfec_sender = flexfec_sender;
  configuration.outgoing_transport = outgoing_transport;
  configuration.intra_frame_callback = intra_frame_callback;
  configuration.bandwidth_callback = bandwidth_callback;
  configuration.transport_feedback_callback =
      transport->transport_feedback_observer();
  configuration.rtt_stats = rtt_stats;
  configuration.rtcp_packet_type_counter_observer = stats_proxy;
  configuration.paced_sender = transport->packet_sender();
  configuration.transport_sequence_number_allocator =
      transport->packet_router();
  configuration.send_bitrate_observer = stats_proxy;
  configuration.send_frame_count_observer = stats_proxy;
  configuration.send_side_delay_observer = stats_proxy;
  configuration.send_packet_observer = send_delay_stats;
  configuration.event_log = event_log;
  configuration.retransmission_rate_limiter = retransmission_rate_limiter;
  configuration.overhead_observer = overhead_observer;
  configuration.keepalive_config = keepalive_config;
  std::vector<RtpRtcp*> modules;
  for (size_t i = 0; i < num_modules; ++i) {
    RtpRtcp* rtp_rtcp = RtpRtcp::CreateRtpRtcp(configuration);
    rtp_rtcp->SetSendingStatus(false);
    rtp_rtcp->SetSendingMediaStatus(false);
    rtp_rtcp->SetRTCPStatus(RtcpMode::kCompound);
    modules.push_back(rtp_rtcp);
  }
  return modules;
}

// TODO(brandtr): Update this function when we support multistream protection.
std::unique_ptr<FlexfecSender> MaybeCreateFlexfecSender(
    const VideoSendStream::Config& config,
    const std::map<uint32_t, RtpState>& suspended_ssrcs) {
  if (config.rtp.flexfec.payload_type < 0) {
    return nullptr;
  }
  RTC_DCHECK_GE(config.rtp.flexfec.payload_type, 0);
  RTC_DCHECK_LE(config.rtp.flexfec.payload_type, 127);
  if (config.rtp.flexfec.ssrc == 0) {
    RTC_LOG(LS_WARNING) << "FlexFEC is enabled, but no FlexFEC SSRC given. "
                           "Therefore disabling FlexFEC.";
    return nullptr;
  }
  if (config.rtp.flexfec.protected_media_ssrcs.empty()) {
    RTC_LOG(LS_WARNING)
        << "FlexFEC is enabled, but no protected media SSRC given. "
           "Therefore disabling FlexFEC.";
    return nullptr;
  }

  if (config.rtp.ssrcs.size() > 1) {
    RTC_LOG(LS_WARNING)
        << "Both FlexFEC and simulcast are enabled. This "
           "combination is however not supported by our current "
           "FlexFEC implementation. Therefore disabling FlexFEC.";
    return nullptr;
  }

  if (config.rtp.flexfec.protected_media_ssrcs.size() > 1) {
    RTC_LOG(LS_WARNING)
        << "The supplied FlexfecConfig contained multiple protected "
           "media streams, but our implementation currently only "
           "supports protecting a single media stream. "
           "To avoid confusion, disabling FlexFEC completely.";
    return nullptr;
  }

  const RtpState* rtp_state = nullptr;
  auto it = suspended_ssrcs.find(config.rtp.flexfec.ssrc);
  if (it != suspended_ssrcs.end()) {
    rtp_state = &it->second;
  }

  RTC_DCHECK_EQ(1U, config.rtp.flexfec.protected_media_ssrcs.size());
  return std::unique_ptr<FlexfecSender>(new FlexfecSender(
      config.rtp.flexfec.payload_type, config.rtp.flexfec.ssrc,
      config.rtp.flexfec.protected_media_ssrcs[0], config.rtp.extensions,
      RTPSender::FecExtensionSizes(), rtp_state, Clock::GetRealTimeClock()));
}

bool TransportSeqNumExtensionConfigured(const VideoSendStream::Config& config) {
  const std::vector<RtpExtension>& extensions = config.rtp.extensions;
  return std::find_if(
             extensions.begin(), extensions.end(), [](const RtpExtension& ext) {
               return ext.uri == RtpExtension::kTransportSequenceNumberUri;
             }) != extensions.end();
}

const char kForcedFallbackFieldTrial[] =
    "WebRTC-VP8-Forced-Fallback-Encoder-v2";

rtc::Optional<int> GetFallbackMinBpsFromFieldTrial() {
  if (!webrtc::field_trial::IsEnabled(kForcedFallbackFieldTrial))
    return rtc::nullopt;

  std::string group =
      webrtc::field_trial::FindFullName(kForcedFallbackFieldTrial);
  if (group.empty())
    return rtc::nullopt;

  int min_pixels;
  int max_pixels;
  int min_bps;
  if (sscanf(group.c_str(), "Enabled-%d,%d,%d", &min_pixels, &max_pixels,
             &min_bps) != 3) {
    return rtc::nullopt;
  }

  if (min_bps <= 0)
    return rtc::nullopt;

  return min_bps;
}

int GetEncoderMinBitrateBps() {
  const int kDefaultEncoderMinBitrateBps = 30000;
  return GetFallbackMinBpsFromFieldTrial().value_or(
      kDefaultEncoderMinBitrateBps);
}

bool PayloadTypeSupportsSkippingFecPackets(const std::string& payload_name) {
  const VideoCodecType codecType = PayloadStringToCodecType(payload_name);
  if (codecType == kVideoCodecVP8 || codecType == kVideoCodecVP9) {
    return true;
  }
  return false;
}

int CalculateMaxPadBitrateBps(std::vector<VideoStream> streams,
                              int min_transmit_bitrate_bps,
                              bool pad_to_min_bitrate) {
  int pad_up_to_bitrate_bps = 0;
  // Calculate max padding bitrate for a multi layer codec.
  if (streams.size() > 1) {
    // Pad to min bitrate of the highest layer.
    pad_up_to_bitrate_bps = streams[streams.size() - 1].min_bitrate_bps;
    // Add target_bitrate_bps of the lower layers.
    for (size_t i = 0; i < streams.size() - 1; ++i)
      pad_up_to_bitrate_bps += streams[i].target_bitrate_bps;
  } else if (pad_to_min_bitrate) {
    pad_up_to_bitrate_bps = streams[0].min_bitrate_bps;
  }

  pad_up_to_bitrate_bps =
      std::max(pad_up_to_bitrate_bps, min_transmit_bitrate_bps);

  return pad_up_to_bitrate_bps;
}

uint32_t CalculateOverheadRateBps(int packets_per_second,
                                  size_t overhead_bytes_per_packet,
                                  uint32_t max_overhead_bps) {
  uint32_t overhead_bps =
      static_cast<uint32_t>(8 * overhead_bytes_per_packet * packets_per_second);
  return std::min(overhead_bps, max_overhead_bps);
}

int CalculatePacketRate(uint32_t bitrate_bps, size_t packet_size_bytes) {
  size_t packet_size_bits = 8 * packet_size_bytes;
  // Ceil for int value of bitrate_bps / packet_size_bits.
  return static_cast<int>((bitrate_bps + packet_size_bits - 1) /
                          packet_size_bits);
}

// TODO(pbos): Lower these thresholds (to closer to 100%) when we handle
// pipelining encoders better (multiple input frames before something comes
// out). This should effectively turn off CPU adaptations for systems that
// remotely cope with the load right now.
CpuOveruseOptions GetCpuOveruseOptions(const VideoSendStream::Config& config) {
  CpuOveruseOptions options;

  if (config.encoder_settings.full_overuse_time) {
    options.low_encode_usage_threshold_percent = 150;
    options.high_encode_usage_threshold_percent = 200;
  }
  if (config.encoder_settings.experiment_cpu_load_estimator) {
    options.filter_time_ms = 5 * rtc::kNumMillisecsPerSec;
  }

  return options;
}

}  // namespace

namespace internal {

// VideoSendStreamImpl implements internal::VideoSendStream.
// It is created and destroyed on |worker_queue|. The intent is to decrease the
// need for locking and to ensure methods are called in sequence.
// Public methods except |DeliverRtcp| must be called on |worker_queue|.
// DeliverRtcp is called on the libjingle worker thread or a network thread.
// An encoder may deliver frames through the EncodedImageCallback on an
// arbitrary thread.
class VideoSendStreamImpl : public webrtc::BitrateAllocatorObserver,
                            public webrtc::OverheadObserver,
                            public webrtc::VCMProtectionCallback,
                            public VideoStreamEncoder::EncoderSink,
                            public VideoBitrateAllocationObserver,
                            public webrtc::PacketFeedbackObserver {
 public:
  VideoSendStreamImpl(
      SendStatisticsProxy* stats_proxy,
      rtc::TaskQueue* worker_queue,
      CallStats* call_stats,
      RtpTransportControllerSendInterface* transport,
      BitrateAllocator* bitrate_allocator,
      SendDelayStats* send_delay_stats,
      VideoStreamEncoder* video_stream_encoder,
      RtcEventLog* event_log,
      const VideoSendStream::Config* config,
      int initial_encoder_max_bitrate,
      double initial_encoder_bitrate_priority,
      std::map<uint32_t, RtpState> suspended_ssrcs,
      std::map<uint32_t, RtpPayloadState> suspended_payload_states,
      VideoEncoderConfig::ContentType content_type,
      std::unique_ptr<FecController> fec_controller);
  ~VideoSendStreamImpl() override;

  // RegisterProcessThread register |module_process_thread| with those objects
  // that use it. Registration has to happen on the thread were
  // |module_process_thread| was created (libjingle's worker thread).
  // TODO(perkj): Replace the use of |module_process_thread| with a TaskQueue,
  // maybe |worker_queue|.
  void RegisterProcessThread(ProcessThread* module_process_thread);
  void DeRegisterProcessThread();

  void SignalNetworkState(NetworkState state);
  bool DeliverRtcp(const uint8_t* packet, size_t length);
  void UpdateActiveSimulcastLayers(const std::vector<bool> active_layers);
  void Start();
  void Stop();

  VideoSendStream::RtpStateMap GetRtpStates() const;
  VideoSendStream::RtpPayloadStateMap GetRtpPayloadStates() const;

  void EnableEncodedFrameRecording(const std::vector<rtc::PlatformFile>& files,
                                   size_t byte_limit);

  void SetTransportOverhead(size_t transport_overhead_per_packet);

  rtc::Optional<float> configured_pacing_factor_;

  // From PacketFeedbackObserver.
  void OnPacketAdded(uint32_t ssrc, uint16_t seq_num) override;
  void OnPacketFeedbackVector(
      const std::vector<PacketFeedback>& packet_feedback_vector) override;

 private:
  class CheckEncoderActivityTask;
  class EncoderReconfiguredTask;

  // Implements BitrateAllocatorObserver.
  uint32_t OnBitrateUpdated(uint32_t bitrate_bps,
                            uint8_t fraction_loss,
                            int64_t rtt,
                            int64_t probing_interval_ms) override;

  // Implements webrtc::VCMProtectionCallback.
  int ProtectionRequest(const FecProtectionParams* delta_params,
                        const FecProtectionParams* key_params,
                        uint32_t* sent_video_rate_bps,
                        uint32_t* sent_nack_rate_bps,
                        uint32_t* sent_fec_rate_bps) override;

  // Implements OverheadObserver.
  void OnOverheadChanged(size_t overhead_bytes_per_packet) override;

  void OnEncoderConfigurationChanged(std::vector<VideoStream> streams,
                                     int min_transmit_bitrate_bps) override;

  // Implements EncodedImageCallback. The implementation routes encoded frames
  // to the |payload_router_| and |config.pre_encode_callback| if set.
  // Called on an arbitrary encoder callback thread.
  EncodedImageCallback::Result OnEncodedImage(
      const EncodedImage& encoded_image,
      const CodecSpecificInfo* codec_specific_info,
      const RTPFragmentationHeader* fragmentation) override;

  // Implements VideoBitrateAllocationObserver.
  void OnBitrateAllocationUpdated(const BitrateAllocation& allocation) override;

  // Starts monitoring and sends a keyframe.
  void StartupVideoSendStream();
  // Removes the bitrate observer, stops monitoring and notifies the video
  // encoder of the bitrate update.
  void StopVideoSendStream();

  void ConfigureProtection();
  void ConfigureSsrcs();
  void SignalEncoderTimedOut();
  void SignalEncoderActive();

  const bool send_side_bwe_with_overhead_;

  SendStatisticsProxy* const stats_proxy_;
  const VideoSendStream::Config* const config_;
  std::map<uint32_t, RtpState> suspended_ssrcs_;

  std::unique_ptr<FecController> fec_controller_;
  ProcessThread* module_process_thread_;
  rtc::ThreadChecker module_process_thread_checker_;
  rtc::TaskQueue* const worker_queue_;

  rtc::CriticalSection encoder_activity_crit_sect_;
  CheckEncoderActivityTask* check_encoder_activity_task_
      RTC_GUARDED_BY(encoder_activity_crit_sect_);

  CallStats* const call_stats_;
  RtpTransportControllerSendInterface* const transport_;
  BitrateAllocator* const bitrate_allocator_;

  // TODO(brandtr): Move ownership to PayloadRouter.
  std::unique_ptr<FlexfecSender> flexfec_sender_;

  rtc::CriticalSection ivf_writers_crit_;
  std::unique_ptr<IvfFileWriter>
      file_writers_[kMaxSimulcastStreams] RTC_GUARDED_BY(ivf_writers_crit_);

  int max_padding_bitrate_;
  int encoder_min_bitrate_bps_;
  uint32_t encoder_max_bitrate_bps_;
  uint32_t encoder_target_rate_bps_;
  double encoder_bitrate_priority_;

  VideoStreamEncoder* const video_stream_encoder_;
  EncoderRtcpFeedback encoder_feedback_;

  RtcpBandwidthObserver* const bandwidth_observer_;
  // RtpRtcp modules, declared here as they use other members on construction.
  const std::vector<RtpRtcp*> rtp_rtcp_modules_;
  PayloadRouter payload_router_;

  // |weak_ptr_| to our self. This is used since we can not call
  // |weak_ptr_factory_.GetWeakPtr| from multiple sequences but it is ok to copy
  // an existing WeakPtr.
  rtc::WeakPtr<VideoSendStreamImpl> weak_ptr_;
  // |weak_ptr_factory_| must be declared last to make sure all WeakPtr's are
  // invalidated before any other members are destroyed.
  rtc::WeakPtrFactory<VideoSendStreamImpl> weak_ptr_factory_;

  rtc::CriticalSection overhead_bytes_per_packet_crit_;
  size_t overhead_bytes_per_packet_
      RTC_GUARDED_BY(overhead_bytes_per_packet_crit_);
  size_t transport_overhead_bytes_per_packet_;

  std::set<uint16_t> feedback_packet_seq_num_set_;
  std::vector<bool> loss_mask_vector_;
};

// TODO(tommi): See if there's a more elegant way to create a task that creates
// an object on the correct task queue.
class VideoSendStream::ConstructionTask : public rtc::QueuedTask {
 public:
  ConstructionTask(
      std::unique_ptr<VideoSendStreamImpl>* send_stream,
      rtc::Event* done_event,
      SendStatisticsProxy* stats_proxy,
      VideoStreamEncoder* video_stream_encoder,
      ProcessThread* module_process_thread,
      CallStats* call_stats,
      RtpTransportControllerSendInterface* transport,
      BitrateAllocator* bitrate_allocator,
      SendDelayStats* send_delay_stats,
      RtcEventLog* event_log,
      const VideoSendStream::Config* config,
      int initial_encoder_max_bitrate,
      double initial_encoder_bitrate_priority,
      const std::map<uint32_t, RtpState>& suspended_ssrcs,
      const std::map<uint32_t, RtpPayloadState>& suspended_payload_states,
      VideoEncoderConfig::ContentType content_type,
      std::unique_ptr<FecController> fec_controller)
      : send_stream_(send_stream),
        done_event_(done_event),
        stats_proxy_(stats_proxy),
        video_stream_encoder_(video_stream_encoder),
        call_stats_(call_stats),
        transport_(transport),
        bitrate_allocator_(bitrate_allocator),
        send_delay_stats_(send_delay_stats),
        event_log_(event_log),
        config_(config),
        initial_encoder_max_bitrate_(initial_encoder_max_bitrate),
        initial_encoder_bitrate_priority_(initial_encoder_bitrate_priority),
        suspended_ssrcs_(suspended_ssrcs),
        suspended_payload_states_(suspended_payload_states),
        content_type_(content_type),
        fec_controller_(std::move(fec_controller)) {}

  ~ConstructionTask() override { done_event_->Set(); }

 private:
  bool Run() override {
    send_stream_->reset(new VideoSendStreamImpl(
        stats_proxy_, rtc::TaskQueue::Current(), call_stats_, transport_,
        bitrate_allocator_, send_delay_stats_, video_stream_encoder_,
        event_log_, config_, initial_encoder_max_bitrate_,
        initial_encoder_bitrate_priority_, std::move(suspended_ssrcs_),
        std::move(suspended_payload_states_), content_type_,
        std::move(fec_controller_)));
    return true;
  }

  std::unique_ptr<VideoSendStreamImpl>* const send_stream_;
  rtc::Event* const done_event_;
  SendStatisticsProxy* const stats_proxy_;
  VideoStreamEncoder* const video_stream_encoder_;
  CallStats* const call_stats_;
  RtpTransportControllerSendInterface* const transport_;
  BitrateAllocator* const bitrate_allocator_;
  SendDelayStats* const send_delay_stats_;
  RtcEventLog* const event_log_;
  const VideoSendStream::Config* config_;
  int initial_encoder_max_bitrate_;
  double initial_encoder_bitrate_priority_;
  std::map<uint32_t, RtpState> suspended_ssrcs_;
  std::map<uint32_t, RtpPayloadState> suspended_payload_states_;
  const VideoEncoderConfig::ContentType content_type_;
  std::unique_ptr<FecController> fec_controller_;
};

class VideoSendStream::DestructAndGetRtpStateTask : public rtc::QueuedTask {
 public:
  DestructAndGetRtpStateTask(
      VideoSendStream::RtpStateMap* state_map,
      VideoSendStream::RtpPayloadStateMap* payload_state_map,
      std::unique_ptr<VideoSendStreamImpl> send_stream,
      rtc::Event* done_event)
      : state_map_(state_map),
        payload_state_map_(payload_state_map),
        send_stream_(std::move(send_stream)),
        done_event_(done_event) {}

  ~DestructAndGetRtpStateTask() override { RTC_CHECK(!send_stream_); }

 private:
  bool Run() override {
    send_stream_->Stop();
    *state_map_ = send_stream_->GetRtpStates();
    *payload_state_map_ = send_stream_->GetRtpPayloadStates();
    send_stream_.reset();
    done_event_->Set();
    return true;
  }

  VideoSendStream::RtpStateMap* state_map_;
  VideoSendStream::RtpPayloadStateMap* payload_state_map_;
  std::unique_ptr<VideoSendStreamImpl> send_stream_;
  rtc::Event* done_event_;
};

// CheckEncoderActivityTask is used for tracking when the encoder last produced
// and encoded video frame. If the encoder has not produced anything the last
// kEncoderTimeOutMs we also want to stop sending padding.
class VideoSendStreamImpl::CheckEncoderActivityTask : public rtc::QueuedTask {
 public:
  static const int kEncoderTimeOutMs = 2000;
  explicit CheckEncoderActivityTask(
      const rtc::WeakPtr<VideoSendStreamImpl>& send_stream)
      : activity_(0), send_stream_(std::move(send_stream)), timed_out_(false) {}

  void Stop() {
    RTC_CHECK(task_checker_.CalledSequentially());
    send_stream_.reset();
  }

  void UpdateEncoderActivity() {
    // UpdateEncoderActivity is called from VideoSendStreamImpl::Encoded on
    // whatever thread the real encoder implementation run on. In the case of
    // hardware encoders, there might be several encoders
    // running in parallel on different threads.
    rtc::AtomicOps::ReleaseStore(&activity_, 1);
  }

 private:
  bool Run() override {
    RTC_CHECK(task_checker_.CalledSequentially());
    if (!send_stream_)
      return true;
    if (!rtc::AtomicOps::AcquireLoad(&activity_)) {
      if (!timed_out_) {
        send_stream_->SignalEncoderTimedOut();
      }
      timed_out_ = true;
    } else if (timed_out_) {
      send_stream_->SignalEncoderActive();
      timed_out_ = false;
    }
    rtc::AtomicOps::ReleaseStore(&activity_, 0);

    rtc::TaskQueue::Current()->PostDelayedTask(
        std::unique_ptr<rtc::QueuedTask>(this), kEncoderTimeOutMs);
    // Return false to prevent this task from being deleted. Ownership has been
    // transferred to the task queue when PostDelayedTask was called.
    return false;
  }
  volatile int activity_;

  rtc::SequencedTaskChecker task_checker_;
  rtc::WeakPtr<VideoSendStreamImpl> send_stream_;
  bool timed_out_;
};

class VideoSendStreamImpl::EncoderReconfiguredTask : public rtc::QueuedTask {
 public:
  EncoderReconfiguredTask(const rtc::WeakPtr<VideoSendStreamImpl>& send_stream,
                          std::vector<VideoStream> streams,
                          int min_transmit_bitrate_bps)
      : send_stream_(std::move(send_stream)),
        streams_(std::move(streams)),
        min_transmit_bitrate_bps_(min_transmit_bitrate_bps) {}

 private:
  bool Run() override {
    if (send_stream_)
      send_stream_->OnEncoderConfigurationChanged(std::move(streams_),
                                                  min_transmit_bitrate_bps_);
    return true;
  }

  rtc::WeakPtr<VideoSendStreamImpl> send_stream_;
  std::vector<VideoStream> streams_;
  int min_transmit_bitrate_bps_;
};

VideoSendStream::VideoSendStream(
    int num_cpu_cores,
    ProcessThread* module_process_thread,
    rtc::TaskQueue* worker_queue,
    CallStats* call_stats,
    RtpTransportControllerSendInterface* transport,
    BitrateAllocator* bitrate_allocator,
    SendDelayStats* send_delay_stats,
    RtcEventLog* event_log,
    VideoSendStream::Config config,
    VideoEncoderConfig encoder_config,
    const std::map<uint32_t, RtpState>& suspended_ssrcs,
    const std::map<uint32_t, RtpPayloadState>& suspended_payload_states,
    std::unique_ptr<FecController> fec_controller)
    : worker_queue_(worker_queue),
      thread_sync_event_(false /* manual_reset */, false),
      stats_proxy_(Clock::GetRealTimeClock(),
                   config,
                   encoder_config.content_type),
      config_(std::move(config)),
      content_type_(encoder_config.content_type) {
  video_stream_encoder_ = rtc::MakeUnique<VideoStreamEncoder>(
      num_cpu_cores, &stats_proxy_,
      config_.encoder_settings,
      config_.pre_encode_callback,
      rtc::MakeUnique<OveruseFrameDetector>(
          GetCpuOveruseOptions(config_), &stats_proxy_));

  worker_queue_->PostTask(std::unique_ptr<rtc::QueuedTask>(new ConstructionTask(
      &send_stream_, &thread_sync_event_, &stats_proxy_,
      video_stream_encoder_.get(), module_process_thread, call_stats, transport,
      bitrate_allocator, send_delay_stats, event_log, &config_,
      encoder_config.max_bitrate_bps, encoder_config.bitrate_priority,
      suspended_ssrcs, suspended_payload_states, encoder_config.content_type,
      std::move(fec_controller))));

  // Wait for ConstructionTask to complete so that |send_stream_| can be used.
  // |module_process_thread| must be registered and deregistered on the thread
  // it was created on.
  thread_sync_event_.Wait(rtc::Event::kForever);
  send_stream_->RegisterProcessThread(module_process_thread);
  // TODO(sprang): Enable this also for regular video calls if it works well.
  if (encoder_config.content_type == VideoEncoderConfig::ContentType::kScreen) {
    // Only signal target bitrate for screenshare streams, for now.
    video_stream_encoder_->SetBitrateObserver(send_stream_.get());
  }

  ReconfigureVideoEncoder(std::move(encoder_config));
}

VideoSendStream::~VideoSendStream() {
  RTC_DCHECK_RUN_ON(&thread_checker_);
  RTC_DCHECK(!send_stream_);
}

void VideoSendStream::UpdateActiveSimulcastLayers(
    const std::vector<bool> active_layers) {
  RTC_DCHECK_RUN_ON(&thread_checker_);
  RTC_LOG(LS_INFO) << "VideoSendStream::UpdateActiveSimulcastLayers";
  VideoSendStreamImpl* send_stream = send_stream_.get();
  worker_queue_->PostTask([this, send_stream, active_layers] {
    send_stream->UpdateActiveSimulcastLayers(active_layers);
    thread_sync_event_.Set();
  });

  thread_sync_event_.Wait(rtc::Event::kForever);
}

void VideoSendStream::Start() {
  RTC_DCHECK_RUN_ON(&thread_checker_);
  RTC_LOG(LS_INFO) << "VideoSendStream::Start";
  VideoSendStreamImpl* send_stream = send_stream_.get();
  worker_queue_->PostTask([this, send_stream] {
    send_stream->Start();
    thread_sync_event_.Set();
  });

  // It is expected that after VideoSendStream::Start has been called, incoming
  // frames are not dropped in VideoStreamEncoder. To ensure this, Start has to
  // be synchronized.
  thread_sync_event_.Wait(rtc::Event::kForever);
}

void VideoSendStream::Stop() {
  RTC_DCHECK_RUN_ON(&thread_checker_);
  RTC_LOG(LS_INFO) << "VideoSendStream::Stop";
  VideoSendStreamImpl* send_stream = send_stream_.get();
  worker_queue_->PostTask([send_stream] { send_stream->Stop(); });
}

void VideoSendStream::SetSource(
    rtc::VideoSourceInterface<webrtc::VideoFrame>* source,
    const DegradationPreference& degradation_preference) {
  RTC_DCHECK_RUN_ON(&thread_checker_);
  video_stream_encoder_->SetSource(source, degradation_preference);
}

void VideoSendStream::ReconfigureVideoEncoder(VideoEncoderConfig config) {
  // TODO(perkj): Some test cases in VideoSendStreamTest call
  // ReconfigureVideoEncoder from the network thread.
  // RTC_DCHECK_RUN_ON(&thread_checker_);
  RTC_DCHECK(content_type_ == config.content_type);
  video_stream_encoder_->ConfigureEncoder(std::move(config),
                                          config_.rtp.max_packet_size,
                                          config_.rtp.nack.rtp_history_ms > 0);
}

VideoSendStream::Stats VideoSendStream::GetStats() {
  // TODO(perkj, solenberg): Some test cases in EndToEndTest call GetStats from
  // a network thread. See comment in Call::GetStats().
  // RTC_DCHECK_RUN_ON(&thread_checker_);
  return stats_proxy_.GetStats();
}

rtc::Optional<float> VideoSendStream::GetPacingFactorOverride() const {
  return send_stream_->configured_pacing_factor_;
}

void VideoSendStream::SignalNetworkState(NetworkState state) {
  RTC_DCHECK_RUN_ON(&thread_checker_);
  VideoSendStreamImpl* send_stream = send_stream_.get();
  worker_queue_->PostTask(
      [send_stream, state] { send_stream->SignalNetworkState(state); });
}

void VideoSendStream::StopPermanentlyAndGetRtpStates(
    VideoSendStream::RtpStateMap* rtp_state_map,
    VideoSendStream::RtpPayloadStateMap* payload_state_map) {
  RTC_DCHECK_RUN_ON(&thread_checker_);
  video_stream_encoder_->Stop();
  send_stream_->DeRegisterProcessThread();
  worker_queue_->PostTask(
      std::unique_ptr<rtc::QueuedTask>(new DestructAndGetRtpStateTask(
          rtp_state_map, payload_state_map, std::move(send_stream_),
          &thread_sync_event_)));
  thread_sync_event_.Wait(rtc::Event::kForever);
}

void VideoSendStream::SetTransportOverhead(
    size_t transport_overhead_per_packet) {
  RTC_DCHECK_RUN_ON(&thread_checker_);
  VideoSendStreamImpl* send_stream = send_stream_.get();
  worker_queue_->PostTask([send_stream, transport_overhead_per_packet] {
    send_stream->SetTransportOverhead(transport_overhead_per_packet);
  });
}

bool VideoSendStream::DeliverRtcp(const uint8_t* packet, size_t length) {
  // Called on a network thread.
  return send_stream_->DeliverRtcp(packet, length);
}

void VideoSendStream::EnableEncodedFrameRecording(
    const std::vector<rtc::PlatformFile>& files,
    size_t byte_limit) {
  send_stream_->EnableEncodedFrameRecording(files, byte_limit);
}

VideoSendStreamImpl::VideoSendStreamImpl(
    SendStatisticsProxy* stats_proxy,
    rtc::TaskQueue* worker_queue,
    CallStats* call_stats,
    RtpTransportControllerSendInterface* transport,
    BitrateAllocator* bitrate_allocator,
    SendDelayStats* send_delay_stats,
    VideoStreamEncoder* video_stream_encoder,
    RtcEventLog* event_log,
    const VideoSendStream::Config* config,
    int initial_encoder_max_bitrate,
    double initial_encoder_bitrate_priority,
    std::map<uint32_t, RtpState> suspended_ssrcs,
    std::map<uint32_t, RtpPayloadState> suspended_payload_states,
    VideoEncoderConfig::ContentType content_type,
    std::unique_ptr<FecController> fec_controller)
    : send_side_bwe_with_overhead_(
          webrtc::field_trial::IsEnabled("WebRTC-SendSideBwe-WithOverhead")),
      stats_proxy_(stats_proxy),
      config_(config),
      suspended_ssrcs_(std::move(suspended_ssrcs)),
      fec_controller_(std::move(fec_controller)),
      module_process_thread_(nullptr),
      worker_queue_(worker_queue),
      check_encoder_activity_task_(nullptr),
      call_stats_(call_stats),
      transport_(transport),
      bitrate_allocator_(bitrate_allocator),
      flexfec_sender_(MaybeCreateFlexfecSender(*config_, suspended_ssrcs_)),
      max_padding_bitrate_(0),
      encoder_min_bitrate_bps_(0),
      encoder_max_bitrate_bps_(initial_encoder_max_bitrate),
      encoder_target_rate_bps_(0),
      encoder_bitrate_priority_(initial_encoder_bitrate_priority),
      video_stream_encoder_(video_stream_encoder),
      encoder_feedback_(Clock::GetRealTimeClock(),
                        config_->rtp.ssrcs,
                        video_stream_encoder),
      bandwidth_observer_(transport->send_side_cc()->GetBandwidthObserver()),
      rtp_rtcp_modules_(CreateRtpRtcpModules(
          config_->send_transport,
          &encoder_feedback_,
          bandwidth_observer_,
          transport,
          call_stats_->rtcp_rtt_stats(),
          flexfec_sender_.get(),
          stats_proxy_,
          send_delay_stats,
          event_log,
          transport->send_side_cc()->GetRetransmissionRateLimiter(),
          this,
          config_->rtp.ssrcs.size(),
          transport->keepalive_config(),
          RtcpIntervalConfig{config_->rtcp.video_report_interval_ms,
                             config_->rtcp.audio_report_interval_ms})),
      payload_router_(rtp_rtcp_modules_,
                      config_->rtp.ssrcs,
                      config_->encoder_settings.payload_type,
                      suspended_payload_states),
      weak_ptr_factory_(this),
      overhead_bytes_per_packet_(0),
      transport_overhead_bytes_per_packet_(0) {
  RTC_DCHECK_RUN_ON(worker_queue_);
  RTC_LOG(LS_INFO) << "VideoSendStreamInternal: " << config_->ToString();
  weak_ptr_ = weak_ptr_factory_.GetWeakPtr();
  module_process_thread_checker_.DetachFromThread();

  RTC_DCHECK(!config_->rtp.ssrcs.empty());
  RTC_DCHECK(call_stats_);
  RTC_DCHECK(transport_);
  RTC_DCHECK(transport_->send_side_cc());
  RTC_DCHECK_GT(encoder_max_bitrate_bps_, 0);

  RTC_CHECK(AlrExperimentSettings::MaxOneFieldTrialEnabled());
  // If send-side BWE is enabled, check if we should apply updated probing and
  // pacing settings.
  if (TransportSeqNumExtensionConfigured(*config_)) {
    rtc::Optional<AlrExperimentSettings> alr_settings;
    if (content_type == VideoEncoderConfig::ContentType::kScreen) {
      alr_settings = AlrExperimentSettings::CreateFromFieldTrial(
          AlrExperimentSettings::kScreenshareProbingBweExperimentName);
    } else {
      alr_settings = AlrExperimentSettings::CreateFromFieldTrial(
          AlrExperimentSettings::kStrictPacingAndProbingExperimentName);
    }
    if (alr_settings) {
      transport->send_side_cc()->EnablePeriodicAlrProbing(true);
      transport->send_side_cc()->SetPacingFactor(alr_settings->pacing_factor);
      configured_pacing_factor_ = alr_settings->pacing_factor;
      transport->pacer()->SetQueueTimeLimit(alr_settings->max_paced_queue_time);
    }
  }

  if (config_->periodic_alr_bandwidth_probing) {
    transport->send_side_cc()->EnablePeriodicAlrProbing(true);
  }

  // RTP/RTCP initialization.

  // We add the highest spatial layer first to ensure it'll be prioritized
  // when sending padding, with the hope that the packet rate will be smaller,
  // and that it's more important to protect than the lower layers.
  for (RtpRtcp* rtp_rtcp : rtp_rtcp_modules_) {
    constexpr bool remb_candidate = true;
    transport->packet_router()->AddSendRtpModule(rtp_rtcp, remb_candidate);
  }

  for (size_t i = 0; i < config_->rtp.extensions.size(); ++i) {
    const std::string& extension = config_->rtp.extensions[i].uri;
    int id = config_->rtp.extensions[i].id;
    // One-byte-extension local identifiers are in the range 1-14 inclusive.
    RTC_DCHECK_GE(id, 1);
    RTC_DCHECK_LE(id, 14);
    RTC_DCHECK(RtpExtension::IsSupportedForVideo(extension));
    for (RtpRtcp* rtp_rtcp : rtp_rtcp_modules_) {
      RTC_CHECK_EQ(0, rtp_rtcp->RegisterSendRtpHeaderExtension(
                          StringToRtpExtensionType(extension), id));
    }
  }

  ConfigureProtection();
  ConfigureSsrcs();

  // TODO(pbos): Should we set CNAME on all RTP modules?
  rtp_rtcp_modules_.front()->SetCNAME(config_->rtp.c_name.c_str());

  for (RtpRtcp* rtp_rtcp : rtp_rtcp_modules_) {
    rtp_rtcp->RegisterRtcpStatisticsCallback(stats_proxy_);
    rtp_rtcp->RegisterSendChannelRtpStatisticsCallback(stats_proxy_);
    rtp_rtcp->SetMaxRtpPacketSize(config_->rtp.max_packet_size);
    rtp_rtcp->RegisterVideoSendPayload(
        config_->encoder_settings.payload_type,
        config_->encoder_settings.payload_name.c_str());
  }

  fec_controller_->SetProtectionCallback(this);
  // Signal congestion controller this object is ready for OnPacket* callbacks.
  if (fec_controller_->UseLossVectorMask()) {
    transport_->send_side_cc()->RegisterPacketFeedbackObserver(this);
  }

  RTC_DCHECK(config_->encoder_settings.encoder);
  RTC_DCHECK_GE(config_->encoder_settings.payload_type, 0);
  RTC_DCHECK_LE(config_->encoder_settings.payload_type, 127);

  video_stream_encoder_->SetStartBitrate(
      bitrate_allocator_->GetStartBitrate(this));

  // Only request rotation at the source when we positively know that the remote
  // side doesn't support the rotation extension. This allows us to prepare the
  // encoder in the expectation that rotation is supported - which is the common
  // case.
  bool rotation_applied =
      std::find_if(config_->rtp.extensions.begin(),
                   config_->rtp.extensions.end(),
                   [](const RtpExtension& extension) {
                     return extension.uri == RtpExtension::kVideoRotationUri;
                   }) == config_->rtp.extensions.end();

  video_stream_encoder_->SetSink(this, rotation_applied);
}

void VideoSendStreamImpl::RegisterProcessThread(
    ProcessThread* module_process_thread) {
  RTC_DCHECK_RUN_ON(&module_process_thread_checker_);
  RTC_DCHECK(!module_process_thread_);
  module_process_thread_ = module_process_thread;

  for (RtpRtcp* rtp_rtcp : rtp_rtcp_modules_)
    module_process_thread_->RegisterModule(rtp_rtcp, RTC_FROM_HERE);
}

void VideoSendStreamImpl::DeRegisterProcessThread() {
  RTC_DCHECK_RUN_ON(&module_process_thread_checker_);
  for (RtpRtcp* rtp_rtcp : rtp_rtcp_modules_)
    module_process_thread_->DeRegisterModule(rtp_rtcp);
}

VideoSendStreamImpl::~VideoSendStreamImpl() {
  RTC_DCHECK_RUN_ON(worker_queue_);
  RTC_DCHECK(!payload_router_.IsActive())
      << "VideoSendStreamImpl::Stop not called";
  RTC_LOG(LS_INFO) << "~VideoSendStreamInternal: " << config_->ToString();
  if (fec_controller_->UseLossVectorMask()) {
    transport_->send_side_cc()->DeRegisterPacketFeedbackObserver(this);
  }
  for (RtpRtcp* rtp_rtcp : rtp_rtcp_modules_) {
    transport_->packet_router()->RemoveSendRtpModule(rtp_rtcp);
    delete rtp_rtcp;
  }
}

bool VideoSendStreamImpl::DeliverRtcp(const uint8_t* packet, size_t length) {
  // Runs on a network thread.
  RTC_DCHECK(!worker_queue_->IsCurrent());
  for (RtpRtcp* rtp_rtcp : rtp_rtcp_modules_)
    rtp_rtcp->IncomingRtcpPacket(packet, length);
  return true;
}

void VideoSendStreamImpl::UpdateActiveSimulcastLayers(
    const std::vector<bool> active_layers) {
  RTC_DCHECK_RUN_ON(worker_queue_);
  RTC_DCHECK_EQ(rtp_rtcp_modules_.size(), active_layers.size());
  RTC_LOG(LS_INFO) << "VideoSendStream::UpdateActiveSimulcastLayers";
  bool previously_active = payload_router_.IsActive();
  payload_router_.SetActiveModules(active_layers);
  if (!payload_router_.IsActive() && previously_active) {
    // Payload router switched from active to inactive.
    StopVideoSendStream();
  } else if (payload_router_.IsActive() && !previously_active) {
    // Payload router switched from inactive to active.
    StartupVideoSendStream();
  }
}

void VideoSendStreamImpl::Start() {
  RTC_DCHECK_RUN_ON(worker_queue_);
  RTC_LOG(LS_INFO) << "VideoSendStream::Start";
  if (payload_router_.IsActive())
    return;
  TRACE_EVENT_INSTANT0("webrtc", "VideoSendStream::Start");
  payload_router_.SetActive(true);
  StartupVideoSendStream();
}

void VideoSendStreamImpl::StartupVideoSendStream() {
  RTC_DCHECK_RUN_ON(worker_queue_);
  bitrate_allocator_->AddObserver(
      this, encoder_min_bitrate_bps_, encoder_max_bitrate_bps_,
      max_padding_bitrate_, !config_->suspend_below_min_bitrate,
      config_->track_id, encoder_bitrate_priority_);
  // Start monitoring encoder activity.
  {
    rtc::CritScope lock(&encoder_activity_crit_sect_);
    RTC_DCHECK(!check_encoder_activity_task_);
    check_encoder_activity_task_ = new CheckEncoderActivityTask(weak_ptr_);
    worker_queue_->PostDelayedTask(
        std::unique_ptr<rtc::QueuedTask>(check_encoder_activity_task_),
        CheckEncoderActivityTask::kEncoderTimeOutMs);
  }

  video_stream_encoder_->SendKeyFrame();
}

void VideoSendStreamImpl::Stop() {
  RTC_DCHECK_RUN_ON(worker_queue_);
  RTC_LOG(LS_INFO) << "VideoSendStream::Stop";
  if (!payload_router_.IsActive())
    return;
  TRACE_EVENT_INSTANT0("webrtc", "VideoSendStream::Stop");
  payload_router_.SetActive(false);
  StopVideoSendStream();
}

void VideoSendStreamImpl::StopVideoSendStream() {
  bitrate_allocator_->RemoveObserver(this);
  {
    rtc::CritScope lock(&encoder_activity_crit_sect_);
    check_encoder_activity_task_->Stop();
    check_encoder_activity_task_ = nullptr;
  }
  video_stream_encoder_->OnBitrateUpdated(0, 0, 0);
  stats_proxy_->OnSetEncoderTargetRate(0);
}

void VideoSendStreamImpl::SignalEncoderTimedOut() {
  RTC_DCHECK_RUN_ON(worker_queue_);
  // If the encoder has not produced anything the last kEncoderTimeOutMs and it
  // is supposed to, deregister as BitrateAllocatorObserver. This can happen
  // if a camera stops producing frames.
  if (encoder_target_rate_bps_ > 0) {
    RTC_LOG(LS_INFO) << "SignalEncoderTimedOut, Encoder timed out.";
    bitrate_allocator_->RemoveObserver(this);
  }
}

void VideoSendStreamImpl::OnBitrateAllocationUpdated(
    const BitrateAllocation& allocation) {
  payload_router_.OnBitrateAllocationUpdated(allocation);
}

void VideoSendStreamImpl::SignalEncoderActive() {
  RTC_DCHECK_RUN_ON(worker_queue_);
  RTC_LOG(LS_INFO) << "SignalEncoderActive, Encoder is active.";
  bitrate_allocator_->AddObserver(
      this, encoder_min_bitrate_bps_, encoder_max_bitrate_bps_,
      max_padding_bitrate_, !config_->suspend_below_min_bitrate,
      config_->track_id, encoder_bitrate_priority_);
}

void VideoSendStreamImpl::OnEncoderConfigurationChanged(
    std::vector<VideoStream> streams,
    int min_transmit_bitrate_bps) {
  if (!worker_queue_->IsCurrent()) {
    worker_queue_->PostTask(
        std::unique_ptr<rtc::QueuedTask>(new EncoderReconfiguredTask(
            weak_ptr_, std::move(streams), min_transmit_bitrate_bps)));
    return;
  }
  RTC_DCHECK_GE(config_->rtp.ssrcs.size(), streams.size());
  TRACE_EVENT0("webrtc", "VideoSendStream::OnEncoderConfigurationChanged");
  RTC_DCHECK_GE(config_->rtp.ssrcs.size(), streams.size());
  RTC_DCHECK_RUN_ON(worker_queue_);

  encoder_min_bitrate_bps_ =
      std::max(streams[0].min_bitrate_bps, GetEncoderMinBitrateBps());
  encoder_max_bitrate_bps_ = 0;
  double stream_bitrate_priority_sum = 0;
  for (const auto& stream : streams) {
    // We don't want to allocate more bitrate than needed to inactive streams.
    encoder_max_bitrate_bps_ += stream.active ? stream.max_bitrate_bps : 0;
    if (stream.bitrate_priority) {
      RTC_DCHECK_GT(*stream.bitrate_priority, 0);
      stream_bitrate_priority_sum += *stream.bitrate_priority;
    }
  }
  RTC_DCHECK_GT(stream_bitrate_priority_sum, 0);
  encoder_bitrate_priority_ = stream_bitrate_priority_sum;
  encoder_max_bitrate_bps_ =
      std::max(static_cast<uint32_t>(encoder_min_bitrate_bps_),
               encoder_max_bitrate_bps_);
  max_padding_bitrate_ = CalculateMaxPadBitrateBps(
      streams, min_transmit_bitrate_bps, config_->suspend_below_min_bitrate);

  // Clear stats for disabled layers.
  for (size_t i = streams.size(); i < config_->rtp.ssrcs.size(); ++i) {
    stats_proxy_->OnInactiveSsrc(config_->rtp.ssrcs[i]);
  }

  size_t number_of_temporal_layers =
      streams.back().temporal_layer_thresholds_bps.size() + 1;
  fec_controller_->SetEncodingData(streams[0].width, streams[0].height,
                                   number_of_temporal_layers,
                                   config_->rtp.max_packet_size);

  if (payload_router_.IsActive()) {
    // The send stream is started already. Update the allocator with new bitrate
    // limits.
    bitrate_allocator_->AddObserver(
        this, encoder_min_bitrate_bps_, encoder_max_bitrate_bps_,
        max_padding_bitrate_, !config_->suspend_below_min_bitrate,
        config_->track_id, encoder_bitrate_priority_);
  }
}

EncodedImageCallback::Result VideoSendStreamImpl::OnEncodedImage(
    const EncodedImage& encoded_image,
    const CodecSpecificInfo* codec_specific_info,
    const RTPFragmentationHeader* fragmentation) {
  // Encoded is called on whatever thread the real encoder implementation run
  // on. In the case of hardware encoders, there might be several encoders
  // running in parallel on different threads.
  size_t simulcast_idx = 0;
  if (codec_specific_info->codecType == kVideoCodecVP8) {
    simulcast_idx = codec_specific_info->codecSpecific.VP8.simulcastIdx;
  }
  if (config_->post_encode_callback) {
    config_->post_encode_callback->EncodedFrameCallback(EncodedFrame(
        encoded_image._buffer, encoded_image._length, encoded_image._frameType,
        simulcast_idx, encoded_image._timeStamp));
  }
  {
    rtc::CritScope lock(&encoder_activity_crit_sect_);
    if (check_encoder_activity_task_)
      check_encoder_activity_task_->UpdateEncoderActivity();
  }

  fec_controller_->UpdateWithEncodedData(encoded_image);
  EncodedImageCallback::Result result = payload_router_.OnEncodedImage(
      encoded_image, codec_specific_info, fragmentation);

  RTC_DCHECK(codec_specific_info);

  int layer = codec_specific_info->codecType == kVideoCodecVP8
                  ? codec_specific_info->codecSpecific.VP8.simulcastIdx
                  : 0;
  {
    rtc::CritScope lock(&ivf_writers_crit_);
    if (file_writers_[layer].get()) {
      bool ok = file_writers_[layer]->WriteFrame(
          encoded_image, codec_specific_info->codecType);
      RTC_DCHECK(ok);
    }
  }

  return result;
}

void VideoSendStreamImpl::ConfigureProtection() {
  RTC_DCHECK_RUN_ON(worker_queue_);

  // Consistency of FlexFEC parameters is checked in MaybeCreateFlexfecSender.
  const bool flexfec_enabled = (flexfec_sender_ != nullptr);

  // Consistency of NACK and RED+ULPFEC parameters is checked in this function.
  const bool nack_enabled = config_->rtp.nack.rtp_history_ms > 0;
  int red_payload_type = config_->rtp.ulpfec.red_payload_type;
  int ulpfec_payload_type = config_->rtp.ulpfec.ulpfec_payload_type;

  // Shorthands.
  auto IsRedEnabled = [&]() { return red_payload_type >= 0; };
  auto DisableRed = [&]() { red_payload_type = -1; };
  auto IsUlpfecEnabled = [&]() { return ulpfec_payload_type >= 0; };
  auto DisableUlpfec = [&]() { ulpfec_payload_type = -1; };

  if (webrtc::field_trial::IsEnabled("WebRTC-DisableUlpFecExperiment")) {
    RTC_LOG(LS_INFO) << "Experiment to disable sending ULPFEC is enabled.";
    DisableUlpfec();
  }

  // If enabled, FlexFEC takes priority over RED+ULPFEC.
  if (flexfec_enabled) {
    // We can safely disable RED here, because if the remote supports FlexFEC,
    // we know that it has a receiver without the RED/RTX workaround.
    // See http://crbug.com/webrtc/6650 for more information.
    if (IsRedEnabled()) {
      RTC_LOG(LS_INFO) << "Both FlexFEC and RED are configured. Disabling RED.";
      DisableRed();
    }
    if (IsUlpfecEnabled()) {
      RTC_LOG(LS_INFO)
          << "Both FlexFEC and ULPFEC are configured. Disabling ULPFEC.";
      DisableUlpfec();
    }
  }

  // Payload types without picture ID cannot determine that a stream is complete
  // without retransmitting FEC, so using ULPFEC + NACK for H.264 (for instance)
  // is a waste of bandwidth since FEC packets still have to be transmitted.
  // Note that this is not the case with FlexFEC.
  if (nack_enabled && IsUlpfecEnabled() &&
      !PayloadTypeSupportsSkippingFecPackets(
          config_->encoder_settings.payload_name)) {
    RTC_LOG(LS_WARNING)
        << "Transmitting payload type without picture ID using "
           "NACK+ULPFEC is a waste of bandwidth since ULPFEC packets "
           "also have to be retransmitted. Disabling ULPFEC.";
    DisableUlpfec();
  }

  // Verify payload types.
  //
  // Due to how old receivers work, we need to always send RED if it has been
  // negotiated. This is a remnant of an old RED/RTX workaround, see
  // https://codereview.webrtc.org/2469093003.
  // TODO(brandtr): This change went into M56, so we can remove it in ~M59.
  // At that time, we can disable RED whenever ULPFEC is disabled, as there is
  // no point in using RED without ULPFEC.
  if (IsRedEnabled()) {
    RTC_DCHECK_GE(red_payload_type, 0);
    RTC_DCHECK_LE(red_payload_type, 127);
  }
  if (IsUlpfecEnabled()) {
    RTC_DCHECK_GE(ulpfec_payload_type, 0);
    RTC_DCHECK_LE(ulpfec_payload_type, 127);
    if (!IsRedEnabled()) {
      RTC_LOG(LS_WARNING)
          << "ULPFEC is enabled but RED is disabled. Disabling ULPFEC.";
      DisableUlpfec();
    }
  }

  for (RtpRtcp* rtp_rtcp : rtp_rtcp_modules_) {
    // Set NACK.
    rtp_rtcp->SetStorePacketsStatus(
        true,
        kMinSendSidePacketHistorySize);
    // Set RED/ULPFEC information.
    rtp_rtcp->SetUlpfecConfig(red_payload_type, ulpfec_payload_type);
  }

  // Currently, both ULPFEC and FlexFEC use the same FEC rate calculation logic,
  // so enable that logic if either of those FEC schemes are enabled.
  fec_controller_->SetProtectionMethod(flexfec_enabled || IsUlpfecEnabled(),
                                       nack_enabled);
}

void VideoSendStreamImpl::ConfigureSsrcs() {
  RTC_DCHECK_RUN_ON(worker_queue_);
  // Configure regular SSRCs.
  for (size_t i = 0; i < config_->rtp.ssrcs.size(); ++i) {
    uint32_t ssrc = config_->rtp.ssrcs[i];
    RtpRtcp* const rtp_rtcp = rtp_rtcp_modules_[i];
    rtp_rtcp->SetSSRC(ssrc);

    // Restore RTP state if previous existed.
    VideoSendStream::RtpStateMap::iterator it = suspended_ssrcs_.find(ssrc);
    if (it != suspended_ssrcs_.end())
      rtp_rtcp->SetRtpState(it->second);
  }

  // Set up RTX if available.
  if (config_->rtp.rtx.ssrcs.empty())
    return;

  // Configure RTX SSRCs.
  RTC_DCHECK_EQ(config_->rtp.rtx.ssrcs.size(), config_->rtp.ssrcs.size());
  for (size_t i = 0; i < config_->rtp.rtx.ssrcs.size(); ++i) {
    uint32_t ssrc = config_->rtp.rtx.ssrcs[i];
    RtpRtcp* const rtp_rtcp = rtp_rtcp_modules_[i];
    rtp_rtcp->SetRtxSsrc(ssrc);
    VideoSendStream::RtpStateMap::iterator it = suspended_ssrcs_.find(ssrc);
    if (it != suspended_ssrcs_.end())
      rtp_rtcp->SetRtxState(it->second);
  }

  // Configure RTX payload types.
  RTC_DCHECK_GE(config_->rtp.rtx.payload_type, 0);
  for (RtpRtcp* rtp_rtcp : rtp_rtcp_modules_) {
    rtp_rtcp->SetRtxSendPayloadType(config_->rtp.rtx.payload_type,
                                    config_->encoder_settings.payload_type);
    rtp_rtcp->SetRtxSendStatus(kRtxRetransmitted | kRtxRedundantPayloads);
  }
  if (config_->rtp.ulpfec.red_payload_type != -1 &&
      config_->rtp.ulpfec.red_rtx_payload_type != -1) {
    for (RtpRtcp* rtp_rtcp : rtp_rtcp_modules_) {
      rtp_rtcp->SetRtxSendPayloadType(config_->rtp.ulpfec.red_rtx_payload_type,
                                      config_->rtp.ulpfec.red_payload_type);
    }
  }
}

std::map<uint32_t, RtpState> VideoSendStreamImpl::GetRtpStates() const {
  RTC_DCHECK_RUN_ON(worker_queue_);
  std::map<uint32_t, RtpState> rtp_states;

  for (size_t i = 0; i < config_->rtp.ssrcs.size(); ++i) {
    uint32_t ssrc = config_->rtp.ssrcs[i];
    RTC_DCHECK_EQ(ssrc, rtp_rtcp_modules_[i]->SSRC());
    rtp_states[ssrc] = rtp_rtcp_modules_[i]->GetRtpState();
  }

  for (size_t i = 0; i < config_->rtp.rtx.ssrcs.size(); ++i) {
    uint32_t ssrc = config_->rtp.rtx.ssrcs[i];
    rtp_states[ssrc] = rtp_rtcp_modules_[i]->GetRtxState();
  }

  if (flexfec_sender_) {
    uint32_t ssrc = config_->rtp.flexfec.ssrc;
    rtp_states[ssrc] = flexfec_sender_->GetRtpState();
  }

  return rtp_states;
}

std::map<uint32_t, RtpPayloadState> VideoSendStreamImpl::GetRtpPayloadStates()
    const {
  RTC_DCHECK_RUN_ON(worker_queue_);
  return payload_router_.GetRtpPayloadStates();
}

void VideoSendStreamImpl::SignalNetworkState(NetworkState state) {
  RTC_DCHECK_RUN_ON(worker_queue_);
  for (RtpRtcp* rtp_rtcp : rtp_rtcp_modules_) {
    rtp_rtcp->SetRTCPStatus(state == kNetworkUp ? config_->rtp.rtcp_mode
                                                : RtcpMode::kOff);
  }
}

uint32_t VideoSendStreamImpl::OnBitrateUpdated(uint32_t bitrate_bps,
                                               uint8_t fraction_loss,
                                               int64_t rtt,
                                               int64_t probing_interval_ms) {
  RTC_DCHECK_RUN_ON(worker_queue_);
  RTC_DCHECK(payload_router_.IsActive())
      << "VideoSendStream::Start has not been called.";

  // Substract overhead from bitrate.
  rtc::CritScope lock(&overhead_bytes_per_packet_crit_);
  uint32_t payload_bitrate_bps = bitrate_bps;
  if (send_side_bwe_with_overhead_) {
    payload_bitrate_bps -= CalculateOverheadRateBps(
        CalculatePacketRate(bitrate_bps,
                            config_->rtp.max_packet_size +
                                transport_overhead_bytes_per_packet_),
        overhead_bytes_per_packet_ + transport_overhead_bytes_per_packet_,
        bitrate_bps);
  }

  // Get the encoder target rate. It is the estimated network rate -
  // protection overhead.
  encoder_target_rate_bps_ = fec_controller_->UpdateFecRates(
      payload_bitrate_bps, stats_proxy_->GetSendFrameRate(), fraction_loss,
      loss_mask_vector_, rtt);
  loss_mask_vector_.clear();

  uint32_t encoder_overhead_rate_bps =
      send_side_bwe_with_overhead_
          ? CalculateOverheadRateBps(
                CalculatePacketRate(encoder_target_rate_bps_,
                                    config_->rtp.max_packet_size +
                                        transport_overhead_bytes_per_packet_ -
                                        overhead_bytes_per_packet_),
                overhead_bytes_per_packet_ +
                    transport_overhead_bytes_per_packet_,
                bitrate_bps - encoder_target_rate_bps_)
          : 0;

  // When the field trial "WebRTC-SendSideBwe-WithOverhead" is enabled
  // protection_bitrate includes overhead.
  uint32_t protection_bitrate =
      bitrate_bps - (encoder_target_rate_bps_ + encoder_overhead_rate_bps);

  encoder_target_rate_bps_ =
      std::min(encoder_max_bitrate_bps_, encoder_target_rate_bps_);
  video_stream_encoder_->OnBitrateUpdated(encoder_target_rate_bps_,
                                          fraction_loss, rtt);
  stats_proxy_->OnSetEncoderTargetRate(encoder_target_rate_bps_);
  return protection_bitrate;
}

void VideoSendStreamImpl::EnableEncodedFrameRecording(
    const std::vector<rtc::PlatformFile>& files,
    size_t byte_limit) {
  {
    rtc::CritScope lock(&ivf_writers_crit_);
    for (unsigned int i = 0; i < kMaxSimulcastStreams; ++i) {
      if (i < files.size()) {
        file_writers_[i] = IvfFileWriter::Wrap(rtc::File(files[i]), byte_limit);
      } else {
        file_writers_[i].reset();
      }
    }
  }

  if (!files.empty()) {
    // Make a keyframe appear as early as possible in the logs, to give actually
    // decodable output.
    video_stream_encoder_->SendKeyFrame();
  }
}

int VideoSendStreamImpl::ProtectionRequest(
    const FecProtectionParams* delta_params,
    const FecProtectionParams* key_params,
    uint32_t* sent_video_rate_bps,
    uint32_t* sent_nack_rate_bps,
    uint32_t* sent_fec_rate_bps) {
  RTC_DCHECK_RUN_ON(worker_queue_);
  *sent_video_rate_bps = 0;
  *sent_nack_rate_bps = 0;
  *sent_fec_rate_bps = 0;
  for (RtpRtcp* rtp_rtcp : rtp_rtcp_modules_) {
    uint32_t not_used = 0;
    uint32_t module_video_rate = 0;
    uint32_t module_fec_rate = 0;
    uint32_t module_nack_rate = 0;
    rtp_rtcp->SetFecParameters(*delta_params, *key_params);
    rtp_rtcp->BitrateSent(&not_used, &module_video_rate, &module_fec_rate,
                          &module_nack_rate);
    *sent_video_rate_bps += module_video_rate;
    *sent_nack_rate_bps += module_nack_rate;
    *sent_fec_rate_bps += module_fec_rate;
  }
  return 0;
}

void VideoSendStreamImpl::OnOverheadChanged(size_t overhead_bytes_per_packet) {
  rtc::CritScope lock(&overhead_bytes_per_packet_crit_);
  overhead_bytes_per_packet_ = overhead_bytes_per_packet;
}

void VideoSendStreamImpl::SetTransportOverhead(
    size_t transport_overhead_bytes_per_packet) {
  if (transport_overhead_bytes_per_packet >= static_cast<int>(kPathMTU)) {
    RTC_LOG(LS_ERROR) << "Transport overhead exceeds size of ethernet frame";
    return;
  }

  transport_overhead_bytes_per_packet_ = transport_overhead_bytes_per_packet;

  transport_->send_side_cc()->SetTransportOverhead(
      transport_overhead_bytes_per_packet_);

  size_t rtp_packet_size =
      std::min(config_->rtp.max_packet_size,
               kPathMTU - transport_overhead_bytes_per_packet_);

  for (RtpRtcp* rtp_rtcp : rtp_rtcp_modules_) {
    rtp_rtcp->SetMaxRtpPacketSize(rtp_packet_size);
  }
}

void VideoSendStreamImpl::OnPacketAdded(uint32_t ssrc, uint16_t seq_num) {
  if (!worker_queue_->IsCurrent()) {
    auto ptr = weak_ptr_;
    worker_queue_->PostTask([=] {
      if (!ptr.get())
        return;
      ptr->OnPacketAdded(ssrc, seq_num);
    });
    return;
  }
  const auto ssrcs = config_->rtp.ssrcs;
  if (std::find(ssrcs.begin(), ssrcs.end(), ssrc) != ssrcs.end()) {
    feedback_packet_seq_num_set_.insert(seq_num);
    if (feedback_packet_seq_num_set_.size() > kSendSideSeqNumSetMaxSize) {
      RTC_LOG(LS_WARNING) << "Feedback packet sequence number set exceed it's "
                             "max size', will get reset.";
      feedback_packet_seq_num_set_.clear();
    }
  }
}

void VideoSendStreamImpl::OnPacketFeedbackVector(
    const std::vector<PacketFeedback>& packet_feedback_vector) {
  if (!worker_queue_->IsCurrent()) {
    auto ptr = weak_ptr_;
    worker_queue_->PostTask([=] {
      if (!ptr.get())
        return;
      ptr->OnPacketFeedbackVector(packet_feedback_vector);
    });
    return;
  }
  // Lost feedbacks are not considered to be lost packets.
  for (const PacketFeedback& packet : packet_feedback_vector) {
    if (auto it = feedback_packet_seq_num_set_.find(packet.sequence_number) !=
                  feedback_packet_seq_num_set_.end()) {
      const bool lost = packet.arrival_time_ms == PacketFeedback::kNotReceived;
      loss_mask_vector_.push_back(lost);
      feedback_packet_seq_num_set_.erase(it);
    }
  }
}
}  // namespace internal
}  // namespace webrtc