video/video_send_stream_impl.cc

/*
 *  Copyright 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 "video/video_send_stream_impl.h"

#include <stdio.h>

#include <algorithm>
#include <cstdint>
#include <string>
#include <utility>

#include "absl/algorithm/container.h"
#include "api/crypto/crypto_options.h"
#include "api/rtp_parameters.h"
#include "api/scoped_refptr.h"
#include "api/video_codecs/video_codec.h"
#include "call/rtp_transport_controller_send_interface.h"
#include "call/video_send_stream.h"
#include "modules/pacing/paced_sender.h"
#include "rtc_base/atomic_ops.h"
#include "rtc_base/checks.h"
#include "rtc_base/experiments/alr_experiment.h"
#include "rtc_base/experiments/field_trial_parser.h"
#include "rtc_base/experiments/rate_control_settings.h"
#include "rtc_base/logging.h"
#include "rtc_base/numerics/safe_conversions.h"
#include "rtc_base/synchronization/sequence_checker.h"
#include "rtc_base/thread_checker.h"
#include "rtc_base/trace_event.h"
#include "system_wrappers/include/clock.h"
#include "system_wrappers/include/field_trial.h"

namespace webrtc {
namespace internal {
namespace {

// Max positive size difference to treat allocations as "similar".
static constexpr int kMaxVbaSizeDifferencePercent = 10;
// Max time we will throttle similar video bitrate allocations.
static constexpr int64_t kMaxVbaThrottleTimeMs = 500;

constexpr TimeDelta kEncoderTimeOut = TimeDelta::Seconds<2>();

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

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

const int kDefaultEncoderMinBitrateBps = 30000;
const char kMinVideoBitrateExperiment[] = "WebRTC-Video-MinVideoBitrate";

struct MinVideoBitrateConfig {
  webrtc::FieldTrialParameter<webrtc::DataRate> min_video_bitrate;

  MinVideoBitrateConfig()
      : min_video_bitrate("br",
                          webrtc::DataRate::bps(kDefaultEncoderMinBitrateBps)) {
    webrtc::ParseFieldTrial(
        {&min_video_bitrate},
        webrtc::field_trial::FindFullName(kMinVideoBitrateExperiment));
  }
};

absl::optional<int> GetFallbackMinBpsFromFieldTrial(VideoCodecType type) {
  if (type != kVideoCodecVP8)
    return absl::nullopt;

  if (!webrtc::field_trial::IsEnabled(kForcedFallbackFieldTrial))
    return absl::nullopt;

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

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

  return min_bps;
}

int GetEncoderMinBitrateBps(VideoCodecType type) {
  if (GetFallbackMinBpsFromFieldTrial(type).has_value()) {
    return GetFallbackMinBpsFromFieldTrial(type).value();
  }
  if (webrtc::field_trial::IsEnabled(kMinVideoBitrateExperiment)) {
    return MinVideoBitrateConfig().min_video_bitrate->bps();
  }
  return kDefaultEncoderMinBitrateBps;
}

// Calculate max padding bitrate for a multi layer codec.
int CalculateMaxPadBitrateBps(const std::vector<VideoStream>& streams,
                              VideoEncoderConfig::ContentType content_type,
                              int min_transmit_bitrate_bps,
                              bool pad_to_min_bitrate,
                              bool alr_probing) {
  int pad_up_to_bitrate_bps = 0;

  // Filter out only the active streams;
  std::vector<VideoStream> active_streams;
  for (const VideoStream& stream : streams) {
    if (stream.active)
      active_streams.emplace_back(stream);
  }

  if (active_streams.size() > 1) {
    if (alr_probing) {
      // With alr probing, just pad to the min bitrate of the lowest stream,
      // probing will handle the rest of the rampup.
      pad_up_to_bitrate_bps = active_streams[0].min_bitrate_bps;
    } else {
      // Without alr probing, pad up to start bitrate of the
      // highest active stream.
      const double hysteresis_factor =
          RateControlSettings::ParseFromFieldTrials()
              .GetSimulcastHysteresisFactor(content_type);
      const size_t top_active_stream_idx = active_streams.size() - 1;
      pad_up_to_bitrate_bps = std::min(
          static_cast<int>(
              hysteresis_factor *
                  active_streams[top_active_stream_idx].min_bitrate_bps +
              0.5),
          active_streams[top_active_stream_idx].target_bitrate_bps);

      // Add target_bitrate_bps of the lower active streams.
      for (size_t i = 0; i < top_active_stream_idx; ++i) {
        pad_up_to_bitrate_bps += active_streams[i].target_bitrate_bps;
      }
    }
  } else if (!active_streams.empty() && pad_to_min_bitrate) {
    pad_up_to_bitrate_bps = active_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;
}

RtpSenderFrameEncryptionConfig CreateFrameEncryptionConfig(
    const VideoSendStream::Config* config) {
  RtpSenderFrameEncryptionConfig frame_encryption_config;
  frame_encryption_config.frame_encryptor = config->frame_encryptor;
  frame_encryption_config.crypto_options = config->crypto_options;
  return frame_encryption_config;
}

RtpSenderObservers CreateObservers(CallStats* call_stats,
                                   EncoderRtcpFeedback* encoder_feedback,
                                   SendStatisticsProxy* stats_proxy,
                                   SendDelayStats* send_delay_stats) {
  RtpSenderObservers observers;
  observers.rtcp_rtt_stats = call_stats;
  observers.intra_frame_callback = encoder_feedback;
  observers.rtcp_loss_notification_observer = encoder_feedback;
  observers.rtcp_stats = stats_proxy;
  observers.report_block_data_observer = stats_proxy;
  observers.rtp_stats = stats_proxy;
  observers.bitrate_observer = stats_proxy;
  observers.frame_count_observer = stats_proxy;
  observers.rtcp_type_observer = stats_proxy;
  observers.send_delay_observer = stats_proxy;
  observers.send_packet_observer = send_delay_stats;
  return observers;
}

absl::optional<AlrExperimentSettings> GetAlrSettings(
    VideoEncoderConfig::ContentType content_type) {
  if (content_type == VideoEncoderConfig::ContentType::kScreen) {
    return AlrExperimentSettings::CreateFromFieldTrial(
        AlrExperimentSettings::kScreenshareProbingBweExperimentName);
  }
  return AlrExperimentSettings::CreateFromFieldTrial(
      AlrExperimentSettings::kStrictPacingAndProbingExperimentName);
}

bool SameStreamsEnabled(const VideoBitrateAllocation& lhs,
                        const VideoBitrateAllocation& rhs) {
  for (size_t si = 0; si < kMaxSpatialLayers; ++si) {
    for (size_t ti = 0; ti < kMaxTemporalStreams; ++ti) {
      if (lhs.HasBitrate(si, ti) != rhs.HasBitrate(si, ti)) {
        return false;
      }
    }
  }
  return true;
}
}  // namespace

PacingConfig::PacingConfig()
    : pacing_factor("factor", PacedSender::kDefaultPaceMultiplier),
      max_pacing_delay("max_delay",
                       TimeDelta::ms(PacedSender::kMaxQueueLengthMs)) {
  ParseFieldTrial({&pacing_factor, &max_pacing_delay},
                  field_trial::FindFullName("WebRTC-Video-Pacing"));
}
PacingConfig::PacingConfig(const PacingConfig&) = default;
PacingConfig::~PacingConfig() = default;

VideoSendStreamImpl::VideoSendStreamImpl(
    Clock* clock,
    SendStatisticsProxy* stats_proxy,
    rtc::TaskQueue* worker_queue,
    CallStats* call_stats,
    RtpTransportControllerSendInterface* transport,
    BitrateAllocatorInterface* bitrate_allocator,
    SendDelayStats* send_delay_stats,
    VideoStreamEncoderInterface* 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,
    MediaTransportInterface* media_transport)
    : clock_(clock),
      has_alr_probing_(config->periodic_alr_bandwidth_probing ||
                       GetAlrSettings(content_type)),
      pacing_config_(PacingConfig()),
      stats_proxy_(stats_proxy),
      config_(config),
      worker_queue_(worker_queue),
      timed_out_(false),
      call_stats_(call_stats),
      transport_(transport),
      bitrate_allocator_(bitrate_allocator),
      disable_padding_(true),
      max_padding_bitrate_(0),
      encoder_min_bitrate_bps_(0),
      encoder_target_rate_bps_(0),
      encoder_bitrate_priority_(initial_encoder_bitrate_priority),
      has_packet_feedback_(false),
      video_stream_encoder_(video_stream_encoder),
      encoder_feedback_(clock, config_->rtp.ssrcs, video_stream_encoder),
      bandwidth_observer_(transport->GetBandwidthObserver()),
      rtp_video_sender_(transport_->CreateRtpVideoSender(
          suspended_ssrcs,
          suspended_payload_states,
          config_->rtp,
          config_->rtcp_report_interval_ms,
          config_->send_transport,
          CreateObservers(call_stats,
                          &encoder_feedback_,
                          stats_proxy_,
                          send_delay_stats),
          event_log,
          std::move(fec_controller),
          CreateFrameEncryptionConfig(config_))),
      weak_ptr_factory_(this),
      media_transport_(media_transport) {
  video_stream_encoder->SetFecControllerOverride(rtp_video_sender_);
  RTC_DCHECK_RUN_ON(worker_queue_);
  RTC_LOG(LS_INFO) << "VideoSendStreamInternal: " << config_->ToString();
  weak_ptr_ = weak_ptr_factory_.GetWeakPtr();

  encoder_feedback_.SetRtpVideoSender(rtp_video_sender_);

  if (media_transport_) {
    // The configured ssrc is interpreted as a channel id, so there must be
    // exactly one.
    RTC_DCHECK_EQ(config_->rtp.ssrcs.size(), 1);
    media_transport_->SetKeyFrameRequestCallback(&encoder_feedback_);
  } else {
    RTC_DCHECK(!config_->rtp.ssrcs.empty());
  }
  RTC_DCHECK(call_stats_);
  RTC_DCHECK(transport_);
  RTC_DCHECK_NE(initial_encoder_max_bitrate, 0);

  if (initial_encoder_max_bitrate > 0) {
    encoder_max_bitrate_bps_ =
        rtc::dchecked_cast<uint32_t>(initial_encoder_max_bitrate);
  } else {
    // TODO(srte): Make sure max bitrate is not set to negative values. We don't
    // have any way to handle unset values in downstream code, such as the
    // bitrate allocator. Previously -1 was implicitly casted to UINT32_MAX, a
    // behaviour that is not safe. Converting to 10 Mbps should be safe for
    // reasonable use cases as it allows adding the max of multiple streams
    // without wrappping around.
    const int kFallbackMaxBitrateBps = 10000000;
    RTC_DLOG(LS_ERROR) << "ERROR: Initial encoder max bitrate = "
                       << initial_encoder_max_bitrate << " which is <= 0!";
    RTC_DLOG(LS_INFO) << "Using default encoder max bitrate = 10 Mbps";
    encoder_max_bitrate_bps_ = kFallbackMaxBitrateBps;
  }

  RTC_CHECK(AlrExperimentSettings::MaxOneFieldTrialEnabled());
  // If send-side BWE is enabled, check if we should apply updated probing and
  // pacing settings.
  if (TransportSeqNumExtensionConfigured(*config_)) {
    has_packet_feedback_ = true;

    absl::optional<AlrExperimentSettings> alr_settings =
        GetAlrSettings(content_type);
    if (alr_settings) {
      transport->EnablePeriodicAlrProbing(true);
      transport->SetPacingFactor(alr_settings->pacing_factor);
      configured_pacing_factor_ = alr_settings->pacing_factor;
      transport->SetQueueTimeLimit(alr_settings->max_paced_queue_time);
    } else {
      RateControlSettings rate_control_settings =
          RateControlSettings::ParseFromFieldTrials();

      transport->EnablePeriodicAlrProbing(
          rate_control_settings.UseAlrProbing());
      const double pacing_factor =
          rate_control_settings.GetPacingFactor().value_or(
              pacing_config_.pacing_factor);
      transport->SetPacingFactor(pacing_factor);
      configured_pacing_factor_ = pacing_factor;
      transport->SetQueueTimeLimit(pacing_config_.max_pacing_delay.Get().ms());
    }
  }

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

  RTC_DCHECK_GE(config_->rtp.payload_type, 0);
  RTC_DCHECK_LE(config_->rtp.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 = absl::c_none_of(
      config_->rtp.extensions, [](const RtpExtension& extension) {
        return extension.uri == RtpExtension::kVideoRotationUri;
      });

  video_stream_encoder_->SetSink(this, rotation_applied);
}

VideoSendStreamImpl::~VideoSendStreamImpl() {
  RTC_DCHECK_RUN_ON(worker_queue_);
  RTC_DCHECK(!rtp_video_sender_->IsActive())
      << "VideoSendStreamImpl::Stop not called";
  RTC_LOG(LS_INFO) << "~VideoSendStreamInternal: " << config_->ToString();
  transport_->DestroyRtpVideoSender(rtp_video_sender_);
  if (media_transport_) {
    media_transport_->SetKeyFrameRequestCallback(nullptr);
  }
}

void VideoSendStreamImpl::RegisterProcessThread(
    ProcessThread* module_process_thread) {
  rtp_video_sender_->RegisterProcessThread(module_process_thread);
}

void VideoSendStreamImpl::DeRegisterProcessThread() {
  rtp_video_sender_->DeRegisterProcessThread();
}

void VideoSendStreamImpl::DeliverRtcp(const uint8_t* packet, size_t length) {
  // Runs on a network thread.
  RTC_DCHECK(!worker_queue_->IsCurrent());
  rtp_video_sender_->DeliverRtcp(packet, length);
}

void VideoSendStreamImpl::UpdateActiveSimulcastLayers(
    const std::vector<bool> active_layers) {
  RTC_DCHECK_RUN_ON(worker_queue_);
  RTC_LOG(LS_INFO) << "VideoSendStream::UpdateActiveSimulcastLayers";
  bool previously_active = rtp_video_sender_->IsActive();
  rtp_video_sender_->SetActiveModules(active_layers);
  if (!rtp_video_sender_->IsActive() && previously_active) {
    // Payload router switched from active to inactive.
    StopVideoSendStream();
  } else if (rtp_video_sender_->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 (rtp_video_sender_->IsActive())
    return;
  TRACE_EVENT_INSTANT0("webrtc", "VideoSendStream::Start");
  rtp_video_sender_->SetActive(true);
  StartupVideoSendStream();
}

void VideoSendStreamImpl::StartupVideoSendStream() {
  RTC_DCHECK_RUN_ON(worker_queue_);
  bitrate_allocator_->AddObserver(this, GetAllocationConfig());
  // Start monitoring encoder activity.
  {
    RTC_DCHECK(!check_encoder_activity_task_.Running());

    activity_ = false;
    timed_out_ = false;
    check_encoder_activity_task_ = RepeatingTaskHandle::DelayedStart(
        worker_queue_->Get(), kEncoderTimeOut, [this] {
          RTC_DCHECK_RUN_ON(worker_queue_);
          if (!activity_) {
            if (!timed_out_) {
              SignalEncoderTimedOut();
            }
            timed_out_ = true;
            disable_padding_ = true;
          } else if (timed_out_) {
            SignalEncoderActive();
            timed_out_ = false;
          }
          activity_ = false;
          return kEncoderTimeOut;
        });
  }

  video_stream_encoder_->SendKeyFrame();
}

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

void VideoSendStreamImpl::StopVideoSendStream() {
  bitrate_allocator_->RemoveObserver(this);
  check_encoder_activity_task_.Stop();
  video_stream_encoder_->OnBitrateUpdated(DataRate::Zero(), DataRate::Zero(), 0,
                                          0);
  stats_proxy_->OnSetEncoderTargetRate(0);
}

void VideoSendStreamImpl::SignalEncoderTimedOut() {
  RTC_DCHECK_RUN_ON(worker_queue_);
  // If the encoder has not produced anything the last kEncoderTimeOut 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 VideoBitrateAllocation& allocation) {
  if (!worker_queue_->IsCurrent()) {
    auto ptr = weak_ptr_;
    worker_queue_->PostTask([=] {
      if (!ptr.get())
        return;
      ptr->OnBitrateAllocationUpdated(allocation);
    });
    return;
  }

  RTC_DCHECK_RUN_ON(worker_queue_);

  int64_t now_ms = clock_->TimeInMilliseconds();
  if (encoder_target_rate_bps_ != 0) {
    if (video_bitrate_allocation_context_) {
      // If new allocation is within kMaxVbaSizeDifferencePercent larger than
      // the previously sent allocation and the same streams are still enabled,
      // it is considered "similar". We do not want send similar allocations
      // more once per kMaxVbaThrottleTimeMs.
      const VideoBitrateAllocation& last =
          video_bitrate_allocation_context_->last_sent_allocation;
      const bool is_similar =
          allocation.get_sum_bps() >= last.get_sum_bps() &&
          allocation.get_sum_bps() <
              (last.get_sum_bps() * (100 + kMaxVbaSizeDifferencePercent)) /
                  100 &&
          SameStreamsEnabled(allocation, last);
      if (is_similar &&
          (now_ms - video_bitrate_allocation_context_->last_send_time_ms) <
              kMaxVbaThrottleTimeMs) {
        // This allocation is too similar, cache it and return.
        video_bitrate_allocation_context_->throttled_allocation = allocation;
        return;
      }
    } else {
      video_bitrate_allocation_context_.emplace();
    }

    video_bitrate_allocation_context_->last_sent_allocation = allocation;
    video_bitrate_allocation_context_->throttled_allocation.reset();
    video_bitrate_allocation_context_->last_send_time_ms = now_ms;

    // Send bitrate allocation metadata only if encoder is not paused.
    rtp_video_sender_->OnBitrateAllocationUpdated(allocation);
  }
}

void VideoSendStreamImpl::SignalEncoderActive() {
  RTC_DCHECK_RUN_ON(worker_queue_);
  if (rtp_video_sender_->IsActive()) {
    RTC_LOG(LS_INFO) << "SignalEncoderActive, Encoder is active.";
    bitrate_allocator_->AddObserver(this, GetAllocationConfig());
  }
}

MediaStreamAllocationConfig VideoSendStreamImpl::GetAllocationConfig() const {
  return MediaStreamAllocationConfig{
      static_cast<uint32_t>(encoder_min_bitrate_bps_),
      encoder_max_bitrate_bps_,
      static_cast<uint32_t>(disable_padding_ ? 0 : max_padding_bitrate_),
      /* priority_bitrate */ 0,
      !config_->suspend_below_min_bitrate,
      encoder_bitrate_priority_};
}

void VideoSendStreamImpl::OnEncoderConfigurationChanged(
    std::vector<VideoStream> streams,
    VideoEncoderConfig::ContentType content_type,
    int min_transmit_bitrate_bps) {
  if (!worker_queue_->IsCurrent()) {
    rtc::WeakPtr<VideoSendStreamImpl> send_stream = weak_ptr_;
    worker_queue_->PostTask([send_stream, streams, content_type,
                             min_transmit_bitrate_bps]() mutable {
      if (send_stream) {
        send_stream->OnEncoderConfigurationChanged(
            std::move(streams), content_type, 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(
                   PayloadStringToCodecType(config_->rtp.payload_name)));
  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_);

  // TODO(bugs.webrtc.org/10266): Query the VideoBitrateAllocator instead.
  const VideoCodecType codec_type =
      PayloadStringToCodecType(config_->rtp.payload_name);
  if (codec_type == kVideoCodecVP9) {
    max_padding_bitrate_ = has_alr_probing_ ? streams[0].min_bitrate_bps
                                            : streams[0].target_bitrate_bps;
  } else {
    max_padding_bitrate_ = CalculateMaxPadBitrateBps(
        streams, content_type, min_transmit_bitrate_bps,
        config_->suspend_below_min_bitrate, has_alr_probing_);
  }

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

  const size_t num_temporal_layers =
      streams.back().num_temporal_layers.value_or(1);

  rtp_video_sender_->SetEncodingData(streams[0].width, streams[0].height,
                                     num_temporal_layers);

  if (rtp_video_sender_->IsActive()) {
    // The send stream is started already. Update the allocator with new bitrate
    // limits.
    bitrate_allocator_->AddObserver(this, GetAllocationConfig());
  }
}

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.

  // Indicate that there still is activity going on.
  activity_ = true;

  auto enable_padding_task = [this]() {
    if (disable_padding_) {
      RTC_DCHECK_RUN_ON(worker_queue_);
      disable_padding_ = false;
      // To ensure that padding bitrate is propagated to the bitrate allocator.
      SignalEncoderActive();
    }
  };
  if (!worker_queue_->IsCurrent()) {
    worker_queue_->PostTask(enable_padding_task);
  } else {
    enable_padding_task();
  }

  EncodedImageCallback::Result result(EncodedImageCallback::Result::OK);
  if (media_transport_) {
    int64_t frame_id;
    {
      // TODO(nisse): Responsibility for allocation of frame ids should move to
      // VideoStreamEncoder.
      rtc::CritScope cs(&media_transport_id_lock_);
      frame_id = media_transport_frame_id_++;
    }
    // TODO(nisse): Responsibility for reference meta data should be moved
    // upstream, ideally close to the encoders, but probably VideoStreamEncoder
    // will need to do some translation to produce reference info using frame
    // ids.
    std::vector<int64_t> referenced_frame_ids;
    if (encoded_image._frameType != VideoFrameType::kVideoFrameKey) {
      RTC_DCHECK_GT(frame_id, 0);
      referenced_frame_ids.push_back(frame_id - 1);
    }
    media_transport_->SendVideoFrame(
        config_->rtp.ssrcs[0], webrtc::MediaTransportEncodedVideoFrame(
                                   frame_id, referenced_frame_ids,
                                   config_->rtp.payload_type, encoded_image));
  } else {
    result = rtp_video_sender_->OnEncodedImage(
        encoded_image, codec_specific_info, fragmentation);
  }
  // Check if there's a throttled VideoBitrateAllocation that we should try
  // sending.
  rtc::WeakPtr<VideoSendStreamImpl> send_stream = weak_ptr_;
  auto update_task = [send_stream]() {
    if (send_stream) {
      RTC_DCHECK_RUN_ON(send_stream->worker_queue_);
      auto& context = send_stream->video_bitrate_allocation_context_;
      if (context && context->throttled_allocation) {
        send_stream->OnBitrateAllocationUpdated(*context->throttled_allocation);
      }
    }
  };
  if (!worker_queue_->IsCurrent()) {
    worker_queue_->PostTask(update_task);
  } else {
    update_task();
  }

  return result;
}

std::map<uint32_t, RtpState> VideoSendStreamImpl::GetRtpStates() const {
  return rtp_video_sender_->GetRtpStates();
}

std::map<uint32_t, RtpPayloadState> VideoSendStreamImpl::GetRtpPayloadStates()
    const {
  return rtp_video_sender_->GetRtpPayloadStates();
}

uint32_t VideoSendStreamImpl::OnBitrateUpdated(BitrateAllocationUpdate update) {
  RTC_DCHECK_RUN_ON(worker_queue_);
  RTC_DCHECK(rtp_video_sender_->IsActive())
      << "VideoSendStream::Start has not been called.";

  rtp_video_sender_->OnBitrateUpdated(
      update.target_bitrate.bps(),
      rtc::dchecked_cast<uint8_t>(update.packet_loss_ratio * 256),
      update.round_trip_time.ms(), stats_proxy_->GetSendFrameRate());
  encoder_target_rate_bps_ = rtp_video_sender_->GetPayloadBitrateBps();
  const uint32_t protection_bitrate_bps =
      rtp_video_sender_->GetProtectionBitrateBps();
  DataRate link_allocation = DataRate::Zero();
  if (encoder_target_rate_bps_ > protection_bitrate_bps) {
    link_allocation =
        DataRate::bps(encoder_target_rate_bps_ - protection_bitrate_bps);
  }
  encoder_target_rate_bps_ =
      std::min(encoder_max_bitrate_bps_, encoder_target_rate_bps_);

  DataRate encoder_target_rate = DataRate::bps(encoder_target_rate_bps_);
  link_allocation = std::max(encoder_target_rate, link_allocation);
  video_stream_encoder_->OnBitrateUpdated(
      encoder_target_rate, link_allocation,
      rtc::dchecked_cast<uint8_t>(update.packet_loss_ratio * 256),
      update.round_trip_time.ms());
  stats_proxy_->OnSetEncoderTargetRate(encoder_target_rate_bps_);
  return protection_bitrate_bps;
}

}  // namespace internal
}  // namespace webrtc