webrtc/call/flexfec_receive_stream_impl.cc

/*
 *  Copyright (c) 2016 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 "webrtc/call/flexfec_receive_stream_impl.h"

#include <string>

#include "webrtc/base/checks.h"
#include "webrtc/base/location.h"
#include "webrtc/base/logging.h"
#include "webrtc/call/rtp_stream_receiver_controller_interface.h"
#include "webrtc/modules/rtp_rtcp/include/flexfec_receiver.h"
#include "webrtc/modules/rtp_rtcp/include/receive_statistics.h"
#include "webrtc/modules/rtp_rtcp/include/rtp_rtcp.h"
#include "webrtc/modules/rtp_rtcp/source/rtp_packet_received.h"
#include "webrtc/modules/utility/include/process_thread.h"
#include "webrtc/system_wrappers/include/clock.h"

namespace webrtc {

std::string FlexfecReceiveStream::Stats::ToString(int64_t time_ms) const {
  std::stringstream ss;
  ss << "FlexfecReceiveStream stats: " << time_ms
     << ", {flexfec_bitrate_bps: " << flexfec_bitrate_bps << "}";
  return ss.str();
}

std::string FlexfecReceiveStream::Config::ToString() const {
  std::stringstream ss;
  ss << "{payload_type: " << payload_type;
  ss << ", remote_ssrc: " << remote_ssrc;
  ss << ", local_ssrc: " << local_ssrc;
  ss << ", protected_media_ssrcs: [";
  size_t i = 0;
  for (; i + 1 < protected_media_ssrcs.size(); ++i)
    ss << protected_media_ssrcs[i] << ", ";
  if (!protected_media_ssrcs.empty())
    ss << protected_media_ssrcs[i];
  ss << "], transport_cc: " << (transport_cc ? "on" : "off");
  ss << ", rtp_header_extensions: [";
  i = 0;
  for (; i + 1 < rtp_header_extensions.size(); ++i)
    ss << rtp_header_extensions[i].ToString() << ", ";
  if (!rtp_header_extensions.empty())
    ss << rtp_header_extensions[i].ToString();
  ss << "]}";
  return ss.str();
}

bool FlexfecReceiveStream::Config::IsCompleteAndEnabled() const {
  // Check if FlexFEC is enabled.
  if (payload_type < 0)
    return false;
  // Do we have the necessary SSRC information?
  if (remote_ssrc == 0)
    return false;
  // TODO(brandtr): Update this check when we support multistream protection.
  if (protected_media_ssrcs.size() != 1u)
    return false;
  return true;
}

namespace {

// TODO(brandtr): Update this function when we support multistream protection.
std::unique_ptr<FlexfecReceiver> MaybeCreateFlexfecReceiver(
    const FlexfecReceiveStream::Config& config,
    RecoveredPacketReceiver* recovered_packet_receiver) {
  if (config.payload_type < 0) {
    LOG(LS_WARNING) << "Invalid FlexFEC payload type given. "
                    << "This FlexfecReceiveStream will therefore be useless.";
    return nullptr;
  }
  RTC_DCHECK_GE(config.payload_type, 0);
  RTC_DCHECK_LE(config.payload_type, 127);
  if (config.remote_ssrc == 0) {
    LOG(LS_WARNING) << "Invalid FlexFEC SSRC given. "
                    << "This FlexfecReceiveStream will therefore be useless.";
    return nullptr;
  }
  if (config.protected_media_ssrcs.empty()) {
    LOG(LS_WARNING) << "No protected media SSRC supplied. "
                    << "This FlexfecReceiveStream will therefore be useless.";
    return nullptr;
  }

  if (config.protected_media_ssrcs.size() > 1) {
    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;
  }
  RTC_DCHECK_EQ(1U, config.protected_media_ssrcs.size());
  return std::unique_ptr<FlexfecReceiver>(
      new FlexfecReceiver(config.remote_ssrc, config.protected_media_ssrcs[0],
                          recovered_packet_receiver));
}

std::unique_ptr<RtpRtcp> CreateRtpRtcpModule(
    ReceiveStatistics* receive_statistics,
    Transport* rtcp_send_transport,
    RtcpRttStats* rtt_stats) {
  RtpRtcp::Configuration configuration;
  configuration.audio = false;
  configuration.receiver_only = true;
  configuration.clock = Clock::GetRealTimeClock();
  configuration.receive_statistics = receive_statistics;
  configuration.outgoing_transport = rtcp_send_transport;
  configuration.rtt_stats = rtt_stats;
  std::unique_ptr<RtpRtcp> rtp_rtcp(RtpRtcp::CreateRtpRtcp(configuration));
  return rtp_rtcp;
}

}  // namespace

FlexfecReceiveStreamImpl::FlexfecReceiveStreamImpl(
    RtpStreamReceiverControllerInterface* receiver_controller,
    const Config& config,
    RecoveredPacketReceiver* recovered_packet_receiver,
    RtcpRttStats* rtt_stats,
    ProcessThread* process_thread)
    : config_(config),
      started_(false),
      receiver_(MaybeCreateFlexfecReceiver(config_, recovered_packet_receiver)),
      rtp_receive_statistics_(
          ReceiveStatistics::Create(Clock::GetRealTimeClock())),
      rtp_rtcp_(CreateRtpRtcpModule(rtp_receive_statistics_.get(),
                                    config_.rtcp_send_transport,
                                    rtt_stats)),
      process_thread_(process_thread) {
  LOG(LS_INFO) << "FlexfecReceiveStreamImpl: " << config_.ToString();

  // RTCP reporting.
  rtp_rtcp_->SetRTCPStatus(config_.rtcp_mode);
  rtp_rtcp_->SetSSRC(config_.local_ssrc);
  process_thread_->RegisterModule(rtp_rtcp_.get(), RTC_FROM_HERE);

  // Register with transport.
  // TODO(nisse): OnRtpPacket in this class delegates all real work to
  // |receiver_|. So maybe we don't need to implement RtpPacketSinkInterface
  // here at all, we'd then delete the OnRtpPacket method and instead register
  // |receiver_| as the RtpPacketSinkInterface for this stream.
  // TODO(nisse): Passing |this| from the constructor to the RtpDemuxer, before
  // the object is fully initialized, is risky. But it works in this case
  // because locking in our caller, Call::CreateFlexfecReceiveStream, ensures
  // that the demuxer doesn't call OnRtpPacket before this object is fully
  // constructed. Registering |receiver_| instead of |this| would solve this
  // problem too.
  rtp_stream_receiver_ =
      receiver_controller->CreateReceiver(config_.remote_ssrc, this);
  for (uint32_t ssrc : config.protected_media_ssrcs)
    receiver_controller->AddSink(ssrc, this);
}

FlexfecReceiveStreamImpl::~FlexfecReceiveStreamImpl() {
  LOG(LS_INFO) << "~FlexfecReceiveStreamImpl: " << config_.ToString();
  Stop();
  process_thread_->DeRegisterModule(rtp_rtcp_.get());
}

void FlexfecReceiveStreamImpl::OnRtpPacket(const RtpPacketReceived& packet) {
  {
    rtc::CritScope cs(&crit_);
    if (!started_)
      return;
  }

  if (!receiver_)
    return;

  receiver_->OnRtpPacket(packet);

  // Do not report media packets in the RTCP RRs generated by |rtp_rtcp_|.
  if (packet.Ssrc() == config_.remote_ssrc) {
    RTPHeader header;
    packet.GetHeader(&header);
    // FlexFEC packets are never retransmitted.
    const bool kNotRetransmitted = false;
    rtp_receive_statistics_->IncomingPacket(header, packet.size(),
                                            kNotRetransmitted);
  }
}

void FlexfecReceiveStreamImpl::Start() {
  rtc::CritScope cs(&crit_);
  started_ = true;
}

void FlexfecReceiveStreamImpl::Stop() {
  rtc::CritScope cs(&crit_);
  started_ = false;
}

// TODO(brandtr): Implement this member function when we have designed the
// stats for FlexFEC.
FlexfecReceiveStreamImpl::Stats FlexfecReceiveStreamImpl::GetStats() const {
  return FlexfecReceiveStream::Stats();
}

}  // namespace webrtc