modules/video_coding/video_receiver.cc

/*
 *  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 <stddef.h>
#include <cstdint>
#include <vector>

#include "api/rtp_headers.h"
#include "api/video_codecs/video_codec.h"
#include "api/video_codecs/video_decoder.h"
#include "common_types.h"  // NOLINT(build/include)
#include "modules/include/module_common_types.h"
#include "modules/utility/include/process_thread.h"
#include "modules/video_coding/decoder_database.h"
#include "modules/video_coding/encoded_frame.h"
#include "modules/video_coding/generic_decoder.h"
#include "modules/video_coding/include/video_coding.h"
#include "modules/video_coding/include/video_coding_defines.h"
#include "modules/video_coding/internal_defines.h"
#include "modules/video_coding/jitter_buffer.h"
#include "modules/video_coding/media_opt_util.h"
#include "modules/video_coding/packet.h"
#include "modules/video_coding/receiver.h"
#include "modules/video_coding/timing.h"
#include "modules/video_coding/video_coding_impl.h"
#include "rtc_base/checks.h"
#include "rtc_base/critical_section.h"
#include "rtc_base/location.h"
#include "rtc_base/logging.h"
#include "rtc_base/one_time_event.h"
#include "rtc_base/thread_checker.h"
#include "rtc_base/trace_event.h"
#include "system_wrappers/include/clock.h"

namespace webrtc {
namespace vcm {

VideoReceiver::VideoReceiver(Clock* clock,
                             VCMTiming* timing,
                             NackSender* nack_sender,
                             KeyFrameRequestSender* keyframe_request_sender)
    : clock_(clock),
      _timing(timing),
      _receiver(_timing,
                clock_,
                nack_sender,
                keyframe_request_sender),
      _decodedFrameCallback(_timing, clock_),
      _frameTypeCallback(nullptr),
      _receiveStatsCallback(nullptr),
      _packetRequestCallback(nullptr),
      _scheduleKeyRequest(false),
      drop_frames_until_keyframe_(false),
      max_nack_list_size_(0),
      _codecDataBase(),
      _receiveStatsTimer(1000, clock_),
      _retransmissionTimer(10, clock_),
      _keyRequestTimer(500, clock_) {
  decoder_thread_checker_.DetachFromThread();
  module_thread_checker_.DetachFromThread();
}

VideoReceiver::~VideoReceiver() {
  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
}

void VideoReceiver::Process() {
  RTC_DCHECK_RUN_ON(&module_thread_checker_);
  // Receive-side statistics

  // TODO(philipel): Remove this if block when we know what to do with
  //                 ReceiveStatisticsProxy::QualitySample.
  if (_receiveStatsTimer.TimeUntilProcess() == 0) {
    _receiveStatsTimer.Processed();
    if (_receiveStatsCallback != nullptr) {
      _receiveStatsCallback->OnReceiveRatesUpdated(0, 0);
    }
  }

  // Key frame requests
  if (_keyRequestTimer.TimeUntilProcess() == 0) {
    _keyRequestTimer.Processed();
    bool request_key_frame = _frameTypeCallback != nullptr;
    if (request_key_frame) {
      rtc::CritScope cs(&process_crit_);
      request_key_frame = _scheduleKeyRequest;
    }
    if (request_key_frame)
      RequestKeyFrame();
  }

  // Packet retransmission requests
  // TODO(holmer): Add API for changing Process interval and make sure it's
  // disabled when NACK is off.
  if (_retransmissionTimer.TimeUntilProcess() == 0) {
    _retransmissionTimer.Processed();
    bool callback_registered = _packetRequestCallback != nullptr;
    uint16_t length = max_nack_list_size_;
    if (callback_registered && length > 0) {
      // Collect sequence numbers from the default receiver.
      bool request_key_frame = false;
      std::vector<uint16_t> nackList = _receiver.NackList(&request_key_frame);
      int32_t ret = VCM_OK;
      if (request_key_frame) {
        ret = RequestKeyFrame();
      }
      if (ret == VCM_OK && !nackList.empty()) {
        rtc::CritScope cs(&process_crit_);
        if (_packetRequestCallback != nullptr) {
          _packetRequestCallback->ResendPackets(&nackList[0], nackList.size());
        }
      }
    }
  }
}

void VideoReceiver::ProcessThreadAttached(ProcessThread* process_thread) {
  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
  if (process_thread) {
    is_attached_to_process_thread_ = true;
    RTC_DCHECK(!process_thread_ || process_thread_ == process_thread);
    process_thread_ = process_thread;
  } else {
    is_attached_to_process_thread_ = false;
  }
}

int64_t VideoReceiver::TimeUntilNextProcess() {
  RTC_DCHECK_RUN_ON(&module_thread_checker_);
  int64_t timeUntilNextProcess = _receiveStatsTimer.TimeUntilProcess();
  if (_receiver.NackMode() != kNoNack) {
    // We need a Process call more often if we are relying on
    // retransmissions
    timeUntilNextProcess =
        VCM_MIN(timeUntilNextProcess, _retransmissionTimer.TimeUntilProcess());
  }
  timeUntilNextProcess =
      VCM_MIN(timeUntilNextProcess, _keyRequestTimer.TimeUntilProcess());

  return timeUntilNextProcess;
}

int32_t VideoReceiver::SetReceiveChannelParameters(int64_t rtt) {
  RTC_DCHECK_RUN_ON(&module_thread_checker_);
  _receiver.UpdateRtt(rtt);
  return 0;
}

// Enable or disable a video protection method.
// Note: This API should be deprecated, as it does not offer a distinction
// between the protection method and decoding with or without errors.
int32_t VideoReceiver::SetVideoProtection(VCMVideoProtection videoProtection,
                                          bool enable) {
  // By default, do not decode with errors.
  _receiver.SetDecodeErrorMode(kNoErrors);
  switch (videoProtection) {
    case kProtectionNack: {
      RTC_DCHECK(enable);
      _receiver.SetNackMode(kNack, -1, -1);
      break;
    }

    case kProtectionNackFEC: {
      RTC_DCHECK(enable);
      _receiver.SetNackMode(kNack, media_optimization::kLowRttNackMs,
                            media_optimization::kMaxRttDelayThreshold);
      _receiver.SetDecodeErrorMode(kNoErrors);
      break;
    }
    case kProtectionFEC:
    case kProtectionNone:
      // No receiver-side protection.
      RTC_DCHECK(enable);
      _receiver.SetNackMode(kNoNack, -1, -1);
      _receiver.SetDecodeErrorMode(kWithErrors);
      break;
  }
  return VCM_OK;
}

// Register a receive callback. Will be called whenever there is a new frame
// ready for rendering.
int32_t VideoReceiver::RegisterReceiveCallback(
    VCMReceiveCallback* receiveCallback) {
  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
  RTC_DCHECK(!IsDecoderThreadRunning());
  // This value is set before the decoder thread starts and unset after
  // the decoder thread has been stopped.
  _decodedFrameCallback.SetUserReceiveCallback(receiveCallback);
  return VCM_OK;
}

int32_t VideoReceiver::RegisterReceiveStatisticsCallback(
    VCMReceiveStatisticsCallback* receiveStats) {
  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
  RTC_DCHECK(!IsDecoderThreadRunning() && !is_attached_to_process_thread_);
  // |_receiver| is used on both the decoder and module threads.
  // However, since we make sure that we never do anything on the module thread
  // when the decoder thread is not running, we don't need a lock for the
  // |_receiver| or |_receiveStatsCallback| here.
  _receiver.RegisterStatsCallback(receiveStats);
  _receiveStatsCallback = receiveStats;
  return VCM_OK;
}

// Register an externally defined decoder object.
void VideoReceiver::RegisterExternalDecoder(VideoDecoder* externalDecoder,
                                            uint8_t payloadType) {
  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
  RTC_DCHECK(!IsDecoderThreadRunning());
  if (externalDecoder == nullptr) {
    RTC_CHECK(_codecDataBase.DeregisterExternalDecoder(payloadType));
    return;
  }
  _codecDataBase.RegisterExternalDecoder(externalDecoder, payloadType);
}

// Register a frame type request callback.
int32_t VideoReceiver::RegisterFrameTypeCallback(
    VCMFrameTypeCallback* frameTypeCallback) {
  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
  RTC_DCHECK(!IsDecoderThreadRunning() && !is_attached_to_process_thread_);
  // This callback is used on the module thread, but since we don't get
  // callbacks on the module thread while the decoder thread isn't running
  // (and this function must not be called when the decoder is running),
  // we don't need a lock here.
  _frameTypeCallback = frameTypeCallback;
  return VCM_OK;
}

int32_t VideoReceiver::RegisterPacketRequestCallback(
    VCMPacketRequestCallback* callback) {
  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
  RTC_DCHECK(!IsDecoderThreadRunning() && !is_attached_to_process_thread_);
  // This callback is used on the module thread, but since we don't get
  // callbacks on the module thread while the decoder thread isn't running
  // (and this function must not be called when the decoder is running),
  // we don't need a lock here.
  _packetRequestCallback = callback;
  return VCM_OK;
}

void VideoReceiver::TriggerDecoderShutdown() {
  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
  RTC_DCHECK(IsDecoderThreadRunning());
  _receiver.TriggerDecoderShutdown();
}

void VideoReceiver::DecoderThreadStarting() {
  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
  RTC_DCHECK(!IsDecoderThreadRunning());
  if (process_thread_ && !is_attached_to_process_thread_) {
    process_thread_->RegisterModule(this, RTC_FROM_HERE);
  }
#if RTC_DCHECK_IS_ON
  decoder_thread_is_running_ = true;
#endif
}

void VideoReceiver::DecoderThreadStopped() {
  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
  RTC_DCHECK(IsDecoderThreadRunning());
  if (process_thread_ && is_attached_to_process_thread_) {
    process_thread_->DeRegisterModule(this);
  }
#if RTC_DCHECK_IS_ON
  decoder_thread_is_running_ = false;
  decoder_thread_checker_.DetachFromThread();
#endif
}

// Decode next frame, blocking.
// Should be called as often as possible to get the most out of the decoder.
int32_t VideoReceiver::Decode(uint16_t maxWaitTimeMs) {
  RTC_DCHECK_RUN_ON(&decoder_thread_checker_);
  VCMEncodedFrame* frame = _receiver.FrameForDecoding(
      maxWaitTimeMs, _codecDataBase.PrefersLateDecoding());

  if (!frame)
    return VCM_FRAME_NOT_READY;

  bool drop_frame = false;
  {
    rtc::CritScope cs(&process_crit_);
    if (drop_frames_until_keyframe_) {
      // Still getting delta frames, schedule another keyframe request as if
      // decode failed.
      if (frame->FrameType() != kVideoFrameKey) {
        drop_frame = true;
        _scheduleKeyRequest = true;
        // TODO(tommi): Consider if we could instead post a task to the module
        // thread and call RequestKeyFrame directly. Here we call WakeUp so that
        // TimeUntilNextProcess() gets called straight away.
        process_thread_->WakeUp(this);
      } else {
        drop_frames_until_keyframe_ = false;
      }
    }
  }

  if (drop_frame) {
    _receiver.ReleaseFrame(frame);
    return VCM_FRAME_NOT_READY;
  }

  // If this frame was too late, we should adjust the delay accordingly
  _timing->UpdateCurrentDelay(frame->RenderTimeMs(),
                              clock_->TimeInMilliseconds());

  if (first_frame_received_()) {
    RTC_LOG(LS_INFO) << "Received first "
                     << (frame->Complete() ? "complete" : "incomplete")
                     << " decodable video frame";
  }

  const int32_t ret = Decode(*frame);
  _receiver.ReleaseFrame(frame);
  return ret;
}

// Used for the new jitter buffer.
// TODO(philipel): Clean up among the Decode functions as we replace
//                 VCMEncodedFrame with FrameObject.
int32_t VideoReceiver::Decode(const webrtc::VCMEncodedFrame* frame) {
  RTC_DCHECK_RUN_ON(&decoder_thread_checker_);
  return Decode(*frame);
}

int32_t VideoReceiver::RequestKeyFrame() {
  RTC_DCHECK_RUN_ON(&module_thread_checker_);

  // Since we deregister from the module thread when the decoder thread isn't
  // running, we should get no calls here if decoding isn't being done.
  RTC_DCHECK(IsDecoderThreadRunning());

  TRACE_EVENT0("webrtc", "RequestKeyFrame");
  if (_frameTypeCallback != nullptr) {
    const int32_t ret = _frameTypeCallback->RequestKeyFrame();
    if (ret < 0) {
      return ret;
    }
    rtc::CritScope cs(&process_crit_);
    _scheduleKeyRequest = false;
  } else {
    return VCM_MISSING_CALLBACK;
  }
  return VCM_OK;
}

// Must be called from inside the receive side critical section.
int32_t VideoReceiver::Decode(const VCMEncodedFrame& frame) {
  RTC_DCHECK_RUN_ON(&decoder_thread_checker_);
  TRACE_EVENT0("webrtc", "VideoReceiver::Decode");
  // Change decoder if payload type has changed
  VCMGenericDecoder* decoder =
      _codecDataBase.GetDecoder(frame, &_decodedFrameCallback);
  if (decoder == nullptr) {
    return VCM_NO_CODEC_REGISTERED;
  }
  return decoder->Decode(frame, clock_->TimeInMilliseconds());
}

// Register possible receive codecs, can be called multiple times
int32_t VideoReceiver::RegisterReceiveCodec(const VideoCodec* receiveCodec,
                                            int32_t numberOfCores,
                                            bool requireKeyFrame) {
  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
  RTC_DCHECK(!IsDecoderThreadRunning());
  if (receiveCodec == nullptr) {
    return VCM_PARAMETER_ERROR;
  }
  if (!_codecDataBase.RegisterReceiveCodec(receiveCodec, numberOfCores,
                                           requireKeyFrame)) {
    return -1;
  }
  return 0;
}

// Incoming packet from network parsed and ready for decode, non blocking.
int32_t VideoReceiver::IncomingPacket(const uint8_t* incomingPayload,
                                      size_t payloadLength,
                                      const WebRtcRTPHeader& rtpInfo) {
  RTC_DCHECK_RUN_ON(&module_thread_checker_);
  if (rtpInfo.frameType == kVideoFrameKey) {
    TRACE_EVENT1("webrtc", "VCM::PacketKeyFrame", "seqnum",
                 rtpInfo.header.sequenceNumber);
  }
  if (incomingPayload == nullptr) {
    // The jitter buffer doesn't handle non-zero payload lengths for packets
    // without payload.
    // TODO(holmer): We should fix this in the jitter buffer.
    payloadLength = 0;
  }
  const VCMPacket packet(incomingPayload, payloadLength, rtpInfo);
  int32_t ret = _receiver.InsertPacket(packet);

  // TODO(holmer): Investigate if this somehow should use the key frame
  // request scheduling to throttle the requests.
  if (ret == VCM_FLUSH_INDICATOR) {
    {
      rtc::CritScope cs(&process_crit_);
      drop_frames_until_keyframe_ = true;
    }
    RequestKeyFrame();
  } else if (ret < 0) {
    return ret;
  }
  return VCM_OK;
}

// Minimum playout delay (used for lip-sync). This is the minimum delay required
// to sync with audio. Not included in  VideoCodingModule::Delay()
// Defaults to 0 ms.
int32_t VideoReceiver::SetMinimumPlayoutDelay(uint32_t minPlayoutDelayMs) {
  RTC_DCHECK_RUN_ON(&module_thread_checker_);
  _timing->set_min_playout_delay(minPlayoutDelayMs);
  return VCM_OK;
}

// The estimated delay caused by rendering, defaults to
// kDefaultRenderDelayMs = 10 ms
int32_t VideoReceiver::SetRenderDelay(uint32_t timeMS) {
  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
  RTC_DCHECK(!IsDecoderThreadRunning());
  _timing->set_render_delay(timeMS);
  return VCM_OK;
}

// Current video delay
int32_t VideoReceiver::Delay() const {
  RTC_DCHECK_RUN_ON(&module_thread_checker_);
  return _timing->TargetVideoDelay();
}

// Only used by VCMRobustnessTest.
int VideoReceiver::SetReceiverRobustnessMode(
    VideoCodingModule::ReceiverRobustness robustnessMode,
    VCMDecodeErrorMode decode_error_mode) {
  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
  RTC_DCHECK(!IsDecoderThreadRunning());
  switch (robustnessMode) {
    case VideoCodingModule::kNone:
      _receiver.SetNackMode(kNoNack, -1, -1);
      break;
    case VideoCodingModule::kHardNack:
      // Always wait for retransmissions (except when decoding with errors).
      _receiver.SetNackMode(kNack, -1, -1);
      break;
    default:
      RTC_NOTREACHED();
      return VCM_PARAMETER_ERROR;
  }
  _receiver.SetDecodeErrorMode(decode_error_mode);
  return VCM_OK;
}

void VideoReceiver::SetDecodeErrorMode(VCMDecodeErrorMode decode_error_mode) {
  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
  RTC_DCHECK(!IsDecoderThreadRunning());
  _receiver.SetDecodeErrorMode(decode_error_mode);
}

void VideoReceiver::SetNackSettings(size_t max_nack_list_size,
                                    int max_packet_age_to_nack,
                                    int max_incomplete_time_ms) {
  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
  RTC_DCHECK(!IsDecoderThreadRunning());
  if (max_nack_list_size != 0) {
    max_nack_list_size_ = max_nack_list_size;
  }
  _receiver.SetNackSettings(max_nack_list_size, max_packet_age_to_nack,
                            max_incomplete_time_ms);
}

bool VideoReceiver::IsDecoderThreadRunning() {
#if RTC_DCHECK_IS_ON
  return decoder_thread_is_running_;
#else
  return true;
#endif
}

}  // namespace vcm
}  // namespace webrtc