modules/video_coding/session_info.cc - src/webrtc - Git at Google

 /*
  *  Copyright (c) 2012 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/modules/video_coding/session_info.h"

 #include "webrtc/base/logging.h"
 #include "webrtc/modules/video_coding/packet.h"

 namespace webrtc {

 namespace {

 uint16_t BufferToUWord16(const uint8_t* dataBuffer) {
   return (dataBuffer[0] << 8) | dataBuffer[1];
 }

 }  // namespace

 VCMSessionInfo::VCMSessionInfo()
     : session_nack_(false),
       complete_(false),
       decodable_(false),
       frame_type_(kVideoFrameDelta),
       packets_(),
       empty_seq_num_low_(-1),
       empty_seq_num_high_(-1),
       first_packet_seq_num_(-1),
       last_packet_seq_num_(-1) {}

 void VCMSessionInfo::UpdateDataPointers(const uint8_t* old_base_ptr,
                                         const uint8_t* new_base_ptr) {
   for (PacketIterator it = packets_.begin(); it != packets_.end(); ++it)
     if ((*it).dataPtr != NULL) {
       assert(old_base_ptr != NULL && new_base_ptr != NULL);
       (*it).dataPtr = new_base_ptr + ((*it).dataPtr - old_base_ptr);
     }
 }

 int VCMSessionInfo::LowSequenceNumber() const {
   if (packets_.empty())
     return empty_seq_num_low_;
   return packets_.front().seqNum;
 }

 int VCMSessionInfo::HighSequenceNumber() const {
   if (packets_.empty())
     return empty_seq_num_high_;
   if (empty_seq_num_high_ == -1)
     return packets_.back().seqNum;
   return LatestSequenceNumber(packets_.back().seqNum, empty_seq_num_high_);
 }

 int VCMSessionInfo::PictureId() const {
   if (packets_.empty())
     return kNoPictureId;
   if (packets_.front().video_header.codec == kRtpVideoVp8) {
     return packets_.front().video_header.codecHeader.VP8.pictureId;
   } else if (packets_.front().video_header.codec == kRtpVideoVp9) {
     return packets_.front().video_header.codecHeader.VP9.picture_id;
   } else {
     return kNoPictureId;
   }
 }

 int VCMSessionInfo::TemporalId() const {
   if (packets_.empty())
     return kNoTemporalIdx;
   if (packets_.front().video_header.codec == kRtpVideoVp8) {
     return packets_.front().video_header.codecHeader.VP8.temporalIdx;
   } else if (packets_.front().video_header.codec == kRtpVideoVp9) {
     return packets_.front().video_header.codecHeader.VP9.temporal_idx;
   } else {
     return kNoTemporalIdx;
   }
 }

 bool VCMSessionInfo::LayerSync() const {
   if (packets_.empty())
     return false;
   if (packets_.front().video_header.codec == kRtpVideoVp8) {
     return packets_.front().video_header.codecHeader.VP8.layerSync;
   } else if (packets_.front().video_header.codec == kRtpVideoVp9) {
     return packets_.front().video_header.codecHeader.VP9.temporal_up_switch;
   } else {
     return false;
   }
 }

 int VCMSessionInfo::Tl0PicId() const {
   if (packets_.empty())
     return kNoTl0PicIdx;
   if (packets_.front().video_header.codec == kRtpVideoVp8) {
     return packets_.front().video_header.codecHeader.VP8.tl0PicIdx;
   } else if (packets_.front().video_header.codec == kRtpVideoVp9) {
     return packets_.front().video_header.codecHeader.VP9.tl0_pic_idx;
   } else {
     return kNoTl0PicIdx;
   }
 }

 bool VCMSessionInfo::NonReference() const {
   if (packets_.empty() || packets_.front().video_header.codec != kRtpVideoVp8)
     return false;
   return packets_.front().video_header.codecHeader.VP8.nonReference;
 }

 std::vector<NaluInfo> VCMSessionInfo::GetNaluInfos() const {
   if (packets_.empty() || packets_.front().video_header.codec != kRtpVideoH264)
     return std::vector<NaluInfo>();
   std::vector<NaluInfo> nalu_infos;
   for (const VCMPacket& packet : packets_) {
     for (size_t i = 0; i < packet.video_header.codecHeader.H264.nalus_length;
          ++i) {
       nalu_infos.push_back(packet.video_header.codecHeader.H264.nalus[i]);
     }
   }
   return nalu_infos;
 }

 void VCMSessionInfo::SetGofInfo(const GofInfoVP9& gof_info, size_t idx) {
   if (packets_.empty() || packets_.front().video_header.codec != kRtpVideoVp9 ||
       packets_.front().video_header.codecHeader.VP9.flexible_mode) {
     return;
   }
   packets_.front().video_header.codecHeader.VP9.temporal_idx =
       gof_info.temporal_idx[idx];
   packets_.front().video_header.codecHeader.VP9.temporal_up_switch =
       gof_info.temporal_up_switch[idx];
   packets_.front().video_header.codecHeader.VP9.num_ref_pics =
       gof_info.num_ref_pics[idx];
   for (uint8_t i = 0; i < gof_info.num_ref_pics[idx]; ++i) {
     packets_.front().video_header.codecHeader.VP9.pid_diff[i] =
         gof_info.pid_diff[idx][i];
   }
 }

 void VCMSessionInfo::Reset() {
   session_nack_ = false;
   complete_ = false;
   decodable_ = false;
   frame_type_ = kVideoFrameDelta;
   packets_.clear();
   empty_seq_num_low_ = -1;
   empty_seq_num_high_ = -1;
   first_packet_seq_num_ = -1;
   last_packet_seq_num_ = -1;
 }

 size_t VCMSessionInfo::SessionLength() const {
   size_t length = 0;
   for (PacketIteratorConst it = packets_.begin(); it != packets_.end(); ++it)
     length += (*it).sizeBytes;
   return length;
 }

 int VCMSessionInfo::NumPackets() const {
   return packets_.size();
 }

 size_t VCMSessionInfo::InsertBuffer(uint8_t* frame_buffer,
                                     PacketIterator packet_it) {
   VCMPacket& packet = *packet_it;
   PacketIterator it;

   // Calculate the offset into the frame buffer for this packet.
   size_t offset = 0;
   for (it = packets_.begin(); it != packet_it; ++it)
     offset += (*it).sizeBytes;

   // Set the data pointer to pointing to the start of this packet in the
   // frame buffer.
   const uint8_t* packet_buffer = packet.dataPtr;
   packet.dataPtr = frame_buffer + offset;

   // We handle H.264 STAP-A packets in a special way as we need to remove the
   // two length bytes between each NAL unit, and potentially add start codes.
   // TODO(pbos): Remove H264 parsing from this step and use a fragmentation
   // header supplied by the H264 depacketizer.
   const size_t kH264NALHeaderLengthInBytes = 1;
   const size_t kLengthFieldLength = 2;
   if (packet.video_header.codec == kRtpVideoH264 &&
       packet.video_header.codecHeader.H264.packetization_type == kH264StapA) {
     size_t required_length = 0;
     const uint8_t* nalu_ptr = packet_buffer + kH264NALHeaderLengthInBytes;
     while (nalu_ptr < packet_buffer + packet.sizeBytes) {
       size_t length = BufferToUWord16(nalu_ptr);
       required_length +=
           length + (packet.insertStartCode ? kH264StartCodeLengthBytes : 0);
       nalu_ptr += kLengthFieldLength + length;
     }
     ShiftSubsequentPackets(packet_it, required_length);
     nalu_ptr = packet_buffer + kH264NALHeaderLengthInBytes;
     uint8_t* frame_buffer_ptr = frame_buffer + offset;
     while (nalu_ptr < packet_buffer + packet.sizeBytes) {
       size_t length = BufferToUWord16(nalu_ptr);
       nalu_ptr += kLengthFieldLength;
       frame_buffer_ptr += Insert(nalu_ptr, length, packet.insertStartCode,
                                  const_cast<uint8_t*>(frame_buffer_ptr));
       nalu_ptr += length;
     }
     packet.sizeBytes = required_length;
     return packet.sizeBytes;
   }
   ShiftSubsequentPackets(
       packet_it, packet.sizeBytes +
                      (packet.insertStartCode ? kH264StartCodeLengthBytes : 0));

   packet.sizeBytes =
       Insert(packet_buffer, packet.sizeBytes, packet.insertStartCode,
              const_cast<uint8_t*>(packet.dataPtr));
   return packet.sizeBytes;
 }

 size_t VCMSessionInfo::Insert(const uint8_t* buffer,
                               size_t length,
                               bool insert_start_code,
                               uint8_t* frame_buffer) {
   if (insert_start_code) {
     const unsigned char startCode[] = {0, 0, 0, 1};
     memcpy(frame_buffer, startCode, kH264StartCodeLengthBytes);
   }
   memcpy(frame_buffer + (insert_start_code ? kH264StartCodeLengthBytes : 0),
          buffer, length);
   length += (insert_start_code ? kH264StartCodeLengthBytes : 0);

   return length;
 }

 void VCMSessionInfo::ShiftSubsequentPackets(PacketIterator it,
                                             int steps_to_shift) {
   ++it;
   if (it == packets_.end())
     return;
   uint8_t* first_packet_ptr = const_cast<uint8_t*>((*it).dataPtr);
   int shift_length = 0;
   // Calculate the total move length and move the data pointers in advance.
   for (; it != packets_.end(); ++it) {
     shift_length += (*it).sizeBytes;
     if ((*it).dataPtr != NULL)
       (*it).dataPtr += steps_to_shift;
   }
   memmove(first_packet_ptr + steps_to_shift, first_packet_ptr, shift_length);
 }

 void VCMSessionInfo::UpdateCompleteSession() {
   if (HaveFirstPacket() && HaveLastPacket()) {
     // Do we have all the packets in this session?
     bool complete_session = true;
     PacketIterator it = packets_.begin();
     PacketIterator prev_it = it;
     ++it;
     for (; it != packets_.end(); ++it) {
       if (!InSequence(it, prev_it)) {
         complete_session = false;
         break;
       }
       prev_it = it;
     }
     complete_ = complete_session;
   }
 }

 void VCMSessionInfo::UpdateDecodableSession(const FrameData& frame_data) {
   // Irrelevant if session is already complete or decodable
   if (complete_ || decodable_)
     return;
   // TODO(agalusza): Account for bursty loss.
   // TODO(agalusza): Refine these values to better approximate optimal ones.
   // Do not decode frames if the RTT is lower than this.
   const int64_t kRttThreshold = 100;
   // Do not decode frames if the number of packets is between these two
   // thresholds.
   const float kLowPacketPercentageThreshold = 0.2f;
   const float kHighPacketPercentageThreshold = 0.8f;
   if (frame_data.rtt_ms < kRttThreshold || frame_type_ == kVideoFrameKey ||
       !HaveFirstPacket() ||
       (NumPackets() <= kHighPacketPercentageThreshold *
                            frame_data.rolling_average_packets_per_frame &&
        NumPackets() > kLowPacketPercentageThreshold *
                           frame_data.rolling_average_packets_per_frame))
     return;

   decodable_ = true;
 }

 bool VCMSessionInfo::complete() const {
   return complete_;
 }

 bool VCMSessionInfo::decodable() const {
   return decodable_;
 }

 // Find the end of the NAL unit which the packet pointed to by |packet_it|
 // belongs to. Returns an iterator to the last packet of the frame if the end
 // of the NAL unit wasn't found.
 VCMSessionInfo::PacketIterator VCMSessionInfo::FindNaluEnd(
     PacketIterator packet_it) const {
   if ((*packet_it).completeNALU == kNaluEnd ||
       (*packet_it).completeNALU == kNaluComplete) {
     return packet_it;
   }
   // Find the end of the NAL unit.
   for (; packet_it != packets_.end(); ++packet_it) {
     if (((*packet_it).completeNALU == kNaluComplete &&
          (*packet_it).sizeBytes > 0) ||
         // Found next NALU.
         (*packet_it).completeNALU == kNaluStart)
       return --packet_it;
     if ((*packet_it).completeNALU == kNaluEnd)
       return packet_it;
   }
   // The end wasn't found.
   return --packet_it;
 }

 size_t VCMSessionInfo::DeletePacketData(PacketIterator start,
                                         PacketIterator end) {
   size_t bytes_to_delete = 0;  // The number of bytes to delete.
   PacketIterator packet_after_end = end;
   ++packet_after_end;

   // Get the number of bytes to delete.
   // Clear the size of these packets.
   for (PacketIterator it = start; it != packet_after_end; ++it) {
     bytes_to_delete += (*it).sizeBytes;
     (*it).sizeBytes = 0;
     (*it).dataPtr = NULL;
   }
   if (bytes_to_delete > 0)
     ShiftSubsequentPackets(end, -static_cast<int>(bytes_to_delete));
   return bytes_to_delete;
 }

 VCMSessionInfo::PacketIterator VCMSessionInfo::FindNextPartitionBeginning(
     PacketIterator it) const {
   while (it != packets_.end()) {
     if ((*it).video_header.codecHeader.VP8.beginningOfPartition) {
       return it;
     }
     ++it;
   }
   return it;
 }

 VCMSessionInfo::PacketIterator VCMSessionInfo::FindPartitionEnd(
     PacketIterator it) const {
   assert((*it).codec == kVideoCodecVP8);
   PacketIterator prev_it = it;
   const int partition_id = (*it).video_header.codecHeader.VP8.partitionId;
   while (it != packets_.end()) {
     bool beginning = (*it).video_header.codecHeader.VP8.beginningOfPartition;
     int current_partition_id = (*it).video_header.codecHeader.VP8.partitionId;
     bool packet_loss_found = (!beginning && !InSequence(it, prev_it));
     if (packet_loss_found ||
         (beginning && current_partition_id != partition_id)) {
       // Missing packet, the previous packet was the last in sequence.
       return prev_it;
     }
     prev_it = it;
     ++it;
   }
   return prev_it;
 }

 bool VCMSessionInfo::InSequence(const PacketIterator& packet_it,
                                 const PacketIterator& prev_packet_it) {
   // If the two iterators are pointing to the same packet they are considered
   // to be in sequence.
   return (packet_it == prev_packet_it ||
           (static_cast<uint16_t>((*prev_packet_it).seqNum + 1) ==
            (*packet_it).seqNum));
 }

 size_t VCMSessionInfo::MakeDecodable() {
   size_t return_length = 0;
   if (packets_.empty()) {
     return 0;
   }
   PacketIterator it = packets_.begin();
   // Make sure we remove the first NAL unit if it's not decodable.
   if ((*it).completeNALU == kNaluIncomplete || (*it).completeNALU == kNaluEnd) {
     PacketIterator nalu_end = FindNaluEnd(it);
     return_length += DeletePacketData(it, nalu_end);
     it = nalu_end;
   }
   PacketIterator prev_it = it;
   // Take care of the rest of the NAL units.
   for (; it != packets_.end(); ++it) {
     bool start_of_nalu = ((*it).completeNALU == kNaluStart ||
                           (*it).completeNALU == kNaluComplete);
     if (!start_of_nalu && !InSequence(it, prev_it)) {
       // Found a sequence number gap due to packet loss.
       PacketIterator nalu_end = FindNaluEnd(it);
       return_length += DeletePacketData(it, nalu_end);
       it = nalu_end;
     }
     prev_it = it;
   }
   return return_length;
 }

 void VCMSessionInfo::SetNotDecodableIfIncomplete() {
   // We don't need to check for completeness first because the two are
   // orthogonal. If complete_ is true, decodable_ is irrelevant.
   decodable_ = false;
 }

 bool VCMSessionInfo::HaveFirstPacket() const {
   return !packets_.empty() && (first_packet_seq_num_ != -1);
 }

 bool VCMSessionInfo::HaveLastPacket() const {
   return !packets_.empty() && (last_packet_seq_num_ != -1);
 }

 bool VCMSessionInfo::session_nack() const {
   return session_nack_;
 }

 int VCMSessionInfo::InsertPacket(const VCMPacket& packet,
                                  uint8_t* frame_buffer,
                                  VCMDecodeErrorMode decode_error_mode,
                                  const FrameData& frame_data) {
   if (packet.frameType == kEmptyFrame) {
     // Update sequence number of an empty packet.
     // Only media packets are inserted into the packet list.
     InformOfEmptyPacket(packet.seqNum);
     return 0;
   }

   if (packets_.size() == kMaxPacketsInSession) {
     LOG(LS_ERROR) << "Max number of packets per frame has been reached.";
     return -1;
   }

   // Find the position of this packet in the packet list in sequence number
   // order and insert it. Loop over the list in reverse order.
   ReversePacketIterator rit = packets_.rbegin();
   for (; rit != packets_.rend(); ++rit)
     if (LatestSequenceNumber(packet.seqNum, (*rit).seqNum) == packet.seqNum)
       break;

   // Check for duplicate packets.
   if (rit != packets_.rend() && (*rit).seqNum == packet.seqNum &&
       (*rit).sizeBytes > 0)
     return -2;

   if (packet.codec == kVideoCodecH264) {
     frame_type_ = packet.frameType;
     if (packet.isFirstPacket &&
         (first_packet_seq_num_ == -1 ||
          IsNewerSequenceNumber(first_packet_seq_num_, packet.seqNum))) {
       first_packet_seq_num_ = packet.seqNum;
     }
     if (packet.markerBit &&
         (last_packet_seq_num_ == -1 ||
          IsNewerSequenceNumber(packet.seqNum, last_packet_seq_num_))) {
       last_packet_seq_num_ = packet.seqNum;
     }
   } else {
     // Only insert media packets between first and last packets (when
     // available).
     // Placing check here, as to properly account for duplicate packets.
     // Check if this is first packet (only valid for some codecs)
     // Should only be set for one packet per session.
     if (packet.isFirstPacket && first_packet_seq_num_ == -1) {
       // The first packet in a frame signals the frame type.
       frame_type_ = packet.frameType;
       // Store the sequence number for the first packet.
       first_packet_seq_num_ = static_cast<int>(packet.seqNum);
     } else if (first_packet_seq_num_ != -1 &&
                IsNewerSequenceNumber(first_packet_seq_num_, packet.seqNum)) {
       LOG(LS_WARNING) << "Received packet with a sequence number which is out "
                          "of frame boundaries";
       return -3;
     } else if (frame_type_ == kEmptyFrame && packet.frameType != kEmptyFrame) {
       // Update the frame type with the type of the first media packet.
       // TODO(mikhal): Can this trigger?
       frame_type_ = packet.frameType;
     }

     // Track the marker bit, should only be set for one packet per session.
     if (packet.markerBit && last_packet_seq_num_ == -1) {
       last_packet_seq_num_ = static_cast<int>(packet.seqNum);
     } else if (last_packet_seq_num_ != -1 &&
                IsNewerSequenceNumber(packet.seqNum, last_packet_seq_num_)) {
       LOG(LS_WARNING) << "Received packet with a sequence number which is out "
                          "of frame boundaries";
       return -3;
     }
   }

   // The insert operation invalidates the iterator |rit|.
   PacketIterator packet_list_it = packets_.insert(rit.base(), packet);

   size_t returnLength = InsertBuffer(frame_buffer, packet_list_it);
   UpdateCompleteSession();
   if (decode_error_mode == kWithErrors)
     decodable_ = true;
   else if (decode_error_mode == kSelectiveErrors)
     UpdateDecodableSession(frame_data);
   return static_cast<int>(returnLength);
 }

 void VCMSessionInfo::InformOfEmptyPacket(uint16_t seq_num) {
   // Empty packets may be FEC or filler packets. They are sequential and
   // follow the data packets, therefore, we should only keep track of the high
   // and low sequence numbers and may assume that the packets in between are
   // empty packets belonging to the same frame (timestamp).
   if (empty_seq_num_high_ == -1)
     empty_seq_num_high_ = seq_num;
   else
     empty_seq_num_high_ = LatestSequenceNumber(seq_num, empty_seq_num_high_);
   if (empty_seq_num_low_ == -1 ||
       IsNewerSequenceNumber(empty_seq_num_low_, seq_num))
     empty_seq_num_low_ = seq_num;
 }

 }  // namespace webrtc
	/*
	* Copyright (c) 2012 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/modules/video_coding/session_info.h"

	#include "webrtc/base/logging.h"
	#include "webrtc/modules/video_coding/packet.h"

	namespace webrtc {

	namespace {

	uint16_t BufferToUWord16(const uint8_t* dataBuffer) {
	return (dataBuffer[0] << 8) \| dataBuffer[1];
	}

	} // namespace

	VCMSessionInfo::VCMSessionInfo()
	: session_nack_(false),
	complete_(false),
	decodable_(false),
	frame_type_(kVideoFrameDelta),
	packets_(),
	empty_seq_num_low_(-1),
	empty_seq_num_high_(-1),
	first_packet_seq_num_(-1),
	last_packet_seq_num_(-1) {}

	void VCMSessionInfo::UpdateDataPointers(const uint8_t* old_base_ptr,
	const uint8_t* new_base_ptr) {
	for (PacketIterator it = packets_.begin(); it != packets_.end(); ++it)
	if ((*it).dataPtr != NULL) {
	assert(old_base_ptr != NULL && new_base_ptr != NULL);
	(it).dataPtr = new_base_ptr + ((it).dataPtr - old_base_ptr);
	}
	}

	int VCMSessionInfo::LowSequenceNumber() const {
	if (packets_.empty())
	return empty_seq_num_low_;
	return packets_.front().seqNum;
	}

	int VCMSessionInfo::HighSequenceNumber() const {
	if (packets_.empty())
	return empty_seq_num_high_;
	if (empty_seq_num_high_ == -1)
	return packets_.back().seqNum;
	return LatestSequenceNumber(packets_.back().seqNum, empty_seq_num_high_);
	}

	int VCMSessionInfo::PictureId() const {
	if (packets_.empty())
	return kNoPictureId;
	if (packets_.front().video_header.codec == kRtpVideoVp8) {
	return packets_.front().video_header.codecHeader.VP8.pictureId;
	} else if (packets_.front().video_header.codec == kRtpVideoVp9) {
	return packets_.front().video_header.codecHeader.VP9.picture_id;
	} else {
	return kNoPictureId;
	}
	}

	int VCMSessionInfo::TemporalId() const {
	if (packets_.empty())
	return kNoTemporalIdx;
	if (packets_.front().video_header.codec == kRtpVideoVp8) {
	return packets_.front().video_header.codecHeader.VP8.temporalIdx;
	} else if (packets_.front().video_header.codec == kRtpVideoVp9) {
	return packets_.front().video_header.codecHeader.VP9.temporal_idx;
	} else {
	return kNoTemporalIdx;
	}
	}

	bool VCMSessionInfo::LayerSync() const {
	if (packets_.empty())
	return false;
	if (packets_.front().video_header.codec == kRtpVideoVp8) {
	return packets_.front().video_header.codecHeader.VP8.layerSync;
	} else if (packets_.front().video_header.codec == kRtpVideoVp9) {
	return packets_.front().video_header.codecHeader.VP9.temporal_up_switch;
	} else {
	return false;
	}
	}

	int VCMSessionInfo::Tl0PicId() const {
	if (packets_.empty())
	return kNoTl0PicIdx;
	if (packets_.front().video_header.codec == kRtpVideoVp8) {
	return packets_.front().video_header.codecHeader.VP8.tl0PicIdx;
	} else if (packets_.front().video_header.codec == kRtpVideoVp9) {
	return packets_.front().video_header.codecHeader.VP9.tl0_pic_idx;
	} else {
	return kNoTl0PicIdx;
	}
	}

	bool VCMSessionInfo::NonReference() const {
	if (packets_.empty() \|\| packets_.front().video_header.codec != kRtpVideoVp8)
	return false;
	return packets_.front().video_header.codecHeader.VP8.nonReference;
	}

	std::vector<NaluInfo> VCMSessionInfo::GetNaluInfos() const {
	if (packets_.empty() \|\| packets_.front().video_header.codec != kRtpVideoH264)
	return std::vector<NaluInfo>();
	std::vector<NaluInfo> nalu_infos;
	for (const VCMPacket& packet : packets_) {
	for (size_t i = 0; i < packet.video_header.codecHeader.H264.nalus_length;
	++i) {
	nalu_infos.push_back(packet.video_header.codecHeader.H264.nalus[i]);
	}
	}
	return nalu_infos;
	}

	void VCMSessionInfo::SetGofInfo(const GofInfoVP9& gof_info, size_t idx) {
	if (packets_.empty() \|\| packets_.front().video_header.codec != kRtpVideoVp9 \|\|
	packets_.front().video_header.codecHeader.VP9.flexible_mode) {
	return;
	}
	packets_.front().video_header.codecHeader.VP9.temporal_idx =
	gof_info.temporal_idx[idx];
	packets_.front().video_header.codecHeader.VP9.temporal_up_switch =
	gof_info.temporal_up_switch[idx];
	packets_.front().video_header.codecHeader.VP9.num_ref_pics =
	gof_info.num_ref_pics[idx];
	for (uint8_t i = 0; i < gof_info.num_ref_pics[idx]; ++i) {
	packets_.front().video_header.codecHeader.VP9.pid_diff[i] =
	gof_info.pid_diff[idx][i];
	}
	}

	void VCMSessionInfo::Reset() {
	session_nack_ = false;
	complete_ = false;
	decodable_ = false;
	frame_type_ = kVideoFrameDelta;
	packets_.clear();
	empty_seq_num_low_ = -1;
	empty_seq_num_high_ = -1;
	first_packet_seq_num_ = -1;
	last_packet_seq_num_ = -1;
	}

	size_t VCMSessionInfo::SessionLength() const {
	size_t length = 0;
	for (PacketIteratorConst it = packets_.begin(); it != packets_.end(); ++it)
	length += (*it).sizeBytes;
	return length;
	}

	int VCMSessionInfo::NumPackets() const {
	return packets_.size();
	}

	size_t VCMSessionInfo::InsertBuffer(uint8_t* frame_buffer,
	PacketIterator packet_it) {
	VCMPacket& packet = *packet_it;
	PacketIterator it;

	// Calculate the offset into the frame buffer for this packet.
	size_t offset = 0;
	for (it = packets_.begin(); it != packet_it; ++it)
	offset += (*it).sizeBytes;

	// Set the data pointer to pointing to the start of this packet in the
	// frame buffer.
	const uint8_t* packet_buffer = packet.dataPtr;
	packet.dataPtr = frame_buffer + offset;

	// We handle H.264 STAP-A packets in a special way as we need to remove the
	// two length bytes between each NAL unit, and potentially add start codes.
	// TODO(pbos): Remove H264 parsing from this step and use a fragmentation
	// header supplied by the H264 depacketizer.
	const size_t kH264NALHeaderLengthInBytes = 1;
	const size_t kLengthFieldLength = 2;
	if (packet.video_header.codec == kRtpVideoH264 &&
	packet.video_header.codecHeader.H264.packetization_type == kH264StapA) {
	size_t required_length = 0;
	const uint8_t* nalu_ptr = packet_buffer + kH264NALHeaderLengthInBytes;
	while (nalu_ptr < packet_buffer + packet.sizeBytes) {
	size_t length = BufferToUWord16(nalu_ptr);
	required_length +=
	length + (packet.insertStartCode ? kH264StartCodeLengthBytes : 0);
	nalu_ptr += kLengthFieldLength + length;
	}
	ShiftSubsequentPackets(packet_it, required_length);
	nalu_ptr = packet_buffer + kH264NALHeaderLengthInBytes;
	uint8_t* frame_buffer_ptr = frame_buffer + offset;
	while (nalu_ptr < packet_buffer + packet.sizeBytes) {
	size_t length = BufferToUWord16(nalu_ptr);
	nalu_ptr += kLengthFieldLength;
	frame_buffer_ptr += Insert(nalu_ptr, length, packet.insertStartCode,
	const_cast<uint8_t*>(frame_buffer_ptr));
	nalu_ptr += length;
	}
	packet.sizeBytes = required_length;
	return packet.sizeBytes;
	}
	ShiftSubsequentPackets(
	packet_it, packet.sizeBytes +
	(packet.insertStartCode ? kH264StartCodeLengthBytes : 0));

	packet.sizeBytes =
	Insert(packet_buffer, packet.sizeBytes, packet.insertStartCode,
	const_cast<uint8_t*>(packet.dataPtr));
	return packet.sizeBytes;
	}

	size_t VCMSessionInfo::Insert(const uint8_t* buffer,
	size_t length,
	bool insert_start_code,
	uint8_t* frame_buffer) {
	if (insert_start_code) {
	const unsigned char startCode[] = {0, 0, 0, 1};
	memcpy(frame_buffer, startCode, kH264StartCodeLengthBytes);
	}
	memcpy(frame_buffer + (insert_start_code ? kH264StartCodeLengthBytes : 0),
	buffer, length);
	length += (insert_start_code ? kH264StartCodeLengthBytes : 0);

	return length;
	}

	void VCMSessionInfo::ShiftSubsequentPackets(PacketIterator it,
	int steps_to_shift) {
	++it;
	if (it == packets_.end())
	return;
	uint8_t* first_packet_ptr = const_cast<uint8_t>((it).dataPtr);
	int shift_length = 0;
	// Calculate the total move length and move the data pointers in advance.
	for (; it != packets_.end(); ++it) {
	shift_length += (*it).sizeBytes;
	if ((*it).dataPtr != NULL)
	(*it).dataPtr += steps_to_shift;
	}
	memmove(first_packet_ptr + steps_to_shift, first_packet_ptr, shift_length);
	}

	void VCMSessionInfo::UpdateCompleteSession() {
	if (HaveFirstPacket() && HaveLastPacket()) {
	// Do we have all the packets in this session?
	bool complete_session = true;
	PacketIterator it = packets_.begin();
	PacketIterator prev_it = it;
	++it;
	for (; it != packets_.end(); ++it) {
	if (!InSequence(it, prev_it)) {
	complete_session = false;
	break;
	}
	prev_it = it;
	}
	complete_ = complete_session;
	}
	}

	void VCMSessionInfo::UpdateDecodableSession(const FrameData& frame_data) {
	// Irrelevant if session is already complete or decodable
	if (complete_ \|\| decodable_)
	return;
	// TODO(agalusza): Account for bursty loss.
	// TODO(agalusza): Refine these values to better approximate optimal ones.
	// Do not decode frames if the RTT is lower than this.
	const int64_t kRttThreshold = 100;
	// Do not decode frames if the number of packets is between these two
	// thresholds.
	const float kLowPacketPercentageThreshold = 0.2f;
	const float kHighPacketPercentageThreshold = 0.8f;
	if (frame_data.rtt_ms < kRttThreshold \|\| frame_type_ == kVideoFrameKey \|\|
	!HaveFirstPacket() \|\|
	(NumPackets() <= kHighPacketPercentageThreshold *
	frame_data.rolling_average_packets_per_frame &&
	NumPackets() > kLowPacketPercentageThreshold *
	frame_data.rolling_average_packets_per_frame))
	return;

	decodable_ = true;
	}

	bool VCMSessionInfo::complete() const {
	return complete_;
	}

	bool VCMSessionInfo::decodable() const {
	return decodable_;
	}

	// Find the end of the NAL unit which the packet pointed to by \|packet_it\|
	// belongs to. Returns an iterator to the last packet of the frame if the end
	// of the NAL unit wasn't found.
	VCMSessionInfo::PacketIterator VCMSessionInfo::FindNaluEnd(
	PacketIterator packet_it) const {
	if ((*packet_it).completeNALU == kNaluEnd \|\|
	(*packet_it).completeNALU == kNaluComplete) {
	return packet_it;
	}
	// Find the end of the NAL unit.
	for (; packet_it != packets_.end(); ++packet_it) {
	if (((*packet_it).completeNALU == kNaluComplete &&
	(*packet_it).sizeBytes > 0) \|\|
	// Found next NALU.
	(*packet_it).completeNALU == kNaluStart)
	return --packet_it;
	if ((*packet_it).completeNALU == kNaluEnd)
	return packet_it;
	}
	// The end wasn't found.
	return --packet_it;
	}

	size_t VCMSessionInfo::DeletePacketData(PacketIterator start,
	PacketIterator end) {
	size_t bytes_to_delete = 0; // The number of bytes to delete.
	PacketIterator packet_after_end = end;
	++packet_after_end;

	// Get the number of bytes to delete.
	// Clear the size of these packets.
	for (PacketIterator it = start; it != packet_after_end; ++it) {
	bytes_to_delete += (*it).sizeBytes;
	(*it).sizeBytes = 0;
	(*it).dataPtr = NULL;
	}
	if (bytes_to_delete > 0)
	ShiftSubsequentPackets(end, -static_cast<int>(bytes_to_delete));
	return bytes_to_delete;
	}

	VCMSessionInfo::PacketIterator VCMSessionInfo::FindNextPartitionBeginning(
	PacketIterator it) const {
	while (it != packets_.end()) {
	if ((*it).video_header.codecHeader.VP8.beginningOfPartition) {
	return it;
	}
	++it;
	}
	return it;
	}

	VCMSessionInfo::PacketIterator VCMSessionInfo::FindPartitionEnd(
	PacketIterator it) const {
	assert((*it).codec == kVideoCodecVP8);
	PacketIterator prev_it = it;
	const int partition_id = (*it).video_header.codecHeader.VP8.partitionId;
	while (it != packets_.end()) {
	bool beginning = (*it).video_header.codecHeader.VP8.beginningOfPartition;
	int current_partition_id = (*it).video_header.codecHeader.VP8.partitionId;
	bool packet_loss_found = (!beginning && !InSequence(it, prev_it));
	if (packet_loss_found \|\|
	(beginning && current_partition_id != partition_id)) {
	// Missing packet, the previous packet was the last in sequence.
	return prev_it;
	}
	prev_it = it;
	++it;
	}
	return prev_it;
	}

	bool VCMSessionInfo::InSequence(const PacketIterator& packet_it,
	const PacketIterator& prev_packet_it) {
	// If the two iterators are pointing to the same packet they are considered
	// to be in sequence.
	return (packet_it == prev_packet_it \|\|
	(static_cast<uint16_t>((*prev_packet_it).seqNum + 1) ==
	(*packet_it).seqNum));
	}

	size_t VCMSessionInfo::MakeDecodable() {
	size_t return_length = 0;
	if (packets_.empty()) {
	return 0;
	}
	PacketIterator it = packets_.begin();
	// Make sure we remove the first NAL unit if it's not decodable.
	if ((it).completeNALU == kNaluIncomplete \|\| (it).completeNALU == kNaluEnd) {
	PacketIterator nalu_end = FindNaluEnd(it);
	return_length += DeletePacketData(it, nalu_end);
	it = nalu_end;
	}
	PacketIterator prev_it = it;
	// Take care of the rest of the NAL units.
	for (; it != packets_.end(); ++it) {
	bool start_of_nalu = ((*it).completeNALU == kNaluStart \|\|
	(*it).completeNALU == kNaluComplete);
	if (!start_of_nalu && !InSequence(it, prev_it)) {
	// Found a sequence number gap due to packet loss.
	PacketIterator nalu_end = FindNaluEnd(it);
	return_length += DeletePacketData(it, nalu_end);
	it = nalu_end;
	}
	prev_it = it;
	}
	return return_length;
	}

	void VCMSessionInfo::SetNotDecodableIfIncomplete() {
	// We don't need to check for completeness first because the two are
	// orthogonal. If complete_ is true, decodable_ is irrelevant.
	decodable_ = false;
	}

	bool VCMSessionInfo::HaveFirstPacket() const {
	return !packets_.empty() && (first_packet_seq_num_ != -1);
	}

	bool VCMSessionInfo::HaveLastPacket() const {
	return !packets_.empty() && (last_packet_seq_num_ != -1);
	}

	bool VCMSessionInfo::session_nack() const {
	return session_nack_;
	}

	int VCMSessionInfo::InsertPacket(const VCMPacket& packet,
	uint8_t* frame_buffer,
	VCMDecodeErrorMode decode_error_mode,
	const FrameData& frame_data) {
	if (packet.frameType == kEmptyFrame) {
	// Update sequence number of an empty packet.
	// Only media packets are inserted into the packet list.
	InformOfEmptyPacket(packet.seqNum);
	return 0;
	}

	if (packets_.size() == kMaxPacketsInSession) {
	LOG(LS_ERROR) << "Max number of packets per frame has been reached.";
	return -1;
	}

	// Find the position of this packet in the packet list in sequence number
	// order and insert it. Loop over the list in reverse order.
	ReversePacketIterator rit = packets_.rbegin();
	for (; rit != packets_.rend(); ++rit)
	if (LatestSequenceNumber(packet.seqNum, (*rit).seqNum) == packet.seqNum)
	break;

	// Check for duplicate packets.
	if (rit != packets_.rend() && (*rit).seqNum == packet.seqNum &&
	(*rit).sizeBytes > 0)
	return -2;

	if (packet.codec == kVideoCodecH264) {
	frame_type_ = packet.frameType;
	if (packet.isFirstPacket &&
	(first_packet_seq_num_ == -1 \|\|
	IsNewerSequenceNumber(first_packet_seq_num_, packet.seqNum))) {
	first_packet_seq_num_ = packet.seqNum;
	}
	if (packet.markerBit &&
	(last_packet_seq_num_ == -1 \|\|
	IsNewerSequenceNumber(packet.seqNum, last_packet_seq_num_))) {
	last_packet_seq_num_ = packet.seqNum;
	}
	} else {
	// Only insert media packets between first and last packets (when
	// available).
	// Placing check here, as to properly account for duplicate packets.
	// Check if this is first packet (only valid for some codecs)
	// Should only be set for one packet per session.
	if (packet.isFirstPacket && first_packet_seq_num_ == -1) {
	// The first packet in a frame signals the frame type.
	frame_type_ = packet.frameType;
	// Store the sequence number for the first packet.
	first_packet_seq_num_ = static_cast<int>(packet.seqNum);
	} else if (first_packet_seq_num_ != -1 &&
	IsNewerSequenceNumber(first_packet_seq_num_, packet.seqNum)) {
	LOG(LS_WARNING) << "Received packet with a sequence number which is out "
	"of frame boundaries";
	return -3;
	} else if (frame_type_ == kEmptyFrame && packet.frameType != kEmptyFrame) {
	// Update the frame type with the type of the first media packet.
	// TODO(mikhal): Can this trigger?
	frame_type_ = packet.frameType;
	}

	// Track the marker bit, should only be set for one packet per session.
	if (packet.markerBit && last_packet_seq_num_ == -1) {
	last_packet_seq_num_ = static_cast<int>(packet.seqNum);
	} else if (last_packet_seq_num_ != -1 &&
	IsNewerSequenceNumber(packet.seqNum, last_packet_seq_num_)) {
	LOG(LS_WARNING) << "Received packet with a sequence number which is out "
	"of frame boundaries";
	return -3;
	}
	}

	// The insert operation invalidates the iterator \|rit\|.
	PacketIterator packet_list_it = packets_.insert(rit.base(), packet);

	size_t returnLength = InsertBuffer(frame_buffer, packet_list_it);
	UpdateCompleteSession();
	if (decode_error_mode == kWithErrors)
	decodable_ = true;
	else if (decode_error_mode == kSelectiveErrors)
	UpdateDecodableSession(frame_data);
	return static_cast<int>(returnLength);
	}

	void VCMSessionInfo::InformOfEmptyPacket(uint16_t seq_num) {
	// Empty packets may be FEC or filler packets. They are sequential and
	// follow the data packets, therefore, we should only keep track of the high
	// and low sequence numbers and may assume that the packets in between are
	// empty packets belonging to the same frame (timestamp).
	if (empty_seq_num_high_ == -1)
	empty_seq_num_high_ = seq_num;
	else
	empty_seq_num_high_ = LatestSequenceNumber(seq_num, empty_seq_num_high_);
	if (empty_seq_num_low_ == -1 \|\|
	IsNewerSequenceNumber(empty_seq_num_low_, seq_num))
	empty_seq_num_low_ = seq_num;
	}

	} // namespace webrtc