DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Header

Mercurial (cdf352f02ac4)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492
/*
 *  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 "modules/video_coding/packet_buffer.h"

#include <algorithm>
#include <limits>
#include <sstream>
#include <utility>

#include "common_video/h264/h264_common.h"
#include "modules/video_coding/frame_object.h"
#include "rtc_base/atomicops.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "system_wrappers/include/clock.h"
#include "system_wrappers/include/field_trial.h"

namespace webrtc {
namespace video_coding {

rtc::scoped_refptr<PacketBuffer> PacketBuffer::Create(
    Clock* clock,
    size_t start_buffer_size,
    size_t max_buffer_size,
    OnReceivedFrameCallback* received_frame_callback) {
  return rtc::scoped_refptr<PacketBuffer>(new PacketBuffer(
      clock, start_buffer_size, max_buffer_size, received_frame_callback));
}

PacketBuffer::PacketBuffer(Clock* clock,
                           size_t start_buffer_size,
                           size_t max_buffer_size,
                           OnReceivedFrameCallback* received_frame_callback)
    : clock_(clock),
      size_(start_buffer_size),
      max_size_(max_buffer_size),
      first_seq_num_(0),
      first_packet_received_(false),
      is_cleared_to_first_seq_num_(false),
      data_buffer_(start_buffer_size),
      sequence_buffer_(start_buffer_size),
      received_frame_callback_(received_frame_callback),
      sps_pps_idr_is_h264_keyframe_(
          field_trial::IsEnabled("WebRTC-SpsPpsIdrIsH264Keyframe")) {
  RTC_DCHECK_LE(start_buffer_size, max_buffer_size);
  // Buffer size must always be a power of 2.
  RTC_DCHECK((start_buffer_size & (start_buffer_size - 1)) == 0);
  RTC_DCHECK((max_buffer_size & (max_buffer_size - 1)) == 0);
}

PacketBuffer::~PacketBuffer() {
  Clear();
}

bool PacketBuffer::InsertPacket(VCMPacket* packet) {
  std::vector<std::unique_ptr<RtpFrameObject>> found_frames;
  {
    rtc::CritScope lock(&crit_);

    uint16_t seq_num = packet->seqNum;
    size_t index = seq_num % size_;

    if (!first_packet_received_) {
      first_seq_num_ = seq_num;
      first_packet_received_ = true;
    } else if (AheadOf(first_seq_num_, seq_num)) {
      // If we have explicitly cleared past this packet then it's old,
      // don't insert it.
      if (is_cleared_to_first_seq_num_) {
        delete[] packet->dataPtr;
        packet->dataPtr = nullptr;
        return false;
      }

      first_seq_num_ = seq_num;
    }

    if (sequence_buffer_[index].used) {
      // Duplicate packet, just delete the payload.
      if (data_buffer_[index].seqNum == packet->seqNum) {
        delete[] packet->dataPtr;
        packet->dataPtr = nullptr;
        return true;
      }

      // The packet buffer is full, try to expand the buffer.
      while (ExpandBufferSize() && sequence_buffer_[seq_num % size_].used) {
      }
      index = seq_num % size_;

      // Packet buffer is still full.
      if (sequence_buffer_[index].used) {
        delete[] packet->dataPtr;
        packet->dataPtr = nullptr;
        return false;
      }
    }

    sequence_buffer_[index].frame_begin = packet->is_first_packet_in_frame;
    sequence_buffer_[index].frame_end = packet->markerBit;
    sequence_buffer_[index].seq_num = packet->seqNum;
    sequence_buffer_[index].continuous = false;
    sequence_buffer_[index].frame_created = false;
    sequence_buffer_[index].used = true;
    data_buffer_[index] = *packet;
    packet->dataPtr = nullptr;

    UpdateMissingPackets(packet->seqNum);

    int64_t now_ms = clock_->TimeInMilliseconds();
    last_received_packet_ms_ = now_ms;
    if (packet->frameType == kVideoFrameKey)
      last_received_keyframe_packet_ms_ = now_ms;

    found_frames = FindFrames(seq_num);
  }

  for (std::unique_ptr<RtpFrameObject>& frame : found_frames)
    received_frame_callback_->OnReceivedFrame(std::move(frame));

  return true;
}

void PacketBuffer::ClearTo(uint16_t seq_num) {
  rtc::CritScope lock(&crit_);
  // We have already cleared past this sequence number, no need to do anything.
  if (is_cleared_to_first_seq_num_ &&
      AheadOf<uint16_t>(first_seq_num_, seq_num)) {
    return;
  }

  // If the packet buffer was cleared between a frame was created and returned.
  if (!first_packet_received_)
    return;

  // Avoid iterating over the buffer more than once by capping the number of
  // iterations to the |size_| of the buffer.
  ++seq_num;
  size_t diff = ForwardDiff<uint16_t>(first_seq_num_, seq_num);
  size_t iterations = std::min(diff, size_);
  for (size_t i = 0; i < iterations; ++i) {
    size_t index = first_seq_num_ % size_;
    RTC_DCHECK_EQ(data_buffer_[index].seqNum, sequence_buffer_[index].seq_num);
    if (AheadOf<uint16_t>(seq_num, sequence_buffer_[index].seq_num)) {
      delete[] data_buffer_[index].dataPtr;
      data_buffer_[index].dataPtr = nullptr;
      sequence_buffer_[index].used = false;
    }
    ++first_seq_num_;
  }

  // If |diff| is larger than |iterations| it means that we don't increment
  // |first_seq_num_| until we reach |seq_num|, so we set it here.
  first_seq_num_ = seq_num;

  is_cleared_to_first_seq_num_ = true;
  auto clear_to_it = missing_packets_.upper_bound(seq_num);
  if (clear_to_it != missing_packets_.begin()) {
    --clear_to_it;
    missing_packets_.erase(missing_packets_.begin(), clear_to_it);
  }
}

void PacketBuffer::Clear() {
  rtc::CritScope lock(&crit_);
  for (size_t i = 0; i < size_; ++i) {
    delete[] data_buffer_[i].dataPtr;
    data_buffer_[i].dataPtr = nullptr;
    sequence_buffer_[i].used = false;
  }

  first_packet_received_ = false;
  is_cleared_to_first_seq_num_ = false;
  last_received_packet_ms_.reset();
  last_received_keyframe_packet_ms_.reset();
  newest_inserted_seq_num_.reset();
  missing_packets_.clear();
}

void PacketBuffer::PaddingReceived(uint16_t seq_num) {
  std::vector<std::unique_ptr<RtpFrameObject>> found_frames;
  {
    rtc::CritScope lock(&crit_);
    UpdateMissingPackets(seq_num);
    found_frames = FindFrames(static_cast<uint16_t>(seq_num + 1));
  }

  for (std::unique_ptr<RtpFrameObject>& frame : found_frames)
    received_frame_callback_->OnReceivedFrame(std::move(frame));
}

rtc::Optional<int64_t> PacketBuffer::LastReceivedPacketMs() const {
  rtc::CritScope lock(&crit_);
  return last_received_packet_ms_;
}

rtc::Optional<int64_t> PacketBuffer::LastReceivedKeyframePacketMs() const {
  rtc::CritScope lock(&crit_);
  return last_received_keyframe_packet_ms_;
}

bool PacketBuffer::ExpandBufferSize() {
  if (size_ == max_size_) {
    RTC_LOG(LS_WARNING) << "PacketBuffer is already at max size (" << max_size_
                        << "), failed to increase size. Clearing PacketBuffer.";
    Clear();
    return false;
  }

  size_t new_size = std::min(max_size_, 2 * size_);
  std::vector<VCMPacket> new_data_buffer(new_size);
  std::vector<ContinuityInfo> new_sequence_buffer(new_size);
  for (size_t i = 0; i < size_; ++i) {
    if (sequence_buffer_[i].used) {
      size_t index = sequence_buffer_[i].seq_num % new_size;
      new_sequence_buffer[index] = sequence_buffer_[i];
      new_data_buffer[index] = data_buffer_[i];
    }
  }
  size_ = new_size;
  sequence_buffer_ = std::move(new_sequence_buffer);
  data_buffer_ = std::move(new_data_buffer);
  RTC_LOG(LS_INFO) << "PacketBuffer size expanded to " << new_size;
  return true;
}

bool PacketBuffer::PotentialNewFrame(uint16_t seq_num) const {
  size_t index = seq_num % size_;
  int prev_index = index > 0 ? index - 1 : size_ - 1;

  if (!sequence_buffer_[index].used)
    return false;
  if (sequence_buffer_[index].seq_num != seq_num)
    return false;
  if (sequence_buffer_[index].frame_created)
    return false;
  if (sequence_buffer_[index].frame_begin)
    return true;
  if (!sequence_buffer_[prev_index].used)
    return false;
  if (sequence_buffer_[prev_index].frame_created)
    return false;
  if (sequence_buffer_[prev_index].seq_num !=
      static_cast<uint16_t>(sequence_buffer_[index].seq_num - 1)) {
    return false;
  }
  if (sequence_buffer_[prev_index].continuous)
    return true;

  return false;
}

std::vector<std::unique_ptr<RtpFrameObject>> PacketBuffer::FindFrames(
    uint16_t seq_num) {
  std::vector<std::unique_ptr<RtpFrameObject>> found_frames;
  for (size_t i = 0; i < size_ && PotentialNewFrame(seq_num); ++i) {
    size_t index = seq_num % size_;
    sequence_buffer_[index].continuous = true;

    // If all packets of the frame is continuous, find the first packet of the
    // frame and create an RtpFrameObject.
    if (sequence_buffer_[index].frame_end) {
      size_t frame_size = 0;
      int max_nack_count = -1;
      uint16_t start_seq_num = seq_num;

      // Find the start index by searching backward until the packet with
      // the |frame_begin| flag is set.
      int start_index = index;
      size_t tested_packets = 0;
      int64_t frame_timestamp = data_buffer_[start_index].timestamp;

      // Identify H.264 keyframes by means of SPS, PPS, and IDR.
      bool is_h264 = data_buffer_[start_index].codec == kVideoCodecH264;
      bool has_h264_sps = false;
      bool has_h264_pps = false;
      bool has_h264_idr = false;
      bool is_h264_keyframe = false;

      while (true) {
        ++tested_packets;
        frame_size += data_buffer_[start_index].sizeBytes;
        max_nack_count =
            std::max(max_nack_count, data_buffer_[start_index].timesNacked);
        sequence_buffer_[start_index].frame_created = true;

        if (!is_h264 && sequence_buffer_[start_index].frame_begin)
          break;

        if (is_h264 && !is_h264_keyframe) {
          const RTPVideoHeaderH264& header =
              data_buffer_[start_index].video_header.codecHeader.H264;

          if (header.nalus_length >= kMaxNalusPerPacket)
            return found_frames;

          for (size_t j = 0; j < header.nalus_length; ++j) {
            if (header.nalus[j].type == H264::NaluType::kSps) {
              has_h264_sps = true;
            } else if (header.nalus[j].type == H264::NaluType::kPps) {
              has_h264_pps = true;
            } else if (header.nalus[j].type == H264::NaluType::kIdr) {
              has_h264_idr = true;
            }
          }
          if ((sps_pps_idr_is_h264_keyframe_ && has_h264_idr && has_h264_sps &&
               has_h264_pps) ||
              (!sps_pps_idr_is_h264_keyframe_ && has_h264_idr)) {
            is_h264_keyframe = true;
          }
        }

        if (tested_packets == size_)
          break;

        start_index = start_index > 0 ? start_index - 1 : size_ - 1;

        // In the case of H264 we don't have a frame_begin bit (yes,
        // |frame_begin| might be set to true but that is a lie). So instead
        // we traverese backwards as long as we have a previous packet and
        // the timestamp of that packet is the same as this one. This may cause
        // the PacketBuffer to hand out incomplete frames.
        // See: https://bugs.chromium.org/p/webrtc/issues/detail?id=7106
        if (is_h264 &&
            (!sequence_buffer_[start_index].used ||
             data_buffer_[start_index].timestamp != frame_timestamp)) {
          break;
        }

        --start_seq_num;
      }

      if (is_h264) {
        // Warn if this is an unsafe frame.
        if (has_h264_idr && (!has_h264_sps || !has_h264_pps)) {
          std::stringstream ss;
          ss << "Received H.264-IDR frame "
             << "(SPS: " << has_h264_sps << ", PPS: " << has_h264_pps << "). ";
          if (sps_pps_idr_is_h264_keyframe_) {
            ss << "Treating as delta frame since "
                  "WebRTC-SpsPpsIdrIsH264Keyframe is enabled.";
          } else {
            ss << "Treating as key frame since "
                  "WebRTC-SpsPpsIdrIsH264Keyframe is disabled.";
          }
          RTC_LOG(LS_WARNING) << ss.str();
        }

        // Now that we have decided whether to treat this frame as a key frame
        // or delta frame in the frame buffer, we update the field that
        // determines if the RtpFrameObject is a key frame or delta frame.
        const size_t first_packet_index = start_seq_num % size_;
        RTC_CHECK_LT(first_packet_index, size_);
        if (is_h264_keyframe) {
          data_buffer_[first_packet_index].frameType = kVideoFrameKey;
        } else {
          data_buffer_[first_packet_index].frameType = kVideoFrameDelta;
        }

        // If this is not a keyframe, make sure there are no gaps in the
        // packet sequence numbers up until this point.
        if (!is_h264_keyframe && missing_packets_.upper_bound(start_seq_num) !=
                                     missing_packets_.begin()) {
          uint16_t stop_index = (index + 1) % size_;
          while (start_index != stop_index) {
            sequence_buffer_[start_index].frame_created = false;
            start_index = (start_index + 1) % size_;
          }

          return found_frames;
        }
      }

      missing_packets_.erase(missing_packets_.begin(),
                             missing_packets_.upper_bound(seq_num));

      found_frames.emplace_back(
          new RtpFrameObject(this, start_seq_num, seq_num, frame_size,
                             max_nack_count, clock_->TimeInMilliseconds()));
    }
    ++seq_num;
  }
  return found_frames;
}

void PacketBuffer::ReturnFrame(RtpFrameObject* frame) {
  rtc::CritScope lock(&crit_);
  size_t index = frame->first_seq_num() % size_;
  size_t end = (frame->last_seq_num() + 1) % size_;
  uint16_t seq_num = frame->first_seq_num();
  while (index != end) {
    if (sequence_buffer_[index].seq_num == seq_num) {
      delete[] data_buffer_[index].dataPtr;
      data_buffer_[index].dataPtr = nullptr;
      sequence_buffer_[index].used = false;
    }

    index = (index + 1) % size_;
    ++seq_num;
  }
}

bool PacketBuffer::GetBitstream(const RtpFrameObject& frame,
                                uint8_t* destination) {
  rtc::CritScope lock(&crit_);

  size_t index = frame.first_seq_num() % size_;
  size_t end = (frame.last_seq_num() + 1) % size_;
  uint16_t seq_num = frame.first_seq_num();
  uint8_t* destination_end = destination + frame.size();

  do {
    if (!sequence_buffer_[index].used ||
        sequence_buffer_[index].seq_num != seq_num) {
      return false;
    }

    RTC_DCHECK_EQ(data_buffer_[index].seqNum, sequence_buffer_[index].seq_num);
    size_t length = data_buffer_[index].sizeBytes;
    if (destination + length > destination_end) {
      RTC_LOG(LS_WARNING) << "Frame (" << frame.picture_id << ":"
                          << static_cast<int>(frame.spatial_layer) << ")"
                          << " bitstream buffer is not large enough.";
      return false;
    }

    const uint8_t* source = data_buffer_[index].dataPtr;
    memcpy(destination, source, length);
    destination += length;
    index = (index + 1) % size_;
    ++seq_num;
  } while (index != end);

  return true;
}

VCMPacket* PacketBuffer::GetPacket(uint16_t seq_num) {
  size_t index = seq_num % size_;
  if (!sequence_buffer_[index].used ||
      seq_num != sequence_buffer_[index].seq_num) {
    return nullptr;
  }
  return &data_buffer_[index];
}

int PacketBuffer::AddRef() const {
  return rtc::AtomicOps::Increment(&ref_count_);
}

int PacketBuffer::Release() const {
  int count = rtc::AtomicOps::Decrement(&ref_count_);
  if (!count) {
    delete this;
  }
  return count;
}

void PacketBuffer::UpdateMissingPackets(uint16_t seq_num) {
  if (!newest_inserted_seq_num_)
    newest_inserted_seq_num_ = seq_num;

  const int kMaxPaddingAge = 1000;
  if (AheadOf(seq_num, *newest_inserted_seq_num_)) {
    uint16_t old_seq_num = seq_num - kMaxPaddingAge;
    auto erase_to = missing_packets_.lower_bound(old_seq_num);
    missing_packets_.erase(missing_packets_.begin(), erase_to);

    // Guard against inserting a large amount of missing packets if there is a
    // jump in the sequence number.
    if (AheadOf(old_seq_num, *newest_inserted_seq_num_))
      *newest_inserted_seq_num_ = old_seq_num;

    ++*newest_inserted_seq_num_;
    while (AheadOf(seq_num, *newest_inserted_seq_num_)) {
      missing_packets_.insert(*newest_inserted_seq_num_);
      ++*newest_inserted_seq_num_;
    }
  } else {
    missing_packets_.erase(seq_num);
  }
}

}  // namespace video_coding
}  // namespace webrtc