Danil Chapovalov | 096a46f | 2019-11-28 12:42:50 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2019 The WebRTC project authors. All Rights Reserved. |
| 3 | * |
| 4 | * Use of this source code is governed by a BSD-style license |
| 5 | * that can be found in the LICENSE file in the root of the source |
| 6 | * tree. An additional intellectual property rights grant can be found |
| 7 | * in the file PATENTS. All contributing project authors may |
| 8 | * be found in the AUTHORS file in the root of the source tree. |
| 9 | */ |
| 10 | #include "modules/rtp_rtcp/source/rtp_packetizer_av1.h" |
| 11 | |
| 12 | #include <stddef.h> |
| 13 | #include <stdint.h> |
| 14 | |
| 15 | #include <algorithm> |
| 16 | |
| 17 | #include "api/array_view.h" |
| 18 | #include "api/video/video_frame_type.h" |
Danil Chapovalov | e6b3f48 | 2023-01-13 11:33:41 | [diff] [blame] | 19 | #include "modules/rtp_rtcp/source/leb128.h" |
Danil Chapovalov | 096a46f | 2019-11-28 12:42:50 | [diff] [blame] | 20 | #include "modules/rtp_rtcp/source/rtp_packet_to_send.h" |
| 21 | #include "rtc_base/byte_buffer.h" |
| 22 | #include "rtc_base/checks.h" |
| 23 | #include "rtc_base/logging.h" |
| 24 | |
| 25 | namespace webrtc { |
| 26 | namespace { |
Danil Chapovalov | 096a46f | 2019-11-28 12:42:50 | [diff] [blame] | 27 | constexpr int kAggregationHeaderSize = 1; |
| 28 | // when there are 3 or less OBU (fragments) in a packet, size of the last one |
| 29 | // can be omited. |
| 30 | constexpr int kMaxNumObusToOmitSize = 3; |
| 31 | constexpr uint8_t kObuSizePresentBit = 0b0'0000'010; |
| 32 | constexpr int kObuTypeSequenceHeader = 1; |
| 33 | constexpr int kObuTypeTemporalDelimiter = 2; |
| 34 | constexpr int kObuTypeTileList = 8; |
| 35 | constexpr int kObuTypePadding = 15; |
| 36 | |
Philipp Hancke | acfd279 | 2024-04-30 14:09:37 | [diff] [blame] | 37 | // Overhead introduced by "even distribution" of packet sizes. |
| 38 | constexpr size_t kBytesOverheadEvenDistribution = 1; |
| 39 | // Experimentally determined minimum amount of potential savings per packet to |
| 40 | // make "even distribution" of packet sizes worthwhile. |
| 41 | constexpr size_t kMinBytesSavedPerPacketWithEvenDistribution = 10; |
| 42 | |
Danil Chapovalov | 096a46f | 2019-11-28 12:42:50 | [diff] [blame] | 43 | bool ObuHasExtension(uint8_t obu_header) { |
| 44 | return obu_header & 0b0'0000'100; |
| 45 | } |
| 46 | |
| 47 | bool ObuHasSize(uint8_t obu_header) { |
| 48 | return obu_header & kObuSizePresentBit; |
| 49 | } |
| 50 | |
| 51 | int ObuType(uint8_t obu_header) { |
| 52 | return (obu_header & 0b0'1111'000) >> 3; |
| 53 | } |
| 54 | |
Artem Titov | 913cfa7 | 2021-07-28 21:57:33 | [diff] [blame] | 55 | // Given `remaining_bytes` free bytes left in a packet, returns max size of an |
Danil Chapovalov | 096a46f | 2019-11-28 12:42:50 | [diff] [blame] | 56 | // OBU fragment that can fit into the packet. |
| 57 | // i.e. MaxFragmentSize + Leb128Size(MaxFragmentSize) <= remaining_bytes. |
| 58 | int MaxFragmentSize(int remaining_bytes) { |
| 59 | if (remaining_bytes <= 1) { |
| 60 | return 0; |
| 61 | } |
| 62 | for (int i = 1;; ++i) { |
| 63 | if (remaining_bytes < (1 << 7 * i) + i) { |
| 64 | return remaining_bytes - i; |
| 65 | } |
| 66 | } |
| 67 | } |
| 68 | |
| 69 | } // namespace |
| 70 | |
| 71 | RtpPacketizerAv1::RtpPacketizerAv1(rtc::ArrayView<const uint8_t> payload, |
| 72 | RtpPacketizer::PayloadSizeLimits limits, |
Danil Chapovalov | 62a9a32 | 2020-11-11 15:15:07 | [diff] [blame] | 73 | VideoFrameType frame_type, |
Philipp Hancke | acfd279 | 2024-04-30 14:09:37 | [diff] [blame] | 74 | bool is_last_frame_in_picture, |
| 75 | bool even_distribution) |
Danil Chapovalov | 096a46f | 2019-11-28 12:42:50 | [diff] [blame] | 76 | : frame_type_(frame_type), |
| 77 | obus_(ParseObus(payload)), |
Philipp Hancke | acfd279 | 2024-04-30 14:09:37 | [diff] [blame] | 78 | packets_(even_distribution ? PacketizeAboutEqually(obus_, limits) |
| 79 | : Packetize(obus_, limits)), |
Danil Chapovalov | 62a9a32 | 2020-11-11 15:15:07 | [diff] [blame] | 80 | is_last_frame_in_picture_(is_last_frame_in_picture) {} |
Danil Chapovalov | 096a46f | 2019-11-28 12:42:50 | [diff] [blame] | 81 | |
| 82 | std::vector<RtpPacketizerAv1::Obu> RtpPacketizerAv1::ParseObus( |
| 83 | rtc::ArrayView<const uint8_t> payload) { |
| 84 | std::vector<Obu> result; |
Harald Alvestrand | 572502c | 2023-11-22 10:19:06 | [diff] [blame] | 85 | rtc::ByteBufferReader payload_reader(payload); |
Danil Chapovalov | 096a46f | 2019-11-28 12:42:50 | [diff] [blame] | 86 | while (payload_reader.Length() > 0) { |
| 87 | Obu obu; |
| 88 | payload_reader.ReadUInt8(&obu.header); |
| 89 | obu.size = 1; |
| 90 | if (ObuHasExtension(obu.header)) { |
| 91 | if (payload_reader.Length() == 0) { |
| 92 | RTC_DLOG(LS_ERROR) << "Malformed AV1 input: expected extension_header, " |
| 93 | "no more bytes in the buffer. Offset: " |
| 94 | << (payload.size() - payload_reader.Length()); |
| 95 | return {}; |
| 96 | } |
| 97 | payload_reader.ReadUInt8(&obu.extension_header); |
| 98 | ++obu.size; |
| 99 | } |
| 100 | if (!ObuHasSize(obu.header)) { |
| 101 | obu.payload = rtc::MakeArrayView( |
| 102 | reinterpret_cast<const uint8_t*>(payload_reader.Data()), |
| 103 | payload_reader.Length()); |
| 104 | payload_reader.Consume(payload_reader.Length()); |
| 105 | } else { |
| 106 | uint64_t size = 0; |
| 107 | if (!payload_reader.ReadUVarint(&size) || |
| 108 | size > payload_reader.Length()) { |
| 109 | RTC_DLOG(LS_ERROR) << "Malformed AV1 input: declared size " << size |
| 110 | << " is larger than remaining buffer size " |
| 111 | << payload_reader.Length(); |
| 112 | return {}; |
| 113 | } |
| 114 | obu.payload = rtc::MakeArrayView( |
| 115 | reinterpret_cast<const uint8_t*>(payload_reader.Data()), size); |
| 116 | payload_reader.Consume(size); |
| 117 | } |
| 118 | obu.size += obu.payload.size(); |
| 119 | // Skip obus that shouldn't be transfered over rtp. |
| 120 | int obu_type = ObuType(obu.header); |
| 121 | if (obu_type != kObuTypeTemporalDelimiter && // |
| 122 | obu_type != kObuTypeTileList && // |
| 123 | obu_type != kObuTypePadding) { |
| 124 | result.push_back(obu); |
| 125 | } |
| 126 | } |
| 127 | return result; |
| 128 | } |
| 129 | |
| 130 | int RtpPacketizerAv1::AdditionalBytesForPreviousObuElement( |
| 131 | const Packet& packet) { |
| 132 | if (packet.packet_size == 0) { |
| 133 | // Packet is still empty => no last OBU element, no need to reserve space |
| 134 | // for it. |
| 135 | return 0; |
| 136 | } |
| 137 | if (packet.num_obu_elements > kMaxNumObusToOmitSize) { |
| 138 | // There is so many obu elements in the packet, all of them must be |
| 139 | // prepended with the length field. That imply space for the length of the |
| 140 | // last obu element is already reserved. |
| 141 | return 0; |
| 142 | } |
| 143 | // No space was reserved for length field of the last OBU element, but that |
| 144 | // element becoming non-last, so it now requires explicit length field. |
| 145 | // Calculate how many bytes are needed to store the length in leb128 format. |
| 146 | return Leb128Size(packet.last_obu_size); |
| 147 | } |
| 148 | |
| 149 | std::vector<RtpPacketizerAv1::Packet> RtpPacketizerAv1::Packetize( |
| 150 | rtc::ArrayView<const Obu> obus, |
| 151 | PayloadSizeLimits limits) { |
| 152 | std::vector<Packet> packets; |
| 153 | if (obus.empty()) { |
| 154 | return packets; |
| 155 | } |
| 156 | // Ignore certian edge cases where packets should be very small. They are |
| 157 | // inpractical but adds complexity to handle. |
| 158 | if (limits.max_payload_len - limits.last_packet_reduction_len < 3 || |
| 159 | limits.max_payload_len - limits.first_packet_reduction_len < 3) { |
| 160 | RTC_DLOG(LS_ERROR) << "Failed to packetize AV1 frame: requested packet " |
| 161 | "size is unreasonable small."; |
| 162 | return packets; |
| 163 | } |
| 164 | // Aggregation header is present in all packets. |
| 165 | limits.max_payload_len -= kAggregationHeaderSize; |
| 166 | |
| 167 | // Assemble packets. Push to current packet as much as it can hold before |
| 168 | // considering next one. That would normally cause uneven distribution across |
| 169 | // packets, specifically last one would be generally smaller. |
| 170 | packets.emplace_back(/*first_obu_index=*/0); |
| 171 | int packet_remaining_bytes = |
| 172 | limits.max_payload_len - limits.first_packet_reduction_len; |
| 173 | for (size_t obu_index = 0; obu_index < obus.size(); ++obu_index) { |
| 174 | const bool is_last_obu = obu_index == obus.size() - 1; |
| 175 | const Obu& obu = obus[obu_index]; |
| 176 | |
Artem Titov | 913cfa7 | 2021-07-28 21:57:33 | [diff] [blame] | 177 | // Putting `obu` into the last packet would make last obu element stored in |
Danil Chapovalov | 096a46f | 2019-11-28 12:42:50 | [diff] [blame] | 178 | // that packet not last. All not last OBU elements must be prepend with the |
| 179 | // element length. AdditionalBytesForPreviousObuElement calculates how many |
| 180 | // bytes are needed to store that length. |
| 181 | int previous_obu_extra_size = |
| 182 | AdditionalBytesForPreviousObuElement(packets.back()); |
| 183 | int min_required_size = |
| 184 | packets.back().num_obu_elements >= kMaxNumObusToOmitSize ? 2 : 1; |
| 185 | if (packet_remaining_bytes < previous_obu_extra_size + min_required_size) { |
| 186 | // Start a new packet. |
| 187 | packets.emplace_back(/*first_obu_index=*/obu_index); |
| 188 | packet_remaining_bytes = limits.max_payload_len; |
| 189 | previous_obu_extra_size = 0; |
| 190 | } |
| 191 | Packet& packet = packets.back(); |
| 192 | // Start inserting current obu into the packet. |
| 193 | packet.packet_size += previous_obu_extra_size; |
| 194 | packet_remaining_bytes -= previous_obu_extra_size; |
| 195 | packet.num_obu_elements++; |
| 196 | |
| 197 | bool must_write_obu_element_size = |
| 198 | packet.num_obu_elements > kMaxNumObusToOmitSize; |
| 199 | // Can fit all of the obu into the packet? |
| 200 | int required_bytes = obu.size; |
| 201 | if (must_write_obu_element_size) { |
| 202 | required_bytes += Leb128Size(obu.size); |
| 203 | } |
| 204 | int available_bytes = packet_remaining_bytes; |
| 205 | if (is_last_obu) { |
| 206 | // If this packet would be the last packet, available size is smaller. |
| 207 | if (packets.size() == 1) { |
| 208 | available_bytes += limits.first_packet_reduction_len; |
| 209 | available_bytes -= limits.single_packet_reduction_len; |
| 210 | } else { |
| 211 | available_bytes -= limits.last_packet_reduction_len; |
| 212 | } |
| 213 | } |
| 214 | if (required_bytes <= available_bytes) { |
| 215 | // Insert the obu into the packet unfragmented. |
| 216 | packet.last_obu_size = obu.size; |
| 217 | packet.packet_size += required_bytes; |
| 218 | packet_remaining_bytes -= required_bytes; |
| 219 | continue; |
| 220 | } |
| 221 | |
| 222 | // Fragment the obu. |
| 223 | int max_first_fragment_size = must_write_obu_element_size |
| 224 | ? MaxFragmentSize(packet_remaining_bytes) |
| 225 | : packet_remaining_bytes; |
| 226 | // Because available_bytes might be different than |
| 227 | // packet_remaining_bytes it might happen that max_first_fragment_size >= |
Artem Titov | 913cfa7 | 2021-07-28 21:57:33 | [diff] [blame] | 228 | // obu.size. Also, since checks above verified `obu` should not be put |
| 229 | // completely into the `packet`, leave at least 1 byte for later packet. |
Danil Chapovalov | 096a46f | 2019-11-28 12:42:50 | [diff] [blame] | 230 | int first_fragment_size = std::min(obu.size - 1, max_first_fragment_size); |
| 231 | if (first_fragment_size == 0) { |
| 232 | // Rather than writing 0-size element at the tail of the packet, |
Artem Titov | 913cfa7 | 2021-07-28 21:57:33 | [diff] [blame] | 233 | // 'uninsert' the `obu` from the `packet`. |
Danil Chapovalov | 096a46f | 2019-11-28 12:42:50 | [diff] [blame] | 234 | packet.num_obu_elements--; |
| 235 | packet.packet_size -= previous_obu_extra_size; |
| 236 | } else { |
| 237 | packet.packet_size += first_fragment_size; |
| 238 | if (must_write_obu_element_size) { |
| 239 | packet.packet_size += Leb128Size(first_fragment_size); |
| 240 | } |
| 241 | packet.last_obu_size = first_fragment_size; |
| 242 | } |
| 243 | |
| 244 | // Add middle fragments that occupy all of the packet. |
| 245 | // These are easy because |
| 246 | // - one obu per packet imply no need to store the size of the obu. |
| 247 | // - this packets are nor the first nor the last packets of the frame, so |
| 248 | // packet capacity is always limits.max_payload_len. |
| 249 | int obu_offset; |
| 250 | for (obu_offset = first_fragment_size; |
| 251 | obu_offset + limits.max_payload_len < obu.size; |
| 252 | obu_offset += limits.max_payload_len) { |
| 253 | packets.emplace_back(/*first_obu_index=*/obu_index); |
| 254 | Packet& packet = packets.back(); |
| 255 | packet.num_obu_elements = 1; |
| 256 | packet.first_obu_offset = obu_offset; |
| 257 | int middle_fragment_size = limits.max_payload_len; |
| 258 | packet.last_obu_size = middle_fragment_size; |
| 259 | packet.packet_size = middle_fragment_size; |
| 260 | } |
| 261 | |
| 262 | // Add the last fragment of the obu. |
| 263 | int last_fragment_size = obu.size - obu_offset; |
| 264 | // Check for corner case where last fragment of the last obu is too large |
| 265 | // to fit into last packet, but may fully fit into semi-last packet. |
| 266 | if (is_last_obu && |
| 267 | last_fragment_size > |
| 268 | limits.max_payload_len - limits.last_packet_reduction_len) { |
| 269 | // Split last fragments into two. |
| 270 | RTC_DCHECK_GE(last_fragment_size, 2); |
| 271 | // Try to even packet sizes rather than payload sizes across the last |
| 272 | // two packets. |
| 273 | int semi_last_fragment_size = |
| 274 | (last_fragment_size + limits.last_packet_reduction_len) / 2; |
| 275 | // But leave at least one payload byte for the last packet to avoid |
| 276 | // weird scenarios where size of the fragment is zero and rtp payload has |
| 277 | // nothing except for an aggregation header. |
| 278 | if (semi_last_fragment_size >= last_fragment_size) { |
| 279 | semi_last_fragment_size = last_fragment_size - 1; |
| 280 | } |
| 281 | last_fragment_size -= semi_last_fragment_size; |
| 282 | |
| 283 | packets.emplace_back(/*first_obu_index=*/obu_index); |
| 284 | Packet& packet = packets.back(); |
| 285 | packet.num_obu_elements = 1; |
| 286 | packet.first_obu_offset = obu_offset; |
| 287 | packet.last_obu_size = semi_last_fragment_size; |
| 288 | packet.packet_size = semi_last_fragment_size; |
| 289 | obu_offset += semi_last_fragment_size; |
| 290 | } |
| 291 | packets.emplace_back(/*first_obu_index=*/obu_index); |
| 292 | Packet& last_packet = packets.back(); |
| 293 | last_packet.num_obu_elements = 1; |
| 294 | last_packet.first_obu_offset = obu_offset; |
| 295 | last_packet.last_obu_size = last_fragment_size; |
| 296 | last_packet.packet_size = last_fragment_size; |
| 297 | packet_remaining_bytes = limits.max_payload_len - last_fragment_size; |
| 298 | } |
| 299 | return packets; |
| 300 | } |
| 301 | |
Philipp Hancke | acfd279 | 2024-04-30 14:09:37 | [diff] [blame] | 302 | std::vector<RtpPacketizerAv1::Packet> RtpPacketizerAv1::PacketizeAboutEqually( |
| 303 | rtc::ArrayView<const Obu> obus, |
| 304 | PayloadSizeLimits limits) { |
| 305 | std::vector<Packet> packets = Packetize(obus, limits); |
| 306 | if (packets.size() <= 1) { |
| 307 | return packets; |
| 308 | } |
| 309 | size_t packet_index = 0; |
| 310 | size_t packet_size_left_unused = 0; |
| 311 | for (const auto& packet : packets) { |
| 312 | // Every packet has to have an aggregation header of size |
| 313 | // kAggregationHeaderSize. |
| 314 | int available_bytes = limits.max_payload_len - kAggregationHeaderSize; |
| 315 | |
| 316 | if (packet_index == 0) { |
| 317 | available_bytes -= limits.first_packet_reduction_len; |
| 318 | } else if (packet_index == packets.size() - 1) { |
| 319 | available_bytes -= limits.last_packet_reduction_len; |
| 320 | } |
| 321 | if (available_bytes >= packet.packet_size) { |
| 322 | packet_size_left_unused += (available_bytes - packet.packet_size); |
| 323 | } |
| 324 | packet_index++; |
| 325 | } |
| 326 | if (packet_size_left_unused > |
| 327 | packets.size() * kMinBytesSavedPerPacketWithEvenDistribution) { |
| 328 | // Calculate new limits with a reduced max_payload_len. |
| 329 | size_t size_reduction = packet_size_left_unused / packets.size(); |
| 330 | RTC_DCHECK_GT(limits.max_payload_len, size_reduction); |
| 331 | RTC_DCHECK_GT(size_reduction, kBytesOverheadEvenDistribution); |
| 332 | limits.max_payload_len -= (size_reduction - kBytesOverheadEvenDistribution); |
| 333 | if (limits.max_payload_len - limits.last_packet_reduction_len < 3 || |
| 334 | limits.max_payload_len - limits.first_packet_reduction_len < 3) { |
| 335 | return packets; |
| 336 | } |
| 337 | std::vector<Packet> packets_even = Packetize(obus, limits); |
| 338 | // The number of packets should not change in the second pass. If it does, |
| 339 | // conservatively return the original packets. |
| 340 | if (packets_even.size() == packets.size()) { |
| 341 | return packets_even; |
| 342 | } |
| 343 | RTC_LOG(LS_WARNING) << "AV1 even distribution caused a regression in " |
| 344 | "number of packets from " |
| 345 | << packets.size() << " to " << packets_even.size(); |
| 346 | } |
| 347 | return packets; |
| 348 | } |
| 349 | |
Danil Chapovalov | 096a46f | 2019-11-28 12:42:50 | [diff] [blame] | 350 | uint8_t RtpPacketizerAv1::AggregationHeader() const { |
| 351 | const Packet& packet = packets_[packet_index_]; |
| 352 | uint8_t aggregation_header = 0; |
| 353 | |
| 354 | // Set Z flag: first obu element is continuation of the previous OBU. |
| 355 | bool first_obu_element_is_fragment = packet.first_obu_offset > 0; |
| 356 | if (first_obu_element_is_fragment) |
| 357 | aggregation_header |= (1 << 7); |
| 358 | |
| 359 | // Set Y flag: last obu element will be continuated in the next packet. |
| 360 | int last_obu_offset = |
| 361 | packet.num_obu_elements == 1 ? packet.first_obu_offset : 0; |
| 362 | bool last_obu_is_fragment = |
| 363 | last_obu_offset + packet.last_obu_size < |
| 364 | obus_[packet.first_obu + packet.num_obu_elements - 1].size; |
| 365 | if (last_obu_is_fragment) |
| 366 | aggregation_header |= (1 << 6); |
| 367 | |
| 368 | // Set W field: number of obu elements in the packet (when not too large). |
| 369 | if (packet.num_obu_elements <= kMaxNumObusToOmitSize) |
| 370 | aggregation_header |= packet.num_obu_elements << 4; |
| 371 | |
| 372 | // Set N flag: beginning of a new coded video sequence. |
| 373 | // Encoder may produce key frame without a sequence header, thus double check |
| 374 | // incoming frame includes the sequence header. Since Temporal delimiter is |
| 375 | // already filtered out, sequence header should be the first obu when present. |
| 376 | if (frame_type_ == VideoFrameType::kVideoFrameKey && packet_index_ == 0 && |
| 377 | ObuType(obus_.front().header) == kObuTypeSequenceHeader) { |
| 378 | aggregation_header |= (1 << 3); |
| 379 | } |
| 380 | return aggregation_header; |
| 381 | } |
| 382 | |
| 383 | bool RtpPacketizerAv1::NextPacket(RtpPacketToSend* packet) { |
| 384 | if (packet_index_ >= packets_.size()) { |
| 385 | return false; |
| 386 | } |
| 387 | const Packet& next_packet = packets_[packet_index_]; |
| 388 | |
| 389 | RTC_DCHECK_GT(next_packet.num_obu_elements, 0); |
| 390 | RTC_DCHECK_LT(next_packet.first_obu_offset, |
| 391 | obus_[next_packet.first_obu].size); |
| 392 | RTC_DCHECK_LE( |
| 393 | next_packet.last_obu_size, |
| 394 | obus_[next_packet.first_obu + next_packet.num_obu_elements - 1].size); |
| 395 | |
| 396 | uint8_t* const rtp_payload = |
| 397 | packet->AllocatePayload(kAggregationHeaderSize + next_packet.packet_size); |
| 398 | uint8_t* write_at = rtp_payload; |
| 399 | |
| 400 | *write_at++ = AggregationHeader(); |
| 401 | |
| 402 | int obu_offset = next_packet.first_obu_offset; |
| 403 | // Store all OBU elements except the last one. |
| 404 | for (int i = 0; i < next_packet.num_obu_elements - 1; ++i) { |
| 405 | const Obu& obu = obus_[next_packet.first_obu + i]; |
| 406 | size_t fragment_size = obu.size - obu_offset; |
| 407 | write_at += WriteLeb128(fragment_size, write_at); |
| 408 | if (obu_offset == 0) { |
| 409 | *write_at++ = obu.header & ~kObuSizePresentBit; |
| 410 | } |
| 411 | if (obu_offset <= 1 && ObuHasExtension(obu.header)) { |
| 412 | *write_at++ = obu.extension_header; |
| 413 | } |
| 414 | int payload_offset = |
| 415 | std::max(0, obu_offset - (ObuHasExtension(obu.header) ? 2 : 1)); |
| 416 | size_t payload_size = obu.payload.size() - payload_offset; |
Byoungchan Lee | 8c725f3 | 2022-09-13 08:53:49 | [diff] [blame] | 417 | if (!obu.payload.empty() && payload_size > 0) { |
| 418 | memcpy(write_at, obu.payload.data() + payload_offset, payload_size); |
| 419 | } |
Danil Chapovalov | 096a46f | 2019-11-28 12:42:50 | [diff] [blame] | 420 | write_at += payload_size; |
| 421 | // All obus are stored from the beginning, except, may be, the first one. |
| 422 | obu_offset = 0; |
| 423 | } |
| 424 | // Store the last OBU element. |
| 425 | const Obu& last_obu = |
| 426 | obus_[next_packet.first_obu + next_packet.num_obu_elements - 1]; |
| 427 | int fragment_size = next_packet.last_obu_size; |
| 428 | RTC_DCHECK_GT(fragment_size, 0); |
| 429 | if (next_packet.num_obu_elements > kMaxNumObusToOmitSize) { |
| 430 | write_at += WriteLeb128(fragment_size, write_at); |
| 431 | } |
| 432 | if (obu_offset == 0 && fragment_size > 0) { |
| 433 | *write_at++ = last_obu.header & ~kObuSizePresentBit; |
| 434 | --fragment_size; |
| 435 | } |
| 436 | if (obu_offset <= 1 && ObuHasExtension(last_obu.header) && |
| 437 | fragment_size > 0) { |
| 438 | *write_at++ = last_obu.extension_header; |
| 439 | --fragment_size; |
| 440 | } |
| 441 | RTC_DCHECK_EQ(write_at - rtp_payload + fragment_size, |
| 442 | kAggregationHeaderSize + next_packet.packet_size); |
| 443 | int payload_offset = |
| 444 | std::max(0, obu_offset - (ObuHasExtension(last_obu.header) ? 2 : 1)); |
| 445 | memcpy(write_at, last_obu.payload.data() + payload_offset, fragment_size); |
| 446 | write_at += fragment_size; |
| 447 | |
| 448 | RTC_DCHECK_EQ(write_at - rtp_payload, |
| 449 | kAggregationHeaderSize + next_packet.packet_size); |
| 450 | |
| 451 | ++packet_index_; |
Danil Chapovalov | 62a9a32 | 2020-11-11 15:15:07 | [diff] [blame] | 452 | bool is_last_packet_in_frame = packet_index_ == packets_.size(); |
| 453 | packet->SetMarker(is_last_packet_in_frame && is_last_frame_in_picture_); |
Danil Chapovalov | 096a46f | 2019-11-28 12:42:50 | [diff] [blame] | 454 | return true; |
| 455 | } |
| 456 | |
| 457 | } // namespace webrtc |