| /* |
| * Copyright (c) 2020 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/rtp_rtcp/source/video_rtp_depacketizer_h264.h" |
| |
| #include <cstddef> |
| #include <cstdint> |
| #include <utility> |
| #include <vector> |
| |
| #include "absl/types/optional.h" |
| #include "absl/types/variant.h" |
| #include "common_video/h264/h264_common.h" |
| #include "common_video/h264/pps_parser.h" |
| #include "common_video/h264/sps_parser.h" |
| #include "common_video/h264/sps_vui_rewriter.h" |
| #include "modules/rtp_rtcp/source/byte_io.h" |
| #include "modules/rtp_rtcp/source/video_rtp_depacketizer.h" |
| #include "rtc_base/checks.h" |
| #include "rtc_base/copy_on_write_buffer.h" |
| #include "rtc_base/logging.h" |
| |
| namespace webrtc { |
| namespace { |
| |
| constexpr size_t kNalHeaderSize = 1; |
| constexpr size_t kFuAHeaderSize = 2; |
| constexpr size_t kLengthFieldSize = 2; |
| constexpr size_t kStapAHeaderSize = kNalHeaderSize + kLengthFieldSize; |
| |
| // Bit masks for FU (A and B) indicators. |
| enum NalDefs : uint8_t { kFBit = 0x80, kNriMask = 0x60, kTypeMask = 0x1F }; |
| |
| // Bit masks for FU (A and B) headers. |
| enum FuDefs : uint8_t { kSBit = 0x80, kEBit = 0x40, kRBit = 0x20 }; |
| |
| // TODO(pbos): Avoid parsing this here as well as inside the jitter buffer. |
| bool ParseStapAStartOffsets(const uint8_t* nalu_ptr, |
| size_t length_remaining, |
| std::vector<size_t>* offsets) { |
| size_t offset = 0; |
| while (length_remaining > 0) { |
| // Buffer doesn't contain room for additional nalu length. |
| if (length_remaining < sizeof(uint16_t)) |
| return false; |
| uint16_t nalu_size = ByteReader<uint16_t>::ReadBigEndian(nalu_ptr); |
| nalu_ptr += sizeof(uint16_t); |
| length_remaining -= sizeof(uint16_t); |
| if (nalu_size > length_remaining) |
| return false; |
| nalu_ptr += nalu_size; |
| length_remaining -= nalu_size; |
| |
| offsets->push_back(offset + kStapAHeaderSize); |
| offset += kLengthFieldSize + nalu_size; |
| } |
| return true; |
| } |
| |
| absl::optional<VideoRtpDepacketizer::ParsedRtpPayload> ProcessStapAOrSingleNalu( |
| rtc::CopyOnWriteBuffer rtp_payload) { |
| const uint8_t* const payload_data = rtp_payload.cdata(); |
| absl::optional<VideoRtpDepacketizer::ParsedRtpPayload> parsed_payload( |
| absl::in_place); |
| bool modified_buffer = false; |
| parsed_payload->video_payload = rtp_payload; |
| parsed_payload->video_header.width = 0; |
| parsed_payload->video_header.height = 0; |
| parsed_payload->video_header.codec = kVideoCodecH264; |
| parsed_payload->video_header.simulcastIdx = 0; |
| parsed_payload->video_header.is_first_packet_in_frame = true; |
| auto& h264_header = parsed_payload->video_header.video_type_header |
| .emplace<RTPVideoHeaderH264>(); |
| |
| const uint8_t* nalu_start = payload_data + kNalHeaderSize; |
| const size_t nalu_length = rtp_payload.size() - kNalHeaderSize; |
| uint8_t nal_type = payload_data[0] & kTypeMask; |
| std::vector<size_t> nalu_start_offsets; |
| if (nal_type == H264::NaluType::kStapA) { |
| // Skip the StapA header (StapA NAL type + length). |
| if (rtp_payload.size() <= kStapAHeaderSize) { |
| RTC_LOG(LS_ERROR) << "StapA header truncated."; |
| return absl::nullopt; |
| } |
| |
| if (!ParseStapAStartOffsets(nalu_start, nalu_length, &nalu_start_offsets)) { |
| RTC_LOG(LS_ERROR) << "StapA packet with incorrect NALU packet lengths."; |
| return absl::nullopt; |
| } |
| |
| h264_header.packetization_type = kH264StapA; |
| nal_type = payload_data[kStapAHeaderSize] & kTypeMask; |
| } else { |
| h264_header.packetization_type = kH264SingleNalu; |
| nalu_start_offsets.push_back(0); |
| } |
| h264_header.nalu_type = nal_type; |
| parsed_payload->video_header.frame_type = VideoFrameType::kVideoFrameDelta; |
| |
| nalu_start_offsets.push_back(rtp_payload.size() + |
| kLengthFieldSize); // End offset. |
| for (size_t i = 0; i < nalu_start_offsets.size() - 1; ++i) { |
| size_t start_offset = nalu_start_offsets[i]; |
| // End offset is actually start offset for next unit, excluding length field |
| // so remove that from this units length. |
| size_t end_offset = nalu_start_offsets[i + 1] - kLengthFieldSize; |
| if (end_offset - start_offset < H264::kNaluTypeSize) { |
| RTC_LOG(LS_ERROR) << "STAP-A packet too short"; |
| return absl::nullopt; |
| } |
| |
| NaluInfo nalu; |
| nalu.type = payload_data[start_offset] & kTypeMask; |
| nalu.sps_id = -1; |
| nalu.pps_id = -1; |
| start_offset += H264::kNaluTypeSize; |
| |
| switch (nalu.type) { |
| case H264::NaluType::kSps: { |
| // Check if VUI is present in SPS and if it needs to be modified to |
| // avoid |
| // excessive decoder latency. |
| |
| // Copy any previous data first (likely just the first header). |
| rtc::Buffer output_buffer; |
| if (start_offset) |
| output_buffer.AppendData(payload_data, start_offset); |
| |
| absl::optional<SpsParser::SpsState> sps; |
| |
| SpsVuiRewriter::ParseResult result = SpsVuiRewriter::ParseAndRewriteSps( |
| &payload_data[start_offset], end_offset - start_offset, &sps, |
| nullptr, &output_buffer, SpsVuiRewriter::Direction::kIncoming); |
| |
| if (result == SpsVuiRewriter::ParseResult::kVuiRewritten) { |
| if (modified_buffer) { |
| RTC_LOG(LS_WARNING) |
| << "More than one H264 SPS NAL units needing " |
| "rewriting found within a single STAP-A packet. " |
| "Keeping the first and rewriting the last."; |
| } |
| |
| // Rewrite length field to new SPS size. |
| if (h264_header.packetization_type == kH264StapA) { |
| size_t length_field_offset = |
| start_offset - (H264::kNaluTypeSize + kLengthFieldSize); |
| // Stap-A Length includes payload data and type header. |
| size_t rewritten_size = |
| output_buffer.size() - start_offset + H264::kNaluTypeSize; |
| ByteWriter<uint16_t>::WriteBigEndian( |
| &output_buffer[length_field_offset], rewritten_size); |
| } |
| |
| parsed_payload->video_payload.SetData(output_buffer.data(), |
| output_buffer.size()); |
| // Append rest of packet. |
| parsed_payload->video_payload.AppendData( |
| &payload_data[end_offset], |
| nalu_length + kNalHeaderSize - end_offset); |
| |
| modified_buffer = true; |
| } |
| |
| if (sps) { |
| parsed_payload->video_header.width = sps->width; |
| parsed_payload->video_header.height = sps->height; |
| nalu.sps_id = sps->id; |
| } else { |
| RTC_LOG(LS_WARNING) << "Failed to parse SPS id from SPS slice."; |
| } |
| parsed_payload->video_header.frame_type = |
| VideoFrameType::kVideoFrameKey; |
| break; |
| } |
| case H264::NaluType::kPps: { |
| uint32_t pps_id; |
| uint32_t sps_id; |
| if (PpsParser::ParsePpsIds(&payload_data[start_offset], |
| end_offset - start_offset, &pps_id, |
| &sps_id)) { |
| nalu.pps_id = pps_id; |
| nalu.sps_id = sps_id; |
| } else { |
| RTC_LOG(LS_WARNING) |
| << "Failed to parse PPS id and SPS id from PPS slice."; |
| } |
| break; |
| } |
| case H264::NaluType::kIdr: |
| parsed_payload->video_header.frame_type = |
| VideoFrameType::kVideoFrameKey; |
| [[fallthrough]]; |
| case H264::NaluType::kSlice: { |
| absl::optional<uint32_t> pps_id = PpsParser::ParsePpsIdFromSlice( |
| &payload_data[start_offset], end_offset - start_offset); |
| if (pps_id) { |
| nalu.pps_id = *pps_id; |
| } else { |
| RTC_LOG(LS_WARNING) << "Failed to parse PPS id from slice of type: " |
| << static_cast<int>(nalu.type); |
| } |
| break; |
| } |
| // Slices below don't contain SPS or PPS ids. |
| case H264::NaluType::kAud: |
| case H264::NaluType::kEndOfSequence: |
| case H264::NaluType::kEndOfStream: |
| case H264::NaluType::kFiller: |
| case H264::NaluType::kSei: |
| break; |
| case H264::NaluType::kStapA: |
| case H264::NaluType::kFuA: |
| RTC_LOG(LS_WARNING) << "Unexpected STAP-A or FU-A received."; |
| return absl::nullopt; |
| } |
| |
| if (h264_header.nalus_length == kMaxNalusPerPacket) { |
| RTC_LOG(LS_WARNING) |
| << "Received packet containing more than " << kMaxNalusPerPacket |
| << " NAL units. Will not keep track sps and pps ids for all of them."; |
| } else { |
| h264_header.nalus[h264_header.nalus_length++] = nalu; |
| } |
| } |
| |
| return parsed_payload; |
| } |
| |
| absl::optional<VideoRtpDepacketizer::ParsedRtpPayload> ParseFuaNalu( |
| rtc::CopyOnWriteBuffer rtp_payload) { |
| if (rtp_payload.size() < kFuAHeaderSize) { |
| RTC_LOG(LS_ERROR) << "FU-A NAL units truncated."; |
| return absl::nullopt; |
| } |
| absl::optional<VideoRtpDepacketizer::ParsedRtpPayload> parsed_payload( |
| absl::in_place); |
| uint8_t fnri = rtp_payload.cdata()[0] & (kFBit | kNriMask); |
| uint8_t original_nal_type = rtp_payload.cdata()[1] & kTypeMask; |
| bool first_fragment = (rtp_payload.cdata()[1] & kSBit) > 0; |
| NaluInfo nalu; |
| nalu.type = original_nal_type; |
| nalu.sps_id = -1; |
| nalu.pps_id = -1; |
| if (first_fragment) { |
| absl::optional<uint32_t> pps_id = |
| PpsParser::ParsePpsIdFromSlice(rtp_payload.cdata() + 2 * kNalHeaderSize, |
| rtp_payload.size() - 2 * kNalHeaderSize); |
| if (pps_id) { |
| nalu.pps_id = *pps_id; |
| } else { |
| RTC_LOG(LS_WARNING) |
| << "Failed to parse PPS from first fragment of FU-A NAL " |
| "unit with original type: " |
| << static_cast<int>(nalu.type); |
| } |
| uint8_t original_nal_header = fnri | original_nal_type; |
| rtp_payload = |
| rtp_payload.Slice(kNalHeaderSize, rtp_payload.size() - kNalHeaderSize); |
| rtp_payload.MutableData()[0] = original_nal_header; |
| parsed_payload->video_payload = std::move(rtp_payload); |
| } else { |
| parsed_payload->video_payload = |
| rtp_payload.Slice(kFuAHeaderSize, rtp_payload.size() - kFuAHeaderSize); |
| } |
| |
| if (original_nal_type == H264::NaluType::kIdr) { |
| parsed_payload->video_header.frame_type = VideoFrameType::kVideoFrameKey; |
| } else { |
| parsed_payload->video_header.frame_type = VideoFrameType::kVideoFrameDelta; |
| } |
| parsed_payload->video_header.width = 0; |
| parsed_payload->video_header.height = 0; |
| parsed_payload->video_header.codec = kVideoCodecH264; |
| parsed_payload->video_header.simulcastIdx = 0; |
| parsed_payload->video_header.is_first_packet_in_frame = first_fragment; |
| auto& h264_header = parsed_payload->video_header.video_type_header |
| .emplace<RTPVideoHeaderH264>(); |
| h264_header.packetization_type = kH264FuA; |
| h264_header.nalu_type = original_nal_type; |
| if (first_fragment) { |
| h264_header.nalus[h264_header.nalus_length] = nalu; |
| h264_header.nalus_length = 1; |
| } |
| return parsed_payload; |
| } |
| |
| } // namespace |
| |
| absl::optional<VideoRtpDepacketizer::ParsedRtpPayload> |
| VideoRtpDepacketizerH264::Parse(rtc::CopyOnWriteBuffer rtp_payload) { |
| if (rtp_payload.size() == 0) { |
| RTC_LOG(LS_ERROR) << "Empty payload."; |
| return absl::nullopt; |
| } |
| |
| uint8_t nal_type = rtp_payload.cdata()[0] & kTypeMask; |
| |
| if (nal_type == H264::NaluType::kFuA) { |
| // Fragmented NAL units (FU-A). |
| return ParseFuaNalu(std::move(rtp_payload)); |
| } else { |
| // We handle STAP-A and single NALU's the same way here. The jitter buffer |
| // will depacketize the STAP-A into NAL units later. |
| return ProcessStapAOrSingleNalu(std::move(rtp_payload)); |
| } |
| } |
| |
| } // namespace webrtc |
