| /* |
| * Copyright (c) 2015 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 "common_video/h264/h264_bitstream_parser.h" |
| |
| #include <stdlib.h> |
| |
| #include <cstdint> |
| #include <vector> |
| |
| #include "common_video/h264/h264_common.h" |
| #include "rtc_base/bitstream_reader.h" |
| #include "rtc_base/logging.h" |
| |
| namespace webrtc { |
| namespace { |
| |
| constexpr int kMaxAbsQpDeltaValue = 51; |
| constexpr int kMinQpValue = 0; |
| constexpr int kMaxQpValue = 51; |
| |
| } // namespace |
| |
| H264BitstreamParser::H264BitstreamParser() = default; |
| H264BitstreamParser::~H264BitstreamParser() = default; |
| |
| H264BitstreamParser::Result H264BitstreamParser::ParseNonParameterSetNalu( |
| const uint8_t* source, |
| size_t source_length, |
| uint8_t nalu_type) { |
| if (!sps_ || !pps_) |
| return kInvalidStream; |
| |
| last_slice_qp_delta_ = absl::nullopt; |
| const std::vector<uint8_t> slice_rbsp = |
| H264::ParseRbsp(source, source_length); |
| if (slice_rbsp.size() < H264::kNaluTypeSize) |
| return kInvalidStream; |
| |
| BitstreamReader slice_reader(slice_rbsp); |
| slice_reader.ConsumeBits(H264::kNaluTypeSize * 8); |
| |
| // Check to see if this is an IDR slice, which has an extra field to parse |
| // out. |
| bool is_idr = (source[0] & 0x0F) == H264::NaluType::kIdr; |
| uint8_t nal_ref_idc = (source[0] & 0x60) >> 5; |
| |
| // first_mb_in_slice: ue(v) |
| slice_reader.ReadExponentialGolomb(); |
| // slice_type: ue(v) |
| uint32_t slice_type = slice_reader.ReadExponentialGolomb(); |
| // slice_type's 5..9 range is used to indicate that all slices of a picture |
| // have the same value of slice_type % 5, we don't care about that, so we map |
| // to the corresponding 0..4 range. |
| slice_type %= 5; |
| // pic_parameter_set_id: ue(v) |
| slice_reader.ReadExponentialGolomb(); |
| if (sps_->separate_colour_plane_flag == 1) { |
| // colour_plane_id |
| slice_reader.ConsumeBits(2); |
| } |
| // frame_num: u(v) |
| // Represented by log2_max_frame_num bits. |
| slice_reader.ConsumeBits(sps_->log2_max_frame_num); |
| bool field_pic_flag = false; |
| if (sps_->frame_mbs_only_flag == 0) { |
| // field_pic_flag: u(1) |
| field_pic_flag = slice_reader.Read<bool>(); |
| if (field_pic_flag) { |
| // bottom_field_flag: u(1) |
| slice_reader.ConsumeBits(1); |
| } |
| } |
| if (is_idr) { |
| // idr_pic_id: ue(v) |
| slice_reader.ReadExponentialGolomb(); |
| } |
| // pic_order_cnt_lsb: u(v) |
| // Represented by sps_.log2_max_pic_order_cnt_lsb bits. |
| if (sps_->pic_order_cnt_type == 0) { |
| slice_reader.ConsumeBits(sps_->log2_max_pic_order_cnt_lsb); |
| if (pps_->bottom_field_pic_order_in_frame_present_flag && !field_pic_flag) { |
| // delta_pic_order_cnt_bottom: se(v) |
| slice_reader.ReadExponentialGolomb(); |
| } |
| } |
| if (sps_->pic_order_cnt_type == 1 && |
| !sps_->delta_pic_order_always_zero_flag) { |
| // delta_pic_order_cnt[0]: se(v) |
| slice_reader.ReadExponentialGolomb(); |
| if (pps_->bottom_field_pic_order_in_frame_present_flag && !field_pic_flag) { |
| // delta_pic_order_cnt[1]: se(v) |
| slice_reader.ReadExponentialGolomb(); |
| } |
| } |
| if (pps_->redundant_pic_cnt_present_flag) { |
| // redundant_pic_cnt: ue(v) |
| slice_reader.ReadExponentialGolomb(); |
| } |
| if (slice_type == H264::SliceType::kB) { |
| // direct_spatial_mv_pred_flag: u(1) |
| slice_reader.ConsumeBits(1); |
| } |
| switch (slice_type) { |
| case H264::SliceType::kP: |
| case H264::SliceType::kB: |
| case H264::SliceType::kSp: |
| // num_ref_idx_active_override_flag: u(1) |
| if (slice_reader.Read<bool>()) { |
| // num_ref_idx_l0_active_minus1: ue(v) |
| slice_reader.ReadExponentialGolomb(); |
| if (slice_type == H264::SliceType::kB) { |
| // num_ref_idx_l1_active_minus1: ue(v) |
| slice_reader.ReadExponentialGolomb(); |
| } |
| } |
| break; |
| default: |
| break; |
| } |
| if (!slice_reader.Ok()) { |
| return kInvalidStream; |
| } |
| // assume nal_unit_type != 20 && nal_unit_type != 21: |
| if (nalu_type == 20 || nalu_type == 21) { |
| RTC_LOG(LS_ERROR) << "Unsupported nal unit type."; |
| return kUnsupportedStream; |
| } |
| // if (nal_unit_type == 20 || nal_unit_type == 21) |
| // ref_pic_list_mvc_modification() |
| // else |
| { |
| // ref_pic_list_modification(): |
| // `slice_type` checks here don't use named constants as they aren't named |
| // in the spec for this segment. Keeping them consistent makes it easier to |
| // verify that they are both the same. |
| if (slice_type % 5 != 2 && slice_type % 5 != 4) { |
| // ref_pic_list_modification_flag_l0: u(1) |
| if (slice_reader.Read<bool>()) { |
| uint32_t modification_of_pic_nums_idc; |
| do { |
| // modification_of_pic_nums_idc: ue(v) |
| modification_of_pic_nums_idc = slice_reader.ReadExponentialGolomb(); |
| if (modification_of_pic_nums_idc == 0 || |
| modification_of_pic_nums_idc == 1) { |
| // abs_diff_pic_num_minus1: ue(v) |
| slice_reader.ReadExponentialGolomb(); |
| } else if (modification_of_pic_nums_idc == 2) { |
| // long_term_pic_num: ue(v) |
| slice_reader.ReadExponentialGolomb(); |
| } |
| } while (modification_of_pic_nums_idc != 3 && slice_reader.Ok()); |
| } |
| } |
| if (slice_type % 5 == 1) { |
| // ref_pic_list_modification_flag_l1: u(1) |
| if (slice_reader.Read<bool>()) { |
| uint32_t modification_of_pic_nums_idc; |
| do { |
| // modification_of_pic_nums_idc: ue(v) |
| modification_of_pic_nums_idc = slice_reader.ReadExponentialGolomb(); |
| if (modification_of_pic_nums_idc == 0 || |
| modification_of_pic_nums_idc == 1) { |
| // abs_diff_pic_num_minus1: ue(v) |
| slice_reader.ReadExponentialGolomb(); |
| } else if (modification_of_pic_nums_idc == 2) { |
| // long_term_pic_num: ue(v) |
| slice_reader.ReadExponentialGolomb(); |
| } |
| } while (modification_of_pic_nums_idc != 3 && slice_reader.Ok()); |
| } |
| } |
| } |
| if (!slice_reader.Ok()) { |
| return kInvalidStream; |
| } |
| // TODO(pbos): Do we need support for pred_weight_table()? |
| if ((pps_->weighted_pred_flag && (slice_type == H264::SliceType::kP || |
| slice_type == H264::SliceType::kSp)) || |
| (pps_->weighted_bipred_idc == 1 && slice_type == H264::SliceType::kB)) { |
| RTC_LOG(LS_ERROR) << "Streams with pred_weight_table unsupported."; |
| return kUnsupportedStream; |
| } |
| // if ((weighted_pred_flag && (slice_type == P || slice_type == SP)) || |
| // (weighted_bipred_idc == 1 && slice_type == B)) { |
| // pred_weight_table() |
| // } |
| if (nal_ref_idc != 0) { |
| // dec_ref_pic_marking(): |
| if (is_idr) { |
| // no_output_of_prior_pics_flag: u(1) |
| // long_term_reference_flag: u(1) |
| slice_reader.ConsumeBits(2); |
| } else { |
| // adaptive_ref_pic_marking_mode_flag: u(1) |
| if (slice_reader.Read<bool>()) { |
| uint32_t memory_management_control_operation; |
| do { |
| // memory_management_control_operation: ue(v) |
| memory_management_control_operation = |
| slice_reader.ReadExponentialGolomb(); |
| if (memory_management_control_operation == 1 || |
| memory_management_control_operation == 3) { |
| // difference_of_pic_nums_minus1: ue(v) |
| slice_reader.ReadExponentialGolomb(); |
| } |
| if (memory_management_control_operation == 2) { |
| // long_term_pic_num: ue(v) |
| slice_reader.ReadExponentialGolomb(); |
| } |
| if (memory_management_control_operation == 3 || |
| memory_management_control_operation == 6) { |
| // long_term_frame_idx: ue(v) |
| slice_reader.ReadExponentialGolomb(); |
| } |
| if (memory_management_control_operation == 4) { |
| // max_long_term_frame_idx_plus1: ue(v) |
| slice_reader.ReadExponentialGolomb(); |
| } |
| } while (memory_management_control_operation != 0 && slice_reader.Ok()); |
| } |
| } |
| } |
| if (pps_->entropy_coding_mode_flag && slice_type != H264::SliceType::kI && |
| slice_type != H264::SliceType::kSi) { |
| // cabac_init_idc: ue(v) |
| slice_reader.ReadExponentialGolomb(); |
| } |
| |
| int last_slice_qp_delta = slice_reader.ReadSignedExponentialGolomb(); |
| if (!slice_reader.Ok()) { |
| return kInvalidStream; |
| } |
| if (abs(last_slice_qp_delta) > kMaxAbsQpDeltaValue) { |
| // Something has gone wrong, and the parsed value is invalid. |
| RTC_LOG(LS_WARNING) << "Parsed QP value out of range."; |
| return kInvalidStream; |
| } |
| |
| last_slice_qp_delta_ = last_slice_qp_delta; |
| return kOk; |
| } |
| |
| void H264BitstreamParser::ParseSlice(const uint8_t* slice, size_t length) { |
| H264::NaluType nalu_type = H264::ParseNaluType(slice[0]); |
| switch (nalu_type) { |
| case H264::NaluType::kSps: { |
| sps_ = SpsParser::ParseSps(slice + H264::kNaluTypeSize, |
| length - H264::kNaluTypeSize); |
| if (!sps_) |
| RTC_DLOG(LS_WARNING) << "Unable to parse SPS from H264 bitstream."; |
| break; |
| } |
| case H264::NaluType::kPps: { |
| pps_ = PpsParser::ParsePps(slice + H264::kNaluTypeSize, |
| length - H264::kNaluTypeSize); |
| if (!pps_) |
| RTC_DLOG(LS_WARNING) << "Unable to parse PPS from H264 bitstream."; |
| break; |
| } |
| case H264::NaluType::kAud: |
| case H264::NaluType::kSei: |
| case H264::NaluType::kPrefix: |
| break; // Ignore these nalus, as we don't care about their contents. |
| default: |
| Result res = ParseNonParameterSetNalu(slice, length, nalu_type); |
| if (res != kOk) |
| RTC_DLOG(LS_INFO) << "Failed to parse bitstream. Error: " << res; |
| break; |
| } |
| } |
| |
| void H264BitstreamParser::ParseBitstream( |
| rtc::ArrayView<const uint8_t> bitstream) { |
| std::vector<H264::NaluIndex> nalu_indices = |
| H264::FindNaluIndices(bitstream.data(), bitstream.size()); |
| for (const H264::NaluIndex& index : nalu_indices) |
| ParseSlice(bitstream.data() + index.payload_start_offset, |
| index.payload_size); |
| } |
| |
| absl::optional<int> H264BitstreamParser::GetLastSliceQp() const { |
| if (!last_slice_qp_delta_ || !pps_) |
| return absl::nullopt; |
| const int qp = 26 + pps_->pic_init_qp_minus26 + *last_slice_qp_delta_; |
| if (qp < kMinQpValue || qp > kMaxQpValue) { |
| RTC_LOG(LS_ERROR) << "Parsed invalid QP from bitstream."; |
| return absl::nullopt; |
| } |
| return qp; |
| } |
| |
| } // namespace webrtc |
