/* * 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 "webrtc/modules/rtp_rtcp/source/h264_bitstream_parser.h" #include <vector> #include "webrtc/base/bitbuffer.h" #include "webrtc/base/bytebuffer.h" #include "webrtc/base/checks.h" #include "webrtc/base/logging.h" #include "webrtc/base/scoped_ptr.h" namespace webrtc { namespace { // The size of a NALU header {0 0 0 1}. static const size_t kNaluHeaderSize = 4; // The size of a NALU header plus the type byte. static const size_t kNaluHeaderAndTypeSize = kNaluHeaderSize + 1; // The NALU type. static const uint8_t kNaluSps = 0x7; static const uint8_t kNaluPps = 0x8; static const uint8_t kNaluIdr = 0x5; static const uint8_t kNaluTypeMask = 0x1F; static const uint8_t kSliceTypeP = 0x0; static const uint8_t kSliceTypeB = 0x1; static const uint8_t kSliceTypeSp = 0x3; // Returns a vector of the NALU start sequences (0 0 0 1) in the given buffer. std::vector<size_t> FindNaluStartSequences(const uint8_t* buffer, size_t buffer_size) { std::vector<size_t> sequences; // This is sorta like Boyer-Moore, but with only the first optimization step: // given a 4-byte sequence we're looking at, if the 4th byte isn't 1 or 0, // skip ahead to the next 4-byte sequence. 0s and 1s are relatively rare, so // this will skip the majority of reads/checks. const uint8_t* end = buffer + buffer_size - 4; for (const uint8_t* head = buffer; head < end;) { if (head[3] > 1) { head += 4; } else if (head[3] == 1 && head[2] == 0 && head[1] == 0 && head[0] == 0) { sequences.push_back(static_cast<size_t>(head - buffer)); head += 4; } else { head++; } } return sequences; } } // namespace // Parses RBSP from source bytes. Removes emulation bytes, but leaves the // rbsp_trailing_bits() in the stream, since none of the parsing reads all the // way to the end of a parsed RBSP sequence. When writing, that means the // rbsp_trailing_bits() should be preserved and don't need to be restored (i.e. // the rbsp_stop_one_bit, which is just a 1, then zero padded), and alignment // should "just work". // TODO(pbos): Make parsing RBSP something that can be integrated into BitBuffer // so we don't have to copy the entire frames when only interested in the // headers. rtc::ByteBuffer* ParseRbsp(const uint8_t* bytes, size_t length) { // Copied from webrtc::H264SpsParser::Parse. rtc::ByteBuffer* rbsp_buffer = new rtc::ByteBuffer; for (size_t i = 0; i < length;) { if (length - i >= 3 && bytes[i] == 0 && bytes[i + 1] == 0 && bytes[i + 2] == 3) { rbsp_buffer->WriteBytes(reinterpret_cast<const char*>(bytes) + i, 2); i += 3; } else { rbsp_buffer->WriteBytes(reinterpret_cast<const char*>(bytes) + i, 1); i++; } } return rbsp_buffer; } #define RETURN_FALSE_ON_FAIL(x) \ if (!(x)) { \ LOG_F(LS_ERROR) << "FAILED: " #x; \ return false; \ } H264BitstreamParser::PpsState::PpsState() {} H264BitstreamParser::SpsState::SpsState() {} // These functions are similar to webrtc::H264SpsParser::Parse, and based on the // same version of the H.264 standard. You can find it here: // http://www.itu.int/rec/T-REC-H.264 bool H264BitstreamParser::ParseSpsNalu(const uint8_t* sps, size_t length) { // Reset SPS state. sps_ = SpsState(); sps_parsed_ = false; // Parse out the SPS RBSP. It should be small, so it's ok that we create a // copy. We'll eventually write this back. rtc::scoped_ptr<rtc::ByteBuffer> sps_rbsp( ParseRbsp(sps + kNaluHeaderAndTypeSize, length - kNaluHeaderAndTypeSize)); rtc::BitBuffer sps_parser(reinterpret_cast<const uint8_t*>(sps_rbsp->Data()), sps_rbsp->Length()); uint8_t byte_tmp; uint32_t golomb_tmp; uint32_t bits_tmp; // profile_idc: u(8). uint8_t profile_idc; RETURN_FALSE_ON_FAIL(sps_parser.ReadUInt8(&profile_idc)); // constraint_set0_flag through constraint_set5_flag + reserved_zero_2bits // 1 bit each for the flags + 2 bits = 8 bits = 1 byte. RETURN_FALSE_ON_FAIL(sps_parser.ReadUInt8(&byte_tmp)); // level_idc: u(8) RETURN_FALSE_ON_FAIL(sps_parser.ReadUInt8(&byte_tmp)); // seq_parameter_set_id: ue(v) RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp)); sps_.separate_colour_plane_flag = 0; // See if profile_idc has chroma format information. if (profile_idc == 100 || profile_idc == 110 || profile_idc == 122 || profile_idc == 244 || profile_idc == 44 || profile_idc == 83 || profile_idc == 86 || profile_idc == 118 || profile_idc == 128 || profile_idc == 138 || profile_idc == 139 || profile_idc == 134) { // chroma_format_idc: ue(v) uint32_t chroma_format_idc; RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&chroma_format_idc)); if (chroma_format_idc == 3) { // separate_colour_plane_flag: u(1) RETURN_FALSE_ON_FAIL( sps_parser.ReadBits(&sps_.separate_colour_plane_flag, 1)); } // bit_depth_luma_minus8: ue(v) RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp)); // bit_depth_chroma_minus8: ue(v) RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp)); // qpprime_y_zero_transform_bypass_flag: u(1) RETURN_FALSE_ON_FAIL(sps_parser.ReadBits(&bits_tmp, 1)); // seq_scaling_matrix_present_flag: u(1) uint32_t seq_scaling_matrix_present_flag; RETURN_FALSE_ON_FAIL( sps_parser.ReadBits(&seq_scaling_matrix_present_flag, 1)); if (seq_scaling_matrix_present_flag) { // seq_scaling_list_present_flags. Either 8 or 12, depending on // chroma_format_idc. uint32_t seq_scaling_list_present_flags; if (chroma_format_idc != 3) { RETURN_FALSE_ON_FAIL( sps_parser.ReadBits(&seq_scaling_list_present_flags, 8)); } else { RETURN_FALSE_ON_FAIL( sps_parser.ReadBits(&seq_scaling_list_present_flags, 12)); } // TODO(pbos): Support parsing scaling lists if they're seen in practice. RTC_CHECK(seq_scaling_list_present_flags == 0) << "SPS contains scaling lists, which are unsupported."; } } // log2_max_frame_num_minus4: ue(v) RETURN_FALSE_ON_FAIL( sps_parser.ReadExponentialGolomb(&sps_.log2_max_frame_num_minus4)); // pic_order_cnt_type: ue(v) RETURN_FALSE_ON_FAIL( sps_parser.ReadExponentialGolomb(&sps_.pic_order_cnt_type)); if (sps_.pic_order_cnt_type == 0) { // log2_max_pic_order_cnt_lsb_minus4: ue(v) RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb( &sps_.log2_max_pic_order_cnt_lsb_minus4)); } else if (sps_.pic_order_cnt_type == 1) { // delta_pic_order_always_zero_flag: u(1) RETURN_FALSE_ON_FAIL( sps_parser.ReadBits(&sps_.delta_pic_order_always_zero_flag, 1)); // offset_for_non_ref_pic: se(v) RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp)); // offset_for_top_to_bottom_field: se(v) RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp)); uint32_t num_ref_frames_in_pic_order_cnt_cycle; // num_ref_frames_in_pic_order_cnt_cycle: ue(v) RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb( &num_ref_frames_in_pic_order_cnt_cycle)); for (uint32_t i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; i++) { // offset_for_ref_frame[i]: se(v) RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp)); } } // max_num_ref_frames: ue(v) RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp)); // gaps_in_frame_num_value_allowed_flag: u(1) RETURN_FALSE_ON_FAIL(sps_parser.ReadBits(&bits_tmp, 1)); // pic_width_in_mbs_minus1: ue(v) RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp)); // pic_height_in_map_units_minus1: ue(v) RETURN_FALSE_ON_FAIL(sps_parser.ReadExponentialGolomb(&golomb_tmp)); // frame_mbs_only_flag: u(1) RETURN_FALSE_ON_FAIL(sps_parser.ReadBits(&sps_.frame_mbs_only_flag, 1)); sps_parsed_ = true; return true; } bool H264BitstreamParser::ParsePpsNalu(const uint8_t* pps, size_t length) { RTC_CHECK(sps_parsed_); // We're starting a new stream, so reset picture type rewriting values. pps_ = PpsState(); pps_parsed_ = false; rtc::scoped_ptr<rtc::ByteBuffer> buffer( ParseRbsp(pps + kNaluHeaderAndTypeSize, length - kNaluHeaderAndTypeSize)); rtc::BitBuffer parser(reinterpret_cast<const uint8_t*>(buffer->Data()), buffer->Length()); uint32_t bits_tmp; uint32_t golomb_ignored; // pic_parameter_set_id: ue(v) RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored)); // seq_parameter_set_id: ue(v) RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored)); // entropy_coding_mode_flag: u(1) uint32_t entropy_coding_mode_flag; RETURN_FALSE_ON_FAIL(parser.ReadBits(&entropy_coding_mode_flag, 1)); // TODO(pbos): Implement CABAC support if spotted in the wild. RTC_CHECK(entropy_coding_mode_flag == 0) << "Don't know how to parse CABAC streams."; // bottom_field_pic_order_in_frame_present_flag: u(1) uint32_t bottom_field_pic_order_in_frame_present_flag; RETURN_FALSE_ON_FAIL( parser.ReadBits(&bottom_field_pic_order_in_frame_present_flag, 1)); pps_.bottom_field_pic_order_in_frame_present_flag = bottom_field_pic_order_in_frame_present_flag != 0; // num_slice_groups_minus1: ue(v) uint32_t num_slice_groups_minus1; RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&num_slice_groups_minus1)); if (num_slice_groups_minus1 > 0) { uint32_t slice_group_map_type; // slice_group_map_type: ue(v) RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&slice_group_map_type)); if (slice_group_map_type == 0) { for (uint32_t i_group = 0; i_group <= num_slice_groups_minus1; ++i_group) { // run_length_minus1[iGroup]: ue(v) RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored)); } } else if (slice_group_map_type == 2) { for (uint32_t i_group = 0; i_group <= num_slice_groups_minus1; ++i_group) { // top_left[iGroup]: ue(v) RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored)); // bottom_right[iGroup]: ue(v) RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored)); } } else if (slice_group_map_type == 3 || slice_group_map_type == 4 || slice_group_map_type == 5) { // slice_group_change_direction_flag: u(1) RETURN_FALSE_ON_FAIL(parser.ReadBits(&bits_tmp, 1)); // slice_group_change_rate_minus1: ue(v) RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored)); } else if (slice_group_map_type == 6) { // pic_size_in_map_units_minus1: ue(v) uint32_t pic_size_in_map_units_minus1; RETURN_FALSE_ON_FAIL( parser.ReadExponentialGolomb(&pic_size_in_map_units_minus1)); uint32_t slice_group_id_bits = 0; uint32_t num_slice_groups = num_slice_groups_minus1 + 1; // If num_slice_groups is not a power of two an additional bit is required // to account for the ceil() of log2() below. if ((num_slice_groups & (num_slice_groups - 1)) != 0) ++slice_group_id_bits; while (num_slice_groups > 0) { num_slice_groups >>= 1; ++slice_group_id_bits; } for (uint32_t i = 0; i <= pic_size_in_map_units_minus1; i++) { // slice_group_id[i]: u(v) // Represented by ceil(log2(num_slice_groups_minus1 + 1)) bits. RETURN_FALSE_ON_FAIL(parser.ReadBits(&bits_tmp, slice_group_id_bits)); } } } // num_ref_idx_l0_default_active_minus1: ue(v) RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored)); // num_ref_idx_l1_default_active_minus1: ue(v) RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored)); // weighted_pred_flag: u(1) uint32_t weighted_pred_flag; RETURN_FALSE_ON_FAIL(parser.ReadBits(&weighted_pred_flag, 1)); pps_.weighted_pred_flag = weighted_pred_flag != 0; // weighted_bipred_idc: u(2) RETURN_FALSE_ON_FAIL(parser.ReadBits(&pps_.weighted_bipred_idc, 2)); // pic_init_qp_minus26: se(v) RETURN_FALSE_ON_FAIL( parser.ReadSignedExponentialGolomb(&pps_.pic_init_qp_minus26)); // pic_init_qs_minus26: se(v) RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored)); // chroma_qp_index_offset: se(v) RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored)); // deblocking_filter_control_present_flag: u(1) // constrained_intra_pred_flag: u(1) RETURN_FALSE_ON_FAIL(parser.ReadBits(&bits_tmp, 2)); // redundant_pic_cnt_present_flag: u(1) RETURN_FALSE_ON_FAIL( parser.ReadBits(&pps_.redundant_pic_cnt_present_flag, 1)); pps_parsed_ = true; return true; } bool H264BitstreamParser::ParseNonParameterSetNalu(const uint8_t* source, size_t source_length, uint8_t nalu_type) { RTC_CHECK(sps_parsed_); RTC_CHECK(pps_parsed_); last_slice_qp_delta_parsed_ = false; rtc::scoped_ptr<rtc::ByteBuffer> slice_rbsp(ParseRbsp( source + kNaluHeaderAndTypeSize, source_length - kNaluHeaderAndTypeSize)); rtc::BitBuffer slice_reader( reinterpret_cast<const uint8_t*>(slice_rbsp->Data()), slice_rbsp->Length()); // Check to see if this is an IDR slice, which has an extra field to parse // out. bool is_idr = (source[kNaluHeaderSize] & 0x0F) == kNaluIdr; uint8_t nal_ref_idc = (source[kNaluHeaderSize] & 0x60) >> 5; uint32_t golomb_tmp; uint32_t bits_tmp; // first_mb_in_slice: ue(v) RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp)); // slice_type: ue(v) uint32_t slice_type; RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&slice_type)); // 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) RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp)); if (sps_.separate_colour_plane_flag == 1) { // colour_plane_id RETURN_FALSE_ON_FAIL(slice_reader.ReadBits(&bits_tmp, 2)); } // frame_num: u(v) // Represented by log2_max_frame_num_minus4 + 4 bits. RETURN_FALSE_ON_FAIL( slice_reader.ReadBits(&bits_tmp, sps_.log2_max_frame_num_minus4 + 4)); uint32_t field_pic_flag = 0; if (sps_.frame_mbs_only_flag == 0) { // field_pic_flag: u(1) RETURN_FALSE_ON_FAIL(slice_reader.ReadBits(&field_pic_flag, 1)); if (field_pic_flag != 0) { // bottom_field_flag: u(1) RETURN_FALSE_ON_FAIL(slice_reader.ReadBits(&bits_tmp, 1)); } } if (is_idr) { // idr_pic_id: ue(v) RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp)); } // pic_order_cnt_lsb: u(v) // Represented by sps_.log2_max_pic_order_cnt_lsb_minus4 + 4 bits. if (sps_.pic_order_cnt_type == 0) { RETURN_FALSE_ON_FAIL(slice_reader.ReadBits( &bits_tmp, sps_.log2_max_pic_order_cnt_lsb_minus4 + 4)); if (pps_.bottom_field_pic_order_in_frame_present_flag && field_pic_flag == 0) { // delta_pic_order_cnt_bottom: se(v) RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp)); } } if (sps_.pic_order_cnt_type == 1 && !sps_.delta_pic_order_always_zero_flag) { // delta_pic_order_cnt[0]: se(v) RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp)); if (pps_.bottom_field_pic_order_in_frame_present_flag && !field_pic_flag) { // delta_pic_order_cnt[1]: se(v) RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp)); } } if (pps_.redundant_pic_cnt_present_flag) { // redundant_pic_cnt: ue(v) RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp)); } if (slice_type == kSliceTypeB) { // direct_spatial_mv_pred_flag: u(1) RETURN_FALSE_ON_FAIL(slice_reader.ReadBits(&bits_tmp, 1)); } if (slice_type == kSliceTypeP || slice_type == kSliceTypeSp || slice_type == kSliceTypeB) { uint32_t num_ref_idx_active_override_flag; // num_ref_idx_active_override_flag: u(1) RETURN_FALSE_ON_FAIL( slice_reader.ReadBits(&num_ref_idx_active_override_flag, 1)); if (num_ref_idx_active_override_flag != 0) { // num_ref_idx_l0_active_minus1: ue(v) RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp)); if (slice_type == kSliceTypeB) { // num_ref_idx_l1_active_minus1: ue(v) RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb(&golomb_tmp)); } } } // assume nal_unit_type != 20 && nal_unit_type != 21: RTC_CHECK_NE(nalu_type, 20); RTC_CHECK_NE(nalu_type, 21); // 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) uint32_t ref_pic_list_modification_flag_l0; RETURN_FALSE_ON_FAIL( slice_reader.ReadBits(&ref_pic_list_modification_flag_l0, 1)); if (ref_pic_list_modification_flag_l0) { uint32_t modification_of_pic_nums_idc; do { // modification_of_pic_nums_idc: ue(v) RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb( &modification_of_pic_nums_idc)); if (modification_of_pic_nums_idc == 0 || modification_of_pic_nums_idc == 1) { // abs_diff_pic_num_minus1: ue(v) RETURN_FALSE_ON_FAIL( slice_reader.ReadExponentialGolomb(&golomb_tmp)); } else if (modification_of_pic_nums_idc == 2) { // long_term_pic_num: ue(v) RETURN_FALSE_ON_FAIL( slice_reader.ReadExponentialGolomb(&golomb_tmp)); } } while (modification_of_pic_nums_idc != 3); } } if (slice_type % 5 == 1) { // ref_pic_list_modification_flag_l1: u(1) uint32_t ref_pic_list_modification_flag_l1; RETURN_FALSE_ON_FAIL( slice_reader.ReadBits(&ref_pic_list_modification_flag_l1, 1)); if (ref_pic_list_modification_flag_l1) { uint32_t modification_of_pic_nums_idc; do { // modification_of_pic_nums_idc: ue(v) RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb( &modification_of_pic_nums_idc)); if (modification_of_pic_nums_idc == 0 || modification_of_pic_nums_idc == 1) { // abs_diff_pic_num_minus1: ue(v) RETURN_FALSE_ON_FAIL( slice_reader.ReadExponentialGolomb(&golomb_tmp)); } else if (modification_of_pic_nums_idc == 2) { // long_term_pic_num: ue(v) RETURN_FALSE_ON_FAIL( slice_reader.ReadExponentialGolomb(&golomb_tmp)); } } while (modification_of_pic_nums_idc != 3); } } } // TODO(pbos): Do we need support for pred_weight_table()? RTC_CHECK(!((pps_.weighted_pred_flag && (slice_type == kSliceTypeP || slice_type == kSliceTypeSp)) || (pps_.weighted_bipred_idc != 0 && slice_type == kSliceTypeB))) << "Missing support for pred_weight_table()."; // 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) RETURN_FALSE_ON_FAIL(slice_reader.ReadBits(&bits_tmp, 2)); } else { // adaptive_ref_pic_marking_mode_flag: u(1) uint32_t adaptive_ref_pic_marking_mode_flag; RETURN_FALSE_ON_FAIL( slice_reader.ReadBits(&adaptive_ref_pic_marking_mode_flag, 1)); if (adaptive_ref_pic_marking_mode_flag) { uint32_t memory_management_control_operation; do { // memory_management_control_operation: ue(v) RETURN_FALSE_ON_FAIL(slice_reader.ReadExponentialGolomb( &memory_management_control_operation)); if (memory_management_control_operation == 1 || memory_management_control_operation == 3) { // difference_of_pic_nums_minus1: ue(v) RETURN_FALSE_ON_FAIL( slice_reader.ReadExponentialGolomb(&golomb_tmp)); } if (memory_management_control_operation == 2) { // long_term_pic_num: ue(v) RETURN_FALSE_ON_FAIL( slice_reader.ReadExponentialGolomb(&golomb_tmp)); } if (memory_management_control_operation == 3 || memory_management_control_operation == 6) { // long_term_frame_idx: ue(v) RETURN_FALSE_ON_FAIL( slice_reader.ReadExponentialGolomb(&golomb_tmp)); } if (memory_management_control_operation == 4) { // max_long_term_frame_idx_plus1: ue(v) RETURN_FALSE_ON_FAIL( slice_reader.ReadExponentialGolomb(&golomb_tmp)); } } while (memory_management_control_operation != 0); } } } // cabac not supported: entropy_coding_mode_flag == 0 asserted above. // if (entropy_coding_mode_flag && slice_type != I && slice_type != SI) // cabac_init_idc RETURN_FALSE_ON_FAIL( slice_reader.ReadSignedExponentialGolomb(&last_slice_qp_delta_)); last_slice_qp_delta_parsed_ = true; return true; } void H264BitstreamParser::ParseSlice(const uint8_t* slice, size_t length) { uint8_t nalu_type = slice[4] & kNaluTypeMask; switch (nalu_type) { case kNaluSps: RTC_CHECK(ParseSpsNalu(slice, length)) << "Failed to parse bitstream SPS."; break; case kNaluPps: RTC_CHECK(ParsePpsNalu(slice, length)) << "Failed to parse bitstream PPS."; break; default: RTC_CHECK(ParseNonParameterSetNalu(slice, length, nalu_type)) << "Failed to parse picture slice."; break; } } void H264BitstreamParser::ParseBitstream(const uint8_t* bitstream, size_t length) { RTC_CHECK_GE(length, 4u); std::vector<size_t> slice_markers = FindNaluStartSequences(bitstream, length); RTC_CHECK(!slice_markers.empty()); for (size_t i = 0; i < slice_markers.size() - 1; ++i) { ParseSlice(bitstream + slice_markers[i], slice_markers[i + 1] - slice_markers[i]); } // Parse the last slice. ParseSlice(bitstream + slice_markers.back(), length - slice_markers.back()); } bool H264BitstreamParser::GetLastSliceQp(int* qp) const { if (!last_slice_qp_delta_parsed_) return false; *qp = 26 + pps_.pic_init_qp_minus26 + last_slice_qp_delta_; return true; } } // namespace webrtc