h265_sps_parser.h - mozsearch

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/*

 *  Copyright (c) 2023 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.

*/

#ifndef COMMON_VIDEO_H265_H265_SPS_PARSER_H_

#define COMMON_VIDEO_H265_H265_SPS_PARSER_H_

#include <optional>

#include <vector>

#include "api/array_view.h"

#include "rtc_base/bitstream_reader.h"

#include "rtc_base/system/rtc_export.h"

namespace webrtc {

// For explanations of each struct and its members, see H.265 specification

// at http://www.itu.int/rec/T-REC-H.265.

enum {

  kMaxLongTermRefPicSets = 32,   // 7.4.3.2.1

  kMaxShortTermRefPicSets = 64,  // 7.4.3.2.1

  kMaxSubLayers = 7,  // 7.4.3.1 & 7.4.3.2.1 [v|s]ps_max_sub_layers_minus1 + 1

};

enum H265ProfileIdc {

  kProfileIdcMain = 1,

  kProfileIdcMain10 = 2,

  kProfileIdcMainStill = 3,

  kProfileIdcRangeExtensions = 4,

  kProfileIdcHighThroughput = 5,

  kProfileIdcMultiviewMain = 6,

  kProfileIdcScalableMain = 7,

  kProfileIdc3dMain = 8,

  kProfileIdcScreenContentCoding = 9,

  kProfileIdcScalableRangeExtensions = 10,

  kProfileIdcHighThroughputScreenContentCoding = 11,

};

// A class for parsing out sequence parameter set (SPS) data from an H265 NALU.

class RTC_EXPORT H265SpsParser {

 public:

  struct ProfileTierLevel {

    ProfileTierLevel();

    // Syntax elements.

    int general_profile_idc = 0;

    int general_level_idc = 0;  // 30x the actual level.

    uint32_t general_profile_compatibility_flags = 0;

    bool general_progressive_source_flag = false;

    bool general_interlaced_source_flag = false;

    bool general_non_packed_constraint_flag = false;

    bool general_frame_only_constraint_flag = false;

    bool general_one_picture_only_constraint_flag = false;

};

  struct ShortTermRefPicSet {

    ShortTermRefPicSet();

    // Syntax elements.

    uint32_t num_negative_pics = 0;

    uint32_t num_positive_pics = 0;

    uint32_t delta_poc_s0[kMaxShortTermRefPicSets] = {};

    uint32_t used_by_curr_pic_s0[kMaxShortTermRefPicSets] = {};

    uint32_t delta_poc_s1[kMaxShortTermRefPicSets] = {};

    uint32_t used_by_curr_pic_s1[kMaxShortTermRefPicSets] = {};

    // Calculated fields.

    uint32_t num_delta_pocs = 0;

};

  // The parsed state of the SPS. Only some select values are stored.

  // Add more as they are actually needed.

  struct RTC_EXPORT SpsState {

    SpsState() = default;

    uint32_t sps_max_sub_layers_minus1 = 0;

    uint32_t chroma_format_idc = 0;

    uint32_t separate_colour_plane_flag = 0;

    uint32_t pic_width_in_luma_samples = 0;

    uint32_t pic_height_in_luma_samples = 0;

    uint32_t log2_max_pic_order_cnt_lsb_minus4 = 0;

    uint32_t sps_max_dec_pic_buffering_minus1[kMaxSubLayers] = {};

    uint32_t log2_min_luma_coding_block_size_minus3 = 0;

    uint32_t log2_diff_max_min_luma_coding_block_size = 0;

    uint32_t sample_adaptive_offset_enabled_flag = 0;

    uint32_t num_short_term_ref_pic_sets = 0;

    std::vector<H265SpsParser::ShortTermRefPicSet> short_term_ref_pic_set;

    uint32_t long_term_ref_pics_present_flag = 0;

    uint32_t num_long_term_ref_pics_sps = 0;

    std::vector<uint32_t> used_by_curr_pic_lt_sps_flag;

    uint32_t sps_temporal_mvp_enabled_flag = 0;

    uint32_t width = 0;

    uint32_t height = 0;

    uint32_t sps_id = 0;

    uint32_t vps_id = 0;

    uint32_t pic_width_in_ctbs_y = 0;

    uint32_t pic_height_in_ctbs_y = 0;

    uint32_t bit_depth_luma_minus8 = 0;

};

  // Unpack RBSP and parse SPS state from the supplied buffer.

  static std::optional<SpsState> ParseSps(rtc::ArrayView<const uint8_t> data);

  // TODO: bugs.webrtc.org/42225170 - Deprecate.

  static inline std::optional<SpsState> ParseSps(const uint8_t* data,

                                                 size_t length) {

    return ParseSps(rtc::MakeArrayView(data, length));

  static bool ParseScalingListData(BitstreamReader& reader);

  static std::optional<ShortTermRefPicSet> ParseShortTermRefPicSet(

      uint32_t st_rps_idx,

      uint32_t num_short_term_ref_pic_sets,

      const std::vector<ShortTermRefPicSet>& ref_pic_sets,

      uint32_t sps_max_dec_pic_buffering_minus1,

      BitstreamReader& reader);

  static std::optional<H265SpsParser::ProfileTierLevel> ParseProfileTierLevel(

      bool profile_present,

      int max_num_sub_layers_minus1,

      BitstreamReader& reader);

 protected:

  // Parse the SPS state, for a bit buffer where RBSP decoding has already been

  // performed.

  static std::optional<SpsState> ParseSpsInternal(

      rtc::ArrayView<const uint8_t> buffer);

  // From Table A.8 - General tier and level limits.

  static int GetMaxLumaPs(int general_level_idc);

  // From A.4.2 - Profile-specific level limits for the video profiles.

  static size_t GetDpbMaxPicBuf(int general_profile_idc);

};

}  // namespace webrtc

#endif  // COMMON_VIDEO_H265_H265_SPS_PARSER_H_