// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "media/parsers/h265_parser.h"

#include <stddef.h>

#include <algorithm>
#include <cmath>
#include <cstring>

#include "base/bits.h"
#include "base/logging.h"
#include "base/notreached.h"
#include "base/numerics/safe_conversions.h"
#include "media/base/decrypt_config.h"
#include "media/base/video_codecs.h"
#include "media/parsers/bit_reader_macros.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/size.h"
#include "ui/gfx/hdr_metadata.h"

namespace media {

namespace {

// Based on section 7.4.5 (equation 7-44), the elements of
// ScalingList[0][matrixId][i] are expected to define a 4x4 matrix in up-right
// diagonal scan order. Thus, the following 4x4 matrix (indexed by x and y):
//
//         x=0 x=1 x=2 x=3
//        ________________
//   y=0 |   a   b   c   d
//   y=1 |   e   f   g   h
//   y=2 |   i   j   k   l
//   y=3 |   m   n   o   p
//
// is expected to appear in ScalingList[0][matrixId][...] as
//
//    {a, e, b, i, f, c, m, j, g, d, n, k, h, o, l, p}
//   i=0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15
//
// The relationship between i and (x, y) is defined by the algorithm in 6.5.3
// with an input of (1 << log2BlockSize) (see 7.4.3.2.1) where log2BlockSize is
// 2 for a 4x4 matrix.
//
// Some APIs (such as the VA-API) want the scaling lists in raster scan order
// instead of up-right diagonal scan order. That is, for the matrix above, they
// expect:
//
//    {a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p}
//   j=0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15
//
// Therefore, given j and the data in up-right diagonal order, we need to get
// the corresponding entry in raster order. The
// k4x4RasterScanOrderIdxToUpRightDiagScanOrderIdx array allows us to do this.
// It's an array where the index is j and the corresponding element is i. This
// array is derived from the algorithm in 6.5.3 by simply setting:
//
//   k4x4RasterScanOrderIdxToUpRightDiagScanOrderIdx[blkSize * y + x] = i
//
// every time diagScanX and diagScanY are updated.
//
// As a usage example, let's say we want to get the entry at index 6 of the
// raster scan order. We get k4x4RasterScanOrderIdxToUpRightDiagScanOrderIdx[6]
// which is 8. Then we get arrayInUpRightDiagOrder[8] which in the example above
// is 'g'.
constexpr std::array<size_t, 16>
    k4x4RasterScanOrderIdxToUpRightDiagScanOrderIdx = {
        0, 2, 5, 9, 1, 4, 8, 12, 3, 7, 11, 14, 6, 10, 13, 15,
};

// k8x8RasterScanOrderIdxToUpRightDiagScanOrderIdx serves the same purpose as
// k4x4RasterScanOrderIdxToUpRightDiagScanOrderIdx but for 8x8 matrices. This
// array is also derived from the algorithm in 6.5.3 in a similar manner with
// (1 << log2BlockSize) as the input where log2BlockSize is 3.
constexpr std::array<size_t, 64>
    k8x8RasterScanOrderIdxToUpRightDiagScanOrderIdx = {
        0,  2,  5,  9,  14, 20, 27, 35, 1,  4,  8,  13, 19, 26, 34, 42,
        3,  7,  12, 18, 25, 33, 41, 48, 6,  11, 17, 24, 32, 40, 47, 53,
        10, 16, 23, 31, 39, 46, 52, 57, 15, 22, 30, 38, 45, 51, 56, 60,
        21, 29, 37, 44, 50, 55, 59, 62, 28, 36, 43, 49, 54, 58, 61, 63,
};

// From Table 7-6.
constexpr std::array<uint8_t, H265ScalingListData::kScalingListSizeId1To3Count>
    kDefaultScalingListSize1To3Matrix0To2 = {
        16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 17, 16, 17, 16, 17, 18,
        17, 18, 18, 17, 18, 21, 19, 20, 21, 20, 19, 21, 24, 22, 22, 24,
        24, 22, 22, 24, 25, 25, 27, 30, 27, 25, 25, 29, 31, 35, 35, 31,
        29, 36, 41, 44, 41, 36, 47, 54, 54, 47, 65, 70, 65, 88, 88, 115,
};
constexpr std::array<uint8_t, H265ScalingListData::kScalingListSizeId1To3Count>
    kDefaultScalingListSize1To3Matrix3To5 = {
        16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 17, 18,
        18, 18, 18, 18, 18, 20, 20, 20, 20, 20, 20, 20, 24, 24, 24, 24,
        24, 24, 24, 24, 25, 25, 25, 25, 25, 25, 25, 28, 28, 28, 28, 28,
        28, 33, 33, 33, 33, 33, 41, 41, 41, 41, 54, 54, 54, 71, 71, 91,
};

// VUI parameters: Table E-1 "Interpretation of sample aspect ratio indicator"
constexpr std::array<int, 17> kTableSarWidth = {
    0, 1, 12, 10, 16, 40, 24, 20, 32, 80, 18, 15, 64, 160, 4, 3, 2};
constexpr std::array<int, 17> kTableSarHeight = {
    0, 1, 11, 11, 11, 33, 11, 11, 11, 33, 11, 11, 33, 99, 3, 2, 1};
static_assert(std::size(kTableSarWidth) == std::size(kTableSarHeight),
              "sar tables must have the same size");

void FillInDefaultScalingListData(H265ScalingListData* scaling_list_data,
                                  int size_id,
                                  int matrix_id) {
  if (size_id == 0) {
    scaling_list_data->scaling_list_4x4[matrix_id].fill(
        H265ScalingListData::kDefaultScalingListSize0Values);
    return;
  }

  base::span<uint8_t> dst;
  switch (size_id) {
    case 1:
      dst = scaling_list_data->scaling_list_8x8[matrix_id];
      break;
    case 2:
      dst = scaling_list_data->scaling_list_16x16[matrix_id];
      break;
    case 3:
      dst = scaling_list_data->scaling_list_32x32[matrix_id];
      break;
  }
  base::span<const uint8_t> src;
  if (matrix_id < 3) {
    src = kDefaultScalingListSize1To3Matrix0To2;
  } else {
    src = kDefaultScalingListSize1To3Matrix3To5;
  }
  dst.copy_from(src);

  // These are sixteen because the default for the minus8 values is 8.
  if (size_id == 2)
    scaling_list_data->scaling_list_dc_coef_16x16[matrix_id] = 16;
  else if (size_id == 3)
    scaling_list_data->scaling_list_dc_coef_32x32[matrix_id] = 16;
}

}  // namespace

H265ScalingListData::H265ScalingListData() = default;

uint8_t H265ScalingListData::GetScalingList4x4EntryInRasterOrder(
    size_t matrix_id,
    size_t raster_idx) const {
  // Per equation 7-44, ScalingList[0][matrixId][..] (i.e., the 4x4 scaling list
  // data) is associated with ScanOrder[2][0][..] (i.e., an up-right diagonal
  // scan ordering for a 4x4 matrix).
  const size_t up_right_diag_idx =
      k4x4RasterScanOrderIdxToUpRightDiagScanOrderIdx[raster_idx];
  return scaling_list_4x4[matrix_id][up_right_diag_idx];
}

uint8_t H265ScalingListData::GetScalingList8x8EntryInRasterOrder(
    size_t matrix_id,
    size_t raster_idx) const {
  // Per equation 7-45, ScalingList[1][matrixId][..] (i.e., the 8x8 scaling list
  // data) is associated with ScanOrder[3][0][..] (i.e., an up-right diagonal
  // scan ordering for an 8x8 matrix).
  const size_t up_right_diag_idx =
      k8x8RasterScanOrderIdxToUpRightDiagScanOrderIdx[raster_idx];
  return scaling_list_8x8[matrix_id][up_right_diag_idx];
}

uint8_t H265ScalingListData::GetScalingList16x16EntryInRasterOrder(
    size_t matrix_id,
    size_t raster_idx) const {
  // Per equation 7-46, ScalingList[2][matrixId][..] (i.e., the 16x16 scaling
  // list data) is associated with ScanOrder[3][0][..] (i.e., an up-right
  // diagonal scan ordering for an 8x8 matrix).
  const size_t up_right_diag_idx =
      k8x8RasterScanOrderIdxToUpRightDiagScanOrderIdx[raster_idx];
  return scaling_list_16x16[matrix_id][up_right_diag_idx];
}

uint8_t H265ScalingListData::GetScalingList32x32EntryInRasterOrder(
    size_t matrix_id,
    size_t raster_idx) const {
  // Per equation 7-48, ScalingList[3][matrixId][..] (i.e., the 32x32 scaling
  // list data) is associated with ScanOrder[3][0][..] (i.e., an up-right
  // diagonal scan ordering for an 8x8 matrix).
  const size_t up_right_diag_idx =
      k8x8RasterScanOrderIdxToUpRightDiagScanOrderIdx[raster_idx];
  return scaling_list_32x32[matrix_id][up_right_diag_idx];
}

H265SPS::H265SPS() = default;

H265SPS::H265SPS(H265SPS&&) noexcept = default;

H265ProfileTierLevel::H265ProfileTierLevel() = default;

H265VUIParameters::H265VUIParameters() = default;

H265VUIParameters::H265VUIParameters(H265VUIParameters&&) noexcept = default;

H265PPS::H265PPS() = default;

H265PPS::H265PPS(H265PPS&&) noexcept = default;

H265VPS::H265VPS() = default;

H265VPS::H265VPS(H265VPS&&) noexcept = default;

H265PredWeightTable::H265PredWeightTable() = default;

H265SliceHeader::H265SliceHeader() = default;

H265SEI::H265SEI() = default;

H265SEI::~H265SEI() = default;

H265Parser::H265Parser() = default;

H265Parser::~H265Parser() = default;

int H265ProfileTierLevel::GetMaxLumaPs() const {
  // From Table A.8 - General tier and level limits.
  // |general_level_idc| is 30x the actual level.
  if (general_level_idc <= 30)  // level 1
    return 36864;
  if (general_level_idc <= 60)  // level 2
    return 122880;
  if (general_level_idc <= 63)  // level 2.1
    return 245760;
  if (general_level_idc <= 90)  // level 3
    return 552960;
  if (general_level_idc <= 93)  // level 3.1
    return 983040;
  if (general_level_idc <= 123)  // level 4, 4.1
    return 2228224;
  if (general_level_idc <= 156)  // level 5, 5.1, 5.2
    return 8912896;
  // level 6, 6.1, 6.2 - beyond that there's no actual limit.
  return 35651584;
}

size_t H265ProfileTierLevel::GetDpbMaxPicBuf() const {
  // From A.4.2 - Profile-specific level limits for the video profiles.
  // If sps_curr_pic_ref_enabled_flag is required to be zero, than this is 6
  // otherwise it is 7.
  return (general_profile_idc >= kProfileIdcMain &&
          general_profile_idc <= kProfileIdcHighThroughput)
             ? 6
             : 7;
}

gfx::Size H265SPS::GetCodedSize() const {
  return gfx::Size(pic_width_in_luma_samples, pic_height_in_luma_samples);
}

gfx::Rect H265SPS::GetVisibleRect() const {
  // 7.4.3.2.1
  // These are verified in the parser that they won't overflow.
  int left = (conf_win_left_offset + vui_parameters.def_disp_win_left_offset) *
             sub_width_c;
  int top = (conf_win_top_offset + vui_parameters.def_disp_win_top_offset) *
            sub_height_c;
  int right =
      (conf_win_right_offset + vui_parameters.def_disp_win_right_offset) *
      sub_width_c;
  int bottom =
      (conf_win_bottom_offset + vui_parameters.def_disp_win_bottom_offset) *
      sub_height_c;
  return gfx::Rect(left, top, pic_width_in_luma_samples - left - right,
                   pic_height_in_luma_samples - top - bottom);
}

// From E.3.1 VUI parameters semantics
VideoColorSpace H265SPS::GetColorSpace() const {
  if (!vui_parameters.colour_description_present_flag)
    return VideoColorSpace();

  return VideoColorSpace(
      vui_parameters.colour_primaries, vui_parameters.transfer_characteristics,
      vui_parameters.matrix_coeffs,
      vui_parameters.video_full_range_flag ? gfx::ColorSpace::RangeID::FULL
                                           : gfx::ColorSpace::RangeID::LIMITED);
}

VideoChromaSampling H265SPS::GetChromaSampling() const {
  switch (chroma_format_idc) {
    case 0:
      return VideoChromaSampling::k400;
    case 1:
      return VideoChromaSampling::k420;
    case 2:
      return VideoChromaSampling::k422;
    case 3:
      return VideoChromaSampling::k444;
    default:
      NOTREACHED();
  }
}

bool H265SliceHeader::IsISlice() const {
  return slice_type == kSliceTypeI;
}

bool H265SliceHeader::IsPSlice() const {
  return slice_type == kSliceTypeP;
}

bool H265SliceHeader::IsBSlice() const {
  return slice_type == kSliceTypeB;
}

H265Parser::Result H265Parser::ParseVPS(int* vps_id) {
  DVLOG(4) << "Parsing VPS";
  Result res = kOk;

  DCHECK(vps_id);
  *vps_id = -1;

  std::unique_ptr<H265VPS> vps = std::make_unique<H265VPS>();

  READ_BITS_OR_RETURN(4, &vps->vps_video_parameter_set_id);
  IN_RANGE_OR_RETURN(vps->vps_video_parameter_set_id, 0, 16);
  READ_BOOL_OR_RETURN(&vps->vps_base_layer_internal_flag);
  READ_BOOL_OR_RETURN(&vps->vps_base_layer_available_flag);
  READ_BITS_OR_RETURN(6, &vps->vps_max_layers_minus1);
  IN_RANGE_OR_RETURN(vps->vps_max_layers_minus1, 0, 63);
  READ_BITS_OR_RETURN(3, &vps->vps_max_sub_layers_minus1);
  IN_RANGE_OR_RETURN(vps->vps_max_sub_layers_minus1, 0, kMaxSubLayers - 1);
  READ_BOOL_OR_RETURN(&vps->vps_temporal_id_nesting_flag);
  SKIP_BITS_OR_RETURN(16);  // vps_reserved_0xffff_16bits
  res = ParseProfileTierLevel(true, vps->vps_max_sub_layers_minus1,
                              &vps->profile_tier_level);
  if (res != kOk) {
    return res;
  }

  bool vps_sub_layer_ordering_info_present_flag;
  READ_BOOL_OR_RETURN(&vps_sub_layer_ordering_info_present_flag);

  for (int i = vps_sub_layer_ordering_info_present_flag
                   ? 0
                   : vps->vps_max_sub_layers_minus1;
       i <= vps->vps_max_sub_layers_minus1; ++i) {
    READ_UE_OR_RETURN(&vps->vps_max_dec_pic_buffering_minus1[i]);
    IN_RANGE_OR_RETURN(vps->vps_max_dec_pic_buffering_minus1[i], 0, 15);
    READ_UE_OR_RETURN(&vps->vps_max_num_reorder_pics[i]);
    IN_RANGE_OR_RETURN(vps->vps_max_num_reorder_pics[i], 0,
                       vps->vps_max_dec_pic_buffering_minus1[i]);
    if (i > 0) {
      TRUE_OR_RETURN(vps->vps_max_dec_pic_buffering_minus1[i] >=
                     vps->vps_max_dec_pic_buffering_minus1[i - 1]);
      TRUE_OR_RETURN(vps->vps_max_num_reorder_pics[i] >=
                     vps->vps_max_num_reorder_pics[i - 1]);
    }
    READ_UE_OR_RETURN(&vps->vps_max_latency_increase_plus1[i]);
  }
  if (!vps_sub_layer_ordering_info_present_flag) {
    for (int i = 0; i < vps->vps_max_sub_layers_minus1; ++i) {
      vps->vps_max_dec_pic_buffering_minus1[i] =
          vps->vps_max_dec_pic_buffering_minus1[vps->vps_max_sub_layers_minus1];
      vps->vps_max_num_reorder_pics[i] =
          vps->vps_max_num_reorder_pics[vps->vps_max_sub_layers_minus1];
      vps->vps_max_latency_increase_plus1[i] =
          vps->vps_max_latency_increase_plus1[vps->vps_max_sub_layers_minus1];
    }
  }

  READ_BITS_OR_RETURN(6, &vps->vps_max_layer_id);
  IN_RANGE_OR_RETURN(vps->vps_max_layer_id, 0, 63);
  READ_UE_OR_RETURN(&vps->vps_num_layer_sets_minus1);
  IN_RANGE_OR_RETURN(vps->vps_num_layer_sets_minus1, 0, 1023);
  for (int i = 1; i <= vps->vps_num_layer_sets_minus1; ++i) {
    for (int j = 0; j <= vps->vps_max_layer_id; ++j) {
      SKIP_BITS_OR_RETURN(1);  // layer_id_included_flag[i][j]
    }
  }

  bool vps_timing_info_present_flag;
  READ_BOOL_OR_RETURN(&vps_timing_info_present_flag);
  if (vps_timing_info_present_flag) {
    SKIP_BITS_OR_RETURN(32);  // vps_num_units_in_tick (!= 0)
    SKIP_BITS_OR_RETURN(32);  // vps_time_scale (!= 0)
    bool vps_poc_proportional_to_timing_flag;
    READ_BOOL_OR_RETURN(&vps_poc_proportional_to_timing_flag);
    if (vps_poc_proportional_to_timing_flag) {
      int vps_num_ticks_poc_diff_one_minus1;
      // Valid range is 0 to 2^32 - 2, which doesn't actually fit in an int.
      READ_UE_OR_RETURN(&vps_num_ticks_poc_diff_one_minus1);
    }
    int vps_num_hrd_parameters;
    READ_UE_OR_RETURN(&vps_num_hrd_parameters);
    IN_RANGE_OR_RETURN(vps_num_hrd_parameters, 0,
                       vps->vps_num_layer_sets_minus1 + 1);
    for (int i = 0; i < vps_num_hrd_parameters; ++i) {
      int hrd_layer_set_idx_i;
      READ_UE_OR_RETURN(&hrd_layer_set_idx_i);
      IN_RANGE_OR_RETURN(hrd_layer_set_idx_i,
                         vps->vps_base_layer_internal_flag ? 0 : 1,
                         vps->vps_num_layer_sets_minus1 + 1);
      bool cprms_present_flag = true;
      if (i > 0) {
        READ_BOOL_OR_RETURN(&cprms_present_flag);
      }

      // E.2.2 hrd_parameters()
      bool nal_hrd_parameters_present_flag = false;
      bool vcl_hrd_parameters_present_flag = false;
      bool sub_pic_hrd_params_present_flag = false;
      if (cprms_present_flag) {
        READ_BOOL_OR_RETURN(&nal_hrd_parameters_present_flag);
        READ_BOOL_OR_RETURN(&vcl_hrd_parameters_present_flag);
        if (nal_hrd_parameters_present_flag ||
            vcl_hrd_parameters_present_flag) {
          READ_BOOL_OR_RETURN(&sub_pic_hrd_params_present_flag);
          if (sub_pic_hrd_params_present_flag) {
            SKIP_BITS_OR_RETURN(8);  // tick_divisor_minus2
            SKIP_BITS_OR_RETURN(
                5);  // du_cpb_removal_delay_increment_length_minus1
            SKIP_BITS_OR_RETURN(
                1);  // sub_pic_cpb_params_in_pic_timing_sei_flag
            SKIP_BITS_OR_RETURN(5);  // dpb_output_delay_du_length_minus1
          }
          SKIP_BITS_OR_RETURN(4);  // bit_rate_scale
          SKIP_BITS_OR_RETURN(4);  // cpb_size_scale
          if (sub_pic_hrd_params_present_flag) {
            SKIP_BITS_OR_RETURN(4);  // cpb_size_du_scale
          }
          SKIP_BITS_OR_RETURN(5);  // initial_cpb_removal_delay_length_minus1
          SKIP_BITS_OR_RETURN(5);  // au_cpb_removal_delay_length_minus1
          SKIP_BITS_OR_RETURN(5);  // dpb_output_delay_length_minus1
        }
      }
      for (int j = 0; j <= vps->vps_max_sub_layers_minus1; ++j) {
        bool fixed_pic_rate_general_flag_j;
        READ_BOOL_OR_RETURN(&fixed_pic_rate_general_flag_j);
        bool fixed_pic_rate_within_cvs_flag_j = true;
        if (!fixed_pic_rate_general_flag_j) {
          READ_BOOL_OR_RETURN(&fixed_pic_rate_within_cvs_flag_j);
        }
        bool low_delay_hrd_flag_j = false;
        if (fixed_pic_rate_within_cvs_flag_j) {
          int elemental_duration_in_tc_minus1;
          READ_UE_OR_RETURN(&elemental_duration_in_tc_minus1);
        } else {
          READ_BOOL_OR_RETURN(&low_delay_hrd_flag_j);
        }
        int cpb_cnt_minus1_j = 0;
        if (!low_delay_hrd_flag_j) {
          READ_UE_OR_RETURN(&cpb_cnt_minus1_j);
          IN_RANGE_OR_RETURN(cpb_cnt_minus1_j, 0, 31);
        }
        if (nal_hrd_parameters_present_flag) {
          // E.2.3 sub_layer_hrd_parameters()
          for (int k = 0; k < cpb_cnt_minus1_j + 1; ++k) {
            int bit_rate_value_minus1_k;
            READ_UE_OR_RETURN(&bit_rate_value_minus1_k);
            int cpb_size_value_minus1_k;
            READ_UE_OR_RETURN(&cpb_size_value_minus1_k);
            if (sub_pic_hrd_params_present_flag) {
              int cpb_size_du_value_minus1_k;
              READ_UE_OR_RETURN(&cpb_size_du_value_minus1_k);
              int bit_rate_du_value_minus1_k;
              READ_UE_OR_RETURN(&bit_rate_du_value_minus1_k);
            }
            SKIP_BITS_OR_RETURN(1);  // cbr_flag
          }
        }
        if (vcl_hrd_parameters_present_flag) {
          // E.2.3 sub_layer_hrd_parameters()
          for (int k = 0; k < cpb_cnt_minus1_j + 1; ++k) {
            int bit_rate_value_minus1_k;
            READ_UE_OR_RETURN(&bit_rate_value_minus1_k);
            int cpb_size_value_minus1_k;
            READ_UE_OR_RETURN(&cpb_size_value_minus1_k);
            if (sub_pic_hrd_params_present_flag) {
              int cpb_size_du_value_minus1_k;
              READ_UE_OR_RETURN(&cpb_size_du_value_minus1_k);
              int bit_rate_du_value_minus1_k;
              READ_UE_OR_RETURN(&bit_rate_du_value_minus1_k);
            }
            SKIP_BITS_OR_RETURN(1);  // cbr_flag
          }
        }
      }
    }
  }

  // F.7.3.2.1 multi-layer video_parameter_set_rbsp()
  bool vps_extension_flag;
  READ_BOOL_OR_RETURN(&vps_extension_flag);
  if (vps_extension_flag) {
    BYTE_ALIGNMENT();
    // F.7.3.2.1.1 vps_extension()
    if (vps->vps_max_layers_minus1 > 0 && vps->vps_base_layer_internal_flag) {
      H265ProfileTierLevel profile_tier_level;
      res = ParseProfileTierLevel(false, vps->vps_max_sub_layers_minus1,
                                  &profile_tier_level);
      if (res != kOk) {
        return res;
      }
    }
    bool splitting_flag;
    READ_BOOL_OR_RETURN(&splitting_flag);
    std::array<bool, 16> scalability_mask_flag = {};
    int num_scalability_types = 0;
    for (int i = 0; i < 16; ++i) {
      READ_BOOL_OR_RETURN(&scalability_mask_flag[i]);
      num_scalability_types += scalability_mask_flag[i];
    }
    std::array<int, 16> dimension_id_len_minus1 = {};
    for (int j = 0; j < (num_scalability_types - splitting_flag); ++j) {
      READ_BITS_OR_RETURN(3, &dimension_id_len_minus1[j]);
    }

    std::array<int, 17> dim_bit_offset = {};
    if (splitting_flag) {
      // Equation F-2
      for (int j = 1; j <= num_scalability_types - 1; ++j) {
        dim_bit_offset[j] =
            dim_bit_offset[j - 1] + dimension_id_len_minus1[j - 1] + 1;
      }
      // F.7.4.3.1.1 dimension_id_len_minus1
      // Note: this value is specified to be inferred regardless of the value of
      // NumScalabilityTypes, but the indices would be negative if it were zero.
      if (num_scalability_types) {
        dimension_id_len_minus1[num_scalability_types - 1] =
            5 - dim_bit_offset[num_scalability_types - 1];
      }
      dim_bit_offset[num_scalability_types] = 6;
      if (num_scalability_types) {
        LE_OR_RETURN(dim_bit_offset[num_scalability_types - 1], 5);
      }
    }

    bool vps_nuh_layer_id_present_flag;
    READ_BOOL_OR_RETURN(&vps_nuh_layer_id_present_flag);
    for (int i = 1; i <= std::min(62, vps->vps_max_layers_minus1); ++i) {
      int layer_id_in_nuh_i = i;
      if (vps_nuh_layer_id_present_flag) {
        READ_BITS_OR_RETURN(6, &layer_id_in_nuh_i);
      }
      std::array<int, 16> dimension_id_i = {};
      if (!splitting_flag) {
        for (int j = 0; j < num_scalability_types; ++j) {
          READ_BITS_OR_RETURN(dimension_id_len_minus1[j] + 1,
                              &dimension_id_i[j]);
        }
      } else {
        // F.7.4.3.1.1 dimension_id
        for (int j = 0; j < num_scalability_types; ++j) {
          dimension_id_i[j] =
              (layer_id_in_nuh_i & ((1 << dim_bit_offset[j + 1]) - 1)) >>
              dim_bit_offset[j];
        }
      }

      // F.7.4.3.1.1 dimension_id
      // We can skip layer zero because all dimension_id[0][j] == 0.
      std::array<int, 16> scalability_id_i = {};
      for (int sm_idx = 0, j = 0; sm_idx < 16; ++sm_idx) {
        if (scalability_mask_flag[sm_idx]) {
          scalability_id_i[sm_idx] = dimension_id_i[j++];
        }
      }

      if (scalability_id_i[3] == 1) {
        vps->aux_alpha_layer_id = layer_id_in_nuh_i;
      }
    }
  }

  // If an VPS with the same id already exists, replace it.
  *vps_id = vps->vps_video_parameter_set_id;
  active_vps_[*vps_id] = std::move(vps);

  return res;
}

H265Parser::Result H265Parser::ParseSPS(int* sps_id) {
  // 7.4.3.2
  DVLOG(4) << "Parsing SPS";
  Result res = kOk;

  DCHECK(sps_id);
  *sps_id = -1;

  std::unique_ptr<H265SPS> sps = std::make_unique<H265SPS>();
  READ_BITS_OR_RETURN(4, &sps->sps_video_parameter_set_id);
  IN_RANGE_OR_RETURN(sps->sps_video_parameter_set_id, 0, 15);
  READ_BITS_OR_RETURN(3, &sps->sps_max_sub_layers_minus1);
  IN_RANGE_OR_RETURN(sps->sps_max_sub_layers_minus1, 0, 6);
  READ_BOOL_OR_RETURN(&sps->sps_temporal_id_nesting_flag);

  res = ParseProfileTierLevel(true, sps->sps_max_sub_layers_minus1,
                              &sps->profile_tier_level);
  if (res != kOk)
    return res;

  READ_UE_OR_RETURN(&sps->sps_seq_parameter_set_id);
  IN_RANGE_OR_RETURN(sps->sps_seq_parameter_set_id, 0, 15);
  READ_UE_OR_RETURN(&sps->chroma_format_idc);
  IN_RANGE_OR_RETURN(sps->chroma_format_idc, 0, 3);
  if (sps->chroma_format_idc == 3) {
    READ_BOOL_OR_RETURN(&sps->separate_colour_plane_flag);
  }
  sps->chroma_array_type =
      sps->separate_colour_plane_flag ? 0 : sps->chroma_format_idc;
  // Table 6-1.
  if (sps->chroma_format_idc == 1) {
    sps->sub_width_c = sps->sub_height_c = 2;
  } else if (sps->chroma_format_idc == 2) {
    sps->sub_width_c = 2;
    sps->sub_height_c = 1;
  } else {
    sps->sub_width_c = sps->sub_height_c = 1;
  }
  READ_UE_OR_RETURN(&sps->pic_width_in_luma_samples);
  READ_UE_OR_RETURN(&sps->pic_height_in_luma_samples);
  TRUE_OR_RETURN(sps->pic_width_in_luma_samples != 0);
  TRUE_OR_RETURN(sps->pic_height_in_luma_samples != 0);

  // Equation A-2: Calculate max_dpb_size.
  int max_luma_ps = sps->profile_tier_level.GetMaxLumaPs();
  base::CheckedNumeric<int> pic_size = sps->pic_height_in_luma_samples;
  pic_size *= sps->pic_width_in_luma_samples;
  if (!pic_size.IsValid())
    return kInvalidStream;
  int pic_size_in_samples_y = pic_size.ValueOrDefault(0);
  size_t max_dpb_pic_buf = sps->profile_tier_level.GetDpbMaxPicBuf();
  if (pic_size_in_samples_y <= (max_luma_ps >> 2))
    sps->max_dpb_size = std::min(4 * max_dpb_pic_buf, size_t{16});
  else if (pic_size_in_samples_y <= (max_luma_ps >> 1))
    sps->max_dpb_size = std::min(2 * max_dpb_pic_buf, size_t{16});
  else if (pic_size_in_samples_y <= ((3 * max_luma_ps) >> 2))
    sps->max_dpb_size = std::min((4 * max_dpb_pic_buf) / 3, size_t{16});
  else
    sps->max_dpb_size = max_dpb_pic_buf;

  bool conformance_window_flag;
  READ_BOOL_OR_RETURN(&conformance_window_flag);
  if (conformance_window_flag) {
    READ_UE_OR_RETURN(&sps->conf_win_left_offset);
    READ_UE_OR_RETURN(&sps->conf_win_right_offset);
    READ_UE_OR_RETURN(&sps->conf_win_top_offset);
    READ_UE_OR_RETURN(&sps->conf_win_bottom_offset);
    base::CheckedNumeric<int> width_crop = sps->conf_win_left_offset;
    width_crop += sps->conf_win_right_offset;
    width_crop *= sps->sub_width_c;
    if (!width_crop.IsValid())
      return kInvalidStream;
    TRUE_OR_RETURN(width_crop.ValueOrDefault(0) <
                   sps->pic_width_in_luma_samples);
    base::CheckedNumeric<int> height_crop = sps->conf_win_top_offset;
    height_crop += sps->conf_win_bottom_offset;
    height_crop *= sps->sub_height_c;
    if (!height_crop.IsValid())
      return kInvalidStream;
    TRUE_OR_RETURN(height_crop.ValueOrDefault(0) <
                   sps->pic_height_in_luma_samples);
  }
  READ_UE_OR_RETURN(&sps->bit_depth_luma_minus8);
  IN_RANGE_OR_RETURN(sps->bit_depth_luma_minus8, 0, 8);
  sps->bit_depth_y = sps->bit_depth_luma_minus8 + 8;
  READ_UE_OR_RETURN(&sps->bit_depth_chroma_minus8);
  IN_RANGE_OR_RETURN(sps->bit_depth_chroma_minus8, 0, 8);
  sps->bit_depth_c = sps->bit_depth_chroma_minus8 + 8;
  READ_UE_OR_RETURN(&sps->log2_max_pic_order_cnt_lsb_minus4);
  IN_RANGE_OR_RETURN(sps->log2_max_pic_order_cnt_lsb_minus4, 0, 12);
  sps->max_pic_order_cnt_lsb =
      std::pow(2, sps->log2_max_pic_order_cnt_lsb_minus4 + 4);
  bool sps_sub_layer_ordering_info_present_flag;
  READ_BOOL_OR_RETURN(&sps_sub_layer_ordering_info_present_flag);
  for (int i = sps_sub_layer_ordering_info_present_flag
                   ? 0
                   : sps->sps_max_sub_layers_minus1;
       i <= sps->sps_max_sub_layers_minus1; ++i) {
    READ_UE_OR_RETURN(&sps->sps_max_dec_pic_buffering_minus1[i]);
    IN_RANGE_OR_RETURN(sps->sps_max_dec_pic_buffering_minus1[i], 0,
                       static_cast<int>(sps->max_dpb_size) - 1);
    READ_UE_OR_RETURN(&sps->sps_max_num_reorder_pics[i]);
    IN_RANGE_OR_RETURN(sps->sps_max_num_reorder_pics[i], 0,
                       sps->sps_max_dec_pic_buffering_minus1[i]);
    if (i > 0) {
      TRUE_OR_RETURN(sps->sps_max_dec_pic_buffering_minus1[i] >=
                     sps->sps_max_dec_pic_buffering_minus1[i - 1]);
      TRUE_OR_RETURN(sps->sps_max_num_reorder_pics[i] >=
                     sps->sps_max_num_reorder_pics[i - 1]);
    }
    READ_UE_OR_RETURN(&sps->sps_max_latency_increase_plus1[i]);
    IN_RANGE_OR_RETURN(sps->sps_max_latency_increase_plus1[i], 0, 0xFFFFFFFE);
  }
  if (!sps_sub_layer_ordering_info_present_flag) {
    // Fill in the default values for the other sublayers.
    for (int i = 0; i < sps->sps_max_sub_layers_minus1; ++i) {
      sps->sps_max_dec_pic_buffering_minus1[i] =
          sps->sps_max_dec_pic_buffering_minus1[sps->sps_max_sub_layers_minus1];
      sps->sps_max_num_reorder_pics[i] =
          sps->sps_max_num_reorder_pics[sps->sps_max_sub_layers_minus1];
      sps->sps_max_latency_increase_plus1[i] =
          sps->sps_max_latency_increase_plus1[sps->sps_max_sub_layers_minus1];
    }
  }

  // Equation 7-9: Calculate SpsMaxLatencyPictures.
  for (int i = 0; i <= sps->sps_max_sub_layers_minus1; ++i) {
    if (sps->sps_max_latency_increase_plus1[i] != 0) {
      sps->sps_max_latency_pictures[i] =
          static_cast<uint32_t>(sps->sps_max_num_reorder_pics[i]) +
          sps->sps_max_latency_increase_plus1[i] - 1;
    } else {
      sps->sps_max_latency_pictures[i] = 0;
    }
  }

  READ_UE_OR_RETURN(&sps->log2_min_luma_coding_block_size_minus3);
  // This enforces that min_cb_log2_size_y below will be <= 30 and prevents
  // integer overflow math there.
  TRUE_OR_RETURN(sps->log2_min_luma_coding_block_size_minus3 <= 27);
  READ_UE_OR_RETURN(&sps->log2_diff_max_min_luma_coding_block_size);

  int min_cb_log2_size_y = sps->log2_min_luma_coding_block_size_minus3 + 3;
  base::CheckedNumeric<int> ctb_log2_size_y = min_cb_log2_size_y;
  ctb_log2_size_y += sps->log2_diff_max_min_luma_coding_block_size;
  if (!ctb_log2_size_y.IsValid())
    return kInvalidStream;

  sps->ctb_log2_size_y = ctb_log2_size_y.ValueOrDefault(0);
  TRUE_OR_RETURN(sps->ctb_log2_size_y <= 30);
  int min_cb_size_y = 1 << min_cb_log2_size_y;
  int ctb_size_y = 1 << sps->ctb_log2_size_y;
  sps->pic_width_in_ctbs_y = base::ClampCeil(
      static_cast<float>(sps->pic_width_in_luma_samples) / ctb_size_y);
  sps->pic_height_in_ctbs_y = base::ClampCeil(
      static_cast<float>(sps->pic_height_in_luma_samples) / ctb_size_y);
  base::CheckedNumeric<int> pic_size_in_ctbs_y = sps->pic_width_in_ctbs_y;
  pic_size_in_ctbs_y *= sps->pic_height_in_ctbs_y;
  if (!pic_size_in_ctbs_y.IsValid())
    return kInvalidStream;
  sps->pic_size_in_ctbs_y = pic_size_in_ctbs_y.ValueOrDefault(0);

  TRUE_OR_RETURN(sps->pic_width_in_luma_samples % min_cb_size_y == 0);
  TRUE_OR_RETURN(sps->pic_height_in_luma_samples % min_cb_size_y == 0);
  READ_UE_OR_RETURN(&sps->log2_min_luma_transform_block_size_minus2);
  TRUE_OR_RETURN(sps->log2_min_luma_transform_block_size_minus2 <
                 min_cb_log2_size_y - 2);
  int min_tb_log2_size_y = sps->log2_min_luma_transform_block_size_minus2 + 2;
  READ_UE_OR_RETURN(&sps->log2_diff_max_min_luma_transform_block_size);
  TRUE_OR_RETURN(sps->log2_diff_max_min_luma_transform_block_size <=
                 std::min(sps->ctb_log2_size_y, 5) - min_tb_log2_size_y);
  READ_UE_OR_RETURN(&sps->max_transform_hierarchy_depth_inter);
  IN_RANGE_OR_RETURN(sps->max_transform_hierarchy_depth_inter, 0,
                     sps->ctb_log2_size_y - min_tb_log2_size_y);
  READ_UE_OR_RETURN(&sps->max_transform_hierarchy_depth_intra);
  IN_RANGE_OR_RETURN(sps->max_transform_hierarchy_depth_intra, 0,
                     sps->ctb_log2_size_y - min_tb_log2_size_y);
  READ_BOOL_OR_RETURN(&sps->scaling_list_enabled_flag);
  if (sps->scaling_list_enabled_flag) {
    READ_BOOL_OR_RETURN(&sps->sps_scaling_list_data_present_flag);
  }
  if (sps->sps_scaling_list_data_present_flag) {
    res = ParseScalingListData(&sps->scaling_list_data);
    if (res != kOk)
      return res;
  } else {
    // Fill it in with the default values.
    for (int size_id = 0; size_id < 4; ++size_id) {
      for (int matrix_id = 0; matrix_id < 6;
           matrix_id += (size_id == 3) ? 3 : 1) {
        FillInDefaultScalingListData(&sps->scaling_list_data, size_id,
                                     matrix_id);
      }
    }
  }
  READ_BOOL_OR_RETURN(&sps->amp_enabled_flag);
  READ_BOOL_OR_RETURN(&sps->sample_adaptive_offset_enabled_flag);
  READ_BOOL_OR_RETURN(&sps->pcm_enabled_flag);
  if (sps->pcm_enabled_flag) {
    READ_BITS_OR_RETURN(4, &sps->pcm_sample_bit_depth_luma_minus1);
    TRUE_OR_RETURN(sps->pcm_sample_bit_depth_luma_minus1 + 1 <=
                   sps->bit_depth_y);
    READ_BITS_OR_RETURN(4, &sps->pcm_sample_bit_depth_chroma_minus1);
    TRUE_OR_RETURN(sps->pcm_sample_bit_depth_chroma_minus1 + 1 <=
                   sps->bit_depth_c);
    READ_UE_OR_RETURN(&sps->log2_min_pcm_luma_coding_block_size_minus3);
    IN_RANGE_OR_RETURN(sps->log2_min_pcm_luma_coding_block_size_minus3, 0, 2);
    int log2_min_ipcm_cb_size_y =
        sps->log2_min_pcm_luma_coding_block_size_minus3 + 3;
    IN_RANGE_OR_RETURN(log2_min_ipcm_cb_size_y, std::min(min_cb_log2_size_y, 5),
                       std::min(sps->ctb_log2_size_y, 5));
    READ_UE_OR_RETURN(&sps->log2_diff_max_min_pcm_luma_coding_block_size);
    TRUE_OR_RETURN(sps->log2_diff_max_min_pcm_luma_coding_block_size <=
                   std::min(sps->ctb_log2_size_y, 5) - log2_min_ipcm_cb_size_y);
    READ_BOOL_OR_RETURN(&sps->pcm_loop_filter_disabled_flag);
  }
  READ_UE_OR_RETURN(&sps->num_short_term_ref_pic_sets);
  IN_RANGE_OR_RETURN(sps->num_short_term_ref_pic_sets, 0,
                     kMaxShortTermRefPicSets);
  for (int i = 0; i < sps->num_short_term_ref_pic_sets; ++i) {
    res = ParseStRefPicSet(i, *sps, &sps->st_ref_pic_set[i]);
    if (res != kOk)
      return res;
  }
  READ_BOOL_OR_RETURN(&sps->long_term_ref_pics_present_flag);
  if (sps->long_term_ref_pics_present_flag) {
    READ_UE_OR_RETURN(&sps->num_long_term_ref_pics_sps);
    IN_RANGE_OR_RETURN(sps->num_long_term_ref_pics_sps, 0,
                       kMaxLongTermRefPicSets);
    for (int i = 0; i < sps->num_long_term_ref_pics_sps; ++i) {
      READ_BITS_OR_RETURN(sps->log2_max_pic_order_cnt_lsb_minus4 + 4,
                          &sps->lt_ref_pic_poc_lsb_sps[i]);
      READ_BOOL_OR_RETURN(&sps->used_by_curr_pic_lt_sps_flag[i]);
    }
  }
  READ_BOOL_OR_RETURN(&sps->sps_temporal_mvp_enabled_flag);
  READ_BOOL_OR_RETURN(&sps->strong_intra_smoothing_enabled_flag);
  READ_BOOL_OR_RETURN(&sps->vui_parameters_present_flag);
  if (sps->vui_parameters_present_flag) {
    res = ParseVuiParameters(*sps, &sps->vui_parameters);
    if (res != kOk)
      return res;
    // Verify cropping parameters. We already verified the conformance window
    // ranges previously.
    base::CheckedNumeric<int> width_crop =
        sps->conf_win_left_offset + sps->conf_win_right_offset;
    width_crop += sps->vui_parameters.def_disp_win_left_offset;
    width_crop += sps->vui_parameters.def_disp_win_right_offset;
    width_crop *= sps->sub_width_c;
    if (!width_crop.IsValid())
      return kInvalidStream;
    TRUE_OR_RETURN(width_crop.ValueOrDefault(0) <
                   sps->pic_width_in_luma_samples);
    base::CheckedNumeric<int> height_crop =
        sps->conf_win_top_offset + sps->conf_win_bottom_offset;
    height_crop += sps->vui_parameters.def_disp_win_top_offset;
    height_crop += sps->vui_parameters.def_disp_win_bottom_offset;
    height_crop *= sps->sub_height_c;
    if (!height_crop.IsValid())
      return kInvalidStream;
    TRUE_OR_RETURN(height_crop.ValueOrDefault(0) <
                   sps->pic_height_in_luma_samples);
  }

  READ_BOOL_OR_RETURN(&sps->sps_extension_present_flag);
  if (sps->sps_extension_present_flag) {
    READ_BOOL_OR_RETURN(&sps->sps_range_extension_flag);
    READ_BOOL_OR_RETURN(&sps->sps_multilayer_extension_flag);
    READ_BOOL_OR_RETURN(&sps->sps_3d_extension_flag);
    READ_BOOL_OR_RETURN(&sps->sps_scc_extension_flag);
    SKIP_BITS_OR_RETURN(4);  // sps_extension_4bits
  }
  if (sps->sps_range_extension_flag) {
    READ_BOOL_OR_RETURN(&sps->transform_skip_rotation_enabled_flag);
    READ_BOOL_OR_RETURN(&sps->transform_skip_context_enabled_flag);
    READ_BOOL_OR_RETURN(&sps->implicit_rdpcm_enabled_flag);
    READ_BOOL_OR_RETURN(&sps->explicit_rdpcm_enabled_flag);
    READ_BOOL_OR_RETURN(&sps->extended_precision_processing_flag);
    READ_BOOL_OR_RETURN(&sps->intra_smoothing_disabled_flag);
    READ_BOOL_OR_RETURN(&sps->high_precision_offsets_enabled_flag);
    READ_BOOL_OR_RETURN(&sps->persistent_rice_adaptation_enabled_flag);
    READ_BOOL_OR_RETURN(&sps->cabac_bypass_alignment_enabled_flag);
  }
  if (sps->sps_3d_extension_flag) {
    DVLOG(1) << "HEVC 3D extension not supported";
    return kInvalidStream;
  }
  if (sps->sps_scc_extension_flag) {
    DVLOG(1) << "HEVC SCC extension not supported";
    return kInvalidStream;
  }

  sps->wp_offset_half_range_y = 1 << (sps->high_precision_offsets_enabled_flag
                                          ? sps->bit_depth_luma_minus8 + 7
                                          : 7);
  sps->wp_offset_half_range_c = 1 << (sps->high_precision_offsets_enabled_flag
                                          ? sps->bit_depth_chroma_minus8 + 7
                                          : 7);

  // If an SPS with the same id already exists, replace it.
  *sps_id = sps->sps_seq_parameter_set_id;
  active_sps_[*sps_id] = std::move(sps);

  return res;
}

H265Parser::Result H265Parser::ParsePPS(const H265NALU& nalu, int* pps_id) {
  // 7.4.3.3
  DVLOG(4) << "Parsing PPS";
  Result res = kOk;

  DCHECK(pps_id);
  *pps_id = -1;
  std::unique_ptr<H265PPS> pps = std::make_unique<H265PPS>();

  // Set these defaults if they are not present here.
  pps->uniform_spacing_flag = true;
  pps->loop_filter_across_tiles_enabled_flag = true;

  // 7.4.3.3.1
  READ_UE_OR_RETURN(&pps->pps_pic_parameter_set_id);
  IN_RANGE_OR_RETURN(pps->pps_pic_parameter_set_id, 0, 63);
  READ_UE_OR_RETURN(&pps->pps_seq_parameter_set_id);
  IN_RANGE_OR_RETURN(pps->pps_seq_parameter_set_id, 0, 15);
  const H265SPS* sps = GetSPS(pps->pps_seq_parameter_set_id);
  if (!sps) {
    return kMissingParameterSet;
  }
  READ_BOOL_OR_RETURN(&pps->dependent_slice_segments_enabled_flag);
  READ_BOOL_OR_RETURN(&pps->output_flag_present_flag);
  READ_BITS_OR_RETURN(3, &pps->num_extra_slice_header_bits);
  READ_BOOL_OR_RETURN(&pps->sign_data_hiding_enabled_flag);
  READ_BOOL_OR_RETURN(&pps->cabac_init_present_flag);
  READ_UE_OR_RETURN(&pps->num_ref_idx_l0_default_active_minus1);
  IN_RANGE_OR_RETURN(pps->num_ref_idx_l0_default_active_minus1, 0,
                     kMaxRefIdxActive - 1);
  READ_UE_OR_RETURN(&pps->num_ref_idx_l1_default_active_minus1);
  IN_RANGE_OR_RETURN(pps->num_ref_idx_l1_default_active_minus1, 0,
                     kMaxRefIdxActive - 1);
  READ_SE_OR_RETURN(&pps->init_qp_minus26);
  pps->qp_bd_offset_y = 6 * sps->bit_depth_luma_minus8;
  IN_RANGE_OR_RETURN(pps->init_qp_minus26, -(26 + pps->qp_bd_offset_y), 25);
  READ_BOOL_OR_RETURN(&pps->constrained_intra_pred_flag);
  READ_BOOL_OR_RETURN(&pps->transform_skip_enabled_flag);
  READ_BOOL_OR_RETURN(&pps->cu_qp_delta_enabled_flag);
  if (pps->cu_qp_delta_enabled_flag) {
    READ_UE_OR_RETURN(&pps->diff_cu_qp_delta_depth);
    IN_RANGE_OR_RETURN(pps->diff_cu_qp_delta_depth, 0,
                       sps->log2_diff_max_min_luma_coding_block_size);
  }
  READ_SE_OR_RETURN(&pps->pps_cb_qp_offset);
  IN_RANGE_OR_RETURN(pps->pps_cb_qp_offset, -12, 12);
  READ_SE_OR_RETURN(&pps->pps_cr_qp_offset);
  IN_RANGE_OR_RETURN(pps->pps_cr_qp_offset, -12, 12);
  READ_BOOL_OR_RETURN(&pps->pps_slice_chroma_qp_offsets_present_flag);
  READ_BOOL_OR_RETURN(&pps->weighted_pred_flag);
  READ_BOOL_OR_RETURN(&pps->weighted_bipred_flag);
  READ_BOOL_OR_RETURN(&pps->transquant_bypass_enabled_flag);
  READ_BOOL_OR_RETURN(&pps->tiles_enabled_flag);
  READ_BOOL_OR_RETURN(&pps->entropy_coding_sync_enabled_flag);
  if (pps->tiles_enabled_flag) {
    READ_UE_OR_RETURN(&pps->num_tile_columns_minus1);
    IN_RANGE_OR_RETURN(pps->num_tile_columns_minus1, 0,
                       sps->pic_width_in_ctbs_y - 1);
    TRUE_OR_RETURN(pps->num_tile_columns_minus1 <
                   H265PPS::kMaxNumTileColumnWidth);
    READ_UE_OR_RETURN(&pps->num_tile_rows_minus1);
    IN_RANGE_OR_RETURN(pps->num_tile_rows_minus1, 0,
                       sps->pic_height_in_ctbs_y - 1);
    TRUE_OR_RETURN((pps->num_tile_columns_minus1 != 0) ||
                   (pps->num_tile_rows_minus1 != 0));
    TRUE_OR_RETURN(pps->num_tile_rows_minus1 < H265PPS::kMaxNumTileRowHeight);
    READ_BOOL_OR_RETURN(&pps->uniform_spacing_flag);
    if (!pps->uniform_spacing_flag) {
      pps->column_width_minus1[pps->num_tile_columns_minus1] =
          sps->pic_width_in_ctbs_y - 1;
      for (int i = 0; i < pps->num_tile_columns_minus1; ++i) {
        READ_UE_OR_RETURN(&pps->column_width_minus1[i]);
        IN_RANGE_OR_RETURN(
            pps->column_width_minus1[i], 0,
            pps->column_width_minus1[pps->num_tile_columns_minus1] - 1);
        pps->column_width_minus1[pps->num_tile_columns_minus1] -=
            pps->column_width_minus1[i] + 1;
      }
      pps->row_height_minus1[pps->num_tile_rows_minus1] =
          sps->pic_height_in_ctbs_y - 1;
      for (int i = 0; i < pps->num_tile_rows_minus1; ++i) {
        READ_UE_OR_RETURN(&pps->row_height_minus1[i]);
        IN_RANGE_OR_RETURN(
            pps->row_height_minus1[i], 0,
            pps->row_height_minus1[pps->num_tile_rows_minus1] - 1);
        pps->row_height_minus1[pps->num_tile_rows_minus1] -=
            pps->row_height_minus1[i] + 1;
      }
    }
    READ_BOOL_OR_RETURN(&pps->loop_filter_across_tiles_enabled_flag);
  }
  READ_BOOL_OR_RETURN(&pps->pps_loop_filter_across_slices_enabled_flag);
  READ_BOOL_OR_RETURN(&pps->deblocking_filter_control_present_flag);
  if (pps->deblocking_filter_control_present_flag) {
    READ_BOOL_OR_RETURN(&pps->deblocking_filter_override_enabled_flag);
    READ_BOOL_OR_RETURN(&pps->pps_deblocking_filter_disabled_flag);
    if (!pps->pps_deblocking_filter_disabled_flag) {
      READ_SE_OR_RETURN(&pps->pps_beta_offset_div2);
      IN_RANGE_OR_RETURN(pps->pps_beta_offset_div2, -6, 6);
      READ_SE_OR_RETURN(&pps->pps_tc_offset_div2);
      IN_RANGE_OR_RETURN(pps->pps_tc_offset_div2, -6, 6);
    }
  }
  READ_BOOL_OR_RETURN(&pps->pps_scaling_list_data_present_flag);
  if (pps->pps_scaling_list_data_present_flag) {
    res = ParseScalingListData(&pps->scaling_list_data);
    if (res != kOk)
      return res;
  }
  READ_BOOL_OR_RETURN(&pps->lists_modification_present_flag);
  READ_UE_OR_RETURN(&pps->log2_parallel_merge_level_minus2);
  IN_RANGE_OR_RETURN(pps->log2_parallel_merge_level_minus2, 0,
                     sps->ctb_log2_size_y - 2);
  READ_BOOL_OR_RETURN(&pps->slice_segment_header_extension_present_flag);
  READ_BOOL_OR_RETURN(&pps->pps_extension_present_flag);
  if (pps->pps_extension_present_flag) {
    READ_BOOL_OR_RETURN(&pps->pps_range_extension_flag);
    READ_BOOL_OR_RETURN(&pps->pps_multilayer_extension_flag);
    READ_BOOL_OR_RETURN(&pps->pps_3d_extension_flag);
    READ_BOOL_OR_RETURN(&pps->pps_scc_extension_flag);
    SKIP_BITS_OR_RETURN(4);  // pps_extension_4bits
  }

  if (pps->pps_range_extension_flag) {
    if (pps->transform_skip_enabled_flag) {
      READ_UE_OR_RETURN(&pps->log2_max_transform_skip_block_size_minus2);
      IN_RANGE_OR_RETURN(pps->log2_max_transform_skip_block_size_minus2, 0, 3);
    }
    READ_BOOL_OR_RETURN(&pps->cross_component_prediction_enabled_flag);
    READ_BOOL_OR_RETURN(&pps->chroma_qp_offset_list_enabled_flag);
    if (pps->chroma_qp_offset_list_enabled_flag) {
      READ_UE_OR_RETURN(&pps->diff_cu_chroma_qp_offset_depth);
      IN_RANGE_OR_RETURN(pps->diff_cu_chroma_qp_offset_depth, 0,
                         sps->log2_diff_max_min_luma_coding_block_size);
      READ_UE_OR_RETURN(&pps->chroma_qp_offset_list_len_minus1);
      IN_RANGE_OR_RETURN(pps->chroma_qp_offset_list_len_minus1, 0, 5);
      for (int i = 0; i <= pps->chroma_qp_offset_list_len_minus1; i++) {
        READ_SE_OR_RETURN(&pps->cb_qp_offset_list[i]);
        IN_RANGE_OR_RETURN(pps->cb_qp_offset_list[i], -12, 12);
        READ_SE_OR_RETURN(&pps->cr_qp_offset_list[i]);
        IN_RANGE_OR_RETURN(pps->cr_qp_offset_list[i], -12, 12);
      }
    }
    READ_UE_OR_RETURN(&pps->log2_sao_offset_scale_luma);
    IN_RANGE_OR_RETURN(pps->log2_sao_offset_scale_luma, 0,
                       std::max(sps->bit_depth_luma_minus8 - 2, 0));
    READ_UE_OR_RETURN(&pps->log2_sao_offset_scale_chroma);
    IN_RANGE_OR_RETURN(pps->log2_sao_offset_scale_chroma, 0,
                       std::max(sps->bit_depth_chroma_minus8 - 2, 0));
  }
  if (pps->pps_3d_extension_flag) {
    DVLOG(1) << "HEVC 3D extension not supported";
    return kInvalidStream;
  }
  if (pps->pps_scc_extension_flag) {
    DVLOG(1) << "HEVC SCC extension not supported";
    return kInvalidStream;
  }

  // If a PPS with the same id already exists, replace it.
  *pps_id = pps->pps_pic_parameter_set_id;
  active_pps_[*pps_id] = std::move(pps);

  return res;
}

const H265VPS* H265Parser::GetVPS(int vps_id) const {
  auto it = active_vps_.find(vps_id);
  if (it == active_vps_.end()) {
    DVLOG(1) << "Requested a nonexistent VPS id " << vps_id;
    return nullptr;
  }

  return it->second.get();
}

const H265SPS* H265Parser::GetSPS(int sps_id) const {
  auto it = active_sps_.find(sps_id);
  if (it == active_sps_.end()) {
    DVLOG(1) << "Requested a nonexistent SPS id " << sps_id;
    return nullptr;
  }

  return it->second.get();
}

const H265PPS* H265Parser::GetPPS(int pps_id) const {
  auto it = active_pps_.find(pps_id);
  if (it == active_pps_.end()) {
    DVLOG(1) << "Requested a nonexistent PPS id " << pps_id;
    return nullptr;
  }

  return it->second.get();
}

H265Parser::Result H265Parser::ParseSliceHeaderForPictureParameterSets(
    const H265NALU& nalu,
    int* pps_id) {
  // 7.4.7 Slice segment header
  DVLOG(4) << "Parsing slice header for pps";

  H265SliceHeader shdr;
  READ_BOOL_OR_RETURN(&shdr.first_slice_segment_in_pic_flag);
  shdr.irap_pic = (nalu.nal_unit_type >= H265NALU::BLA_W_LP &&
                   nalu.nal_unit_type <= H265NALU::RSV_IRAP_VCL23);
  if (shdr.irap_pic) {
    READ_BOOL_OR_RETURN(&shdr.no_output_of_prior_pics_flag);
  }
  READ_UE_OR_RETURN(&shdr.slice_pic_parameter_set_id);
  IN_RANGE_OR_RETURN(shdr.slice_pic_parameter_set_id, 0, 63);
  if (pps_id) {
    *pps_id = shdr.slice_pic_parameter_set_id;
  }

  return kOk;
}

H265Parser::Result H265Parser::ParseSliceHeader(const H265NALU& nalu,
                                                H265SliceHeader* shdr,
                                                H265SliceHeader* prior_shdr) {
  // 7.4.7 Slice segment header
  DVLOG(4) << "Parsing slice header";
  Result res = kOk;
  const H265SPS* sps;
  const H265PPS* pps;

  DCHECK(shdr);
  shdr->nal_unit_type = nalu.nal_unit_type;
  shdr->nalu_data = nalu.data.data();
  shdr->nalu_size = nalu.data.size();
  shdr->temporal_id = nalu.nuh_temporal_id_plus1 - 1;

  READ_BOOL_OR_RETURN(&shdr->first_slice_segment_in_pic_flag);
  shdr->irap_pic = (shdr->nal_unit_type >= H265NALU::BLA_W_LP &&
                    shdr->nal_unit_type <= H265NALU::RSV_IRAP_VCL23);
  if (shdr->irap_pic) {
    READ_BOOL_OR_RETURN(&shdr->no_output_of_prior_pics_flag);
  }
  READ_UE_OR_RETURN(&shdr->slice_pic_parameter_set_id);
  IN_RANGE_OR_RETURN(shdr->slice_pic_parameter_set_id, 0, 63);
  pps = GetPPS(shdr->slice_pic_parameter_set_id);
  if (!pps) {
    return kMissingParameterSet;
  }
  sps = GetSPS(pps->pps_seq_parameter_set_id);
  DCHECK(sps);  // We already validated this when we parsed the PPS.

  // Workaround for crbug.com/369963046; Apple encoder produces L1T2 streams
  // with sps_max_sub_layers_minus1 = 0.
  int clamped_temporal_id =
      std::min(shdr->temporal_id, sps->sps_max_sub_layers_minus1);

  if (!shdr->first_slice_segment_in_pic_flag) {
    if (pps->dependent_slice_segments_enabled_flag)
      READ_BOOL_OR_RETURN(&shdr->dependent_slice_segment_flag);
    READ_BITS_OR_RETURN(base::bits::Log2Ceiling(sps->pic_size_in_ctbs_y),
                        &shdr->slice_segment_address);
    IN_RANGE_OR_RETURN(shdr->slice_segment_address, 0,
                       sps->pic_size_in_ctbs_y - 1);
  }
  if (shdr->dependent_slice_segment_flag) {
    if (!prior_shdr) {
      DVLOG(1) << "Cannot parse dependent slice w/out prior slice data";
      return kInvalidStream;
    }
    // Copy everything in the structure starting at |slice_type| going forward.
    // This is copying the dependent slice data that we do not parse below.
    size_t skip_amount = offsetof(H265SliceHeader, slice_type);
    // TODO(crbug.com/40285824): Find more graceful way to copy a part of the
    // struct
    UNSAFE_TODO(memcpy(reinterpret_cast<uint8_t*>(shdr) + skip_amount,
                       reinterpret_cast<uint8_t*>(prior_shdr) + skip_amount,
                       sizeof(H265SliceHeader) - skip_amount));

    // We also need to validate the fields that have conditions that depend on
    // anything unique in this slice (i.e. anything already parsed).
    if ((shdr->irap_pic ||
         sps->sps_max_dec_pic_buffering_minus1[clamped_temporal_id] == 0) &&
        nalu.nuh_layer_id == 0) {
      TRUE_OR_RETURN(shdr->slice_type == 2);
    }
  } else {
    // Set these defaults if they are not present here.
    shdr->pic_output_flag = 1;
    shdr->num_ref_idx_l0_active_minus1 =
        pps->num_ref_idx_l0_default_active_minus1;
    shdr->num_ref_idx_l1_active_minus1 =
        pps->num_ref_idx_l1_default_active_minus1;
    shdr->collocated_from_l0_flag = 1;
    shdr->slice_deblocking_filter_disabled_flag =
        pps->pps_deblocking_filter_disabled_flag;
    shdr->slice_beta_offset_div2 = pps->pps_beta_offset_div2;
    shdr->slice_tc_offset_div2 = pps->pps_tc_offset_div2;
    shdr->slice_loop_filter_across_slices_enabled_flag =
        pps->pps_loop_filter_across_slices_enabled_flag;
    shdr->curr_rps_idx = sps->num_short_term_ref_pic_sets;

    // slice_reserved_flag
    SKIP_BITS_OR_RETURN(pps->num_extra_slice_header_bits);
    READ_UE_OR_RETURN(&shdr->slice_type);
    if ((shdr->irap_pic ||
         sps->sps_max_dec_pic_buffering_minus1[clamped_temporal_id] == 0) &&
        nalu.nuh_layer_id == 0) {
      TRUE_OR_RETURN(shdr->slice_type == 2);
    }
    if (pps->output_flag_present_flag)
      READ_BOOL_OR_RETURN(&shdr->pic_output_flag);
    if (sps->separate_colour_plane_flag) {
      READ_BITS_OR_RETURN(2, &shdr->colour_plane_id);
      IN_RANGE_OR_RETURN(shdr->colour_plane_id, 0, 2);
    }
    if (shdr->nal_unit_type != H265NALU::IDR_W_RADL &&
        shdr->nal_unit_type != H265NALU::IDR_N_LP) {
      READ_BITS_OR_RETURN(sps->log2_max_pic_order_cnt_lsb_minus4 + 4,
                          &shdr->slice_pic_order_cnt_lsb);
      IN_RANGE_OR_RETURN(shdr->slice_pic_order_cnt_lsb, 0,
                         sps->max_pic_order_cnt_lsb - 1);
      READ_BOOL_OR_RETURN(&shdr->short_term_ref_pic_set_sps_flag);
      if (!shdr->short_term_ref_pic_set_sps_flag) {
        off_t bits_left_prior = br_.NumBitsLeft();
        size_t num_epb_prior = br_.NumEmulationPreventionBytesRead();
        res = ParseStRefPicSet(sps->num_short_term_ref_pic_sets, *sps,
                               &shdr->st_ref_pic_set, true);
        if (res != kOk)
          return res;
        shdr->st_rps_bits =
            (bits_left_prior - br_.NumBitsLeft()) -
            8 * (br_.NumEmulationPreventionBytesRead() - num_epb_prior);
      } else if (sps->num_short_term_ref_pic_sets > 1) {
        READ_BITS_OR_RETURN(
            base::bits::Log2Ceiling(sps->num_short_term_ref_pic_sets),
            &shdr->short_term_ref_pic_set_idx);
        IN_RANGE_OR_RETURN(shdr->short_term_ref_pic_set_idx, 0,
                           sps->num_short_term_ref_pic_sets - 1);
      }

      if (shdr->short_term_ref_pic_set_sps_flag)
        shdr->curr_rps_idx = shdr->short_term_ref_pic_set_idx;

      if (sps->long_term_ref_pics_present_flag) {
        off_t bits_left_prior = br_.NumBitsLeft();
        size_t num_epb_prior = br_.NumEmulationPreventionBytesRead();
        if (sps->num_long_term_ref_pics_sps > 0) {
          READ_UE_OR_RETURN(&shdr->num_long_term_sps);
          IN_RANGE_OR_RETURN(shdr->num_long_term_sps, 0,
                             sps->num_long_term_ref_pics_sps);
        }
        READ_UE_OR_RETURN(&shdr->num_long_term_pics);
        if (nalu.nuh_layer_id == 0) {
          TRUE_OR_RETURN(
              shdr->num_long_term_pics <=
              (sps->sps_max_dec_pic_buffering_minus1[clamped_temporal_id] -
               shdr->GetStRefPicSet(sps).num_negative_pics -
               shdr->GetStRefPicSet(sps).num_positive_pics -
               shdr->num_long_term_sps));
        }
        IN_RANGE_OR_RETURN(shdr->num_long_term_pics, 0,
                           kMaxLongTermRefPicSets - shdr->num_long_term_sps);
        for (int i = 0; i < shdr->num_long_term_sps + shdr->num_long_term_pics;
             ++i) {
          if (i < shdr->num_long_term_sps) {
            int lt_idx_sps = 0;
            if (sps->num_long_term_ref_pics_sps > 1) {
              READ_BITS_OR_RETURN(
                  base::bits::Log2Ceiling(sps->num_long_term_ref_pics_sps),
                  &lt_idx_sps);
              IN_RANGE_OR_RETURN(lt_idx_sps, 0,
                                 sps->num_long_term_ref_pics_sps - 1);
            }
            shdr->poc_lsb_lt[i] = sps->lt_ref_pic_poc_lsb_sps[lt_idx_sps];
            shdr->used_by_curr_pic_lt[i] =
                sps->used_by_curr_pic_lt_sps_flag[lt_idx_sps];
          } else {
            READ_BITS_OR_RETURN(sps->log2_max_pic_order_cnt_lsb_minus4 + 4,
                                &shdr->poc_lsb_lt[i]);
            READ_BOOL_OR_RETURN(&shdr->used_by_curr_pic_lt[i]);
          }
          READ_BOOL_OR_RETURN(&shdr->delta_poc_msb_present_flag[i]);
          if (shdr->delta_poc_msb_present_flag[i]) {
            READ_UE_OR_RETURN(&shdr->delta_poc_msb_cycle_lt[i]);
            IN_RANGE_OR_RETURN(
                shdr->delta_poc_msb_cycle_lt[i], 0,
                std::pow(2, 32 - sps->log2_max_pic_order_cnt_lsb_minus4 - 4));
            // Equation 7-52.
            if (i != 0 && i != shdr->num_long_term_sps) {
              shdr->delta_poc_msb_cycle_lt[i] =
                  shdr->delta_poc_msb_cycle_lt[i] +
                  shdr->delta_poc_msb_cycle_lt[i - 1];
            }
          }
        }
        shdr->lt_rps_bits =
            (bits_left_prior - br_.NumBitsLeft()) -
            8 * (br_.NumEmulationPreventionBytesRead() - num_epb_prior);
      }
      if (sps->sps_temporal_mvp_enabled_flag)
        READ_BOOL_OR_RETURN(&shdr->slice_temporal_mvp_enabled_flag);
    }
    if (sps->sample_adaptive_offset_enabled_flag) {
      READ_BOOL_OR_RETURN(&shdr->slice_sao_luma_flag);
      if (sps->chroma_array_type != 0)
        READ_BOOL_OR_RETURN(&shdr->slice_sao_chroma_flag);
    }
    if (shdr->IsPSlice() || shdr->IsBSlice()) {
      READ_BOOL_OR_RETURN(&shdr->num_ref_idx_active_override_flag);
      if (shdr->num_ref_idx_active_override_flag) {
        READ_UE_OR_RETURN(&shdr->num_ref_idx_l0_active_minus1);
        IN_RANGE_OR_RETURN(shdr->num_ref_idx_l0_active_minus1, 0,
                           kMaxRefIdxActive - 1);
        if (shdr->IsBSlice()) {
          READ_UE_OR_RETURN(&shdr->num_ref_idx_l1_active_minus1);
          IN_RANGE_OR_RETURN(shdr->num_ref_idx_l1_active_minus1, 0,
                             kMaxRefIdxActive - 1);
        }
      }

      shdr->num_pic_total_curr = 0;
      const H265StRefPicSet& st_ref_pic = shdr->GetStRefPicSet(sps);
      for (int i = 0; i < st_ref_pic.num_negative_pics; ++i) {
        if (st_ref_pic.used_by_curr_pic_s0[i])
          shdr->num_pic_total_curr++;
      }
      for (int i = 0; i < st_ref_pic.num_positive_pics; ++i) {
        if (st_ref_pic.used_by_curr_pic_s1[i])
          shdr->num_pic_total_curr++;
      }
      for (int i = 0; i < shdr->num_long_term_sps + shdr->num_long_term_pics;
           ++i) {
        if (shdr->used_by_curr_pic_lt[i])
          shdr->num_pic_total_curr++;
      }

      TRUE_OR_RETURN(shdr->num_pic_total_curr);
      if (pps->lists_modification_present_flag &&
          shdr->num_pic_total_curr > 1) {
        res = ParseRefPicListsModifications(*shdr,
                                            &shdr->ref_pic_lists_modification);
        if (res != kOk)
          return res;
      }
      if (shdr->IsBSlice())
        READ_BOOL_OR_RETURN(&shdr->mvd_l1_zero_flag);
      if (pps->cabac_init_present_flag)
        READ_BOOL_OR_RETURN(&shdr->cabac_init_flag);
      if (shdr->slice_temporal_mvp_enabled_flag) {
        if (shdr->IsBSlice())
          READ_BOOL_OR_RETURN(&shdr->collocated_from_l0_flag);
        if ((shdr->collocated_from_l0_flag &&
             shdr->num_ref_idx_l0_active_minus1 > 0) ||
            (!shdr->collocated_from_l0_flag &&
             shdr->num_ref_idx_l1_active_minus1 > 0)) {
          READ_UE_OR_RETURN(&shdr->collocated_ref_idx);
          if ((shdr->IsPSlice() || shdr->IsBSlice()) &&
              shdr->collocated_from_l0_flag) {
            IN_RANGE_OR_RETURN(shdr->collocated_ref_idx, 0,
                               shdr->num_ref_idx_l0_active_minus1);
          }
          if (shdr->IsBSlice() && !shdr->collocated_from_l0_flag) {
            IN_RANGE_OR_RETURN(shdr->collocated_ref_idx, 0,
                               shdr->num_ref_idx_l1_active_minus1);
          }
        }
      }

      if ((pps->weighted_pred_flag && shdr->IsPSlice()) ||
          (pps->weighted_bipred_flag && shdr->IsBSlice())) {
        res = ParsePredWeightTable(*sps, *shdr, &shdr->pred_weight_table);
        if (res != kOk)
          return res;
      }
      READ_UE_OR_RETURN(&shdr->five_minus_max_num_merge_cand);
      IN_RANGE_OR_RETURN(5 - shdr->five_minus_max_num_merge_cand, 1, 5);
    }
    READ_SE_OR_RETURN(&shdr->slice_qp_delta);
    IN_RANGE_OR_RETURN(26 + pps->init_qp_minus26 + shdr->slice_qp_delta,
                       -pps->qp_bd_offset_y, 51);

    if (pps->pps_slice_chroma_qp_offsets_present_flag) {
      READ_SE_OR_RETURN(&shdr->slice_cb_qp_offset);
      IN_RANGE_OR_RETURN(shdr->slice_cb_qp_offset, -12, 12);
      IN_RANGE_OR_RETURN(pps->pps_cb_qp_offset + shdr->slice_cb_qp_offset, -12,
                         12);
      READ_SE_OR_RETURN(&shdr->slice_cr_qp_offset);
      IN_RANGE_OR_RETURN(shdr->slice_cr_qp_offset, -12, 12);
      IN_RANGE_OR_RETURN(pps->pps_cr_qp_offset + shdr->slice_cr_qp_offset, -12,
                         12);
    }

    // pps_slice_act_qp_offsets_present_flag is zero, we don't support SCC ext.

    if (pps->chroma_qp_offset_list_enabled_flag)
      SKIP_BITS_OR_RETURN(1);  // cu_chroma_qp_offset_enabled_flag
    bool deblocking_filter_override_flag = false;
    if (pps->deblocking_filter_override_enabled_flag)
      READ_BOOL_OR_RETURN(&deblocking_filter_override_flag);
    if (deblocking_filter_override_flag) {
      READ_BOOL_OR_RETURN(&shdr->slice_deblocking_filter_disabled_flag);
      if (!shdr->slice_deblocking_filter_disabled_flag) {
        READ_SE_OR_RETURN(&shdr->slice_beta_offset_div2);
        IN_RANGE_OR_RETURN(shdr->slice_beta_offset_div2, -6, 6);
        READ_SE_OR_RETURN(&shdr->slice_tc_offset_div2);
        IN_RANGE_OR_RETURN(shdr->slice_tc_offset_div2, -6, 6);
      }
    }
    if (pps->pps_loop_filter_across_slices_enabled_flag &&
        (shdr->slice_sao_luma_flag || shdr->slice_sao_chroma_flag ||
         !shdr->slice_deblocking_filter_disabled_flag)) {
      READ_BOOL_OR_RETURN(&shdr->slice_loop_filter_across_slices_enabled_flag);
    }
  }

  if (pps->tiles_enabled_flag || pps->entropy_coding_sync_enabled_flag) {
    int num_entry_point_offsets;
    READ_UE_OR_RETURN(&num_entry_point_offsets);
    if (!pps->tiles_enabled_flag) {
      IN_RANGE_OR_RETURN(num_entry_point_offsets, 0,
                         sps->pic_height_in_ctbs_y - 1);
    } else if (!pps->entropy_coding_sync_enabled_flag) {
      IN_RANGE_OR_RETURN(
          num_entry_point_offsets, 0,
          (pps->num_tile_columns_minus1 + 1) * (pps->num_tile_rows_minus1 + 1) -
              1);
    } else {  // both are true
      IN_RANGE_OR_RETURN(
          num_entry_point_offsets, 0,
          (pps->num_tile_columns_minus1 + 1) * sps->pic_height_in_ctbs_y - 1);
    }
    if (num_entry_point_offsets > 0) {
      int offset_len_minus1;
      READ_UE_OR_RETURN(&offset_len_minus1);
      IN_RANGE_OR_RETURN(offset_len_minus1, 0, 31);
      SKIP_BITS_OR_RETURN(num_entry_point_offsets * (offset_len_minus1 + 1));
    }
  }

  if (pps->slice_segment_header_extension_present_flag) {
    int slice_segment_header_extension_length;
    READ_UE_OR_RETURN(&slice_segment_header_extension_length);
    IN_RANGE_OR_RETURN(slice_segment_header_extension_length, 0, 256);
    SKIP_BITS_OR_RETURN(slice_segment_header_extension_length * 8);
  }

  if (prior_shdr && !shdr->first_slice_segment_in_pic_flag) {
    // Validate the fields that must match between slice headers for the same
    // picture.
    EQ_OR_RETURN(shdr, prior_shdr, slice_pic_parameter_set_id);
    EQ_OR_RETURN(shdr, prior_shdr, pic_output_flag);
    EQ_OR_RETURN(shdr, prior_shdr, no_output_of_prior_pics_flag);
    EQ_OR_RETURN(shdr, prior_shdr, slice_pic_order_cnt_lsb);
    EQ_OR_RETURN(shdr, prior_shdr, short_term_ref_pic_set_sps_flag);

    // All the other fields we need to compare are contiguous, so compare them
    // as one memory range.
    size_t block_start = offsetof(H265SliceHeader, short_term_ref_pic_set_idx);
    size_t block_end = offsetof(H265SliceHeader, slice_sao_luma_flag);

    // TODO(crbug.com/40285824): Find more graceful way to compare a part of the
    // struct
    UNSAFE_TODO(TRUE_OR_RETURN(
        !memcmp(reinterpret_cast<uint8_t*>(shdr) + block_start,
                reinterpret_cast<uint8_t*>(prior_shdr) + block_start,
                block_end - block_start)));
  }

  // byte_alignment()
  SKIP_BITS_OR_RETURN(1);  // alignment bit
  int bits_left_to_align = br_.NumBitsLeft() % 8;
  if (bits_left_to_align)
    SKIP_BITS_OR_RETURN(bits_left_to_align);

  shdr->header_emulation_prevention_bytes =
      br_.NumEmulationPreventionBytesRead();
  shdr->header_size = shdr->nalu_size -
                      shdr->header_emulation_prevention_bytes -
                      br_.NumBitsLeft() / 8;
  return res;
}

// static
VideoCodecProfile H265Parser::ProfileIDCToVideoCodecProfile(int profile_idc) {
  switch (profile_idc) {
    case H265ProfileTierLevel::kProfileIdcMain:
      return HEVCPROFILE_MAIN;
    case H265ProfileTierLevel::kProfileIdcMain10:
      return HEVCPROFILE_MAIN10;
    case H265ProfileTierLevel::kProfileIdcMainStill:
      return HEVCPROFILE_MAIN_STILL_PICTURE;
    case H265ProfileTierLevel::kProfileIdcRangeExtensions:
      return HEVCPROFILE_REXT;
    case H265ProfileTierLevel::kProfileIdcHighThroughput:
      return HEVCPROFILE_HIGH_THROUGHPUT;
    case H265ProfileTierLevel::kProfileIdcMultiviewMain:
      return HEVCPROFILE_MULTIVIEW_MAIN;
    case H265ProfileTierLevel::kProfileIdcScalableMain:
      return HEVCPROFILE_SCALABLE_MAIN;
    case H265ProfileTierLevel::kProfileIdc3dMain:
      return HEVCPROFILE_3D_MAIN;
    case H265ProfileTierLevel::kProfileIdcScreenContentCoding:
      return HEVCPROFILE_SCREEN_EXTENDED;
    case H265ProfileTierLevel::kProfileIdcScalableRangeExtensions:
      return HEVCPROFILE_SCALABLE_REXT;
    case H265ProfileTierLevel::kProfileIdcHighThroughputScreenContentCoding:
      return HEVCPROFILE_HIGH_THROUGHPUT_SCREEN_EXTENDED;
    default:
      DVLOG(1) << "unknown video profile: " << profile_idc;
      return VIDEO_CODEC_PROFILE_UNKNOWN;
  }
}

gfx::HdrMetadataCta861_3 H265SEIContentLightLevelInfo::ToGfx() const {
  return gfx::HdrMetadataCta861_3(max_content_light_level,
                                  max_picture_average_light_level);
}

gfx::HdrMetadataSmpteSt2086 H265SEIMasteringDisplayInfo::ToGfx() const {
  constexpr auto kChromaDenominator = 50000.0f;
  constexpr auto kLumaDenoninator = 10000.0f;
  // display primaries are in G/B/R order in MDCV SEI.
  return gfx::HdrMetadataSmpteSt2086(
      {display_primaries[2][0] / kChromaDenominator,
       display_primaries[2][1] / kChromaDenominator,
       display_primaries[0][0] / kChromaDenominator,
       display_primaries[0][1] / kChromaDenominator,
       display_primaries[1][0] / kChromaDenominator,
       display_primaries[1][1] / kChromaDenominator,
       white_points[0] / kChromaDenominator,
       white_points[1] / kChromaDenominator},
      /*luminance_max=*/max_luminance / kLumaDenoninator,
      /*luminance_min=*/min_luminance / kLumaDenoninator);
}

H265Parser::Result H265Parser::ParseProfileTierLevel(
    bool profile_present,
    int max_num_sub_layers_minus1,
    H265ProfileTierLevel* profile_tier_level) {
  // 7.4.4
  DVLOG(4) << "Parsing profile_tier_level";
  if (profile_present) {
    int general_profile_space;
    READ_BITS_OR_RETURN(2, &general_profile_space);
    TRUE_OR_RETURN(general_profile_space == 0);
    SKIP_BITS_OR_RETURN(1);  // general_tier_flag
    READ_BITS_OR_RETURN(5, &profile_tier_level->general_profile_idc);
    IN_RANGE_OR_RETURN(profile_tier_level->general_profile_idc, 0, 11);
    uint16_t general_profile_compatibility_flag_high16;
    uint16_t general_profile_compatibility_flag_low16;
    READ_BITS_OR_RETURN(16, &general_profile_compatibility_flag_high16);
    READ_BITS_OR_RETURN(16, &general_profile_compatibility_flag_low16);
    profile_tier_level->general_profile_compatibility_flags =
        (general_profile_compatibility_flag_high16 << 16) +
        general_profile_compatibility_flag_low16;
    READ_BOOL_OR_RETURN(&profile_tier_level->general_progressive_source_flag);
    READ_BOOL_OR_RETURN(&profile_tier_level->general_interlaced_source_flag);
    if (!profile_tier_level->general_progressive_source_flag &&
        profile_tier_level->general_interlaced_source_flag) {
      DVLOG(1) << "Interlaced streams not supported";
      return kUnsupportedStream;
    }
    READ_BOOL_OR_RETURN(
        &profile_tier_level->general_non_packed_constraint_flag);
    READ_BOOL_OR_RETURN(
        &profile_tier_level->general_frame_only_constraint_flag);
    SKIP_BITS_OR_RETURN(7);  // general_reserved_zero_7bits
    READ_BOOL_OR_RETURN(
        &profile_tier_level->general_one_picture_only_constraint_flag);
    SKIP_BITS_OR_RETURN(35);  // general_reserved_zero_35bits
    SKIP_BITS_OR_RETURN(1);   // general_inbld_flag
  }
  READ_BITS_OR_RETURN(8, &profile_tier_level->general_level_idc);
  std::array<bool, 8> sub_layer_profile_present_flag;
  std::array<bool, 8> sub_layer_level_present_flag;
  for (int i = 0; i < max_num_sub_layers_minus1; ++i) {
    READ_BOOL_OR_RETURN(&sub_layer_profile_present_flag[i]);
    READ_BOOL_OR_RETURN(&sub_layer_level_present_flag[i]);
  }
  if (max_num_sub_layers_minus1 > 0) {
    for (int i = max_num_sub_layers_minus1; i < 8; i++) {
      SKIP_BITS_OR_RETURN(2);
    }
  }
  for (int i = 0; i < max_num_sub_layers_minus1; i++) {
    if (sub_layer_profile_present_flag[i]) {
      SKIP_BITS_OR_RETURN(2);   // sub_layer_profile_space
      SKIP_BITS_OR_RETURN(1);   // sub_layer_tier_flag
      SKIP_BITS_OR_RETURN(5);   // sub_layer_profile_idc
      SKIP_BITS_OR_RETURN(32);  // sub_layer_profile_compatibility_flag
      SKIP_BITS_OR_RETURN(2);  // sub_layer_{progressive,interlaced}_source_flag
      // Ignore sub_layer_non_packed_constraint_flag and
      // sub_layer_frame_only_constraint_flag.
      SKIP_BITS_OR_RETURN(2);
      // Skip the compatibility flags, they are always 43 bits.
      SKIP_BITS_OR_RETURN(43);
      SKIP_BITS_OR_RETURN(1);  // sub_layer_inbld_flag
    }
    if (sub_layer_level_present_flag[i]) {
      SKIP_BITS_OR_RETURN(8);  // sub_layer_level_idc
    }
  }

  return kOk;
}

H265Parser::Result H265Parser::ParseScalingListData(
    H265ScalingListData* scaling_list_data) {
  for (int size_id = 0; size_id < 4; ++size_id) {
    for (int matrix_id = 0; matrix_id < 6;
         matrix_id += (size_id == 3) ? 3 : 1) {
      bool scaling_list_pred_mode_flag;
      READ_BOOL_OR_RETURN(&scaling_list_pred_mode_flag);
      if (!scaling_list_pred_mode_flag) {
        int scaling_list_pred_matrix_id_delta;
        READ_UE_OR_RETURN(&scaling_list_pred_matrix_id_delta);
        if (size_id <= 2) {
          IN_RANGE_OR_RETURN(scaling_list_pred_matrix_id_delta, 0, matrix_id);
        } else {  // size_id == 3
          IN_RANGE_OR_RETURN(scaling_list_pred_matrix_id_delta, 0,
                             matrix_id / 3);
        }
        if (scaling_list_pred_matrix_id_delta == 0) {
          FillInDefaultScalingListData(scaling_list_data, size_id, matrix_id);
        } else {
          int ref_matrix_id = matrix_id - scaling_list_pred_matrix_id_delta *
                                              (size_id == 3 ? 3 : 1);
          switch (size_id) {
            case 0:
              scaling_list_data->scaling_list_4x4[matrix_id] =
                  scaling_list_data->scaling_list_4x4[ref_matrix_id];
              break;
            case 1:
              scaling_list_data->scaling_list_8x8[matrix_id] =
                  scaling_list_data->scaling_list_8x8[ref_matrix_id];
              break;
            case 2:
              scaling_list_data->scaling_list_16x16[matrix_id] =
                  scaling_list_data->scaling_list_16x16[ref_matrix_id];
              break;
            case 3:
              scaling_list_data->scaling_list_32x32[matrix_id] =
                  scaling_list_data->scaling_list_32x32[ref_matrix_id];
              break;
          }

          if (size_id == 2) {
            scaling_list_data->scaling_list_dc_coef_16x16[matrix_id] =
                scaling_list_data->scaling_list_dc_coef_16x16[ref_matrix_id];
          } else if (size_id == 3) {
            scaling_list_data->scaling_list_dc_coef_32x32[matrix_id] =
                scaling_list_data->scaling_list_dc_coef_32x32[ref_matrix_id];
          }
        }
      } else {
        int next_coef = 8;
        int coef_num = std::min(64, (1 << (4 + (size_id << 1))));
        if (size_id > 1) {
          if (size_id == 2) {
            int scaling_list_dc_coef_16x16_minus_8;
            READ_SE_OR_RETURN(&scaling_list_dc_coef_16x16_minus_8);
            IN_RANGE_OR_RETURN(scaling_list_dc_coef_16x16_minus_8, -7, 247);
            // This is parsed as minus8;
            scaling_list_data->scaling_list_dc_coef_16x16[matrix_id] =
                scaling_list_dc_coef_16x16_minus_8 + 8;
            next_coef =
                scaling_list_data->scaling_list_dc_coef_16x16[matrix_id];
          } else {  // size_id == 3
            int scaling_list_dc_coef_32x32_minus_8;
            READ_SE_OR_RETURN(&scaling_list_dc_coef_32x32_minus_8);
            IN_RANGE_OR_RETURN(scaling_list_dc_coef_32x32_minus_8, -7, 247);
            // This is parsed as minus8;
            scaling_list_data->scaling_list_dc_coef_32x32[matrix_id] =
                scaling_list_dc_coef_32x32_minus_8 + 8;
            next_coef =
                scaling_list_data->scaling_list_dc_coef_32x32[matrix_id];
          }
        }
        for (int i = 0; i < coef_num; ++i) {
          int scaling_list_delta_coef;
          READ_SE_OR_RETURN(&scaling_list_delta_coef);
          IN_RANGE_OR_RETURN(scaling_list_delta_coef, -128, 127);
          next_coef = (next_coef + scaling_list_delta_coef + 256) % 256;
          switch (size_id) {
            case 0:
              scaling_list_data->scaling_list_4x4[matrix_id][i] = next_coef;
              break;
            case 1:
              scaling_list_data->scaling_list_8x8[matrix_id][i] = next_coef;
              break;
            case 2:
              scaling_list_data->scaling_list_16x16[matrix_id][i] = next_coef;
              break;
            case 3:
              scaling_list_data->scaling_list_32x32[matrix_id][i] = next_coef;
              break;
          }
        }
      }
    }
  }
  return kOk;
}

H265Parser::Result H265Parser::ParseStRefPicSet(int st_rps_idx,
                                                const H265SPS& sps,
                                                H265StRefPicSet* st_ref_pic_set,
                                                bool is_slice_hdr) {
  // 7.4.8
  bool inter_ref_pic_set_prediction_flag = false;
  if (st_rps_idx != 0) {
    READ_BOOL_OR_RETURN(&inter_ref_pic_set_prediction_flag);
  }
  if (inter_ref_pic_set_prediction_flag) {
    int delta_idx_minus1 = 0;
    if (st_rps_idx == sps.num_short_term_ref_pic_sets) {
      READ_UE_OR_RETURN(&delta_idx_minus1);
      IN_RANGE_OR_RETURN(delta_idx_minus1, 0, st_rps_idx - 1);
    }
    int ref_rps_idx = st_rps_idx - (delta_idx_minus1 + 1);
    int delta_rps_sign;
    int abs_delta_rps_minus1;
    READ_BOOL_OR_RETURN(&delta_rps_sign);
    READ_UE_OR_RETURN(&abs_delta_rps_minus1);
    IN_RANGE_OR_RETURN(abs_delta_rps_minus1, 0, 0x7FFF);
    int delta_rps = (1 - 2 * delta_rps_sign) * (abs_delta_rps_minus1 + 1);
    const H265StRefPicSet& ref_set = sps.st_ref_pic_set[ref_rps_idx];
    if (is_slice_hdr) {
      st_ref_pic_set->rps_idx_num_delta_pocs = ref_set.num_delta_pocs;
    }
    std::array<bool, kMaxShortTermRefPicSets> used_by_curr_pic_flag;
    std::array<bool, kMaxShortTermRefPicSets> use_delta_flag;
    // 7.4.8 - use_delta_flag defaults to 1 if not present.
    use_delta_flag.fill(true);

    for (int j = 0; j <= ref_set.num_delta_pocs; j++) {
      READ_BOOL_OR_RETURN(&used_by_curr_pic_flag[j]);
      if (!used_by_curr_pic_flag[j]) {
        READ_BOOL_OR_RETURN(&use_delta_flag[j]);
      }
    }
    // Calculate delta_poc_s{0,1}, used_by_curr_pic_s{0,1}, num_negative_pics
    // and num_positive_pics.
    // Equation 7-61
    int i = 0;
    for (int j = ref_set.num_positive_pics - 1; j >= 0; --j) {
      int d_poc = ref_set.delta_poc_s1[j] + delta_rps;
      if (d_poc < 0 && use_delta_flag[ref_set.num_negative_pics + j]) {
        st_ref_pic_set->delta_poc_s0[i] = d_poc;
        st_ref_pic_set->used_by_curr_pic_s0[i++] =
            used_by_curr_pic_flag[ref_set.num_negative_pics + j];
      }
    }
    if (delta_rps < 0 && use_delta_flag[ref_set.num_delta_pocs]) {
      st_ref_pic_set->delta_poc_s0[i] = delta_rps;
      st_ref_pic_set->used_by_curr_pic_s0[i++] =
          used_by_curr_pic_flag[ref_set.num_delta_pocs];
    }
    for (int j = 0; j < ref_set.num_negative_pics; ++j) {
      int d_poc = ref_set.delta_poc_s0[j] + delta_rps;
      if (d_poc < 0 && use_delta_flag[j]) {
        st_ref_pic_set->delta_poc_s0[i] = d_poc;
        st_ref_pic_set->used_by_curr_pic_s0[i++] = used_by_curr_pic_flag[j];
      }
    }
    st_ref_pic_set->num_negative_pics = i;
    // Equation 7-62
    i = 0;
    for (int j = ref_set.num_negative_pics - 1; j >= 0; --j) {
      int d_poc = ref_set.delta_poc_s0[j] + delta_rps;
      if (d_poc > 0 && use_delta_flag[j]) {
        st_ref_pic_set->delta_poc_s1[i] = d_poc;
        st_ref_pic_set->used_by_curr_pic_s1[i++] = used_by_curr_pic_flag[j];
      }
    }
    if (delta_rps > 0 && use_delta_flag[ref_set.num_delta_pocs]) {
      st_ref_pic_set->delta_poc_s1[i] = delta_rps;
      st_ref_pic_set->used_by_curr_pic_s1[i++] =
          used_by_curr_pic_flag[ref_set.num_delta_pocs];
    }
    for (int j = 0; j < ref_set.num_positive_pics; ++j) {
      int d_poc = ref_set.delta_poc_s1[j] + delta_rps;
      if (d_poc > 0 && use_delta_flag[ref_set.num_negative_pics + j]) {
        st_ref_pic_set->delta_poc_s1[i] = d_poc;
        st_ref_pic_set->used_by_curr_pic_s1[i++] =
            used_by_curr_pic_flag[ref_set.num_negative_pics + j];
      }
    }
    st_ref_pic_set->num_positive_pics = i;
    IN_RANGE_OR_RETURN(
        st_ref_pic_set->num_negative_pics, 0,
        sps.sps_max_dec_pic_buffering_minus1[sps.sps_max_sub_layers_minus1]);
    IN_RANGE_OR_RETURN(
        st_ref_pic_set->num_positive_pics, 0,
        sps.sps_max_dec_pic_buffering_minus1[sps.sps_max_sub_layers_minus1] -
            st_ref_pic_set->num_negative_pics);
  } else {
    READ_UE_OR_RETURN(&st_ref_pic_set->num_negative_pics);
    READ_UE_OR_RETURN(&st_ref_pic_set->num_positive_pics);
    IN_RANGE_OR_RETURN(
        st_ref_pic_set->num_negative_pics, 0,
        sps.sps_max_dec_pic_buffering_minus1[sps.sps_max_sub_layers_minus1]);
    IN_RANGE_OR_RETURN(
        st_ref_pic_set->num_positive_pics, 0,
        sps.sps_max_dec_pic_buffering_minus1[sps.sps_max_sub_layers_minus1] -
            st_ref_pic_set->num_negative_pics);
    for (int i = 0; i < st_ref_pic_set->num_negative_pics; ++i) {
      int delta_poc_s0_minus1;
      READ_UE_OR_RETURN(&delta_poc_s0_minus1);
      IN_RANGE_OR_RETURN(delta_poc_s0_minus1, 0, 0x7FFF);
      if (i == 0) {
        st_ref_pic_set->delta_poc_s0[i] = -(delta_poc_s0_minus1 + 1);
      } else {
        st_ref_pic_set->delta_poc_s0[i] =
            st_ref_pic_set->delta_poc_s0[i - 1] - (delta_poc_s0_minus1 + 1);
      }
      READ_BOOL_OR_RETURN(&st_ref_pic_set->used_by_curr_pic_s0[i]);
    }
    for (int i = 0; i < st_ref_pic_set->num_positive_pics; ++i) {
      int delta_poc_s1_minus1;
      READ_UE_OR_RETURN(&delta_poc_s1_minus1);
      IN_RANGE_OR_RETURN(delta_poc_s1_minus1, 0, 0x7FFF);
      if (i == 0) {
        st_ref_pic_set->delta_poc_s1[i] = delta_poc_s1_minus1 + 1;
      } else {
        st_ref_pic_set->delta_poc_s1[i] =
            st_ref_pic_set->delta_poc_s1[i - 1] + delta_poc_s1_minus1 + 1;
      }
      READ_BOOL_OR_RETURN(&st_ref_pic_set->used_by_curr_pic_s1[i]);
    }
  }
  // Calculate num_delta_pocs.
  st_ref_pic_set->num_delta_pocs =
      st_ref_pic_set->num_negative_pics + st_ref_pic_set->num_positive_pics;
  return kOk;
}

H265Parser::Result H265Parser::ParseVuiParameters(const H265SPS& sps,
                                                  H265VUIParameters* vui) {
  Result res = kOk;
  bool aspect_ratio_info_present_flag;
  READ_BOOL_OR_RETURN(&aspect_ratio_info_present_flag);
  if (aspect_ratio_info_present_flag) {
    int aspect_ratio_idc;
    READ_BITS_OR_RETURN(8, &aspect_ratio_idc);
    constexpr int kExtendedSar = 255;
    if (aspect_ratio_idc == kExtendedSar) {
      READ_BITS_OR_RETURN(16, &vui->sar_width);
      READ_BITS_OR_RETURN(16, &vui->sar_height);
    } else {
      const int max_aspect_ratio_idc = std::size(kTableSarWidth) - 1;
      IN_RANGE_OR_RETURN(aspect_ratio_idc, 0, max_aspect_ratio_idc);
      vui->sar_width = kTableSarWidth[aspect_ratio_idc];
      vui->sar_height = kTableSarHeight[aspect_ratio_idc];
    }
  }

  int data;
  // Read and ignore overscan info.
  READ_BOOL_OR_RETURN(&data);  // overscan_info_present_flag
  if (data)
    SKIP_BITS_OR_RETURN(1);  // overscan_appropriate_flag

  bool video_signal_type_present_flag;
  READ_BOOL_OR_RETURN(&video_signal_type_present_flag);
  if (video_signal_type_present_flag) {
    SKIP_BITS_OR_RETURN(3);  // video_format
    READ_BOOL_OR_RETURN(&vui->video_full_range_flag);
    READ_BOOL_OR_RETURN(&vui->colour_description_present_flag);
    if (vui->colour_description_present_flag) {
      // color description syntax elements
      READ_BITS_OR_RETURN(8, &vui->colour_primaries);
      READ_BITS_OR_RETURN(8, &vui->transfer_characteristics);
      READ_BITS_OR_RETURN(8, &vui->matrix_coeffs);
    }
  }

  READ_BOOL_OR_RETURN(&data);  // chroma_loc_info_present_flag
  if (data) {
    READ_UE_OR_RETURN(&data);  // chroma_sample_loc_type_top_field
    READ_UE_OR_RETURN(&data);  // chroma_sample_loc_type_bottom_field
  }

  // Ignore neutral_chroma_indication_flag, field_seq_flag and
  // frame_field_info_present_flag.
  SKIP_BITS_OR_RETURN(3);

  bool default_display_window_flag;
  READ_BOOL_OR_RETURN(&default_display_window_flag);
  if (default_display_window_flag) {
    READ_UE_OR_RETURN(&vui->def_disp_win_left_offset);
    READ_UE_OR_RETURN(&vui->def_disp_win_right_offset);
    READ_UE_OR_RETURN(&vui->def_disp_win_top_offset);
    READ_UE_OR_RETURN(&vui->def_disp_win_bottom_offset);
  }

  // Read and ignore timing info.
  READ_BOOL_OR_RETURN(&data);  // timing_info_present_flag
  if (data) {
    SKIP_BITS_OR_RETURN(32);     // vui_num_units_in_tick
    SKIP_BITS_OR_RETURN(32);     // vui_time_scale
    READ_BOOL_OR_RETURN(&data);  // vui_poc_proportional_to_timing_flag
    if (data)
      READ_UE_OR_RETURN(&data);  // vui_num_ticks_poc_diff_one_minus1
    res = ParseAndIgnoreHrdParameters(true, sps.sps_max_sub_layers_minus1);
    if (res != kOk)
      return res;
  }

  READ_BOOL_OR_RETURN(&vui->bitstream_restriction_flag);
  if (vui->bitstream_restriction_flag) {
    // Skip tiles_fixed_structure_flag, motion_vectors_over_pic_boundaries_flag
    // and restricted_ref_pic_lists_flag.
    SKIP_BITS_OR_RETURN(3);
    READ_UE_OR_RETURN(&vui->min_spatial_segmentation_idc);
    READ_UE_OR_RETURN(&vui->max_bytes_per_pic_denom);
    READ_UE_OR_RETURN(&vui->max_bits_per_min_cu_denom);
    READ_UE_OR_RETURN(&vui->log2_max_mv_length_horizontal);
    READ_UE_OR_RETURN(&vui->log2_max_mv_length_vertical);
  }

  return kOk;
}

H265Parser::Result H265Parser::ParseAndIgnoreHrdParameters(
    bool common_inf_present_flag,
    int max_num_sub_layers_minus1) {
  Result res = kOk;
  int data;
  READ_BOOL_OR_RETURN(&data);  // present_flag
  if (!data)
    return res;

  bool nal_hrd_parameters_present_flag = false;
  bool vcl_hrd_parameters_present_flag = false;
  bool sub_pic_hrd_params_present_flag = false;
  if (common_inf_present_flag) {
    READ_BOOL_OR_RETURN(&nal_hrd_parameters_present_flag);
    READ_BOOL_OR_RETURN(&vcl_hrd_parameters_present_flag);
    if (nal_hrd_parameters_present_flag || vcl_hrd_parameters_present_flag) {
      READ_BOOL_OR_RETURN(&sub_pic_hrd_params_present_flag);
      if (sub_pic_hrd_params_present_flag) {
        SKIP_BITS_OR_RETURN(8);  // tick_divisor_minus2
        SKIP_BITS_OR_RETURN(5);  // du_cpb_removal_delay_increment_length_minus1
        SKIP_BITS_OR_RETURN(1);  // sub_pic_cpb_params_in_pic_timing_sei_flag
        SKIP_BITS_OR_RETURN(5);  // dpb_output_delay_du_length_minus1
      }
      SKIP_BITS_OR_RETURN(4);  // bit_rate_scale;
      SKIP_BITS_OR_RETURN(4);  // cpb_size_scale;
      if (sub_pic_hrd_params_present_flag)
        SKIP_BITS_OR_RETURN(4);  // cpb_size_du_scale
      SKIP_BITS_OR_RETURN(5);    // initial_cpb_removal_delay_length_minus1
      SKIP_BITS_OR_RETURN(5);    // au_cpb_removal_delay_length_minus1
      SKIP_BITS_OR_RETURN(5);    // dpb_output_delay_length_minus1
    }
  }
  for (int i = 0; i <= max_num_sub_layers_minus1; ++i) {
    bool fixed_pic_rate_flag;
    READ_BOOL_OR_RETURN(&fixed_pic_rate_flag);  // general
    if (!fixed_pic_rate_flag)
      READ_BOOL_OR_RETURN(&fixed_pic_rate_flag);  // within_cvs
    bool low_delay_hrd_flag = false;
    if (fixed_pic_rate_flag)
      READ_UE_OR_RETURN(&data);  // elemental_duration_in_tc_minus1
    else
      READ_BOOL_OR_RETURN(&low_delay_hrd_flag);
    int cpb_cnt = 1;
    if (!low_delay_hrd_flag) {
      READ_UE_OR_RETURN(&cpb_cnt);
      IN_RANGE_OR_RETURN(cpb_cnt, 0, 31);
      cpb_cnt += 1;  // parsed as minus1
    }
    if (nal_hrd_parameters_present_flag) {
      res = ParseAndIgnoreSubLayerHrdParameters(
          cpb_cnt, sub_pic_hrd_params_present_flag);
      if (res != kOk)
        return res;
    }
    if (vcl_hrd_parameters_present_flag) {
      res = ParseAndIgnoreSubLayerHrdParameters(
          cpb_cnt, sub_pic_hrd_params_present_flag);
      if (res != kOk)
        return res;
    }
  }
  return res;
}

H265Parser::Result H265Parser::ParseAndIgnoreSubLayerHrdParameters(
    int cpb_cnt,
    bool sub_pic_hrd_params_present_flag) {
  int data;
  for (int i = 0; i < cpb_cnt; ++i) {
    READ_UE_OR_RETURN(&data);  // bit_rate_value_minus1[i]
    READ_UE_OR_RETURN(&data);  // cpb_size_value_minus1[i]
    if (sub_pic_hrd_params_present_flag) {
      READ_UE_OR_RETURN(&data);  // cpb_size_du_value_minus1[i]
      READ_UE_OR_RETURN(&data);  // bit_rate_du_value_minus1[i]
    }
    SKIP_BITS_OR_RETURN(1);  // cbr_flag[i]
  }
  return kOk;
}

H265Parser::Result H265Parser::ParseRefPicListsModifications(
    const H265SliceHeader& shdr,
    H265RefPicListsModifications* rpl_mod) {
  READ_BOOL_OR_RETURN(&rpl_mod->ref_pic_list_modification_flag_l0);
  if (rpl_mod->ref_pic_list_modification_flag_l0) {
    for (int i = 0; i <= shdr.num_ref_idx_l0_active_minus1; ++i) {
      READ_BITS_OR_RETURN(base::bits::Log2Ceiling(shdr.num_pic_total_curr),
                          &rpl_mod->list_entry_l0[i]);
      IN_RANGE_OR_RETURN(rpl_mod->list_entry_l0[i], 0,
                         shdr.num_pic_total_curr - 1);
    }
  }
  if (shdr.IsBSlice()) {
    READ_BOOL_OR_RETURN(&rpl_mod->ref_pic_list_modification_flag_l1);
    if (rpl_mod->ref_pic_list_modification_flag_l1) {
      for (int i = 0; i <= shdr.num_ref_idx_l1_active_minus1; ++i) {
        READ_BITS_OR_RETURN(base::bits::Log2Ceiling(shdr.num_pic_total_curr),
                            &rpl_mod->list_entry_l1[i]);
        IN_RANGE_OR_RETURN(rpl_mod->list_entry_l1[i], 0,
                           shdr.num_pic_total_curr - 1);
      }
    }
  }
  return kOk;
}

H265Parser::Result H265Parser::ParsePredWeightTable(
    const H265SPS& sps,
    const H265SliceHeader& shdr,
    H265PredWeightTable* pred_weight_table) {
  // 7.4.6.3 Weighted prediction parameters semantics
  READ_UE_OR_RETURN(&pred_weight_table->luma_log2_weight_denom);
  IN_RANGE_OR_RETURN(pred_weight_table->luma_log2_weight_denom, 0, 7);
  if (sps.chroma_array_type) {
    READ_SE_OR_RETURN(&pred_weight_table->delta_chroma_log2_weight_denom);
    pred_weight_table->chroma_log2_weight_denom =
        pred_weight_table->delta_chroma_log2_weight_denom +
        pred_weight_table->luma_log2_weight_denom;
    IN_RANGE_OR_RETURN(pred_weight_table->chroma_log2_weight_denom, 0, 7);
  }
  std::array<bool, kMaxRefIdxActive> luma_weight_flag;
  std::array<bool, kMaxRefIdxActive> chroma_weight_flag;
  for (int i = 0; i <= shdr.num_ref_idx_l0_active_minus1; ++i) {
    READ_BOOL_OR_RETURN(&luma_weight_flag[i]);
  }
  if (sps.chroma_array_type) {
    for (int i = 0; i <= shdr.num_ref_idx_l0_active_minus1; ++i) {
      READ_BOOL_OR_RETURN(&chroma_weight_flag[i]);
    }
  }
  int sum_weight_l0_flags = 0;
  for (int i = 0; i <= shdr.num_ref_idx_l0_active_minus1; ++i) {
    if (luma_weight_flag[i]) {
      sum_weight_l0_flags++;
      READ_SE_OR_RETURN(&pred_weight_table->delta_luma_weight_l0[i]);
      IN_RANGE_OR_RETURN(pred_weight_table->delta_luma_weight_l0[i], -128, 127);
      READ_SE_OR_RETURN(&pred_weight_table->luma_offset_l0[i]);
      IN_RANGE_OR_RETURN(pred_weight_table->luma_offset_l0[i],
                         -sps.wp_offset_half_range_y,
                         sps.wp_offset_half_range_y - 1);
    }
    if (chroma_weight_flag[i]) {
      sum_weight_l0_flags += 2;
      for (int j = 0; j < 2; ++j) {
        READ_SE_OR_RETURN(&pred_weight_table->delta_chroma_weight_l0[i][j]);
        IN_RANGE_OR_RETURN(pred_weight_table->delta_chroma_weight_l0[i][j],
                           -128, 127);
        READ_SE_OR_RETURN(&pred_weight_table->delta_chroma_offset_l0[i][j]);
        IN_RANGE_OR_RETURN(pred_weight_table->delta_chroma_offset_l0[i][j],
                           -4 * sps.wp_offset_half_range_c,
                           4 * sps.wp_offset_half_range_c - 1);
      }
    }
  }
  if (shdr.IsPSlice())
    TRUE_OR_RETURN(sum_weight_l0_flags <= 24);
  if (shdr.IsBSlice()) {
    chroma_weight_flag.fill(false);
    int sum_weight_l1_flags = 0;
    for (int i = 0; i <= shdr.num_ref_idx_l1_active_minus1; ++i) {
      READ_BOOL_OR_RETURN(&luma_weight_flag[i]);
    }
    if (sps.chroma_array_type) {
      for (int i = 0; i <= shdr.num_ref_idx_l1_active_minus1; ++i) {
        READ_BOOL_OR_RETURN(&chroma_weight_flag[i]);
      }
    }
    for (int i = 0; i <= shdr.num_ref_idx_l1_active_minus1; ++i) {
      if (luma_weight_flag[i]) {
        sum_weight_l1_flags++;
        READ_SE_OR_RETURN(&pred_weight_table->delta_luma_weight_l1[i]);
        IN_RANGE_OR_RETURN(pred_weight_table->delta_luma_weight_l1[i], -128,
                           127);
        READ_SE_OR_RETURN(&pred_weight_table->luma_offset_l1[i]);
        IN_RANGE_OR_RETURN(pred_weight_table->luma_offset_l1[i],
                           -sps.wp_offset_half_range_y,
                           sps.wp_offset_half_range_y - 1);
      }
      if (chroma_weight_flag[i]) {
        sum_weight_l1_flags += 2;
        for (int j = 0; j < 2; ++j) {
          READ_SE_OR_RETURN(&pred_weight_table->delta_chroma_weight_l1[i][j]);
          IN_RANGE_OR_RETURN(pred_weight_table->delta_chroma_weight_l1[i][j],
                             -128, 127);
          READ_SE_OR_RETURN(&pred_weight_table->delta_chroma_offset_l1[i][j]);
          IN_RANGE_OR_RETURN(pred_weight_table->delta_chroma_offset_l1[i][j],
                             -4 * sps.wp_offset_half_range_c,
                             4 * sps.wp_offset_half_range_c - 1);
        }
      }
    }
    TRUE_OR_RETURN(sum_weight_l0_flags + sum_weight_l1_flags <= 24);
  }

  return kOk;
}

H265Parser::Result H265Parser::ParseSEI(H265SEI* sei) {
  int byte;
  int num_parsed_sei_msg = 0;
  // According to spec 7.3.2.4, we should loop parsing SEI NALU
  // as long as `more_rbsp_data` condition is true, which means
  // if the NALU's RBSP data is large enough and `more_rbsp_data`
  // condition keeps true all the time, we are very likely have to
  // loop the parsing millions of times.
  //
  // The spec doesn't provide any pattern to let us validate the
  // the parsed SEI messages, so we have to set a limit here.
  constexpr int kMaxParsedSEIMessages = 64;
  do {
    int type = 0;
    READ_BITS_OR_RETURN(8, &byte);
    while (byte == 0xff) {
      type += 255;
      READ_BITS_OR_RETURN(8, &byte);
    }
    type += byte;

    int payload_size = 0;
    READ_BITS_OR_RETURN(8, &byte);
    while (byte == 0xff) {
      payload_size += 255;
      READ_BITS_OR_RETURN(8, &byte);
    }
    payload_size += byte;
    int num_bits_remain = payload_size * 8;

    DVLOG(4) << "Found SEI message type: " << type
             << " payload size: " << payload_size;

    enum SEIType {
      kSEIMasteringDisplayInfo = 137,
      kSEIContentLightLevelInfo = 144,
      kSEIAlphaChannelInfo = 165,
    };

    H265SEIMessage sei_msg;
    switch (type) {
      case kSEIAlphaChannelInfo: {
        auto& info = sei_msg.emplace<H265SEIAlphaChannelInfo>();
        READ_BOOL_AND_MINUS_BITS_READ_OR_RETURN(&info.alpha_channel_cancel_flag,
                                                &num_bits_remain);
        if (!info.alpha_channel_cancel_flag) {
          READ_BITS_AND_MINUS_BITS_READ_OR_RETURN(
              3, &info.alpha_channel_use_idc, &num_bits_remain);
          READ_BITS_AND_MINUS_BITS_READ_OR_RETURN(
              3, &info.alpha_channel_bit_depth_minus8, &num_bits_remain);
          READ_BITS_AND_MINUS_BITS_READ_OR_RETURN(
              info.alpha_channel_bit_depth_minus8 + 9,
              &info.alpha_transparent_value, &num_bits_remain);
          READ_BITS_AND_MINUS_BITS_READ_OR_RETURN(
              info.alpha_channel_bit_depth_minus8 + 9, &info.alpha_opaque_value,
              &num_bits_remain);
          READ_BOOL_AND_MINUS_BITS_READ_OR_RETURN(&info.alpha_channel_incr_flag,
                                                  &num_bits_remain);
          READ_BOOL_AND_MINUS_BITS_READ_OR_RETURN(&info.alpha_channel_clip_flag,
                                                  &num_bits_remain);
          if (info.alpha_channel_clip_flag) {
            READ_BOOL_AND_MINUS_BITS_READ_OR_RETURN(
                &info.alpha_channel_clip_type_flag, &num_bits_remain);
          }
        }
        break;
      }
      case kSEIContentLightLevelInfo: {
        auto& info = sei_msg.emplace<H265SEIContentLightLevelInfo>();
        READ_BITS_AND_MINUS_BITS_READ_OR_RETURN(
            16, &info.max_content_light_level, &num_bits_remain);
        READ_BITS_AND_MINUS_BITS_READ_OR_RETURN(
            16, &info.max_picture_average_light_level, &num_bits_remain);
        break;
      }
      case kSEIMasteringDisplayInfo: {
        auto& info = sei_msg.emplace<H265SEIMasteringDisplayInfo>();
        for (auto& primary : info.display_primaries) {
          for (auto& component : primary) {
            READ_BITS_AND_MINUS_BITS_READ_OR_RETURN(16, &component,
                                                    &num_bits_remain);
          }
        }
        READ_BITS_AND_MINUS_BITS_READ_OR_RETURN(16, &info.white_points[0],
                                                &num_bits_remain);
        READ_BITS_AND_MINUS_BITS_READ_OR_RETURN(16, &info.white_points[1],
                                                &num_bits_remain);
        uint32_t luminace_high_31bits, luminance_low_1bit;
        READ_BITS_AND_MINUS_BITS_READ_OR_RETURN(31, &luminace_high_31bits,
                                                &num_bits_remain);
        READ_BITS_AND_MINUS_BITS_READ_OR_RETURN(1, &luminance_low_1bit,
                                                &num_bits_remain);
        info.max_luminance =
            (luminace_high_31bits << 1) + (luminance_low_1bit & 0x1);
        READ_BITS_AND_MINUS_BITS_READ_OR_RETURN(31, &luminace_high_31bits,
                                                &num_bits_remain);
        READ_BITS_AND_MINUS_BITS_READ_OR_RETURN(1, &luminance_low_1bit,
                                                &num_bits_remain);
        info.min_luminance =
            (luminace_high_31bits << 1) + (luminance_low_1bit & 0x1);
        break;
      }
      default:
        DVLOG(4) << "Unsupported SEI message";
        break;
    }
    TRUE_OR_RETURN(num_bits_remain >= 0);
    // 7.2 More data in payload or unsupported SEI, skip bits.
    if (num_bits_remain > 0)
      SKIP_BITS_OR_RETURN(num_bits_remain);
    // Only add parsed SEI messages.
    if (num_bits_remain < payload_size * 8) {
      sei->msgs.push_back(sei_msg);
    }
    // In case the loop endless.
    if (++num_parsed_sei_msg > kMaxParsedSEIMessages)
      return kInvalidStream;
  } while (br_.HasMoreRBSPData());

  return kOk;
}

}  // namespace media