// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "packager/media/codecs/h264_parser.h"

#include <memory>

#include "glog/logging.h"
#include "packager/media/base/buffer_reader.h"

#define LOG_ERROR_ONCE(msg)             \
  do {                                  \
    static bool logged_once = false;    \
    LOG_IF(ERROR, !logged_once) << msg; \
    logged_once = true;                 \
  } while (0)

namespace shaka {
namespace media {

// Implemented according to ISO/IEC 14496-10:2005 7.4.2.1 Sequence parameter set
// RBSP semantics.
bool ExtractResolutionFromSps(const H264Sps& sps,
                              uint32_t* coded_width,
                              uint32_t* coded_height,
                              uint32_t* pixel_width,
                              uint32_t* pixel_height) {
  int crop_x = 0;
  int crop_y = 0;
  if (sps.frame_cropping_flag) {
    int sub_width_c = 0;
    int sub_height_c = 0;
    // Table 6-1.
    switch (sps.chroma_format_idc) {
      case 0:  // monochrome
        // SubWidthC and SubHeightC are not defined for monochrome. For ease of
        // computation afterwards, assign both to 1.
        sub_width_c = 1;
        sub_height_c = 1;
        break;
      case 1:  // 4:2:0
        sub_width_c = 2;
        sub_height_c = 2;
        break;
      case 2:  // 4:2:2
        sub_width_c = 2;
        sub_height_c = 1;
        break;
      case 3:  // 4:4:4
        sub_width_c = 1;
        sub_height_c = 1;
        break;
      default:
        LOG(ERROR) << "Unexpected chroma_format_idc " << sps.chroma_format_idc;
        return false;
    }

    // Formula 7-16, 7-17, 7-18, 7-19.
    int crop_unit_x = sub_width_c;
    int crop_unit_y = sub_height_c * (2 - (sps.frame_mbs_only_flag ? 1 : 0));
    crop_x = crop_unit_x *
             (sps.frame_crop_left_offset + sps.frame_crop_right_offset);
    crop_y = crop_unit_y *
             (sps.frame_crop_top_offset + sps.frame_crop_bottom_offset);
  }

  // Formula 7-10, 7-11.
  int pic_width_in_mbs = sps.pic_width_in_mbs_minus1 + 1;
  *coded_width = pic_width_in_mbs * 16 - crop_x;

  // Formula 7-13, 7-15.
  int pic_height_in_mbs = (2 - (sps.frame_mbs_only_flag ? 1 : 0)) *
                          (sps.pic_height_in_map_units_minus1 + 1);
  *coded_height = pic_height_in_mbs * 16 - crop_y;

  // 0 means it wasn't in the SPS and therefore assume 1.
  *pixel_width = sps.sar_width == 0 ? 1 : sps.sar_width;
  *pixel_height = sps.sar_height == 0 ? 1 : sps.sar_height;
  DVLOG(2) << "Found coded_width: " << *coded_width
           << " coded_height: " << *coded_height
           << " pixel_width: " << *pixel_width
           << " pixel_height: " << *pixel_height;
  return true;
}

bool H264SliceHeader::IsPSlice() const {
  return (slice_type % 5 == kPSlice);
}

bool H264SliceHeader::IsBSlice() const {
  return (slice_type % 5 == kBSlice);
}

bool H264SliceHeader::IsISlice() const {
  return (slice_type % 5 == kISlice);
}

bool H264SliceHeader::IsSPSlice() const {
  return (slice_type % 5 == kSPSlice);
}

bool H264SliceHeader::IsSISlice() const {
  return (slice_type % 5 == kSISlice);
}

#define READ_BITS_OR_RETURN(num_bits, out)                                 \
  do {                                                                     \
    if (!br->ReadBits(num_bits, (out))) {                                  \
      DVLOG(1)                                                             \
          << "Error in stream: unexpected EOS while trying to read " #out; \
      return kInvalidStream;                                               \
    }                                                                      \
  } while (0)

#define READ_LONG_OR_RETURN(out)        \
  do {                                  \
    long _out;                          \
    int _tmp_out;                       \
    READ_BITS_OR_RETURN(16, &_tmp_out); \
    _out = (long)(_tmp_out) << 16;      \
    READ_BITS_OR_RETURN(16, &_tmp_out); \
    _out |= _tmp_out;                   \
    *(out) = _out;                      \
  } while(0)

#define READ_BOOL_OR_RETURN(out)                                           \
  do {                                                                     \
    int _out;                                                              \
    if (!br->ReadBits(1, &_out)) {                                         \
      DVLOG(1)                                                             \
          << "Error in stream: unexpected EOS while trying to read " #out; \
      return kInvalidStream;                                               \
    }                                                                      \
    *(out) = _out != 0;                                                    \
  } while (0)

#define READ_UE_OR_RETURN(out)                                                 \
  do {                                                                         \
    if (!br->ReadUE(out)) {                                                    \
      DVLOG(1) << "Error in stream: invalid value while trying to read " #out; \
      return kInvalidStream;                                                   \
    }                                                                          \
  } while (0)

#define READ_SE_OR_RETURN(out)                                                 \
  do {                                                                         \
    if (!br->ReadSE(out)) {                                                    \
      DVLOG(1) << "Error in stream: invalid value while trying to read " #out; \
      return kInvalidStream;                                                   \
    }                                                                          \
  } while (0)

#define IN_RANGE_OR_RETURN(val, min, max)                                   \
  do {                                                                      \
    if ((val) < (min) || (val) > (max)) {                                   \
      DVLOG(1) << "Error in stream: invalid value, expected " #val " to be" \
               << " in range [" << (min) << ":" << (max) << "]"             \
               << " found " << (val) << " instead";                         \
      return kInvalidStream;                                                \
    }                                                                       \
  } while (0)

#define TRUE_OR_RETURN(a)                                            \
  do {                                                               \
    if (!(a)) {                                                      \
      DVLOG(1) << "Error in stream: invalid value, expected " << #a; \
      return kInvalidStream;                                         \
    }                                                                \
  } while (0)

enum AspectRatioIdc {
  kExtendedSar = 255,
};

// ISO 14496 part 10
// VUI parameters: Table E-1 "Meaning of sample aspect ratio indicator"
static const int kTableSarWidth[] = {
  0, 1, 12, 10, 16, 40, 24, 20, 32, 80, 18, 15, 64, 160, 4, 3, 2
};
static const int 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_same_size");

H264Parser::H264Parser() {}

H264Parser::~H264Parser() {}

const H264Pps* H264Parser::GetPps(int pps_id) {
  return active_PPSes_[pps_id].get();
}

const H264Sps* H264Parser::GetSps(int sps_id) {
  return active_SPSes_[sps_id].get();
}

// Default scaling lists (per spec).
static const int kDefault4x4Intra[kH264ScalingList4x4Length] = {
    6, 13, 13, 20, 20, 20, 28, 28, 28, 28, 32, 32, 32, 37, 37, 42, };

static const int kDefault4x4Inter[kH264ScalingList4x4Length] = {
    10, 14, 14, 20, 20, 20, 24, 24, 24, 24, 27, 27, 27, 30, 30, 34, };

static const int kDefault8x8Intra[kH264ScalingList8x8Length] = {
    6,  10, 10, 13, 11, 13, 16, 16, 16, 16, 18, 18, 18, 18, 18, 23,
    23, 23, 23, 23, 23, 25, 25, 25, 25, 25, 25, 25, 27, 27, 27, 27,
    27, 27, 27, 27, 29, 29, 29, 29, 29, 29, 29, 31, 31, 31, 31, 31,
    31, 33, 33, 33, 33, 33, 36, 36, 36, 36, 38, 38, 38, 40, 40, 42, };

static const int kDefault8x8Inter[kH264ScalingList8x8Length] = {
    9,  13, 13, 15, 13, 15, 17, 17, 17, 17, 19, 19, 19, 19, 19, 21,
    21, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22, 22, 24, 24, 24, 24,
    24, 24, 24, 24, 25, 25, 25, 25, 25, 25, 25, 27, 27, 27, 27, 27,
    27, 28, 28, 28, 28, 28, 30, 30, 30, 30, 32, 32, 32, 33, 33, 35, };

static inline void DefaultScalingList4x4(
    int i,
    int scaling_list4x4[][kH264ScalingList4x4Length]) {
  DCHECK_LT(i, 6);

  if (i < 3)
    memcpy(scaling_list4x4[i], kDefault4x4Intra, sizeof(kDefault4x4Intra));
  else if (i < 6)
    memcpy(scaling_list4x4[i], kDefault4x4Inter, sizeof(kDefault4x4Inter));
}

static inline void DefaultScalingList8x8(
    int i,
    int scaling_list8x8[][kH264ScalingList8x8Length]) {
  DCHECK_LT(i, 6);

  if (i % 2 == 0)
    memcpy(scaling_list8x8[i], kDefault8x8Intra, sizeof(kDefault8x8Intra));
  else
    memcpy(scaling_list8x8[i], kDefault8x8Inter, sizeof(kDefault8x8Inter));
}

static void FallbackScalingList4x4(
    int i,
    const int default_scaling_list_intra[],
    const int default_scaling_list_inter[],
    int scaling_list4x4[][kH264ScalingList4x4Length]) {
  static const int kScalingList4x4ByteSize =
      sizeof(scaling_list4x4[0][0]) * kH264ScalingList4x4Length;

  switch (i) {
    case 0:
      memcpy(scaling_list4x4[i], default_scaling_list_intra,
             kScalingList4x4ByteSize);
      break;

    case 1:
      memcpy(scaling_list4x4[i], scaling_list4x4[0], kScalingList4x4ByteSize);
      break;

    case 2:
      memcpy(scaling_list4x4[i], scaling_list4x4[1], kScalingList4x4ByteSize);
      break;

    case 3:
      memcpy(scaling_list4x4[i], default_scaling_list_inter,
             kScalingList4x4ByteSize);
      break;

    case 4:
      memcpy(scaling_list4x4[i], scaling_list4x4[3], kScalingList4x4ByteSize);
      break;

    case 5:
      memcpy(scaling_list4x4[i], scaling_list4x4[4], kScalingList4x4ByteSize);
      break;

    default:
      NOTIMPLEMENTED() << "index out of range [0,5]: " << i;
      break;
  }
}

static void FallbackScalingList8x8(
    int i,
    const int default_scaling_list_intra[],
    const int default_scaling_list_inter[],
    int scaling_list8x8[][kH264ScalingList8x8Length]) {
  static const int kScalingList8x8ByteSize =
      sizeof(scaling_list8x8[0][0]) * kH264ScalingList8x8Length;

  switch (i) {
    case 0:
      memcpy(scaling_list8x8[i], default_scaling_list_intra,
             kScalingList8x8ByteSize);
      break;

    case 1:
      memcpy(scaling_list8x8[i], default_scaling_list_inter,
             kScalingList8x8ByteSize);
      break;

    case 2:
      memcpy(scaling_list8x8[i], scaling_list8x8[0], kScalingList8x8ByteSize);
      break;

    case 3:
      memcpy(scaling_list8x8[i], scaling_list8x8[1], kScalingList8x8ByteSize);
      break;

    case 4:
      memcpy(scaling_list8x8[i], scaling_list8x8[2], kScalingList8x8ByteSize);
      break;

    case 5:
      memcpy(scaling_list8x8[i], scaling_list8x8[3], kScalingList8x8ByteSize);
      break;

    default:
      NOTIMPLEMENTED() << "index out of range [0,5]: " << i;
      break;
  }
}

H264Parser::Result H264Parser::ParseScalingList(H26xBitReader* br,
                                                int size,
                                                int* scaling_list,
                                                bool* use_default) {
  // See chapter 7.3.2.1.1.1.
  int last_scale = 8;
  int next_scale = 8;
  int delta_scale;

  *use_default = false;

  for (int j = 0; j < size; ++j) {
    if (next_scale != 0) {
      READ_SE_OR_RETURN(&delta_scale);
      IN_RANGE_OR_RETURN(delta_scale, -128, 127);
      next_scale = (last_scale + delta_scale + 256) & 0xff;

      if (j == 0 && next_scale == 0) {
        *use_default = true;
        return kOk;
      }
    }

    scaling_list[j] = (next_scale == 0) ? last_scale : next_scale;
    last_scale = scaling_list[j];
  }

  return kOk;
}

H264Parser::Result H264Parser::ParseSpsScalingLists(H26xBitReader* br,
                                                    H264Sps* sps) {
  // See 7.4.2.1.1.
  bool seq_scaling_list_present_flag;
  bool use_default;
  Result res;

  // Parse scaling_list4x4.
  for (int i = 0; i < 6; ++i) {
    READ_BOOL_OR_RETURN(&seq_scaling_list_present_flag);

    if (seq_scaling_list_present_flag) {
      res = ParseScalingList(br, std::size(sps->scaling_list4x4[i]),
                             sps->scaling_list4x4[i], &use_default);
      if (res != kOk)
        return res;

      if (use_default)
        DefaultScalingList4x4(i, sps->scaling_list4x4);

    } else {
      FallbackScalingList4x4(
          i, kDefault4x4Intra, kDefault4x4Inter, sps->scaling_list4x4);
    }
  }

  // Parse scaling_list8x8.
  for (int i = 0; i < ((sps->chroma_format_idc != 3) ? 2 : 6); ++i) {
    READ_BOOL_OR_RETURN(&seq_scaling_list_present_flag);

    if (seq_scaling_list_present_flag) {
      res = ParseScalingList(br, std::size(sps->scaling_list8x8[i]),
                             sps->scaling_list8x8[i], &use_default);
      if (res != kOk)
        return res;

      if (use_default)
        DefaultScalingList8x8(i, sps->scaling_list8x8);

    } else {
      FallbackScalingList8x8(
          i, kDefault8x8Intra, kDefault8x8Inter, sps->scaling_list8x8);
    }
  }

  return kOk;
}

H264Parser::Result H264Parser::ParsePpsScalingLists(H26xBitReader* br,
                                                    const H264Sps& sps,
                                                    H264Pps* pps) {
  // See 7.4.2.2.
  bool pic_scaling_list_present_flag;
  bool use_default;
  Result res;

  for (int i = 0; i < 6; ++i) {
    READ_BOOL_OR_RETURN(&pic_scaling_list_present_flag);

    if (pic_scaling_list_present_flag) {
      res = ParseScalingList(br, std::size(pps->scaling_list4x4[i]),
                             pps->scaling_list4x4[i], &use_default);
      if (res != kOk)
        return res;

      if (use_default)
        DefaultScalingList4x4(i, pps->scaling_list4x4);

    } else {
      if (sps.seq_scaling_matrix_present_flag) {
        // Table 7-2 fallback rule A in spec.
        FallbackScalingList4x4(
            i, kDefault4x4Intra, kDefault4x4Inter, pps->scaling_list4x4);
      } else {
        // Table 7-2 fallback rule B in spec.
        FallbackScalingList4x4(i,
                               sps.scaling_list4x4[0],
                               sps.scaling_list4x4[3],
                               pps->scaling_list4x4);
      }
    }
  }

  if (pps->transform_8x8_mode_flag) {
    for (int i = 0; i < ((sps.chroma_format_idc != 3) ? 2 : 6); ++i) {
      READ_BOOL_OR_RETURN(&pic_scaling_list_present_flag);

      if (pic_scaling_list_present_flag) {
        res = ParseScalingList(br, std::size(pps->scaling_list8x8[i]),
                               pps->scaling_list8x8[i], &use_default);
        if (res != kOk)
          return res;

        if (use_default)
          DefaultScalingList8x8(i, pps->scaling_list8x8);

      } else {
        if (sps.seq_scaling_matrix_present_flag) {
          // Table 7-2 fallback rule A in spec.
          FallbackScalingList8x8(
              i, kDefault8x8Intra, kDefault8x8Inter, pps->scaling_list8x8);
        } else {
          // Table 7-2 fallback rule B in spec.
          FallbackScalingList8x8(i,
                                 sps.scaling_list8x8[0],
                                 sps.scaling_list8x8[1],
                                 pps->scaling_list8x8);
        }
      }
    }
  }
  return kOk;
}

H264Parser::Result H264Parser::ParseAndIgnoreHRDParameters(
    H26xBitReader* br, bool* hrd_parameters_present) {
  int data;
  READ_BOOL_OR_RETURN(&data);  // {nal,vcl}_hrd_parameters_present_flag
  if (!data)
    return kOk;

  *hrd_parameters_present = true;

  int cpb_cnt_minus1;
  READ_UE_OR_RETURN(&cpb_cnt_minus1);
  IN_RANGE_OR_RETURN(cpb_cnt_minus1, 0, 31);
  READ_BITS_OR_RETURN(8, &data);  // bit_rate_scale, cpb_size_scale
  for (int i = 0; i <= cpb_cnt_minus1; ++i) {
    READ_UE_OR_RETURN(&data);  // bit_rate_value_minus1[i]
    READ_UE_OR_RETURN(&data);  // cpb_size_value_minus1[i]
    READ_BOOL_OR_RETURN(&data);  // cbr_flag
  }
  READ_BITS_OR_RETURN(20, &data);  // cpb/dpb delays, etc.

  return kOk;
}

H264Parser::Result H264Parser::ParseVUIParameters(H26xBitReader* br,
                                                  H264Sps* sps) {
  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);
    if (aspect_ratio_idc == kExtendedSar) {
      READ_BITS_OR_RETURN(16, &sps->sar_width);
      READ_BITS_OR_RETURN(16, &sps->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);
      sps->sar_width = kTableSarWidth[aspect_ratio_idc];
      sps->sar_height = kTableSarHeight[aspect_ratio_idc];
    }
  }

  int data;
  // Read and ignore overscan and video signal type info.
  READ_BOOL_OR_RETURN(&data);  // overscan_info_present_flag
  if (data)
    READ_BOOL_OR_RETURN(&data);  // overscan_appropriate_flag

  READ_BOOL_OR_RETURN(&data);  // video_signal_type_present_flag
  if (data) {
    READ_BITS_OR_RETURN(3, &data);  // video_format
    READ_BOOL_OR_RETURN(&data);  // video_full_range_flag
    READ_BOOL_OR_RETURN(&data);  // colour_description_present_flag
    if (data) {
      READ_BITS_OR_RETURN(8, &data);  // colour primaries
      READ_BITS_OR_RETURN(8, &sps->transfer_characteristics);
      READ_BITS_OR_RETURN(8, &data);  // 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
  }

  // Read timing info.
  READ_BOOL_OR_RETURN(&sps->timing_info_present_flag);
  if (sps->timing_info_present_flag) {
    READ_LONG_OR_RETURN(&sps->num_units_in_tick);
    READ_LONG_OR_RETURN(&sps->time_scale);
    READ_BOOL_OR_RETURN(&sps->fixed_frame_rate_flag);
  }

  // Read and ignore NAL HRD parameters, if present.
  bool hrd_parameters_present = false;
  Result res = ParseAndIgnoreHRDParameters(br, &hrd_parameters_present);
  if (res != kOk)
    return res;

  // Read and ignore VCL HRD parameters, if present.
  res = ParseAndIgnoreHRDParameters(br, &hrd_parameters_present);
  if (res != kOk)
    return res;

  if (hrd_parameters_present)  // One of NAL or VCL params present is enough.
    READ_BOOL_OR_RETURN(&data);  // low_delay_hrd_flag

  READ_BOOL_OR_RETURN(&data);  // pic_struct_present_flag
  READ_BOOL_OR_RETURN(&sps->bitstream_restriction_flag);
  if (sps->bitstream_restriction_flag) {
    READ_BOOL_OR_RETURN(&data);  // motion_vectors_over_pic_boundaries_flag
    READ_UE_OR_RETURN(&data);  // max_bytes_per_pic_denom
    READ_UE_OR_RETURN(&data);  // max_bits_per_mb_denom
    READ_UE_OR_RETURN(&data);  // log2_max_mv_length_horizontal
    READ_UE_OR_RETURN(&data);  // log2_max_mv_length_vertical
    READ_UE_OR_RETURN(&sps->max_num_reorder_frames);
    READ_UE_OR_RETURN(&sps->max_dec_frame_buffering);
    TRUE_OR_RETURN(sps->max_dec_frame_buffering >= sps->max_num_ref_frames);
    IN_RANGE_OR_RETURN(
        sps->max_num_reorder_frames, 0, sps->max_dec_frame_buffering);
  }

  return kOk;
}

static void FillDefaultSeqScalingLists(H264Sps* sps) {
  for (int i = 0; i < 6; ++i)
    for (int j = 0; j < kH264ScalingList4x4Length; ++j)
      sps->scaling_list4x4[i][j] = 16;

  for (int i = 0; i < 6; ++i)
    for (int j = 0; j < kH264ScalingList8x8Length; ++j)
      sps->scaling_list8x8[i][j] = 16;
}

H264Parser::Result H264Parser::ParseSps(const Nalu& nalu, int* sps_id) {
  // See 7.4.2.1.
  int data;
  Result res;
  H26xBitReader reader;
  reader.Initialize(nalu.data() + nalu.header_size(), nalu.payload_size());
  H26xBitReader* br = &reader;

  *sps_id = -1;

  std::unique_ptr<H264Sps> sps(new H264Sps());

  READ_BITS_OR_RETURN(8, &sps->profile_idc);
  READ_BOOL_OR_RETURN(&sps->constraint_set0_flag);
  READ_BOOL_OR_RETURN(&sps->constraint_set1_flag);
  READ_BOOL_OR_RETURN(&sps->constraint_set2_flag);
  READ_BOOL_OR_RETURN(&sps->constraint_set3_flag);
  READ_BOOL_OR_RETURN(&sps->constraint_set4_flag);
  READ_BOOL_OR_RETURN(&sps->constraint_set5_flag);
  READ_BITS_OR_RETURN(2, &data);  // reserved_zero_2bits
  READ_BITS_OR_RETURN(8, &sps->level_idc);
  READ_UE_OR_RETURN(&sps->seq_parameter_set_id);
  TRUE_OR_RETURN(sps->seq_parameter_set_id < 32);

  if (sps->profile_idc == 100 || sps->profile_idc == 110 ||
      sps->profile_idc == 122 || sps->profile_idc == 244 ||
      sps->profile_idc == 44 || sps->profile_idc == 83 ||
      sps->profile_idc == 86 || sps->profile_idc == 118 ||
      sps->profile_idc == 128) {
    READ_UE_OR_RETURN(&sps->chroma_format_idc);
    TRUE_OR_RETURN(sps->chroma_format_idc < 4);

    if (sps->chroma_format_idc == 3)
      READ_BOOL_OR_RETURN(&sps->separate_colour_plane_flag);

    READ_UE_OR_RETURN(&sps->bit_depth_luma_minus8);
    TRUE_OR_RETURN(sps->bit_depth_luma_minus8 < 7);

    READ_UE_OR_RETURN(&sps->bit_depth_chroma_minus8);
    TRUE_OR_RETURN(sps->bit_depth_chroma_minus8 < 7);

    READ_BOOL_OR_RETURN(&sps->qpprime_y_zero_transform_bypass_flag);
    READ_BOOL_OR_RETURN(&sps->seq_scaling_matrix_present_flag);

    if (sps->seq_scaling_matrix_present_flag) {
      DVLOG(4) << "Scaling matrix present";
      res = ParseSpsScalingLists(br, sps.get());
      if (res != kOk)
        return res;
    } else {
      FillDefaultSeqScalingLists(sps.get());
    }
  } else {
    sps->chroma_format_idc = 1;
    FillDefaultSeqScalingLists(sps.get());
  }

  if (sps->separate_colour_plane_flag)
    sps->chroma_array_type = 0;
  else
    sps->chroma_array_type = sps->chroma_format_idc;

  READ_UE_OR_RETURN(&sps->log2_max_frame_num_minus4);
  TRUE_OR_RETURN(sps->log2_max_frame_num_minus4 < 13);

  READ_UE_OR_RETURN(&sps->pic_order_cnt_type);
  TRUE_OR_RETURN(sps->pic_order_cnt_type < 3);

  sps->expected_delta_per_pic_order_cnt_cycle = 0;
  if (sps->pic_order_cnt_type == 0) {
    READ_UE_OR_RETURN(&sps->log2_max_pic_order_cnt_lsb_minus4);
    TRUE_OR_RETURN(sps->log2_max_pic_order_cnt_lsb_minus4 < 13);
  } else if (sps->pic_order_cnt_type == 1) {
    READ_BOOL_OR_RETURN(&sps->delta_pic_order_always_zero_flag);
    READ_SE_OR_RETURN(&sps->offset_for_non_ref_pic);
    READ_SE_OR_RETURN(&sps->offset_for_top_to_bottom_field);
    READ_UE_OR_RETURN(&sps->num_ref_frames_in_pic_order_cnt_cycle);
    TRUE_OR_RETURN(sps->num_ref_frames_in_pic_order_cnt_cycle < 255);

    for (int i = 0; i < sps->num_ref_frames_in_pic_order_cnt_cycle; ++i) {
      READ_SE_OR_RETURN(&sps->offset_for_ref_frame[i]);
      sps->expected_delta_per_pic_order_cnt_cycle +=
          sps->offset_for_ref_frame[i];
    }
  }

  READ_UE_OR_RETURN(&sps->max_num_ref_frames);
  READ_BOOL_OR_RETURN(&sps->gaps_in_frame_num_value_allowed_flag);

  READ_UE_OR_RETURN(&sps->pic_width_in_mbs_minus1);
  READ_UE_OR_RETURN(&sps->pic_height_in_map_units_minus1);

  READ_BOOL_OR_RETURN(&sps->frame_mbs_only_flag);
  if (!sps->frame_mbs_only_flag)
    READ_BOOL_OR_RETURN(&sps->mb_adaptive_frame_field_flag);

  READ_BOOL_OR_RETURN(&sps->direct_8x8_inference_flag);

  READ_BOOL_OR_RETURN(&sps->frame_cropping_flag);
  if (sps->frame_cropping_flag) {
    READ_UE_OR_RETURN(&sps->frame_crop_left_offset);
    READ_UE_OR_RETURN(&sps->frame_crop_right_offset);
    READ_UE_OR_RETURN(&sps->frame_crop_top_offset);
    READ_UE_OR_RETURN(&sps->frame_crop_bottom_offset);
  }

  READ_BOOL_OR_RETURN(&sps->vui_parameters_present_flag);
  if (sps->vui_parameters_present_flag) {
    DVLOG(4) << "VUI parameters present";
    res = ParseVUIParameters(br, sps.get());
    if (res != kOk)
      return res;
  }

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

  return kOk;
}

H264Parser::Result H264Parser::ParsePps(const Nalu& nalu, int* pps_id) {
  // See 7.4.2.2.
  const H264Sps* sps;
  Result res;
  H26xBitReader reader;
  reader.Initialize(nalu.data() + nalu.header_size(), nalu.payload_size());
  H26xBitReader* br = &reader;

  *pps_id = -1;

  std::unique_ptr<H264Pps> pps(new H264Pps());

  READ_UE_OR_RETURN(&pps->pic_parameter_set_id);
  READ_UE_OR_RETURN(&pps->seq_parameter_set_id);
  TRUE_OR_RETURN(pps->seq_parameter_set_id < 32);

  sps = GetSps(pps->seq_parameter_set_id);
  TRUE_OR_RETURN(sps);

  READ_BOOL_OR_RETURN(&pps->entropy_coding_mode_flag);
  READ_BOOL_OR_RETURN(&pps->bottom_field_pic_order_in_frame_present_flag);

  READ_UE_OR_RETURN(&pps->num_slice_groups_minus1);
  if (pps->num_slice_groups_minus1 > 1) {
    LOG_ERROR_ONCE("Slice groups not supported");
    return kUnsupportedStream;
  }

  READ_UE_OR_RETURN(&pps->num_ref_idx_l0_default_active_minus1);
  TRUE_OR_RETURN(pps->num_ref_idx_l0_default_active_minus1 < 32);

  READ_UE_OR_RETURN(&pps->num_ref_idx_l1_default_active_minus1);
  TRUE_OR_RETURN(pps->num_ref_idx_l1_default_active_minus1 < 32);

  READ_BOOL_OR_RETURN(&pps->weighted_pred_flag);
  READ_BITS_OR_RETURN(2, &pps->weighted_bipred_idc);
  TRUE_OR_RETURN(pps->weighted_bipred_idc < 3);

  READ_SE_OR_RETURN(&pps->pic_init_qp_minus26);
  IN_RANGE_OR_RETURN(pps->pic_init_qp_minus26, -26, 25);

  READ_SE_OR_RETURN(&pps->pic_init_qs_minus26);
  IN_RANGE_OR_RETURN(pps->pic_init_qs_minus26, -26, 25);

  READ_SE_OR_RETURN(&pps->chroma_qp_index_offset);
  IN_RANGE_OR_RETURN(pps->chroma_qp_index_offset, -12, 12);
  pps->second_chroma_qp_index_offset = pps->chroma_qp_index_offset;

  READ_BOOL_OR_RETURN(&pps->deblocking_filter_control_present_flag);
  READ_BOOL_OR_RETURN(&pps->constrained_intra_pred_flag);
  READ_BOOL_OR_RETURN(&pps->redundant_pic_cnt_present_flag);

  if (br->HasMoreRBSPData()) {
    READ_BOOL_OR_RETURN(&pps->transform_8x8_mode_flag);
    READ_BOOL_OR_RETURN(&pps->pic_scaling_matrix_present_flag);

    if (pps->pic_scaling_matrix_present_flag) {
      DVLOG(4) << "Picture scaling matrix present";
      res = ParsePpsScalingLists(br, *sps, pps.get());
      if (res != kOk)
        return res;
    }

    READ_SE_OR_RETURN(&pps->second_chroma_qp_index_offset);
  }

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

  return kOk;
}

H264Parser::Result H264Parser::ParseRefPicListModification(
    H26xBitReader* br,
    int num_ref_idx_active_minus1,
    H264ModificationOfPicNum* ref_list_mods) {
  H264ModificationOfPicNum* pic_num_mod;

  if (num_ref_idx_active_minus1 >= 32)
    return kInvalidStream;

  for (int i = 0; i < 32; ++i) {
    pic_num_mod = &ref_list_mods[i];
    READ_UE_OR_RETURN(&pic_num_mod->modification_of_pic_nums_idc);
    TRUE_OR_RETURN(pic_num_mod->modification_of_pic_nums_idc < 4);

    switch (pic_num_mod->modification_of_pic_nums_idc) {
      case 0:
      case 1:
        READ_UE_OR_RETURN(&pic_num_mod->abs_diff_pic_num_minus1);
        break;

      case 2:
        READ_UE_OR_RETURN(&pic_num_mod->long_term_pic_num);
        break;

      case 3:
        // Per spec, list cannot be empty.
        if (i == 0)
          return kInvalidStream;
        return kOk;

      default:
        return kInvalidStream;
    }
  }

  // If we got here, we didn't get loop end marker prematurely,
  // so make sure it is there for our client.
  int modification_of_pic_nums_idc;
  READ_UE_OR_RETURN(&modification_of_pic_nums_idc);
  TRUE_OR_RETURN(modification_of_pic_nums_idc == 3);

  return kOk;
}

H264Parser::Result H264Parser::ParseRefPicListModifications(
    H26xBitReader* br, H264SliceHeader* shdr) {
  Result res;

  if (!shdr->IsISlice() && !shdr->IsSISlice()) {
    READ_BOOL_OR_RETURN(&shdr->ref_pic_list_modification_flag_l0);
    if (shdr->ref_pic_list_modification_flag_l0) {
      res = ParseRefPicListModification(br, shdr->num_ref_idx_l0_active_minus1,
                                        shdr->ref_list_l0_modifications);
      if (res != kOk)
        return res;
    }
  }

  if (shdr->IsBSlice()) {
    READ_BOOL_OR_RETURN(&shdr->ref_pic_list_modification_flag_l1);
    if (shdr->ref_pic_list_modification_flag_l1) {
      res = ParseRefPicListModification(br, shdr->num_ref_idx_l1_active_minus1,
                                        shdr->ref_list_l1_modifications);
      if (res != kOk)
        return res;
    }
  }

  return kOk;
}

H264Parser::Result H264Parser::ParseWeightingFactors(
    H26xBitReader* br,
    int num_ref_idx_active_minus1,
    int chroma_array_type,
    int luma_log2_weight_denom,
    int chroma_log2_weight_denom,
    H264WeightingFactors* w_facts) {
  int def_luma_weight = 1 << luma_log2_weight_denom;
  int def_chroma_weight = 1 << chroma_log2_weight_denom;

  for (int i = 0; i < num_ref_idx_active_minus1 + 1; ++i) {
    READ_BOOL_OR_RETURN(&w_facts->luma_weight_flag[i]);
    if (w_facts->luma_weight_flag[i]) {
      READ_SE_OR_RETURN(&w_facts->luma_weight[i]);
      IN_RANGE_OR_RETURN(w_facts->luma_weight[i], -128, 127);

      READ_SE_OR_RETURN(&w_facts->luma_offset[i]);
      IN_RANGE_OR_RETURN(w_facts->luma_offset[i], -128, 127);
    } else {
      w_facts->luma_weight[i] = def_luma_weight;
      w_facts->luma_offset[i] = 0;
    }

    if (chroma_array_type != 0) {
      READ_BOOL_OR_RETURN(&w_facts->chroma_weight_flag[i]);
      if (w_facts->chroma_weight_flag[i]) {
        for (int j = 0; j < 2; ++j) {
          READ_SE_OR_RETURN(&w_facts->chroma_weight[i][j]);
          IN_RANGE_OR_RETURN(w_facts->chroma_weight[i][j], -128, 127);

          READ_SE_OR_RETURN(&w_facts->chroma_offset[i][j]);
          IN_RANGE_OR_RETURN(w_facts->chroma_offset[i][j], -128, 127);
        }
      } else {
        for (int j = 0; j < 2; ++j) {
          w_facts->chroma_weight[i][j] = def_chroma_weight;
          w_facts->chroma_offset[i][j] = 0;
        }
      }
    }
  }

  return kOk;
}

H264Parser::Result H264Parser::ParsePredWeightTable(H26xBitReader* br,
                                                    const H264Sps& sps,
                                                    H264SliceHeader* shdr) {
  READ_UE_OR_RETURN(&shdr->luma_log2_weight_denom);
  TRUE_OR_RETURN(shdr->luma_log2_weight_denom < 8);

  if (sps.chroma_array_type != 0)
    READ_UE_OR_RETURN(&shdr->chroma_log2_weight_denom);
  TRUE_OR_RETURN(shdr->chroma_log2_weight_denom < 8);

  Result res = ParseWeightingFactors(br,
                                     shdr->num_ref_idx_l0_active_minus1,
                                     sps.chroma_array_type,
                                     shdr->luma_log2_weight_denom,
                                     shdr->chroma_log2_weight_denom,
                                     &shdr->pred_weight_table_l0);
  if (res != kOk)
    return res;

  if (shdr->IsBSlice()) {
    res = ParseWeightingFactors(br,
                                shdr->num_ref_idx_l1_active_minus1,
                                sps.chroma_array_type,
                                shdr->luma_log2_weight_denom,
                                shdr->chroma_log2_weight_denom,
                                &shdr->pred_weight_table_l1);
    if (res != kOk)
      return res;
  }

  return kOk;
}

H264Parser::Result H264Parser::ParseDecRefPicMarking(H26xBitReader* br,
                                                     H264SliceHeader* shdr) {
  if (shdr->idr_pic_flag) {
    READ_BOOL_OR_RETURN(&shdr->no_output_of_prior_pics_flag);
    READ_BOOL_OR_RETURN(&shdr->long_term_reference_flag);
  } else {
    READ_BOOL_OR_RETURN(&shdr->adaptive_ref_pic_marking_mode_flag);

    H264DecRefPicMarking* marking;
    if (shdr->adaptive_ref_pic_marking_mode_flag) {
      size_t i;
      for (i = 0; i < std::size(shdr->ref_pic_marking); ++i) {
        marking = &shdr->ref_pic_marking[i];

        READ_UE_OR_RETURN(&marking->memory_mgmnt_control_operation);
        if (marking->memory_mgmnt_control_operation == 0)
          break;

        if (marking->memory_mgmnt_control_operation == 1 ||
            marking->memory_mgmnt_control_operation == 3)
          READ_UE_OR_RETURN(&marking->difference_of_pic_nums_minus1);

        if (marking->memory_mgmnt_control_operation == 2)
          READ_UE_OR_RETURN(&marking->long_term_pic_num);

        if (marking->memory_mgmnt_control_operation == 3 ||
            marking->memory_mgmnt_control_operation == 6)
          READ_UE_OR_RETURN(&marking->long_term_frame_idx);

        if (marking->memory_mgmnt_control_operation == 4)
          READ_UE_OR_RETURN(&marking->max_long_term_frame_idx_plus1);

        if (marking->memory_mgmnt_control_operation > 6)
          return kInvalidStream;
      }

      if (i == std::size(shdr->ref_pic_marking)) {
        LOG_ERROR_ONCE("Ran out of dec ref pic marking fields");
        return kUnsupportedStream;
      }
    }
  }

  return kOk;
}

H264Parser::Result H264Parser::ParseSliceHeader(const Nalu& nalu,
                                                H264SliceHeader* shdr) {
  // See 7.4.3.
  const H264Sps* sps;
  const H264Pps* pps;
  Result res;
  H26xBitReader reader;
  reader.Initialize(nalu.data() + nalu.header_size(), nalu.payload_size());
  H26xBitReader* br = &reader;

  *shdr = {};

  shdr->idr_pic_flag = (nalu.type() == 5);
  shdr->nal_ref_idc = nalu.ref_idc();
  shdr->nalu_data = nalu.data();
  shdr->nalu_size = nalu.header_size() + nalu.payload_size();

  READ_UE_OR_RETURN(&shdr->first_mb_in_slice);
  READ_UE_OR_RETURN(&shdr->slice_type);
  TRUE_OR_RETURN(shdr->slice_type < 10);

  READ_UE_OR_RETURN(&shdr->pic_parameter_set_id);

  pps = GetPps(shdr->pic_parameter_set_id);
  TRUE_OR_RETURN(pps);

  sps = GetSps(pps->seq_parameter_set_id);
  TRUE_OR_RETURN(sps);

  if (sps->separate_colour_plane_flag) {
    LOG_ERROR_ONCE("Interlaced streams not supported");
    return kUnsupportedStream;
  }

  READ_BITS_OR_RETURN(sps->log2_max_frame_num_minus4 + 4, &shdr->frame_num);
  if (!sps->frame_mbs_only_flag) {
    READ_BOOL_OR_RETURN(&shdr->field_pic_flag);
    if (shdr->field_pic_flag) {
      LOG_ERROR_ONCE("Interlaced streams not supported");
      return kUnsupportedStream;
    }
  }

  if (shdr->idr_pic_flag)
    READ_UE_OR_RETURN(&shdr->idr_pic_id);

  if (sps->pic_order_cnt_type == 0) {
    READ_BITS_OR_RETURN(sps->log2_max_pic_order_cnt_lsb_minus4 + 4,
                        &shdr->pic_order_cnt_lsb);
    if (pps->bottom_field_pic_order_in_frame_present_flag &&
        !shdr->field_pic_flag)
      READ_SE_OR_RETURN(&shdr->delta_pic_order_cnt_bottom);
  }

  if (sps->pic_order_cnt_type == 1 && !sps->delta_pic_order_always_zero_flag) {
    READ_SE_OR_RETURN(&shdr->delta_pic_order_cnt[0]);
    if (pps->bottom_field_pic_order_in_frame_present_flag &&
        !shdr->field_pic_flag)
      READ_SE_OR_RETURN(&shdr->delta_pic_order_cnt[1]);
  }

  if (pps->redundant_pic_cnt_present_flag) {
    READ_UE_OR_RETURN(&shdr->redundant_pic_cnt);
    TRUE_OR_RETURN(shdr->redundant_pic_cnt < 128);
  }

  if (shdr->IsBSlice())
    READ_BOOL_OR_RETURN(&shdr->direct_spatial_mv_pred_flag);

  if (shdr->IsPSlice() || shdr->IsSPSlice() || 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);
      if (shdr->IsBSlice())
        READ_UE_OR_RETURN(&shdr->num_ref_idx_l1_active_minus1);
    } else {
      shdr->num_ref_idx_l0_active_minus1 =
          pps->num_ref_idx_l0_default_active_minus1;
      if (shdr->IsBSlice()) {
        shdr->num_ref_idx_l1_active_minus1 =
            pps->num_ref_idx_l1_default_active_minus1;
      }
    }
  }
  if (shdr->field_pic_flag) {
    TRUE_OR_RETURN(shdr->num_ref_idx_l0_active_minus1 < 32);
    TRUE_OR_RETURN(shdr->num_ref_idx_l1_active_minus1 < 32);
  } else {
    TRUE_OR_RETURN(shdr->num_ref_idx_l0_active_minus1 < 16);
    TRUE_OR_RETURN(shdr->num_ref_idx_l1_active_minus1 < 16);
  }

  if (nalu.type() == Nalu::H264_CodedSliceExtension) {
    return kUnsupportedStream;
  } else {
    res = ParseRefPicListModifications(br, shdr);
    if (res != kOk)
      return res;
  }

  if ((pps->weighted_pred_flag && (shdr->IsPSlice() || shdr->IsSPSlice())) ||
      (pps->weighted_bipred_idc == 1 && shdr->IsBSlice())) {
    res = ParsePredWeightTable(br, *sps, shdr);
    if (res != kOk)
      return res;
  }

  if (nalu.ref_idc() != 0) {
    res = ParseDecRefPicMarking(br, shdr);
    if (res != kOk)
      return res;
  }

  if (pps->entropy_coding_mode_flag && !shdr->IsISlice() &&
      !shdr->IsSISlice()) {
    READ_UE_OR_RETURN(&shdr->cabac_init_idc);
    TRUE_OR_RETURN(shdr->cabac_init_idc < 3);
  }

  READ_SE_OR_RETURN(&shdr->slice_qp_delta);

  if (shdr->IsSPSlice() || shdr->IsSISlice()) {
    if (shdr->IsSPSlice())
      READ_BOOL_OR_RETURN(&shdr->sp_for_switch_flag);
    READ_SE_OR_RETURN(&shdr->slice_qs_delta);
  }

  if (pps->deblocking_filter_control_present_flag) {
    READ_UE_OR_RETURN(&shdr->disable_deblocking_filter_idc);
    TRUE_OR_RETURN(shdr->disable_deblocking_filter_idc < 3);

    if (shdr->disable_deblocking_filter_idc != 1) {
      READ_SE_OR_RETURN(&shdr->slice_alpha_c0_offset_div2);
      IN_RANGE_OR_RETURN(shdr->slice_alpha_c0_offset_div2, -6, 6);

      READ_SE_OR_RETURN(&shdr->slice_beta_offset_div2);
      IN_RANGE_OR_RETURN(shdr->slice_beta_offset_div2, -6, 6);
    }
  }

  if (pps->num_slice_groups_minus1 > 0) {
    LOG_ERROR_ONCE("Slice groups not supported");
    return kUnsupportedStream;
  }

  shdr->header_bit_size = nalu.payload_size() * 8 - br->NumBitsLeft();
  return kOk;
}

H264Parser::Result H264Parser::ParseSEI(const Nalu& nalu,
                                        H264SEIMessage* sei_msg) {
  int byte;
  H26xBitReader reader;
  reader.Initialize(nalu.data() + nalu.header_size(), nalu.payload_size());
  H26xBitReader* br = &reader;

  *sei_msg = {};

  READ_BITS_OR_RETURN(8, &byte);
  while (byte == 0xff) {
    sei_msg->type += 255;
    READ_BITS_OR_RETURN(8, &byte);
  }
  sei_msg->type += byte;

  READ_BITS_OR_RETURN(8, &byte);
  while (byte == 0xff) {
    sei_msg->payload_size += 255;
    READ_BITS_OR_RETURN(8, &byte);
  }
  sei_msg->payload_size += byte;

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

  switch (sei_msg->type) {
    case H264SEIMessage::kSEIRecoveryPoint:
      READ_UE_OR_RETURN(&sei_msg->recovery_point.recovery_frame_cnt);
      READ_BOOL_OR_RETURN(&sei_msg->recovery_point.exact_match_flag);
      READ_BOOL_OR_RETURN(&sei_msg->recovery_point.broken_link_flag);
      READ_BITS_OR_RETURN(2, &sei_msg->recovery_point.changing_slice_group_idc);
      break;

    default:
      DVLOG(4) << "Unsupported SEI message";
      break;
  }

  return kOk;
}

}  // namespace media
}  // namespace shaka