moq_vaapi/codec/h264/

parser.rs

// Copyright 2022 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Can't reasonably expect client code to consume everything that has been parsed.
#![allow(dead_code)]

use std::collections::BTreeMap;
use std::io::Cursor;
use std::io::Read;
use std::io::Seek;
use std::io::SeekFrom;
use std::rc::Rc;

use crate::bitstream_utils::BitReader;
use crate::codec::h264::nalu;
use crate::codec::h264::nalu::Header;
use crate::codec::h264::picture::Field;

pub type Nalu<'a> = nalu::Nalu<'a, NaluHeader>;

pub(super) const DEFAULT_4X4_INTRA: [u8; 16] = [6, 13, 13, 20, 20, 20, 28, 28, 28, 28, 32, 32, 32, 37, 37, 42];

pub(super) const DEFAULT_4X4_INTER: [u8; 16] = [10, 14, 14, 20, 20, 20, 24, 24, 24, 24, 27, 27, 27, 30, 30, 34];

pub(super) const DEFAULT_8X8_INTRA: [u8; 64] = [
	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,
];

pub(super) const DEFAULT_8X8_INTER: [u8; 64] = [
	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,
];

const MAX_PPS_COUNT: u16 = 256;
const MAX_SPS_COUNT: u8 = 32;

/// The maximum number of pictures in the DPB, as per A.3.1, clause h)
const DPB_MAX_SIZE: usize = 16;

#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
pub struct Point<T> {
	pub x: T,
	pub y: T,
}

#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
pub struct Rect<T> {
	pub min: Point<T>,
	pub max: Point<T>,
}

#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum NaluType {
	Unknown = 0,
	Slice = 1,
	SliceDpa = 2,
	SliceDpb = 3,
	SliceDpc = 4,
	SliceIdr = 5,
	Sei = 6,
	Sps = 7,
	Pps = 8,
	AuDelimiter = 9,
	SeqEnd = 10,
	StreamEnd = 11,
	FillerData = 12,
	SpsExt = 13,
	PrefixUnit = 14,
	SubsetSps = 15,
	DepthSps = 16,
	SliceAux = 19,
	SliceExt = 20,
	SliceDepth = 21,
}

impl TryFrom<u8> for NaluType {
	type Error = String;

	fn try_from(value: u8) -> Result<Self, Self::Error> {
		match value {
			0 => Ok(NaluType::Unknown),
			1 => Ok(NaluType::Slice),
			2 => Ok(NaluType::SliceDpa),
			3 => Ok(NaluType::SliceDpb),
			4 => Ok(NaluType::SliceDpc),
			5 => Ok(NaluType::SliceIdr),
			6 => Ok(NaluType::Sei),
			7 => Ok(NaluType::Sps),
			8 => Ok(NaluType::Pps),
			9 => Ok(NaluType::AuDelimiter),
			10 => Ok(NaluType::SeqEnd),
			11 => Ok(NaluType::StreamEnd),
			12 => Ok(NaluType::FillerData),
			13 => Ok(NaluType::SpsExt),
			14 => Ok(NaluType::PrefixUnit),
			15 => Ok(NaluType::SubsetSps),
			16 => Ok(NaluType::DepthSps),
			19 => Ok(NaluType::SliceAux),
			20 => Ok(NaluType::SliceExt),
			21 => Ok(NaluType::SliceDepth),
			_ => Err(format!("Invalid NaluType {}", value)),
		}
	}
}

#[derive(Clone, Debug, Default, PartialEq, Eq)]
pub struct RefPicListModification {
	pub modification_of_pic_nums_idc: u8,
	/* if modification_of_pic_nums_idc == 0 || 1 */
	pub abs_diff_pic_num_minus1: u32,
	/* if modification_of_pic_nums_idc == 2 */
	pub long_term_pic_num: u32,
	/* if modification_of_pic_nums_idc == 4 || 5 */
	pub abs_diff_view_idx_minus1: u32,
}

#[derive(Clone, Debug, Default, PartialEq, Eq)]
pub struct PredWeightTable {
	pub luma_log2_weight_denom: u8,
	pub chroma_log2_weight_denom: u8,

	pub luma_weight_l0: [i16; 32],
	pub luma_offset_l0: [i8; 32],

	/* if seq->ChromaArrayType != 0 */
	pub chroma_weight_l0: [[i16; 2]; 32],
	pub chroma_offset_l0: [[i8; 2]; 32],

	/* if slice->slice_type % 5 == 1 */
	pub luma_weight_l1: [i16; 32],
	pub luma_offset_l1: [i16; 32],

	/* and if seq->ChromaArrayType != 0 */
	pub chroma_weight_l1: [[i16; 2]; 32],
	pub chroma_offset_l1: [[i8; 2]; 32],
}

/// Representation of `MaxLongTermFrameIdx`.
///
/// `MaxLongTermFrameIdx` is derived from `max_long_term_frame_idx_plus1`, an unsigned integer with
/// a special value indicating "no long-term frame indices". This type allows easy conversion
/// between the actual and "plus1" representation, while ensuring that the special value is always
/// handled by the code.
#[derive(Default, Debug, Clone, Copy, PartialEq, Eq)]
pub enum MaxLongTermFrameIdx {
	#[default]
	NoLongTermFrameIndices,
	Idx(u32),
}

impl MaxLongTermFrameIdx {
	/// Create a value from `max_long_term_frame_idx_plus1`.
	pub fn from_value_plus1(max_long_term_frame_idx_plus1: u32) -> Self {
		match max_long_term_frame_idx_plus1 {
			0 => Self::NoLongTermFrameIndices,
			i @ 1.. => Self::Idx(i - 1),
		}
	}

	/// Convert this value to the representation used by `max_long_term_frame_idx_plus1`.
	pub fn to_value_plus1(self) -> u32 {
		match self {
			Self::NoLongTermFrameIndices => 0,
			Self::Idx(i) => i + 1,
		}
	}
}

impl PartialEq<u32> for MaxLongTermFrameIdx {
	fn eq(&self, other: &u32) -> bool {
		match self {
			MaxLongTermFrameIdx::NoLongTermFrameIndices => false,
			MaxLongTermFrameIdx::Idx(idx) => idx.eq(other),
		}
	}
}

impl PartialOrd<u32> for MaxLongTermFrameIdx {
	fn partial_cmp(&self, other: &u32) -> Option<std::cmp::Ordering> {
		match self {
			MaxLongTermFrameIdx::NoLongTermFrameIndices => Some(std::cmp::Ordering::Less),
			MaxLongTermFrameIdx::Idx(idx) => Some(idx.cmp(other)),
		}
	}
}

#[derive(Clone, Debug, Default, PartialEq, Eq)]
pub struct RefPicMarkingInner {
	/// Specifies a control operation to be applied to affect the reference
	/// picture marking. The `memory_management_control_operation` syntax element
	/// is followed by data necessary for the operation specified by the value
	/// of `memory_management_control_operation`. The values and control
	/// operations associated with `memory_management_control_operation` are
	/// specified in Table 7-9
	pub memory_management_control_operation: u8,

	/// Used (with memory_management_control_operation equal to 3 or 1) to
	/// assign a long-term frame index to a short-term reference picture or to
	/// mark a short-term reference picture as "unused for reference".
	pub difference_of_pic_nums_minus1: u32,

	/// Used (with memory_management_control_operation equal to 2) to mark a
	/// long-term reference picture as "unused for reference".
	pub long_term_pic_num: u32,

	/// Used (with memory_management_control_operation equal to 3 or 6) to
	/// assign a long-term frame index to a picture.
	pub long_term_frame_idx: u32,

	/// Specifies the maximum value of long-term frame index allowed for
	/// long-term reference pictures (until receipt of another value of
	/// `max_long_term_frame_idx_plus1`).
	pub max_long_term_frame_idx: MaxLongTermFrameIdx,
}

#[derive(Clone, Debug, Default, PartialEq, Eq)]
pub struct RefPicMarking {
	/// Specifies how the previously-decoded pictures in the decoded picture
	/// buffer are treated after decoding of an IDR picture. See Annex C.
	pub no_output_of_prior_pics_flag: bool,

	/// If unset, specifies that the MaxLongTermFrameIdx variable is set equal
	/// to "no long-term frame indices" and that the IDR picture is marked as
	/// "used for short-term reference". If set, specifies that the
	/// MaxLongTermFrameIdx variable is set equal to 0 and that the current IDR
	/// picture is marked "used for long-term reference" and is assigned
	/// LongTermFrameIdx equal to 0.
	pub long_term_reference_flag: bool,

	/// Selects the reference picture marking mode of the currently decoded
	/// picture as specified in Table 7-8.
	pub adaptive_ref_pic_marking_mode_flag: bool,

	/// An Vec with additional data used in the marking process.
	pub inner: Vec<RefPicMarkingInner>,
}

#[derive(Clone, Debug, Default, PartialEq, Eq)]
pub struct SliceHeader {
	/// Specifies the address of the first macroblock in the slice.
	pub first_mb_in_slice: u32,

	/// Specifies the coding type of the slice according to Table 7-6.
	pub slice_type: SliceType,

	// Specifies the picture parameter set in use
	pub pic_parameter_set_id: u8,

	/// Specifies the colour plane associated with the current slice RBSP when
	/// `separate_colour_plane_flag` is set.
	pub colour_plane_id: u8,

	/// Used as an identifier for pictures and shall be represented by
	/// `log2_max_frame_num_minus4 + 4` bits in the bitstream.
	pub frame_num: u16,

	/// If set, specifies that the slice is a slice of a coded field. If not
	/// set, specifies that the slice is a slice of a coded frame.
	pub field_pic_flag: bool,

	/// If set, specifies that the slice is part of a coded bottom field. If not
	/// set, specifies that the picture is a coded top field.
	pub bottom_field_flag: bool,

	/// Identifies an IDR picture. The values of `idr_pic_id` in all the slices
	/// of an IDR picture shall remain unchanged. When two consecutive access
	/// units in decoding order are both IDR access units, the value of
	/// `idr_pic_id` in the slices of the first such IDR access unit shall
	/// differ from the `idr_pic_id` in the second such IDR access unit
	pub idr_pic_id: u16,

	/// Specifies the picture order count modulo `MaxPicOrderCntLsb` for the top
	/// field of a coded frame or for a coded field. The length of the
	/// `pic_order_cnt_lsb` syntax element is
	/// `log2_max_pic_order_cnt_lsb_minus4` + 4 bits.
	pub pic_order_cnt_lsb: u16,

	///  Specifies the picture order count difference between the bottom field
	///  and the top field of a coded frame as follows
	pub delta_pic_order_cnt_bottom: i32,

	/// The first entry specifies the picture order count difference from the
	/// expected picture order count for the top field of a coded frame or for a
	/// coded field as specified in clause 8.2.1 The second entry  specifies the
	/// picture order count difference from the expected picture order count for
	/// the bottom field of a coded frame specified in clause 8.2.1.
	pub delta_pic_order_cnt: [i32; 2],

	/// This value is required by V4L2 stateless decode params so it is calculated
	/// by parser while processing slice header.
	pub pic_order_cnt_bit_size: usize,

	/// Shall be equal to 0 for slices and slice data partitions belonging to
	/// the primary coded picture. The value of `redundant_pic_cnt shall` be
	/// greater than 0 for coded slices or coded slice data partitions of a
	/// redundant coded picture
	pub redundant_pic_cnt: u8,

	/// Specifies the method used in the decoding process to derive motion
	/// vectors and reference indices for inter prediction >
	pub direct_spatial_mv_pred_flag: bool,

	/// If set, specifies that the syntax element `num_ref_idx_l0_active_minus1`
	/// is present for P, SP, and B slices and that the syntax element
	/// `num_ref_idx_l1_active_minus1` is present for B slices. If not set,
	/// specifies that the syntax elements `num_ref_idx_l0_active_minus1` and
	/// `num_ref_idx_l1_active_minus1` are not present.
	pub num_ref_idx_active_override_flag: bool,

	/// Specifies the maximum reference index for reference picture list 0 that
	/// shall be used to decode the slice.
	pub num_ref_idx_l0_active_minus1: u8,

	/// Specifies the maximum reference index for reference picture list 1 that
	/// shall be used to decode the slice.
	pub num_ref_idx_l1_active_minus1: u8,

	/// If set, specifies that the syntax element `modification_of_pic_nums_idc`
	/// is present for specifying reference picture list 0. If not set,
	/// specifies that this syntax element is not present.
	pub ref_pic_list_modification_flag_l0: bool,

	/// Reference picture list 0 modification as parsed with the
	/// `ref_pic_list_modification()` process.
	pub ref_pic_list_modification_l0: Vec<RefPicListModification>,

	/// If set, specifies that the syntax element `modification_of_pic_nums_idc`
	/// is present for specifying reference picture list 1. If not set,
	/// specifies that this syntax element is not present.
	pub ref_pic_list_modification_flag_l1: bool,

	/// Reference picture list 1 modification as parsed with the
	/// `ref_pic_list_modification()` process.
	pub ref_pic_list_modification_l1: Vec<RefPicListModification>,

	/// Prediction weight table as parsed using 7.3.3.2
	pub pred_weight_table: PredWeightTable,

	/// Decoded reference picture marking parsed using 7.3.3.3
	pub dec_ref_pic_marking: RefPicMarking,

	/// This value is required by V4L2 stateless decode params so it is calculated
	/// by parser while processing slice header.
	pub dec_ref_pic_marking_bit_size: usize,

	/// Specifies the index for determining the initialization table used in the
	/// initialization process for context variables.
	pub cabac_init_idc: u8,

	/// Specifies the initial value of QP Y to be used for all the macroblocks
	/// in the slice until modified by the value of `mb_qp_delta` in the
	/// macroblock layer. The initial QPY quantization parameter for the slice
	/// is computed using 7-30.
	pub slice_qp_delta: i8,

	/// Specifies the decoding process to be used to decode P macroblocks in an
	/// SP slice.
	pub sp_for_switch_flag: bool,

	/// Specifies the value of QSY for all the macroblocks in SP and SI slices.
	/// The QSY quantization parameter for the slice is computed using 7-31.
	pub slice_qs_delta: i8,

	/// Specifies whether the operation of the deblocking filter shall be
	/// disabled across some block edges of the slice and specifies for which
	/// edges the filtering is disabled.
	pub disable_deblocking_filter_idc: u8,

	/// Specifies the offset used in accessing the α and tC0 deblocking filter
	/// tables for filtering operations controlled by the macroblocks within the
	/// slice. From this value, the offset that shall be applied when addressing
	/// these tables shall be computed using 7-32.
	pub slice_alpha_c0_offset_div2: i8,

	/// Specifies the offset used in accessing the β deblocking filter table for
	/// filtering operations controlled by the macroblocks within the slice.
	/// From this value, the offset that is applied when addressing the β table
	/// of the deblocking filter shall be computed using 7-33.
	pub slice_beta_offset_div2: i8,

	/// Same as `MaxPicNum` in the specification.
	pub max_pic_num: u32,

	/// Size of the slice_header() in bits
	pub header_bit_size: usize,

	/// Number of emulation prevention bytes (EPB) in this slice_header()
	pub n_emulation_prevention_bytes: usize,
}

impl SliceHeader {
	/// Returns the field that is coded by this header.
	pub fn field(&self) -> Field {
		if self.field_pic_flag {
			if self.bottom_field_flag {
				Field::Bottom
			} else {
				Field::Top
			}
		} else {
			Field::Frame
		}
	}
}

pub struct SliceHeaderBuilder(SliceHeader);

impl SliceHeaderBuilder {
	pub fn new(pps: &Pps) -> Self {
		SliceHeaderBuilder(SliceHeader {
			pic_parameter_set_id: pps.pic_parameter_set_id,
			..Default::default()
		})
	}

	pub fn slice_type(mut self, type_: SliceType) -> Self {
		self.0.slice_type = type_;
		self
	}

	pub fn first_mb_in_slice(mut self, value: u32) -> Self {
		self.0.first_mb_in_slice = value;
		self
	}

	pub fn frame_num(mut self, value: u16) -> Self {
		self.0.frame_num = value;
		self
	}

	pub fn pic_order_cnt_lsb(mut self, value: u16) -> Self {
		self.0.pic_order_cnt_lsb = value;
		self
	}

	pub fn idr_pic_id(mut self, value: u16) -> Self {
		self.0.idr_pic_id = value;
		self
	}

	pub fn num_ref_idx_active_override_flag(mut self, value: bool) -> Self {
		self.0.num_ref_idx_active_override_flag = value;
		self
	}

	pub fn num_ref_idx_l0_active_minus1(mut self, value: u8) -> Self {
		self = self.num_ref_idx_active_override_flag(true);
		self.0.num_ref_idx_l0_active_minus1 = value;
		self
	}

	pub fn num_ref_idx_l0_active(self, value: u8) -> Self {
		self.num_ref_idx_l0_active_minus1(value - 1)
	}

	pub fn num_ref_idx_l1_active_minus1(mut self, value: u8) -> Self {
		self = self.num_ref_idx_active_override_flag(true);
		self.0.num_ref_idx_l1_active_minus1 = value;
		self
	}

	pub fn num_ref_idx_l1_active(self, value: u8) -> Self {
		self.num_ref_idx_l1_active_minus1(value - 1)
	}

	pub fn build(self) -> SliceHeader {
		self.0
	}
}

/// A H264 slice. An integer number of macroblocks or macroblock pairs ordered
/// consecutively in the raster scan within a particular slice group
pub struct Slice<'a> {
	/// The slice header.
	pub header: SliceHeader,
	/// The NAL unit backing this slice.
	pub nalu: Nalu<'a>,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
/// See table 7-6 in the specification.
pub enum SliceType {
	P = 0,
	B = 1,
	I = 2,
	Sp = 3,
	Si = 4,
}

impl TryFrom<u8> for SliceType {
	type Error = String;

	fn try_from(value: u8) -> Result<Self, Self::Error> {
		match value {
			0 => Ok(SliceType::P),
			1 => Ok(SliceType::B),
			2 => Ok(SliceType::I),
			3 => Ok(SliceType::Sp),
			4 => Ok(SliceType::Si),
			_ => Err(format!("Invalid SliceType {}", value)),
		}
	}
}

impl SliceType {
	/// Whether this is a P slice. See table 7-6 in the specification.
	pub fn is_p(&self) -> bool {
		matches!(self, SliceType::P)
	}

	/// Whether this is a B slice. See table 7-6 in the specification.
	pub fn is_b(&self) -> bool {
		matches!(self, SliceType::B)
	}

	/// Whether this is an I slice. See table 7-6 in the specification.
	pub fn is_i(&self) -> bool {
		matches!(self, SliceType::I)
	}

	/// Whether this is a SP slice. See table 7-6 in the specification.
	pub fn is_sp(&self) -> bool {
		matches!(self, SliceType::Sp)
	}

	/// Whether this is a SI slice. See table 7-6 in the specification.
	pub fn is_si(&self) -> bool {
		matches!(self, SliceType::Si)
	}
}

impl Default for SliceType {
	fn default() -> Self {
		Self::P
	}
}

#[derive(Clone, Copy, PartialEq, Eq)]
#[repr(u8)]
pub enum Profile {
	Baseline = 66,
	Main = 77,
	Extended = 88,
	High = 100,
	High10 = 110,
	High422P = 122,
}

impl TryFrom<u8> for Profile {
	type Error = String;

	fn try_from(value: u8) -> Result<Self, Self::Error> {
		match value {
			66 => Ok(Profile::Baseline),
			77 => Ok(Profile::Main),
			88 => Ok(Profile::Extended),
			100 => Ok(Profile::High),
			110 => Ok(Profile::High10),
			122 => Ok(Profile::High422P),
			_ => Err(format!("Invalid Profile {}", value)),
		}
	}
}

#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
pub enum Level {
	#[default]
	L1 = 10,
	L1B = 9,
	L1_1 = 11,
	L1_2 = 12,
	L1_3 = 13,
	L2_0 = 20,
	L2_1 = 21,
	L2_2 = 22,
	L3 = 30,
	L3_1 = 31,
	L3_2 = 32,
	L4 = 40,
	L4_1 = 41,
	L4_2 = 42,
	L5 = 50,
	L5_1 = 51,
	L5_2 = 52,
	L6 = 60,
	L6_1 = 61,
	L6_2 = 62,
}

impl TryFrom<u8> for Level {
	type Error = String;

	fn try_from(value: u8) -> Result<Self, Self::Error> {
		match value {
			10 => Ok(Level::L1),
			9 => Ok(Level::L1B),
			11 => Ok(Level::L1_1),
			12 => Ok(Level::L1_2),
			13 => Ok(Level::L1_3),
			20 => Ok(Level::L2_0),
			21 => Ok(Level::L2_1),
			22 => Ok(Level::L2_2),
			30 => Ok(Level::L3),
			31 => Ok(Level::L3_1),
			32 => Ok(Level::L3_2),
			40 => Ok(Level::L4),
			41 => Ok(Level::L4_1),
			42 => Ok(Level::L4_2),
			50 => Ok(Level::L5),
			51 => Ok(Level::L5_1),
			52 => Ok(Level::L5_2),
			60 => Ok(Level::L6),
			61 => Ok(Level::L6_1),
			62 => Ok(Level::L6_2),
			_ => Err(format!("Invalid Level {}", value)),
		}
	}
}

/// A H264 Sequence Parameter Set. A syntax structure containing syntax elements
/// that apply to zero or more entire coded video sequences as determined by the
/// content of a seq_parameter_set_id syntax element found in the picture
/// parameter set referred to by the pic_parameter_set_id syntax element found
/// in each slice header.
#[derive(Debug, PartialEq, Eq)]
pub struct Sps {
	/// Identifies the sequence parameter set that is referred to by the picture
	/// parameter set
	pub seq_parameter_set_id: u8,

	/// Profile to which the coded video sequence conforms
	pub profile_idc: u8,

	/// Retains the same meaning as in the specification. See 7.4.2.1.1
	pub constraint_set0_flag: bool,
	/// Retains the same meaning as in the specification. See 7.4.2.1.1
	pub constraint_set1_flag: bool,
	/// Retains the same meaning as in the specification. See 7.4.2.1.1
	pub constraint_set2_flag: bool,
	/// Retains the same meaning as in the specification. See 7.4.2.1.1
	pub constraint_set3_flag: bool,
	/// Retains the same meaning as in the specification. See 7.4.2.1.1
	pub constraint_set4_flag: bool,
	/// Retains the same meaning as in the specification. See 7.4.2.1.1
	pub constraint_set5_flag: bool,

	/// Level to which the coded video sequence conforms
	pub level_idc: Level,

	/// Specifies the chroma sampling relative to the luma sampling as specified
	/// in clause 6.2.
	pub chroma_format_idc: u8,

	/// Specifies whether the three colour components of the 4:4:4 chroma format
	/// are coded separately.
	pub separate_colour_plane_flag: bool,

	/// Specifies the bit depth of the samples of the luma array and the value
	/// of the luma quantization parameter range offset QpBdOffsetY. See 7-3 and
	/// 7-4.
	pub bit_depth_luma_minus8: u8,

	/// Specifies the bit depth of the samples of the chroma arrays and the
	/// value of the chroma quantization parameter range offset QpBdOffsetC. See
	/// 7-5 and 7-6.
	pub bit_depth_chroma_minus8: u8,

	/// qpprime_y_zero_transform_bypass_flag equal to 1 specifies that, when
	/// QP′Y is equal to 0, a transform bypass operation for the transform
	/// coefficient decoding process and picture construction process prior to
	/// deblocking filter process as specified in clause 8.5 shall be applied.
	/// qpprime_y_zero_transform_bypass_flag equal to 0 specifies that the
	/// transform coefficient decoding process and picture construction process
	/// prior to deblocking filter process shall not use the transform bypass
	/// operation
	/// QP′Y is defined in 7-38 as QP′Y = QPY + QpBdOffsetY
	pub qpprime_y_zero_transform_bypass_flag: bool,

	/// Whether `seq_scaling_list_present_flag[i]` for i = 0..7 or i = 0..11 is
	/// present or whether the sequence level scaling list shall be specified by
	/// Flat_4x4_16 for i = 0..5 and flat_8x8_16 for i = 6..11
	pub seq_scaling_matrix_present_flag: bool,

	/// 4x4 Scaling list as read with 7.3.2.1.1.1
	pub scaling_lists_4x4: [[u8; 16]; 6],
	/// 8x8 Scaling list as read with 7.3.2.1.1.1
	pub scaling_lists_8x8: [[u8; 64]; 6],

	/// Specifies the value of the variable MaxFrameNum that is used in
	/// frame_num related derivations as follows: MaxFrameNum = 2 ^
	/// (log2_max_frame_num_minus4 + 4 )
	pub log2_max_frame_num_minus4: u8,

	/// Specifies the method to decode picture order count (as specified in
	/// clause 8.2.1)
	pub pic_order_cnt_type: u8,

	/// Specifies the value of the variable MaxPicOrderCntLsb that is used in
	/// the decoding process for picture order count as specified in clause
	/// 8.2.1 as follows: MaxPicOrderCntLsb = 2 ^ (
	/// log2_max_pic_order_cnt_lsb_minus4 + 4 ).
	pub log2_max_pic_order_cnt_lsb_minus4: u8,

	/// If true, specifies that `delta_pic_order_cnt[0]` and
	/// `delta_pic_order_cnt[1]` are not present in the slice headers of the
	/// sequence and shall be inferred to be equal to 0.
	/// If false, specifies that `delta_pic_order_cnt[0]` is present in the
	/// slice headers of the sequence and `delta_pic_order_cnt[1]` may be
	/// present in the slice headers of the sequence.
	pub delta_pic_order_always_zero_flag: bool,

	/// Used to calculate the picture order count of a non-reference picture as
	/// specified in clause 8.2.1.
	pub offset_for_non_ref_pic: i32,

	/// Used to calculate the picture order count of a bottom field as specified
	/// in clause 8.2.1.
	pub offset_for_top_to_bottom_field: i32,

	/// Used in the decoding process for picture order count as specified in
	/// clause 8.2.1
	pub num_ref_frames_in_pic_order_cnt_cycle: u8,

	/// An element of a list of num_ref_frames_in_pic_order_cnt_cycle values
	/// used in the decoding process for picture order count as specified in
	/// clause 8.2.
	pub offset_for_ref_frame: [i32; 255],

	/// Specifies the maximum number of short-term and long-term reference
	/// frames, complementary reference field pairs, and non-paired reference
	/// fields that may be used by the decoding process for inter prediction of
	/// any picture in the coded video sequence. Also
	/// determines the size of the sliding window operation as specified in
	/// clause 8.2.5.3.
	pub max_num_ref_frames: u8,

	/// Specifies the allowed values of frame_num as specified in clause 7.4.3
	/// and the decoding process in case of an inferred gap between values of
	/// frame_num as specified in clause 8.2.5.2
	pub gaps_in_frame_num_value_allowed_flag: bool,

	/// Plus 1 specifies the width of each decoded picture in units of
	/// macroblocks.
	pub pic_width_in_mbs_minus1: u16,
	/// Plus 1 specifies the height in slice group map units of a decoded frame
	/// or field.
	pub pic_height_in_map_units_minus1: u16,

	/// If true,  specifies that every coded picture of the coded video sequence
	/// is a coded frame containing only frame macroblocks, else specifies that
	/// coded pictures of the coded video sequence may either be coded fields or
	/// coded frames.
	pub frame_mbs_only_flag: bool,

	/// If true, specifies the possible use of switching between frame and field
	/// macroblocks within frames, else, specifies no switching between frame
	/// and field macroblocks within a picture.
	pub mb_adaptive_frame_field_flag: bool,

	/// Specifies the method used in the derivation process for luma motion
	/// vectors for B_Skip, B_Direct_16x16 and B_Direct_8x8 as specified in
	/// clause 8.4.1.2.
	pub direct_8x8_inference_flag: bool,

	/// If true, specifies that the frame cropping offset parameters follow next
	/// in the sequence parameter, else specifies that the frame cropping offset
	/// parameters are not present
	pub frame_cropping_flag: bool,

	/// Specify the samples of the pictures in the coded video sequence that are
	/// output from the decoding process, in terms of a rectangular region
	/// specified in frame coordinates for output.
	pub frame_crop_left_offset: u32,
	/// Specify the samples of the pictures in the coded video sequence that are
	/// output from the decoding process, in terms of a rectangular region
	/// specified in frame coordinates for output.
	pub frame_crop_right_offset: u32,
	/// Specify the samples of the pictures in the coded video sequence that are
	/// output from the decoding process, in terms of a rectangular region
	/// specified in frame coordinates for output.
	pub frame_crop_top_offset: u32,
	/// Specify the samples of the pictures in the coded video sequence that are
	/// output from the decoding process, in terms of a rectangular region
	/// specified in frame coordinates for output.
	pub frame_crop_bottom_offset: u32,

	// Calculated
	/// Same as ExpectedDeltaPerPicOrderCntCycle, see 7-12 in the specification.
	pub expected_delta_per_pic_order_cnt_cycle: i32,

	pub vui_parameters_present_flag: bool,
	pub vui_parameters: VuiParams,
}

impl Sps {
	/// Returns the coded width of the stream.
	///
	/// See 7-13 through 7-17 in the specification.
	pub const fn width(&self) -> u32 {
		(self.pic_width_in_mbs_minus1 as u32 + 1) * 16
	}

	/// Returns the coded height of the stream.
	///
	/// See 7-13 through 7-17 in the specification.
	pub const fn height(&self) -> u32 {
		(self.pic_height_in_map_units_minus1 as u32 + 1) * 16 * (2 - self.frame_mbs_only_flag as u32)
	}

	/// Returns `ChromaArrayType`, as computed in the specification.
	pub const fn chroma_array_type(&self) -> u8 {
		match self.separate_colour_plane_flag {
			false => self.chroma_format_idc,
			true => 0,
		}
	}

	/// Returns `SubWidthC` and `SubHeightC`.
	///
	/// See table 6-1 in the specification.
	fn sub_width_height_c(&self) -> (u32, u32) {
		match (self.chroma_format_idc, self.separate_colour_plane_flag) {
			(1, false) => (2, 2),
			(2, false) => (2, 1),
			(3, false) => (1, 1),
			// undefined.
			_ => (1, 1),
		}
	}

	/// Returns `CropUnitX` and `CropUnitY`.
	///
	/// See 7-19 through 7-22 in the specification.
	fn crop_unit_x_y(&self) -> (u32, u32) {
		match self.chroma_array_type() {
			0 => (1, 2 - u32::from(self.frame_mbs_only_flag)),
			_ => {
				let (sub_width_c, sub_height_c) = self.sub_width_height_c();
				(sub_width_c, sub_height_c * (2 - u32::from(self.frame_mbs_only_flag)))
			}
		}
	}

	/// Same as MaxFrameNum. See 7-10 in the specification.
	pub fn max_frame_num(&self) -> u32 {
		1 << (self.log2_max_frame_num_minus4 + 4)
	}

	pub fn visible_rectangle(&self) -> Rect<u32> {
		if !self.frame_cropping_flag {
			return Rect {
				min: Point { x: 0, y: 0 },
				max: Point {
					x: self.width(),
					y: self.height(),
				},
			};
		}

		let (crop_unit_x, crop_unit_y) = self.crop_unit_x_y();

		let crop_left = crop_unit_x * self.frame_crop_left_offset;
		let crop_right = crop_unit_x * self.frame_crop_right_offset;
		let crop_top = crop_unit_y * self.frame_crop_top_offset;
		let crop_bottom = crop_unit_y * self.frame_crop_bottom_offset;

		Rect {
			min: Point {
				x: crop_left,
				y: crop_top,
			},
			max: Point {
				x: self.width() - crop_left - crop_right,
				y: self.height() - crop_top - crop_bottom,
			},
		}
	}

	pub fn max_dpb_frames(&self) -> usize {
		let profile = self.profile_idc;
		let mut level = self.level_idc;

		// A.3.1 and A.3.2: Level 1b for Baseline, Constrained Baseline and Main
		// profile if level_idc == 11 and constraint_set3_flag == 1
		if matches!(level, Level::L1_1)
			&& (profile == Profile::Baseline as u8 || profile == Profile::Main as u8)
			&& self.constraint_set3_flag
		{
			level = Level::L1B;
		};

		// Table A.1
		let max_dpb_mbs = match level {
			Level::L1 => 396,
			Level::L1B => 396,
			Level::L1_1 => 900,
			Level::L1_2 => 2376,
			Level::L1_3 => 2376,
			Level::L2_0 => 2376,
			Level::L2_1 => 4752,
			Level::L2_2 => 8100,
			Level::L3 => 8100,
			Level::L3_1 => 18000,
			Level::L3_2 => 20480,
			Level::L4 => 32768,
			Level::L4_1 => 32768,
			Level::L4_2 => 34816,
			Level::L5 => 110400,
			Level::L5_1 => 184320,
			Level::L5_2 => 184320,
			Level::L6 => 696320,
			Level::L6_1 => 696320,
			Level::L6_2 => 696320,
		};

		let width_mb = self.width() / 16;
		let height_mb = self.height() / 16;

		let max_dpb_frames = std::cmp::min(max_dpb_mbs / (width_mb * height_mb), DPB_MAX_SIZE as u32) as usize;

		let mut max_dpb_frames = std::cmp::max(max_dpb_frames, self.max_num_ref_frames as usize);

		if self.vui_parameters_present_flag && self.vui_parameters.bitstream_restriction_flag {
			max_dpb_frames = std::cmp::max(1, self.vui_parameters.max_dec_frame_buffering as usize);
		}

		max_dpb_frames
	}

	pub fn max_num_order_frames(&self) -> u32 {
		let vui = &self.vui_parameters;
		let present = self.vui_parameters_present_flag && vui.bitstream_restriction_flag;

		if present {
			vui.max_num_reorder_frames
		} else {
			let profile = self.profile_idc;
			if (profile == 44 || profile == 86 || profile == 100 || profile == 110 || profile == 122 || profile == 244)
				&& self.constraint_set3_flag
			{
				0
			} else {
				self.max_dpb_frames() as u32
			}
		}
	}
}

// TODO: Replace with builder
impl Default for Sps {
	fn default() -> Self {
		Self {
			scaling_lists_4x4: [[0; 16]; 6],
			scaling_lists_8x8: [[0; 64]; 6],
			offset_for_ref_frame: [0; 255],
			seq_parameter_set_id: Default::default(),
			profile_idc: Default::default(),
			constraint_set0_flag: Default::default(),
			constraint_set1_flag: Default::default(),
			constraint_set2_flag: Default::default(),
			constraint_set3_flag: Default::default(),
			constraint_set4_flag: Default::default(),
			constraint_set5_flag: Default::default(),
			level_idc: Default::default(),
			chroma_format_idc: Default::default(),
			separate_colour_plane_flag: Default::default(),
			bit_depth_luma_minus8: Default::default(),
			bit_depth_chroma_minus8: Default::default(),
			qpprime_y_zero_transform_bypass_flag: Default::default(),
			seq_scaling_matrix_present_flag: Default::default(),
			log2_max_frame_num_minus4: Default::default(),
			pic_order_cnt_type: Default::default(),
			log2_max_pic_order_cnt_lsb_minus4: Default::default(),
			delta_pic_order_always_zero_flag: Default::default(),
			offset_for_non_ref_pic: Default::default(),
			offset_for_top_to_bottom_field: Default::default(),
			num_ref_frames_in_pic_order_cnt_cycle: Default::default(),
			max_num_ref_frames: Default::default(),
			gaps_in_frame_num_value_allowed_flag: Default::default(),
			pic_width_in_mbs_minus1: Default::default(),
			pic_height_in_map_units_minus1: Default::default(),
			frame_mbs_only_flag: Default::default(),
			mb_adaptive_frame_field_flag: Default::default(),
			direct_8x8_inference_flag: Default::default(),
			frame_cropping_flag: Default::default(),
			frame_crop_left_offset: Default::default(),
			frame_crop_right_offset: Default::default(),
			frame_crop_top_offset: Default::default(),
			frame_crop_bottom_offset: Default::default(),
			expected_delta_per_pic_order_cnt_cycle: Default::default(),
			vui_parameters_present_flag: Default::default(),
			vui_parameters: Default::default(),
		}
	}
}

#[derive(Default)]
pub struct SpsBuilder(Sps);

impl SpsBuilder {
	pub fn new() -> Self {
		Default::default()
	}

	pub fn seq_parameter_set_id(mut self, value: u8) -> Self {
		self.0.seq_parameter_set_id = value;
		self
	}

	pub fn profile_idc(mut self, value: Profile) -> Self {
		self.0.profile_idc = value as u8;
		self
	}

	pub fn level_idc(mut self, value: Level) -> Self {
		self.0.level_idc = value;
		self
	}

	pub fn frame_crop_offsets(mut self, top: u32, bottom: u32, left: u32, right: u32) -> Self {
		self.0.frame_cropping_flag = true;
		self.0.frame_crop_top_offset = top;
		self.0.frame_crop_bottom_offset = bottom;
		self.0.frame_crop_left_offset = left;
		self.0.frame_crop_right_offset = right;
		self
	}

	pub fn frame_crop(self, top: u32, bottom: u32, left: u32, right: u32) -> Self {
		let sub_width_c = if self.0.chroma_format_idc > 2 { 1 } else { 2 };
		let sub_height_c = if self.0.chroma_format_idc > 1 { 1 } else { 2 };

		let crop_unit_x = sub_width_c;
		let crop_unit_y = sub_height_c * (if self.0.frame_mbs_only_flag { 1 } else { 2 });

		self.frame_crop_offsets(
			top / crop_unit_y,
			bottom / crop_unit_y,
			left / crop_unit_x,
			right / crop_unit_x,
		)
	}

	pub fn resolution(mut self, width: u32, height: u32) -> Self {
		const MB_SIZE: u32 = 16;

		let mb_width = (width + MB_SIZE - 1) / MB_SIZE;
		let mb_height = (height + MB_SIZE - 1) / MB_SIZE;

		self.0.pic_width_in_mbs_minus1 = (mb_width - 1) as u16;
		self.0.pic_height_in_map_units_minus1 = (mb_height - 1) as u16;

		let compressed_width = mb_width * MB_SIZE;
		let compressed_height = mb_height * MB_SIZE;

		if compressed_width != width || compressed_height != height {
			self = self.frame_crop(0, compressed_height - height, 0, compressed_width - width);
		}

		self
	}

	pub fn chroma_format_idc(mut self, value: u8) -> Self {
		self.0.chroma_format_idc = value;
		self
	}

	pub fn max_num_ref_frames(mut self, value: u8) -> Self {
		self.0.max_num_ref_frames = value;
		self
	}

	pub fn frame_mbs_only_flag(mut self, value: bool) -> Self {
		self.0.frame_mbs_only_flag = value;
		self
	}

	pub fn mb_adaptive_frame_field_flag(mut self, value: bool) -> Self {
		self.0.mb_adaptive_frame_field_flag = value;
		self
	}

	pub fn seq_scaling_matrix_present_flag(mut self, value: bool) -> Self {
		self.0.seq_scaling_matrix_present_flag = value;
		self
	}

	pub fn direct_8x8_inference_flag(mut self, value: bool) -> Self {
		self.0.direct_8x8_inference_flag = value;
		self
	}

	pub fn vui_parameters_present(mut self) -> Self {
		if self.0.vui_parameters_present_flag {
			return self;
		}

		self.0.vui_parameters_present_flag = true;
		// Disable all options at default
		self.0.vui_parameters.aspect_ratio_info_present_flag = false;
		self.0.vui_parameters.overscan_info_present_flag = false;
		self.0.vui_parameters.video_signal_type_present_flag = false;
		self.0.vui_parameters.colour_description_present_flag = false;
		self.0.vui_parameters.chroma_loc_info_present_flag = false;
		self.0.vui_parameters.timing_info_present_flag = false;
		self.0.vui_parameters.nal_hrd_parameters_present_flag = false;
		self.0.vui_parameters.vcl_hrd_parameters_present_flag = false;
		self.0.vui_parameters.pic_struct_present_flag = false;
		self.0.vui_parameters.bitstream_restriction_flag = false;
		self
	}

	pub fn aspect_ratio_idc(mut self, value: u8) -> Self {
		self = self.vui_parameters_present();
		self.0.vui_parameters.aspect_ratio_info_present_flag = true;
		self.0.vui_parameters.aspect_ratio_idc = value;
		self
	}

	pub fn sar_resolution(mut self, width: u16, height: u16) -> Self {
		self = self.aspect_ratio_idc(255);
		self.0.vui_parameters.sar_width = width;
		self.0.vui_parameters.sar_height = height;
		self
	}

	pub fn aspect_ratio(self, width_ratio: u16, height_ratio: u16) -> Self {
		// H.264 Table E-1
		match (width_ratio, height_ratio) {
			(1, 1) => self.aspect_ratio_idc(1),
			(12, 11) => self.aspect_ratio_idc(2),
			(10, 11) => self.aspect_ratio_idc(3),
			(16, 11) => self.aspect_ratio_idc(4),
			(40, 33) => self.aspect_ratio_idc(5),
			(24, 11) => self.aspect_ratio_idc(6),
			(20, 11) => self.aspect_ratio_idc(7),
			(32, 11) => self.aspect_ratio_idc(8),
			(80, 33) => self.aspect_ratio_idc(9),
			(18, 11) => self.aspect_ratio_idc(10),
			(15, 11) => self.aspect_ratio_idc(11),
			(64, 33) => self.aspect_ratio_idc(12),
			(160, 99) => self.aspect_ratio_idc(13),
			(4, 3) => self.aspect_ratio_idc(14),
			(3, 2) => self.aspect_ratio_idc(15),
			(2, 1) => self.aspect_ratio_idc(16),

			_ => self.sar_resolution(width_ratio, height_ratio),
		}
	}

	pub fn timing_info(mut self, num_units_in_tick: u32, time_scale: u32, fixed_frame_rate_flag: bool) -> Self {
		self = self.vui_parameters_present();
		self.0.vui_parameters.timing_info_present_flag = true;
		self.0.vui_parameters.num_units_in_tick = num_units_in_tick;
		self.0.vui_parameters.time_scale = time_scale;
		self.0.vui_parameters.fixed_frame_rate_flag = fixed_frame_rate_flag;
		self
	}

	/// Labels the stream's color space in the VUI.
	///
	/// `video_format` goes out as 5 (unspecified), the value a decoder infers
	/// when the field is absent, so this only adds the range and the color
	/// description.
	pub fn video_signal_type(
		mut self,
		full_range: bool,
		colour_primaries: u8,
		transfer_characteristics: u8,
		matrix_coefficients: u8,
	) -> Self {
		self = self.vui_parameters_present();
		self.0.vui_parameters.video_signal_type_present_flag = true;
		self.0.vui_parameters.video_format = 5;
		self.0.vui_parameters.video_full_range_flag = full_range;
		self.0.vui_parameters.colour_description_present_flag = true;
		self.0.vui_parameters.colour_primaries = colour_primaries;
		self.0.vui_parameters.transfer_characteristics = transfer_characteristics;
		self.0.vui_parameters.matrix_coefficients = matrix_coefficients;
		self
	}

	pub fn bitstream_restrictions_present(mut self) -> Self {
		if self.0.vui_parameters.bitstream_restriction_flag {
			return self;
		}
		self = self.vui_parameters_present();
		// important to set these before setting the restriction flag as max_num_order_frames
		// only produces the default values we need when that flag is false
		self.0.vui_parameters.max_num_reorder_frames = self.0.max_num_order_frames();
		self.0.vui_parameters.max_dec_frame_buffering = self.0.vui_parameters.max_num_reorder_frames;
		self.0.vui_parameters.bitstream_restriction_flag = true;
		// Set all restrictions to the defaults
		self.0.vui_parameters.motion_vectors_over_pic_boundaries_flag = true;
		self.0.vui_parameters.max_bytes_per_pic_denom = 2;
		self.0.vui_parameters.max_bits_per_mb_denom = 1;
		self.0.vui_parameters.log2_max_mv_length_horizontal = 16;
		self.0.vui_parameters.log2_max_mv_length_vertical = 16;
		self
	}

	pub fn max_num_reorder_frames(mut self, value: u32) -> Self {
		self = self.bitstream_restrictions_present();
		self.0.vui_parameters.max_num_reorder_frames = value;
		self
	}

	pub fn max_dec_frame_buffering(mut self, value: u32) -> Self {
		self = self.bitstream_restrictions_present();
		self.0.vui_parameters.max_dec_frame_buffering = value;
		self
	}

	pub fn log2_max_frame_num_minus4(mut self, value: u8) -> Self {
		self.0.log2_max_frame_num_minus4 = value;
		self
	}

	pub fn max_frame_num(self, value: u32) -> Self {
		self.log2_max_frame_num_minus4(value.ilog2() as u8 - 4u8)
	}

	pub fn pic_order_cnt_type(mut self, value: u8) -> Self {
		self.0.pic_order_cnt_type = value;
		self
	}

	pub fn log2_max_pic_order_cnt_lsb_minus4(mut self, value: u8) -> Self {
		self.0.log2_max_pic_order_cnt_lsb_minus4 = value;
		self
	}

	pub fn max_pic_order_cnt_lsb(self, value: u32) -> Self {
		self.log2_max_pic_order_cnt_lsb_minus4(value.ilog2() as u8 - 4u8)
	}

	pub fn delta_pic_order_always_zero_flag(mut self, value: bool) -> Self {
		self.0.delta_pic_order_always_zero_flag = value;
		self
	}

	pub fn bit_depth_chroma_minus8(mut self, value: u8) -> Self {
		self.0.bit_depth_chroma_minus8 = value;
		self
	}

	pub fn bit_depth_chroma(self, value: u8) -> Self {
		self.bit_depth_luma_minus8(value - 8u8)
	}

	pub fn bit_depth_luma_minus8(mut self, value: u8) -> Self {
		self.0.bit_depth_luma_minus8 = value;
		self
	}

	pub fn bit_depth_luma(self, value: u8) -> Self {
		self.bit_depth_luma_minus8(value - 8u8)
	}

	pub fn build(self) -> Rc<Sps> {
		Rc::new(self.0)
	}
}

#[derive(Clone, Debug, Default, PartialEq, Eq)]
pub struct HrdParams {
	/// Plus 1 specifies the number of alternative CPB specifications in the
	/// bitstream. The value of `cpb_cnt_minus1` shall be in the range of 0 to 31,
	/// inclusive
	pub cpb_cnt_minus1: u8,
	/// Together with `bit_rate_value_minus1[ SchedSelIdx ]` specifies the
	/// maximum input bit rate of the `SchedSelIdx`-th CPB.
	pub bit_rate_scale: u8,
	/// Together with `cpb_size_value_minus1[ SchedSelIdx ]` specifies the CPB
	/// size of the SchedSelIdx-th CPB.
	pub cpb_size_scale: u8,

	/// `[ SchedSelIdx ]` (together with bit_rate_scale) specifies the maximum
	/// input bit rate for the SchedSelIdx-th CPB.
	pub bit_rate_value_minus1: [u32; 32],
	/// `[ SchedSelIdx ]` is used together with cpb_size_scale to specify the
	/// SchedSelIdx-th CPB size.
	pub cpb_size_value_minus1: [u32; 32],
	/// `[ SchedSelIdx ]` equal to 0 specifies that to decode this bitstream by
	/// the HRD using the `SchedSelIdx`-th CPB specification, the hypothetical
	/// stream delivery scheduler (HSS) operates in an intermittent bit rate
	/// mode. `cbr_flag[ SchedSelIdx ]` equal to 1 specifies that the HSS operates
	/// in a constant bit rate (CBR) mode
	pub cbr_flag: [bool; 32],

	/// Specifies the length in bits of the `initial_cpb_removal_delay[
	/// SchedSelIdx ]` and `initial_cpb_removal_delay_offset[ SchedSelIdx ]` syntax
	/// elements of the buffering period SEI message.
	pub initial_cpb_removal_delay_length_minus1: u8,
	/// Specifies the length in bits of the `cpb_removal_delay` syntax element.
	pub cpb_removal_delay_length_minus1: u8,
	/// Specifies the length in bits of the `dpb_output_delay` syntax element.
	pub dpb_output_delay_length_minus1: u8,
	/// If greater than 0, specifies the length in bits of the `time_offset`
	/// syntax element. `time_offset_length` equal to 0 specifies that the
	/// `time_offset` syntax element is not present
	pub time_offset_length: u8,
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct VuiParams {
	/// Specifies whether `aspect_ratio_idc` is present.
	pub aspect_ratio_info_present_flag: bool,
	/// Specifies the value of the sample aspect ratio of the luma samples.
	/// Table E-1 shows the meaning of the code. When aspect_ratio_idc indicates
	/// Extended_SAR, the sample aspect ratio is represented by sar_width :
	/// sar_height. When the aspect_ratio_idc syntax element is not present,
	/// aspect_ratio_idc value shall be inferred to be equal to 0
	pub aspect_ratio_idc: u8,

	/* if aspect_ratio_idc == 255 */
	/// Indicates the horizontal size of the sample aspect ratio (in arbitrary
	/// units)
	pub sar_width: u16,
	/// Indicates the vertical size of the sample aspect ratio (in the same
	/// arbitrary units as sar_width).
	pub sar_height: u16,

	/// If true specifies that the overscan_appropriate_flag is present. Else,
	/// the preferred display method for the video signal is unspecified
	pub overscan_info_present_flag: bool,
	/* if overscan_info_present_flag */
	/// If true, indicates that the cropped decoded pictures output are suitable
	/// for display using overscan. Else, indicates that the cropped decoded
	/// pictures output contain visually important information in the entire
	/// region out to the edges of the cropping rectangle of the picture, such
	/// that the cropped decoded pictures output should not be displayed using
	/// overscan.
	pub overscan_appropriate_flag: bool,

	/// Specifies that video_format, video_full_range_flag and
	/// colour_description_present_flag are present
	pub video_signal_type_present_flag: bool,
	/// Indicates the representation of the pictures as specified in Table E-2,
	/// before being coded in accordance with this Recommendation |
	/// International Standard. When the video_format syntax element is not
	/// present, video_format value shall be inferred to be equal to 5.
	pub video_format: u8,
	/// Indicates the black level and range of the luma and chroma signals as
	/// derived from E′Y, E′PB, and E′PR or E′ R, E′G, and E′B real-valued
	/// component signals.
	pub video_full_range_flag: bool,
	/// Specifies that colour_primaries, transfer_characteristics and
	/// matrix_coefficients are present.
	pub colour_description_present_flag: bool,
	/// Indicates the chromaticity coordinates of the source primaries as
	/// specified in Table E-3 in terms of the CIE 1931 definition of x and y as
	/// specified by ISO 11664-1.
	pub colour_primaries: u8,
	/// Retains same meaning as in the specification.
	pub transfer_characteristics: u8,
	/// Describes the matrix coefficients used in deriving luma and chroma
	/// signals from the green, blue, and red, or Y, Z, and X primaries, as
	/// specified in Table E-5.
	pub matrix_coefficients: u8,

	/// Specifies that chroma_sample_loc_type_top_field and
	/// chroma_sample_loc_type_bottom_field are present
	pub chroma_loc_info_present_flag: bool,
	/// Specify the location of chroma samples. See the spec for more details.
	pub chroma_sample_loc_type_top_field: u8,
	/// Specify the location of chroma samples. See the spec for more details.
	pub chroma_sample_loc_type_bottom_field: u8,

	/// Specifies that num_units_in_tick, time_scale and fixed_frame_rate_flag
	/// are present in the bitstream
	pub timing_info_present_flag: bool,
	/* if timing_info_present_flag */
	/// The number of time units of a clock operating at the frequency
	/// time_scale Hz that corresponds to one increment (called a clock tick) of
	/// a clock tick counter
	pub num_units_in_tick: u32,
	/// The number of time units that pass in one second. For example, a time
	/// coordinate system that measures time using a 27 MHz clock has a
	/// time_scale of 27 000 000. time_scale shall be greater than 0.
	pub time_scale: u32,
	/// Retains the same meaning as the specification.
	pub fixed_frame_rate_flag: bool,

	/// Specifies that NAL HRD parameters (pertaining to Type II bitstream
	/// conformance) are present.
	pub nal_hrd_parameters_present_flag: bool,
	/* if nal_hrd_parameters_present_flag */
	/// The NAL HDR parameters
	pub nal_hrd_parameters: HrdParams,
	/// Specifies that VCL HRD parameters (pertaining to all bitstream
	/// conformance) are present.
	pub vcl_hrd_parameters_present_flag: bool,
	/* if vcl_hrd_parameters_present_flag */
	/// The VCL HRD parameters
	pub vcl_hrd_parameters: HrdParams,

	/// Specifies the HRD operational mode as specified in Annex C.
	pub low_delay_hrd_flag: bool,

	/// Specifies that picture timing SEI messages (clause D.2.3) are present
	/// that include the pic_struct syntax element.
	pub pic_struct_present_flag: bool,

	/// Specifies that the following coded video sequence bitstream restriction
	/// parameters are present
	pub bitstream_restriction_flag: bool,
	/*  if bitstream_restriction_flag */
	/// If false, indicates that no sample outside the picture boundaries and no
	/// sample at a fractional sample position for which the sample value is
	/// derived using one or more samples outside the picture boundaries is used
	/// for inter prediction of any sample. If true, indicates that one or more
	/// samples outside picture boundaries may be used in inter prediction. When
	/// the motion_vectors_over_pic_boundaries_flag syntax element is not
	/// present, motion_vectors_over_pic_boundaries_flag value shall be inferred
	/// to be true.
	pub motion_vectors_over_pic_boundaries_flag: bool,
	/// Indicates a number of bytes not exceeded by the sum of the sizes of the
	/// VCL NAL units associated with any coded picture in the coded video
	/// sequence.
	pub max_bytes_per_pic_denom: u32,
	/// Indicates an upper bound for the number of coded bits of
	/// macroblock_layer( ) data for any macroblock in any picture of the coded
	/// video sequence
	pub max_bits_per_mb_denom: u32,
	/// Retains the same meaning as the specification.
	pub log2_max_mv_length_horizontal: u32,
	/// Retains the same meaning as the specification.
	pub log2_max_mv_length_vertical: u32,
	/// Indicates an upper bound for the number of frames buffers, in the
	/// decoded picture buffer (DPB), that are required for storing frames,
	/// complementary field pairs, and non-paired fields before output. It is a
	/// requirement of bitstream conformance that the maximum number of frames,
	/// complementary field pairs, or non-paired fields that precede any frame,
	/// complementary field pair, or non-paired field in the coded video
	/// sequence in decoding order and follow it in output order shall be less
	/// than or equal to max_num_reorder_frames. The value of
	/// max_num_reorder_frames shall be in the range of 0 to
	/// max_dec_frame_buffering, inclusive.
	///
	/// When the max_num_reorder_frames syntax element is not present, the value
	/// of max_num_reorder_frames value shall be inferred as follows:
	/// If profile_idc is equal to 44, 86, 100, 110, 122, or 244 and
	/// constraint_set3_flag is equal to 1, the value of max_num_reorder_frames
	/// shall be inferred to be equal to 0.
	///
	/// Otherwise (profile_idc is not equal to 44, 86, 100, 110, 122, or 244 or
	/// constraint_set3_flag is equal to 0), the value of max_num_reorder_frames
	/// shall be inferred to be equal to MaxDpbFrames.
	pub max_num_reorder_frames: u32,
	/// Specifies the required size of the HRD decoded picture buffer (DPB) in
	/// units of frame buffers. It is a requirement of bitstream conformance
	/// that the coded video sequence shall not require a decoded picture buffer
	/// with size of more than Max( 1, max_dec_frame_buffering ) frame buffers
	/// to enable the output of decoded pictures at the output times specified
	/// by dpb_output_delay of the picture timing SEI messages. The value of
	/// max_dec_frame_buffering shall be greater than or equal to
	/// max_num_ref_frames. An upper bound for the value of
	/// max_dec_frame_buffering is specified by the level limits in clauses
	/// A.3.1, A.3.2, G.10.2.1, and H.10.2.
	///
	/// When the max_dec_frame_buffering syntax element is not present, the
	/// value of max_dec_frame_buffering shall be inferred as follows:
	///
	/// If profile_idc is equal to 44, 86, 100, 110, 122, or 244 and
	/// constraint_set3_flag is equal to 1, the value of max_dec_frame_buffering
	/// shall be inferred to be equal to 0.
	///
	/// Otherwise (profile_idc is not equal to 44, 86, 100, 110, 122, or 244 or
	/// constraint_set3_flag is equal to 0), the value of
	/// max_dec_frame_buffering shall be inferred to be equal to MaxDpbFrames.
	pub max_dec_frame_buffering: u32,
}

impl Default for VuiParams {
	fn default() -> Self {
		Self {
			aspect_ratio_info_present_flag: Default::default(),
			aspect_ratio_idc: Default::default(),
			sar_width: Default::default(),
			sar_height: Default::default(),
			overscan_info_present_flag: Default::default(),
			overscan_appropriate_flag: Default::default(),
			video_signal_type_present_flag: Default::default(),
			video_format: 5,
			video_full_range_flag: Default::default(),
			colour_description_present_flag: Default::default(),
			colour_primaries: 2,
			transfer_characteristics: 2,
			matrix_coefficients: 2,
			chroma_loc_info_present_flag: Default::default(),
			chroma_sample_loc_type_top_field: Default::default(),
			chroma_sample_loc_type_bottom_field: Default::default(),
			timing_info_present_flag: Default::default(),
			num_units_in_tick: Default::default(),
			time_scale: Default::default(),
			fixed_frame_rate_flag: Default::default(),
			nal_hrd_parameters_present_flag: Default::default(),
			nal_hrd_parameters: Default::default(),
			vcl_hrd_parameters_present_flag: Default::default(),
			vcl_hrd_parameters: Default::default(),
			low_delay_hrd_flag: Default::default(),
			pic_struct_present_flag: Default::default(),
			bitstream_restriction_flag: Default::default(),
			motion_vectors_over_pic_boundaries_flag: Default::default(),
			max_bytes_per_pic_denom: Default::default(),
			max_bits_per_mb_denom: Default::default(),
			log2_max_mv_length_horizontal: Default::default(),
			log2_max_mv_length_vertical: Default::default(),
			max_num_reorder_frames: Default::default(),
			max_dec_frame_buffering: Default::default(),
		}
	}
}

/// A H264 Picture Parameter Set. A syntax structure containing syntax elements
/// that apply to zero or more entire coded pictures as determined by the
/// `pic_parameter_set_id` syntax element found in each slice header.
#[derive(Debug, PartialEq, Eq)]
pub struct Pps {
	/// Identifies the picture parameter set that is referred to in the slice header.
	pub pic_parameter_set_id: u8,

	/// Refers to the active sequence parameter set.
	pub seq_parameter_set_id: u8,

	/// Selects the entropy decoding method to be applied for the syntax
	/// elements for which two descriptors appear in the syntax tables as
	/// follows: If `entropy_coding_mode_flag` is false, the method specified by
	/// the left descriptor in the syntax table is applied (Exp-Golomb coded,
	/// see clause 9.1 or CAVLC, see clause 9.2). Otherwise
	/// (`entropy_coding_mode_flag` is true), the method specified by the right
	/// descriptor in the syntax table is applied (CABAC, see clause 9.3).
	pub entropy_coding_mode_flag: bool,

	/// If true, specifies that the syntax elements delta_pic_order_cnt_bottom
	/// (when `pic_order_cnt_type` is equal to 0) or `delta_pic_order_cnt[1]`
	/// (when `pic_order_cnt_type` is equal to 1), which are related to picture
	/// order counts for the bottom field of a coded frame, are present in the
	/// slice headers for coded frames as specified in clause 7.3.3. Otherwise,
	/// specifies that the syntax elements `delta_pic_order_cnt_bottom` and
	/// `delta_pic_order_cnt[1]` are not present in the slice headers.
	pub bottom_field_pic_order_in_frame_present_flag: bool,

	/// Plus 1 specifies the number of slice groups for a picture. When
	/// `num_slice_groups_minus1` is equal to 0, all slices of the picture
	/// belong to the same slice group. The allowed range of
	/// `num_slice_groups_minus1` is specified in Annex A.
	pub num_slice_groups_minus1: u32,

	/// Specifies how `num_ref_idx_l0_active_minus1` is inferred for P, SP, and
	/// B slices with `num_ref_idx_active_override_flag` not set.
	pub num_ref_idx_l0_default_active_minus1: u8,

	/// Specifies how `num_ref_idx_l1_active_minus1` is inferred for B slices
	/// with `num_ref_idx_active_override_flag` not set.
	pub num_ref_idx_l1_default_active_minus1: u8,

	/// If not set, specifies that the default weighted prediction shall be
	/// applied to P and SP slices. If set, specifies that explicit weighted
	/// prediction shall be applied to P and SP slices.
	pub weighted_pred_flag: bool,

	/// `weighted_bipred_idc` equal to 0 specifies that the default weighted
	/// prediction shall be applied to B slices. `weighted_bipred_idc` equal to
	/// 1 specifies that explicit weighted prediction shall be applied to B
	/// slices. `weighted_bipred_idc` equal to 2 specifies that implicit
	/// weighted prediction shall be applied to B slices
	pub weighted_bipred_idc: u8,

	/// Specifies the initial value minus 26 of SliceQPY for each slice. The
	/// initial value is modified at the slice layer when a non-zero value of
	/// `slice_qp_delta` is decoded, and is modified further when a non-zero
	/// value of `mb_qp_delta` is decoded at the macroblock layer.
	pub pic_init_qp_minus26: i8,

	/// Specifies the initial value minus 26 of SliceQSY for all macroblocks in
	/// SP or SI slices. The initial value is modified at the slice layer when a
	/// non-zero value of `slice_qs_delta` is decoded.
	pub pic_init_qs_minus26: i8,

	/// Specifies the offset that shall be added to QP Y and QSY for addressing
	/// the table of QPC values for the Cb chroma component.
	pub chroma_qp_index_offset: i8,

	/// If set, specifies that a set of syntax elements controlling the
	/// characteristics of the deblocking filter is present in the slice header.
	/// If not set, specifies that the set of syntax elements controlling the
	/// characteristics of the deblocking filter is not present in the slice
	/// headers and their inferred values are in effect.
	pub deblocking_filter_control_present_flag: bool,

	/// If not set, specifies that intra prediction allows usage of residual
	/// data and decoded samples of neighbouring macroblocks coded using Inter
	/// macroblock prediction modes for the prediction of macroblocks coded
	/// using Intra macroblock prediction modes. If set, specifies constrained
	/// intra prediction, in which case prediction of macroblocks coded using
	/// Intra macroblock prediction modes only uses residual data and decoded
	/// samples from I or SI macroblock types.
	pub constrained_intra_pred_flag: bool,

	/// If not set, specifies that the `redundant_pic_cnt` syntax element is not
	/// present in slice headers, coded slice data partition B NAL units, and
	/// coded slice data partition C NAL units that refer (either directly or by
	/// association with a corresponding coded slice data partition A NAL unit)
	/// to the picture parameter set. If set, specifies that the
	/// `redundant_pic_cnt` syntax element is present in all slice headers,
	/// coded slice data partition B NAL units, and coded slice data partition C
	/// NAL units that refer (either directly or by association with a
	/// corresponding coded slice data partition A NAL unit) to the picture
	/// parameter set.
	pub redundant_pic_cnt_present_flag: bool,

	/// If set, specifies that the 8x8 transform decoding process may be in use
	/// (see clause 8.5). If not set, specifies that the 8x8 transform decoding
	/// process is not in use.
	pub transform_8x8_mode_flag: bool,

	///  If set, specifies that parameters are present to modify the scaling
	///  lists specified in the sequence parameter set. If not set, specifies
	///  that the scaling lists used for the picture shall be inferred to be
	///  equal to those specified by the sequence parameter set.
	pub pic_scaling_matrix_present_flag: bool,

	/// 4x4 Scaling list as read with 7.3.2.1.1.1
	pub scaling_lists_4x4: [[u8; 16]; 6],
	/// 8x8 Scaling list as read with 7.3.2.1.1.1
	pub scaling_lists_8x8: [[u8; 64]; 6],

	/// Specifies the offset that shall be added to QPY and QSY for addressing
	/// the table of QPC values for the Cr chroma component. When
	/// `second_chroma_qp_index_offset` is not present, it shall be inferred to be
	/// equal to `chroma_qp_index_offset`.
	pub second_chroma_qp_index_offset: i8,

	/// The SPS referenced by this PPS.
	pub sps: Rc<Sps>,
}

pub struct PpsBuilder(Pps);

impl PpsBuilder {
	pub fn new(sps: Rc<Sps>) -> Self {
		PpsBuilder(Pps {
			pic_parameter_set_id: 0,
			seq_parameter_set_id: sps.seq_parameter_set_id,
			entropy_coding_mode_flag: false,
			bottom_field_pic_order_in_frame_present_flag: false,
			num_slice_groups_minus1: 0,
			num_ref_idx_l0_default_active_minus1: 0,
			num_ref_idx_l1_default_active_minus1: 0,
			weighted_pred_flag: false,
			weighted_bipred_idc: 0,
			pic_init_qp_minus26: 0,
			pic_init_qs_minus26: 0,
			chroma_qp_index_offset: 0,
			deblocking_filter_control_present_flag: false,
			constrained_intra_pred_flag: false,
			redundant_pic_cnt_present_flag: false,
			transform_8x8_mode_flag: false,
			pic_scaling_matrix_present_flag: false,
			scaling_lists_4x4: [[0; 16]; 6],
			scaling_lists_8x8: [[0; 64]; 6],
			second_chroma_qp_index_offset: 0,
			sps,
		})
	}

	pub fn pic_parameter_set_id(mut self, value: u8) -> Self {
		self.0.pic_parameter_set_id = value;
		self
	}

	pub fn pic_init_qp_minus26(mut self, value: i8) -> Self {
		self.0.pic_init_qp_minus26 = value;
		self
	}

	pub fn pic_init_qp(self, value: u8) -> Self {
		self.pic_init_qp_minus26(value as i8 - 26)
	}

	pub fn entropy_coding_mode_flag(mut self, value: bool) -> Self {
		self.0.entropy_coding_mode_flag = value;
		self
	}

	pub fn transform_8x8_mode_flag(mut self, value: bool) -> Self {
		self.0.transform_8x8_mode_flag = value;
		self
	}

	pub fn deblocking_filter_control_present_flag(mut self, value: bool) -> Self {
		self.0.deblocking_filter_control_present_flag = value;
		self
	}

	pub fn num_ref_idx_l0_default_active_minus1(mut self, value: u8) -> Self {
		self.0.num_ref_idx_l0_default_active_minus1 = value;
		self
	}

	pub fn num_ref_idx_l0_default_active(self, value: u8) -> Self {
		self.num_ref_idx_l0_default_active_minus1(value - 1)
	}

	pub fn num_ref_idx_l1_default_active_minus1(mut self, value: u8) -> Self {
		self.0.num_ref_idx_l1_default_active_minus1 = value;
		self
	}

	pub fn num_ref_idx_l1_default_active(self, value: u8) -> Self {
		self.num_ref_idx_l1_default_active_minus1(value - 1)
	}

	pub fn build(self) -> Rc<Pps> {
		Rc::new(self.0)
	}
}

#[derive(Debug, Default)]
pub struct Parser {
	active_spses: BTreeMap<u8, Rc<Sps>>,
	active_ppses: BTreeMap<u8, Rc<Pps>>,
}

impl Parser {
	fn fill_default_scaling_list_4x4(scaling_list4x4: &mut [u8; 16], i: usize) {
		// See table 7.2 in the spec.
		assert!(i < 6);
		if i < 3 {
			*scaling_list4x4 = DEFAULT_4X4_INTRA;
		} else if i < 6 {
			*scaling_list4x4 = DEFAULT_4X4_INTER;
		}
	}

	fn fill_default_scaling_list_8x8(scaling_list8x8: &mut [u8; 64], i: usize) {
		assert!(i < 6);
		if i % 2 == 0 {
			*scaling_list8x8 = DEFAULT_8X8_INTRA;
		} else {
			*scaling_list8x8 = DEFAULT_8X8_INTER;
		}
	}

	fn fill_fallback_scaling_list_4x4(
		scaling_list4x4: &mut [[u8; 16]; 6],
		i: usize,
		default_scaling_list_intra: &[u8; 16],
		default_scaling_list_inter: &[u8; 16],
	) {
		// See table 7.2 in the spec.
		scaling_list4x4[i] = match i {
			0 => *default_scaling_list_intra,
			1 => scaling_list4x4[0],
			2 => scaling_list4x4[1],
			3 => *default_scaling_list_inter,
			4 => scaling_list4x4[3],
			5 => scaling_list4x4[4],
			_ => panic!("Unexpected value {}", i),
		}
	}

	fn fill_fallback_scaling_list_8x8(
		scaling_list8x8: &mut [[u8; 64]; 6],
		i: usize,
		default_scaling_list_intra: &[u8; 64],
		default_scaling_list_inter: &[u8; 64],
	) {
		// See table 7.2 in the spec.
		scaling_list8x8[i] = match i {
			0 => *default_scaling_list_intra,
			1 => *default_scaling_list_inter,
			2 => scaling_list8x8[0],
			3 => scaling_list8x8[1],
			4 => scaling_list8x8[2],
			5 => scaling_list8x8[3],
			_ => panic!("Unexpected value {}", i),
		}
	}

	fn fill_scaling_list_flat(scaling_list4x4: &mut [[u8; 16]; 6], scaling_list8x8: &mut [[u8; 64]; 6]) {
		// (7-8) in the spec.
		for outer in scaling_list4x4 {
			for inner in outer {
				*inner = 16;
			}
		}

		// (7-9) in the spec.
		for outer in scaling_list8x8 {
			for inner in outer {
				*inner = 16;
			}
		}
	}

	fn parse_scaling_list<U: AsMut<[u8]>>(
		r: &mut BitReader,
		scaling_list: &mut U,
		use_default: &mut bool,
	) -> Result<(), String> {
		// 7.3.2.1.1.1
		let mut last_scale = 8u8;
		let mut next_scale = 8u8;

		for j in 0..scaling_list.as_mut().len() {
			if next_scale != 0 {
				let delta_scale = r.read_se::<i32>()?;
				next_scale = ((last_scale as i32 + delta_scale + 256) % 256) as u8;
				*use_default = j == 0 && next_scale == 0;
				if *use_default {
					return Ok(());
				}
			}

			scaling_list.as_mut()[j] = if next_scale == 0 { last_scale } else { next_scale };

			last_scale = scaling_list.as_mut()[j];
		}

		Ok(())
	}

	fn parse_sps_scaling_lists(r: &mut BitReader, sps: &mut Sps) -> Result<(), String> {
		let scaling_lists4x4 = &mut sps.scaling_lists_4x4;
		let scaling_lisst8x8 = &mut sps.scaling_lists_8x8;

		// Parse scaling_list4x4
		for i in 0..6 {
			let seq_scaling_list_present_flag = r.read_bit()?;
			if seq_scaling_list_present_flag {
				let mut use_default = false;

				Parser::parse_scaling_list(r, &mut scaling_lists4x4[i], &mut use_default)?;

				if use_default {
					Parser::fill_default_scaling_list_4x4(&mut scaling_lists4x4[i], i);
				}
			} else {
				Parser::fill_fallback_scaling_list_4x4(scaling_lists4x4, i, &DEFAULT_4X4_INTRA, &DEFAULT_4X4_INTER);
			}
		}

		// Parse scaling_list8x8
		let num_8x8 = if sps.chroma_format_idc != 3 { 2 } else { 6 };
		for i in 0..num_8x8 {
			let seq_scaling_list_present_flag = r.read_bit()?;
			if seq_scaling_list_present_flag {
				let mut use_default = false;
				Parser::parse_scaling_list(r, &mut scaling_lisst8x8[i], &mut use_default)?;

				if use_default {
					Parser::fill_default_scaling_list_8x8(&mut scaling_lisst8x8[i], i);
				}
			} else {
				Parser::fill_fallback_scaling_list_8x8(scaling_lisst8x8, i, &DEFAULT_8X8_INTRA, &DEFAULT_8X8_INTER);
			}
		}
		Ok(())
	}

	fn parse_pps_scaling_lists(r: &mut BitReader, pps: &mut Pps, sps: &Sps) -> Result<(), String> {
		let scaling_lists4x4 = &mut pps.scaling_lists_4x4;
		let scaling_lists8x8 = &mut pps.scaling_lists_8x8;

		for i in 0..6 {
			let pic_scaling_list_present_flag = r.read_bit()?;
			if pic_scaling_list_present_flag {
				let mut use_default = false;

				Parser::parse_scaling_list(r, &mut scaling_lists4x4[i], &mut use_default)?;

				if use_default {
					Parser::fill_default_scaling_list_4x4(&mut scaling_lists4x4[i], i);
				}
			} else if !sps.seq_scaling_matrix_present_flag {
				// Table 7-2: Fallback rule A
				Parser::fill_fallback_scaling_list_4x4(scaling_lists4x4, i, &DEFAULT_4X4_INTRA, &DEFAULT_4X4_INTER);
			} else {
				// Table 7-2: Fallback rule B
				Parser::fill_fallback_scaling_list_4x4(
					scaling_lists4x4,
					i,
					&sps.scaling_lists_4x4[0],
					&sps.scaling_lists_4x4[3],
				);
			}
		}

		if pps.transform_8x8_mode_flag {
			let num8x8 = if sps.chroma_format_idc != 3 { 2 } else { 6 };

			for i in 0..num8x8 {
				let pic_scaling_list_present_flag = r.read_bit()?;
				if pic_scaling_list_present_flag {
					let mut use_default = false;

					Parser::parse_scaling_list(r, &mut scaling_lists8x8[i], &mut use_default)?;

					if use_default {
						Parser::fill_default_scaling_list_8x8(&mut scaling_lists8x8[i], i);
					}
				} else if !sps.seq_scaling_matrix_present_flag {
					// Table 7-2: Fallback rule A
					Parser::fill_fallback_scaling_list_8x8(scaling_lists8x8, i, &DEFAULT_8X8_INTRA, &DEFAULT_8X8_INTER);
				} else {
					// Table 7-2: Fallback rule B
					Parser::fill_fallback_scaling_list_8x8(
						scaling_lists8x8,
						i,
						&sps.scaling_lists_8x8[0],
						&sps.scaling_lists_8x8[1],
					);
				}
			}
		}

		Ok(())
	}

	fn parse_hrd(r: &mut BitReader, hrd: &mut HrdParams) -> Result<(), String> {
		hrd.cpb_cnt_minus1 = r.read_ue_max(31)?;
		hrd.bit_rate_scale = r.read_bits(4)?;
		hrd.cpb_size_scale = r.read_bits(4)?;

		for sched_sel_idx in 0..=usize::from(hrd.cpb_cnt_minus1) {
			hrd.bit_rate_value_minus1[sched_sel_idx] = r.read_ue()?;
			hrd.cpb_size_value_minus1[sched_sel_idx] = r.read_ue()?;
			hrd.cbr_flag[sched_sel_idx] = r.read_bit()?;
		}

		hrd.initial_cpb_removal_delay_length_minus1 = r.read_bits(5)?;
		hrd.cpb_removal_delay_length_minus1 = r.read_bits(5)?;
		hrd.dpb_output_delay_length_minus1 = r.read_bits(5)?;
		hrd.time_offset_length = r.read_bits(5)?;
		Ok(())
	}

	fn parse_vui(r: &mut BitReader, sps: &mut Sps) -> Result<(), String> {
		let vui = &mut sps.vui_parameters;

		vui.aspect_ratio_info_present_flag = r.read_bit()?;
		if vui.aspect_ratio_info_present_flag {
			vui.aspect_ratio_idc = r.read_bits(8)?;
			if vui.aspect_ratio_idc == 255 {
				vui.sar_width = r.read_bits(16)?;
				vui.sar_height = r.read_bits(16)?;
			}
		}

		vui.overscan_info_present_flag = r.read_bit()?;
		if vui.overscan_info_present_flag {
			vui.overscan_appropriate_flag = r.read_bit()?;
		}

		vui.video_signal_type_present_flag = r.read_bit()?;
		if vui.video_signal_type_present_flag {
			vui.video_format = r.read_bits(3)?;
			vui.video_full_range_flag = r.read_bit()?;
			vui.colour_description_present_flag = r.read_bit()?;
			if vui.colour_description_present_flag {
				vui.colour_primaries = r.read_bits(8)?;
				vui.transfer_characteristics = r.read_bits(8)?;
				vui.matrix_coefficients = r.read_bits(8)?;
			}
		}

		vui.chroma_loc_info_present_flag = r.read_bit()?;
		if vui.chroma_loc_info_present_flag {
			vui.chroma_sample_loc_type_top_field = r.read_ue_max(5)?;
			vui.chroma_sample_loc_type_bottom_field = r.read_ue_max(5)?;
		}

		vui.timing_info_present_flag = r.read_bit()?;
		if vui.timing_info_present_flag {
			vui.num_units_in_tick = r.read_bits::<u32>(31)? << 1;
			vui.num_units_in_tick |= r.read_bit()? as u32;
			if vui.num_units_in_tick == 0 {
				return Err("num_units_in_tick == 0, which is not allowed by E.2.1".into());
			}

			vui.time_scale = r.read_bits::<u32>(31)? << 1;
			vui.time_scale |= r.read_bit()? as u32;
			if vui.time_scale == 0 {
				return Err("time_scale == 0, which is not allowed by E.2.1".into());
			}

			vui.fixed_frame_rate_flag = r.read_bit()?;
		}

		vui.nal_hrd_parameters_present_flag = r.read_bit()?;
		if vui.nal_hrd_parameters_present_flag {
			Parser::parse_hrd(r, &mut vui.nal_hrd_parameters)?;
		}

		vui.vcl_hrd_parameters_present_flag = r.read_bit()?;
		if vui.vcl_hrd_parameters_present_flag {
			Parser::parse_hrd(r, &mut vui.vcl_hrd_parameters)?;
		}

		if vui.nal_hrd_parameters_present_flag || vui.vcl_hrd_parameters_present_flag {
			vui.low_delay_hrd_flag = r.read_bit()?;
		}

		vui.pic_struct_present_flag = r.read_bit()?;
		vui.bitstream_restriction_flag = r.read_bit()?;

		if vui.bitstream_restriction_flag {
			vui.motion_vectors_over_pic_boundaries_flag = r.read_bit()?;
			vui.max_bytes_per_pic_denom = r.read_ue()?;
			vui.max_bits_per_mb_denom = r.read_ue_max(16)?;
			vui.log2_max_mv_length_horizontal = r.read_ue_max(16)?;
			vui.log2_max_mv_length_vertical = r.read_ue_max(16)?;
			vui.max_num_reorder_frames = r.read_ue()?;
			vui.max_dec_frame_buffering = r.read_ue()?;
		}

		Ok(())
	}

	/// Parse a SPS and add it to the list of active SPSes.
	///
	/// Returns a reference to the new SPS.
	pub fn parse_sps(&mut self, nalu: &Nalu) -> Result<&Rc<Sps>, String> {
		if !matches!(nalu.header.type_, NaluType::Sps) {
			return Err(format!(
				"Invalid NALU type, expected {:?}, got {:?}",
				NaluType::Sps,
				nalu.header.type_
			));
		}

		let data = nalu.as_ref();
		// Skip the header
		let mut r = BitReader::new(&data[nalu.header.len()..], true);
		let mut sps = Sps {
			profile_idc: r.read_bits(8)?,
			constraint_set0_flag: r.read_bit()?,
			constraint_set1_flag: r.read_bit()?,
			constraint_set2_flag: r.read_bit()?,
			constraint_set3_flag: r.read_bit()?,
			constraint_set4_flag: r.read_bit()?,
			constraint_set5_flag: r.read_bit()?,
			..Default::default()
		};

		// skip reserved_zero_2bits
		r.skip_bits(2)?;

		let level: u8 = r.read_bits(8)?;
		sps.level_idc = Level::try_from(level)?;
		sps.seq_parameter_set_id = r.read_ue_max(31)?;

		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
			|| sps.profile_idc == 138
			|| sps.profile_idc == 139
			|| sps.profile_idc == 134
			|| sps.profile_idc == 135
		{
			sps.chroma_format_idc = r.read_ue_max(3)?;
			if sps.chroma_format_idc == 3 {
				sps.separate_colour_plane_flag = r.read_bit()?;
			}

			sps.bit_depth_luma_minus8 = r.read_ue_max(6)?;
			sps.bit_depth_chroma_minus8 = r.read_ue_max(6)?;
			sps.qpprime_y_zero_transform_bypass_flag = r.read_bit()?;
			sps.seq_scaling_matrix_present_flag = r.read_bit()?;

			if sps.seq_scaling_matrix_present_flag {
				Parser::parse_sps_scaling_lists(&mut r, &mut sps)?;
			} else {
				Parser::fill_scaling_list_flat(&mut sps.scaling_lists_4x4, &mut sps.scaling_lists_8x8);
			}
		} else {
			sps.chroma_format_idc = 1;
			Parser::fill_scaling_list_flat(&mut sps.scaling_lists_4x4, &mut sps.scaling_lists_8x8);
		}

		sps.log2_max_frame_num_minus4 = r.read_ue_max(12)?;

		sps.pic_order_cnt_type = r.read_ue_max(2)?;

		if sps.pic_order_cnt_type == 0 {
			sps.log2_max_pic_order_cnt_lsb_minus4 = r.read_ue_max(12)?;
			sps.expected_delta_per_pic_order_cnt_cycle = 0;
		} else if sps.pic_order_cnt_type == 1 {
			sps.delta_pic_order_always_zero_flag = r.read_bit()?;
			sps.offset_for_non_ref_pic = r.read_se()?;
			sps.offset_for_top_to_bottom_field = r.read_se()?;
			sps.num_ref_frames_in_pic_order_cnt_cycle = r.read_ue_max(254)?;

			let mut offset_acc = 0;
			for i in 0..usize::from(sps.num_ref_frames_in_pic_order_cnt_cycle) {
				sps.offset_for_ref_frame[i] = r.read_se()?;

				// (7-12) in the spec.
				offset_acc += sps.offset_for_ref_frame[i];
			}

			sps.expected_delta_per_pic_order_cnt_cycle = offset_acc;
		}

		sps.max_num_ref_frames = r.read_ue_max(DPB_MAX_SIZE as u32)?;
		sps.gaps_in_frame_num_value_allowed_flag = r.read_bit()?;
		sps.pic_width_in_mbs_minus1 = r.read_ue()?;
		sps.pic_height_in_map_units_minus1 = r.read_ue()?;
		sps.frame_mbs_only_flag = r.read_bit()?;

		if !sps.frame_mbs_only_flag {
			sps.mb_adaptive_frame_field_flag = r.read_bit()?;
		}

		sps.direct_8x8_inference_flag = r.read_bit()?;
		sps.frame_cropping_flag = r.read_bit()?;

		if sps.frame_cropping_flag {
			sps.frame_crop_left_offset = r.read_ue()?;
			sps.frame_crop_right_offset = r.read_ue()?;
			sps.frame_crop_top_offset = r.read_ue()?;
			sps.frame_crop_bottom_offset = r.read_ue()?;

			// Validate that cropping info is valid.
			let (crop_unit_x, crop_unit_y) = sps.crop_unit_x_y();

			let _ = sps
				.frame_crop_left_offset
				.checked_add(sps.frame_crop_right_offset)
				.and_then(|r| r.checked_mul(crop_unit_x))
				.and_then(|r| sps.width().checked_sub(r))
				.ok_or::<String>("Invalid frame crop width".into())?;

			let _ = sps
				.frame_crop_top_offset
				.checked_add(sps.frame_crop_bottom_offset)
				.and_then(|r| r.checked_mul(crop_unit_y))
				.and_then(|r| sps.height().checked_sub(r))
				.ok_or::<String>("invalid frame crop height".into())?;
		}

		sps.vui_parameters_present_flag = r.read_bit()?;
		if sps.vui_parameters_present_flag {
			Parser::parse_vui(&mut r, &mut sps)?;
		}

		let key = sps.seq_parameter_set_id;

		if self.active_spses.keys().len() >= MAX_SPS_COUNT as usize {
			return Err("Broken data: Number of active SPSs > MAX_SPS_COUNT".into());
		}

		let sps = Rc::new(sps);
		self.active_spses.remove(&key);
		Ok(self.active_spses.entry(key).or_insert(sps))
	}

	pub fn parse_pps(&mut self, nalu: &Nalu) -> Result<&Pps, String> {
		if !matches!(nalu.header.type_, NaluType::Pps) {
			return Err(format!(
				"Invalid NALU type, expected {:?}, got {:?}",
				NaluType::Pps,
				nalu.header.type_
			));
		}

		let data = nalu.as_ref();
		// Skip the header
		let mut r = BitReader::new(&data[nalu.header.len()..], true);
		let pic_parameter_set_id = r.read_ue_max(MAX_PPS_COUNT as u32 - 1)?;
		let seq_parameter_set_id = r.read_ue_max(MAX_SPS_COUNT as u32 - 1)?;
		let sps = self.get_sps(seq_parameter_set_id).ok_or::<String>(format!(
			"Could not get SPS for seq_parameter_set_id {}",
			seq_parameter_set_id
		))?;
		let mut pps = Pps {
			pic_parameter_set_id,
			seq_parameter_set_id,
			sps: Rc::clone(sps),
			scaling_lists_4x4: [[0; 16]; 6],
			scaling_lists_8x8: [[0; 64]; 6],
			entropy_coding_mode_flag: Default::default(),
			bottom_field_pic_order_in_frame_present_flag: Default::default(),
			num_slice_groups_minus1: Default::default(),
			num_ref_idx_l0_default_active_minus1: Default::default(),
			num_ref_idx_l1_default_active_minus1: Default::default(),
			weighted_pred_flag: Default::default(),
			weighted_bipred_idc: Default::default(),
			pic_init_qp_minus26: Default::default(),
			pic_init_qs_minus26: Default::default(),
			chroma_qp_index_offset: Default::default(),
			deblocking_filter_control_present_flag: Default::default(),
			constrained_intra_pred_flag: Default::default(),
			redundant_pic_cnt_present_flag: Default::default(),
			transform_8x8_mode_flag: Default::default(),
			second_chroma_qp_index_offset: Default::default(),
			pic_scaling_matrix_present_flag: Default::default(),
		};

		pps.entropy_coding_mode_flag = r.read_bit()?;
		pps.bottom_field_pic_order_in_frame_present_flag = r.read_bit()?;
		pps.num_slice_groups_minus1 = r.read_ue_max(7)?;

		if pps.num_slice_groups_minus1 > 0 {
			return Err("Stream contain unsupported/unimplemented NALs".into());
		}

		pps.num_ref_idx_l0_default_active_minus1 = r.read_ue_max(31)?;
		pps.num_ref_idx_l1_default_active_minus1 = r.read_ue_max(31)?;

		pps.weighted_pred_flag = r.read_bit()?;
		pps.weighted_bipred_idc = r.read_bits(2)?;

		let qp_bd_offset_y = i32::from(6 * (sps.bit_depth_luma_minus8));
		pps.pic_init_qp_minus26 = r.read_se_bounded(-(26 + qp_bd_offset_y), 25)?;
		pps.pic_init_qs_minus26 = r.read_se_bounded(-26, 25)?;

		pps.chroma_qp_index_offset = r.read_se_bounded(-12, 12)?;

		// When second_chroma_qp_index_offset is not present, it shall be
		// inferred to be equal to chroma_qp_index_offset.
		pps.second_chroma_qp_index_offset = pps.chroma_qp_index_offset;

		pps.deblocking_filter_control_present_flag = r.read_bit()?;
		pps.constrained_intra_pred_flag = r.read_bit()?;
		pps.redundant_pic_cnt_present_flag = r.read_bit()?;

		if r.has_more_rsbp_data() {
			pps.transform_8x8_mode_flag = r.read_bit()?;
			pps.pic_scaling_matrix_present_flag = r.read_bit()?;

			if pps.pic_scaling_matrix_present_flag {
				Parser::parse_pps_scaling_lists(&mut r, &mut pps, sps)?;
			}

			pps.second_chroma_qp_index_offset = r.read_se()?;
		}

		if !pps.pic_scaling_matrix_present_flag {
			// If not set, specifies that the scaling lists used for the picture
			// shall be inferred to be equal to those specified by the sequence
			// parameter set. When pic_scaling_matrix_present_flag is not
			// present, it shall be inferred to be not set.
			pps.scaling_lists_4x4 = sps.scaling_lists_4x4;
			pps.scaling_lists_8x8 = sps.scaling_lists_8x8;
		}

		let key = pps.pic_parameter_set_id;

		if self.active_ppses.keys().len() >= MAX_PPS_COUNT as usize {
			return Err("Broken Data: number of active PPSs > MAX_PPS_COUNT".into());
		}

		let pps = Rc::new(pps);
		self.active_ppses.remove(&key);
		Ok(self.active_ppses.entry(key).or_insert(pps))
	}

	fn parse_ref_pic_list_modification(
		r: &mut BitReader,
		num_ref_idx_active_minus1: u8,
		ref_list_mods: &mut Vec<RefPicListModification>,
	) -> Result<(), String> {
		if num_ref_idx_active_minus1 >= 32 {
			return Err("Broken Data: num_ref_idx_active_minus1 >= 32".into());
		}

		loop {
			let mut pic_num_mod = RefPicListModification {
				modification_of_pic_nums_idc: r.read_ue_max(3)?,
				..Default::default()
			};

			match pic_num_mod.modification_of_pic_nums_idc {
				0 | 1 => {
					pic_num_mod.abs_diff_pic_num_minus1 = r.read_ue()?;
				}

				2 => {
					pic_num_mod.long_term_pic_num = r.read_ue()?;
				}

				3 => {
					ref_list_mods.push(pic_num_mod);
					break;
				}

				_ => return Err("Broken Data: modification_of_pic_nums_idc > 3".into()),
			}

			ref_list_mods.push(pic_num_mod);
		}

		Ok(())
	}

	fn parse_ref_pic_list_modifications(r: &mut BitReader, header: &mut SliceHeader) -> Result<(), String> {
		if !header.slice_type.is_i() && !header.slice_type.is_si() {
			header.ref_pic_list_modification_flag_l0 = r.read_bit()?;
			if header.ref_pic_list_modification_flag_l0 {
				Parser::parse_ref_pic_list_modification(
					r,
					header.num_ref_idx_l0_active_minus1,
					&mut header.ref_pic_list_modification_l0,
				)?;
			}
		}

		if header.slice_type.is_b() {
			header.ref_pic_list_modification_flag_l1 = r.read_bit()?;
			if header.ref_pic_list_modification_flag_l1 {
				Parser::parse_ref_pic_list_modification(
					r,
					header.num_ref_idx_l1_active_minus1,
					&mut header.ref_pic_list_modification_l1,
				)?;
			}
		}

		Ok(())
	}

	fn parse_pred_weight_table(r: &mut BitReader, sps: &Sps, header: &mut SliceHeader) -> Result<(), String> {
		let pt = &mut header.pred_weight_table;
		pt.luma_log2_weight_denom = r.read_ue_max(7)?;

		// When luma_weight_l0_flag is equal to 0, luma_weight_l0[i] shall be
		// inferred to be equal to 2 ^ luma_log2_weight_denom for
		// RefPicList0[i].
		let default_luma_weight = 1 << pt.luma_log2_weight_denom;
		for i in 0..=header.num_ref_idx_l0_active_minus1 {
			pt.luma_weight_l0[usize::from(i)] = default_luma_weight;
		}

		// When luma_weight_l1_flag is equal to 1, luma_weight_l1[i] shall be
		// inferred to be equal to 2 ^ luma_log2_weight_denom for
		// RefPicList1[i].
		if header.slice_type.is_b() {
			for i in 0..=header.num_ref_idx_l1_active_minus1 {
				pt.luma_weight_l1[usize::from(i)] = default_luma_weight;
			}
		}

		if sps.chroma_array_type() != 0 {
			pt.chroma_log2_weight_denom = r.read_ue_max(7)?;
			let default_chroma_weight = 1 << pt.chroma_log2_weight_denom;

			// When chroma_weight_l0_flag is equal to 0, chroma_weight_l0[i]
			// shall be inferred to be equal to 2 ^ chroma_log2_weight_denom for
			// RefPicList0[i].
			for i in 0..=header.num_ref_idx_l0_active_minus1 {
				pt.chroma_weight_l0[usize::from(i)][0] = default_chroma_weight;
				pt.chroma_weight_l0[usize::from(i)][1] = default_chroma_weight;
			}

			// When chroma_weight_l1_flag is equal to 0, chroma_weight_l1[i]
			// shall be inferred to be equal to 2 ^ chroma_log2_weight_denom for
			// RefPicList1[i].
			for i in 0..=header.num_ref_idx_l1_active_minus1 {
				pt.chroma_weight_l1[usize::from(i)][0] = default_chroma_weight;
				pt.chroma_weight_l1[usize::from(i)][1] = default_chroma_weight;
			}
		}

		for i in 0..=header.num_ref_idx_l0_active_minus1 {
			let luma_weight_l0_flag = r.read_bit()?;

			if luma_weight_l0_flag {
				pt.luma_weight_l0[usize::from(i)] = r.read_se_bounded(-128, 127)?;
				pt.luma_offset_l0[usize::from(i)] = r.read_se_bounded(-128, 127)?;
			}

			if sps.chroma_array_type() != 0 {
				let chroma_weight_l0_flag = r.read_bit()?;
				if chroma_weight_l0_flag {
					for j in 0..2 {
						pt.chroma_weight_l0[usize::from(i)][j] = r.read_se_bounded(-128, 127)?;
						pt.chroma_offset_l0[usize::from(i)][j] = r.read_se_bounded(-128, 127)?;
					}
				}
			}
		}

		if header.slice_type.is_b() {
			for i in 0..=header.num_ref_idx_l1_active_minus1 {
				let luma_weight_l1_flag = r.read_bit()?;

				if luma_weight_l1_flag {
					pt.luma_weight_l1[usize::from(i)] = r.read_se_bounded(-128, 127)?;
					pt.luma_offset_l1[usize::from(i)] = r.read_se_bounded(-128, 127)?;
				}

				if sps.chroma_array_type() != 0 {
					let chroma_weight_l1_flag = r.read_bit()?;
					if chroma_weight_l1_flag {
						for j in 0..2 {
							pt.chroma_weight_l1[usize::from(i)][j] = r.read_se_bounded(-128, 127)?;
							pt.chroma_offset_l1[usize::from(i)][j] = r.read_se_bounded(-128, 127)?;
						}
					}
				}
			}
		}

		Ok(())
	}

	fn parse_dec_ref_pic_marking(r: &mut BitReader, nalu: &Nalu, header: &mut SliceHeader) -> Result<(), String> {
		let rpm = &mut header.dec_ref_pic_marking;

		let num_bits_left = r.num_bits_left();
		if nalu.header.idr_pic_flag {
			rpm.no_output_of_prior_pics_flag = r.read_bit()?;
			rpm.long_term_reference_flag = r.read_bit()?;
		} else {
			rpm.adaptive_ref_pic_marking_mode_flag = r.read_bit()?;

			if rpm.adaptive_ref_pic_marking_mode_flag {
				loop {
					let mut marking = RefPicMarkingInner::default();

					let mem_mgmt_ctrl_op = r.read_ue_max::<u8>(6)?;
					marking.memory_management_control_operation = mem_mgmt_ctrl_op;

					if mem_mgmt_ctrl_op == 0 {
						break;
					}

					if mem_mgmt_ctrl_op == 1 || mem_mgmt_ctrl_op == 3 {
						marking.difference_of_pic_nums_minus1 = r.read_ue()?;
					}

					if mem_mgmt_ctrl_op == 2 {
						marking.long_term_pic_num = r.read_ue()?;
					}

					if mem_mgmt_ctrl_op == 3 || mem_mgmt_ctrl_op == 6 {
						marking.long_term_frame_idx = r.read_ue()?;
					}

					if mem_mgmt_ctrl_op == 4 {
						marking.max_long_term_frame_idx = MaxLongTermFrameIdx::from_value_plus1(r.read_ue()?);
					}

					rpm.inner.push(marking);
				}
			}
		}
		header.dec_ref_pic_marking_bit_size = num_bits_left - r.num_bits_left();

		Ok(())
	}

	pub fn parse_slice_header<'a>(&self, nalu: Nalu<'a>) -> Result<Slice<'a>, String> {
		if !matches!(
			nalu.header.type_,
			NaluType::Slice
				| NaluType::SliceDpa
				| NaluType::SliceDpb
				| NaluType::SliceDpc
				| NaluType::SliceIdr
				| NaluType::SliceExt
		) {
			return Err(format!(
				"Invalid NALU type: {:?} is not a slice NALU",
				nalu.header.type_
			));
		}

		let data = nalu.as_ref();
		// Skip the header
		let mut r = BitReader::new(&data[nalu.header.len()..], true);

		let mut header = SliceHeader {
			first_mb_in_slice: r.read_ue()?,
			..Default::default()
		};

		let slice_type = r.read_ue_max::<u8>(9)? % 5;
		header.slice_type = SliceType::try_from(slice_type)?;

		header.pic_parameter_set_id = r.read_ue()?;

		let pps = self.get_pps(header.pic_parameter_set_id).ok_or::<String>(format!(
			"Could not get PPS for pic_parameter_set_id {}",
			header.pic_parameter_set_id
		))?;

		let sps = &pps.sps;

		if sps.separate_colour_plane_flag {
			header.colour_plane_id = r.read_bits(2)?;
		}

		header.frame_num = r.read_bits(usize::from(sps.log2_max_frame_num_minus4) + 4)?;

		if !sps.frame_mbs_only_flag {
			header.field_pic_flag = r.read_bit()?;
			if header.field_pic_flag {
				header.bottom_field_flag = r.read_bit()?;
			}
		}

		if header.field_pic_flag {
			header.max_pic_num = 2 * sps.max_frame_num();
		} else {
			header.max_pic_num = sps.max_frame_num();
		}

		if nalu.header.idr_pic_flag {
			header.idr_pic_id = r.read_ue_max(0xffff)?;
		}

		let num_bits_left = r.num_bits_left();
		if sps.pic_order_cnt_type == 0 {
			header.pic_order_cnt_lsb = r.read_bits(usize::from(sps.log2_max_pic_order_cnt_lsb_minus4) + 4)?;

			if pps.bottom_field_pic_order_in_frame_present_flag && !header.field_pic_flag {
				header.delta_pic_order_cnt_bottom = r.read_se()?;
			}
		}

		if sps.pic_order_cnt_type == 1 && !sps.delta_pic_order_always_zero_flag {
			header.delta_pic_order_cnt[0] = r.read_se()?;
			if pps.bottom_field_pic_order_in_frame_present_flag && !header.field_pic_flag {
				header.delta_pic_order_cnt[1] = r.read_se()?;
			}
		}
		header.pic_order_cnt_bit_size = num_bits_left - r.num_bits_left();

		if pps.redundant_pic_cnt_present_flag {
			header.redundant_pic_cnt = r.read_ue_max(127)?;
		}

		if header.slice_type.is_b() {
			header.direct_spatial_mv_pred_flag = r.read_bit()?;
		}

		if header.slice_type.is_p() || header.slice_type.is_sp() || header.slice_type.is_b() {
			header.num_ref_idx_active_override_flag = r.read_bit()?;
			if header.num_ref_idx_active_override_flag {
				header.num_ref_idx_l0_active_minus1 = r.read_ue()?;
				if header.slice_type.is_b() {
					header.num_ref_idx_l1_active_minus1 = r.read_ue()?;
				}
			} else {
				header.num_ref_idx_l0_active_minus1 = pps.num_ref_idx_l0_default_active_minus1;
				if header.slice_type.is_b() {
					header.num_ref_idx_l1_active_minus1 = pps.num_ref_idx_l1_default_active_minus1;
				}
			}
		}

		if header.field_pic_flag {
			if header.num_ref_idx_l0_active_minus1 > 31 || header.num_ref_idx_l1_active_minus1 > 31 {
				return Err("Broken Data".into());
			}
		} else if header.num_ref_idx_l0_active_minus1 > 15 || header.num_ref_idx_l1_active_minus1 > 15 {
			return Err("Broken Data".into());
		}

		if let NaluType::SliceExt = nalu.header.type_ {
			return Err("Stream contain unsupported/unimplemented NALs".into());
		}

		Parser::parse_ref_pic_list_modifications(&mut r, &mut header)?;

		if (pps.weighted_pred_flag && (header.slice_type.is_p() || header.slice_type.is_sp()))
			|| (pps.weighted_bipred_idc == 1 && header.slice_type.is_b())
		{
			Parser::parse_pred_weight_table(&mut r, sps, &mut header)?;
		}

		if nalu.header.ref_idc != 0 {
			Parser::parse_dec_ref_pic_marking(&mut r, &nalu, &mut header)?;
		}

		if pps.entropy_coding_mode_flag && !header.slice_type.is_i() && !header.slice_type.is_si() {
			header.cabac_init_idc = r.read_ue_max(2)?;
		}

		header.slice_qp_delta = r.read_se_bounded(-87, 77)?;

		if header.slice_type.is_sp() || header.slice_type.is_si() {
			if header.slice_type.is_sp() {
				header.sp_for_switch_flag = r.read_bit()?;
			}

			header.slice_qs_delta = r.read_se_bounded(-51, 51)?;
		}

		if pps.deblocking_filter_control_present_flag {
			header.disable_deblocking_filter_idc = r.read_ue_max(2)?;

			if header.disable_deblocking_filter_idc != 1 {
				header.slice_alpha_c0_offset_div2 = r.read_se_bounded(-6, 6)?;
				header.slice_beta_offset_div2 = r.read_se_bounded(-6, 6)?;
			}
		}

		if pps.num_slice_groups_minus1 > 0 {
			return Err("Stream contain unsupported/unimplemented NALs".into());
		}

		let epb = r.num_epb();
		header.header_bit_size = (nalu.size - epb) * 8 - r.num_bits_left();

		header.n_emulation_prevention_bytes = epb;

		Ok(Slice { header, nalu })
	}

	pub fn get_sps(&self, sps_id: u8) -> Option<&Rc<Sps>> {
		self.active_spses.get(&sps_id)
	}

	pub fn get_pps(&self, pps_id: u8) -> Option<&Rc<Pps>> {
		self.active_ppses.get(&pps_id)
	}
}

#[derive(Debug)]
pub struct NaluHeader {
	pub ref_idc: u8,
	pub type_: NaluType,
	pub idr_pic_flag: bool,
}

impl Header for NaluHeader {
	fn parse<T: AsRef<[u8]>>(cursor: &mut Cursor<T>) -> Result<Self, String> {
		let mut byte_buf = [0u8; 1];
		cursor
			.read_exact(&mut byte_buf)
			.map_err(|_| String::from("Broken Data"))?;
		let byte = byte_buf[0];
		let _ = cursor.seek(SeekFrom::Current(-1 * byte_buf.len() as i64));

		let type_ = NaluType::try_from(byte & 0x1f)?;

		if let NaluType::SliceExt = type_ {
			return Err("Stream contain unsupported/unimplemented NALs".into());
		}

		let ref_idc = (byte & 0x60) >> 5;
		let idr_pic_flag = matches!(type_, NaluType::SliceIdr);

		Ok(NaluHeader {
			ref_idc,
			type_,
			idr_pic_flag,
		})
	}

	fn is_end(&self) -> bool {
		matches!(self.type_, NaluType::SeqEnd | NaluType::StreamEnd)
	}

	fn len(&self) -> usize {
		1
	}
}