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//! H.265/HEVC NAL unit header
use media_codec_nal::NalHeader;
use media_core::{invalid_data_error, Result};
/// H.265 NAL unit types as defined in ITU-T H.265 Table 7-1
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
#[repr(u8)]
pub enum NalUnitType {
/// Coded slice segment of a trailing picture (TRAIL_N)
TrailN = 0,
/// Coded slice segment of a trailing picture (TRAIL_R)
TrailR = 1,
/// Coded slice segment of a TSA picture (TSA_N)
TsaN = 2,
/// Coded slice segment of a TSA picture (TSA_R)
TsaR = 3,
/// Coded slice segment of a STSA picture (STSA_N)
StsaN = 4,
/// Coded slice segment of a STSA picture (STSA_R)
StsaR = 5,
/// Coded slice segment of a RADL picture (RADL_N)
RadlN = 6,
/// Coded slice segment of a RADL picture (RADL_R)
RadlR = 7,
/// Coded slice segment of a RASL picture (RASL_N)
RaslN = 8,
/// Coded slice segment of a RASL picture (RASL_R)
RaslR = 9,
// 10-15: Reserved VCL NAL unit types
/// Coded slice segment of a BLA picture (BLA_W_LP)
BlaWLp = 16,
/// Coded slice segment of a BLA picture (BLA_W_RADL)
BlaWRadl = 17,
/// Coded slice segment of a BLA picture (BLA_N_LP)
BlaNLp = 18,
/// Coded slice segment of an IDR picture (IDR_W_RADL)
IdrWRadl = 19,
/// Coded slice segment of an IDR picture (IDR_N_LP)
IdrNLp = 20,
/// Coded slice segment of a CRA picture
CraNut = 21,
// 22-23: Reserved IRAP VCL NAL unit types
// 24-31: Reserved non-IRAP VCL NAL unit types
/// Video parameter set (VPS)
VpsNut = 32,
/// Sequence parameter set (SPS)
SpsNut = 33,
/// Picture parameter set (PPS)
PpsNut = 34,
/// Access unit delimiter
AudNut = 35,
/// End of sequence
EosNut = 36,
/// End of bitstream
EobNut = 37,
/// Filler data
FdNut = 38,
/// Supplemental enhancement information (prefix)
PrefixSeiNut = 39,
/// Supplemental enhancement information (suffix)
SuffixSeiNut = 40,
// 41-47: Reserved
// 48-63: Unspecified
}
impl NalUnitType {
/// Create from raw NAL unit type value
pub fn from_u8(value: u8) -> Option<Self> {
match value {
0 => Some(Self::TrailN),
1 => Some(Self::TrailR),
2 => Some(Self::TsaN),
3 => Some(Self::TsaR),
4 => Some(Self::StsaN),
5 => Some(Self::StsaR),
6 => Some(Self::RadlN),
7 => Some(Self::RadlR),
8 => Some(Self::RaslN),
9 => Some(Self::RaslR),
16 => Some(Self::BlaWLp),
17 => Some(Self::BlaWRadl),
18 => Some(Self::BlaNLp),
19 => Some(Self::IdrWRadl),
20 => Some(Self::IdrNLp),
21 => Some(Self::CraNut),
32 => Some(Self::VpsNut),
33 => Some(Self::SpsNut),
34 => Some(Self::PpsNut),
35 => Some(Self::AudNut),
36 => Some(Self::EosNut),
37 => Some(Self::EobNut),
38 => Some(Self::FdNut),
39 => Some(Self::PrefixSeiNut),
40 => Some(Self::SuffixSeiNut),
_ => None,
}
}
/// Check if this is an IRAP (Intra Random Access Point) NAL unit type
///
/// IRAP NAL units include BLA, IDR, and CRA pictures (types 16-21)
#[inline]
pub fn is_irap(&self) -> bool {
matches!(self, Self::BlaWLp | Self::BlaWRadl | Self::BlaNLp | Self::IdrWRadl | Self::IdrNLp | Self::CraNut)
}
/// Check if this is an IDR (Instantaneous Decoder Refresh) NAL unit type
#[inline]
pub fn is_idr(&self) -> bool {
matches!(self, Self::IdrWRadl | Self::IdrNLp)
}
/// Check if this is a VCL (Video Coding Layer) NAL unit type
#[inline]
pub fn is_vcl(&self) -> bool {
(*self as u8) <= 31
}
/// Check if this is a parameter set NAL unit type (VPS, SPS, or PPS)
#[inline]
pub fn is_parameter_set(&self) -> bool {
matches!(self, Self::VpsNut | Self::SpsNut | Self::PpsNut)
}
}
/// H.265 NAL unit header
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct H265NalHeader {
/// Forbidden zero bit (should always be 0)
pub forbidden_zero_bit: bool,
/// NAL unit type (0-63)
pub nal_unit_type: NalUnitType,
/// Layer ID (0-63)
pub nuh_layer_id: u8,
/// Temporal ID plus 1 (1-7)
pub nuh_temporal_id_plus1: u8,
}
impl H265NalHeader {
/// Create a new H.265 NAL header
pub fn new(forbidden_zero_bit: bool, nal_unit_type: NalUnitType, nuh_layer_id: u8, nuh_temporal_id_plus1: u8) -> Self {
Self {
forbidden_zero_bit,
nal_unit_type,
nuh_layer_id: nuh_layer_id & 0x3F,
nuh_temporal_id_plus1: nuh_temporal_id_plus1 & 0x07,
}
}
/// Get the NAL unit type as an enum
pub fn unit_type(&self) -> NalUnitType {
self.nal_unit_type
}
/// Get the temporal ID (nuh_temporal_id_plus1 - 1)
pub fn temporal_id(&self) -> u8 {
self.nuh_temporal_id_plus1.saturating_sub(1)
}
/// Check if this is an IRAP (Intra Random Access Point) NAL unit
///
/// IRAP NAL units include BLA, IDR, and CRA pictures
pub fn is_irap(&self) -> bool {
self.nal_unit_type.is_irap()
}
/// Encode the header to two bytes
pub fn to_bytes(&self) -> [u8; 2] {
let byte0 = if self.forbidden_zero_bit {
0x80
} else {
0
} | ((self.nal_unit_type as u8 & 0x3F) << 1) |
((self.nuh_layer_id >> 5) & 0x01);
let byte1 = ((self.nuh_layer_id & 0x1F) << 3) | (self.nuh_temporal_id_plus1 & 0x07);
[byte0, byte1]
}
}
impl NalHeader for H265NalHeader {
const HEADER_SIZE: usize = 2;
fn parse(data: &[u8]) -> Result<Self> {
if data.len() < 2 {
return Err(invalid_data_error!("H265 NAL: data too short"));
}
let byte0 = data[0];
let byte1 = data[1];
let forbidden_zero_bit = (byte0 >> 7) != 0;
let nal_unit_type_raw = (byte0 >> 1) & 0x3F;
let nuh_layer_id = ((byte0 & 0x01) << 5) | ((byte1 >> 3) & 0x1F);
let nuh_temporal_id_plus1 = byte1 & 0x07;
// Check forbidden_zero_bit
if forbidden_zero_bit {
return Err(invalid_data_error!("H265 NAL: forbidden bit set"));
}
// Check temporal_id_plus1 is not 0
if nuh_temporal_id_plus1 == 0 {
return Err(invalid_data_error!("H265 NAL: nuh_temporal_id_plus1 cannot be 0"));
}
let nal_unit_type = NalUnitType::from_u8(nal_unit_type_raw).ok_or_else(|| invalid_data_error!("H265 NAL: invalid nal_unit_type"))?;
Ok(Self {
forbidden_zero_bit,
nal_unit_type,
nuh_layer_id,
nuh_temporal_id_plus1,
})
}
fn nal_unit_type(&self) -> u8 {
self.nal_unit_type as u8
}
fn is_vcl(&self) -> bool {
self.nal_unit_type.is_vcl()
}
fn is_idr(&self) -> bool {
self.nal_unit_type.is_idr()
}
fn is_parameter_set(&self) -> bool {
self.nal_unit_type.is_parameter_set()
}
}