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//! NAL unit byte-slice newtypes and typed arrays for AVC/HEVC decoder config records.
//!
//! Each NAL unit is stored as a `Vec<u8>` of its raw bytes (header + payload).
//! Arrays carry them in wire order and compute their own serialized length.
use crate::error::{Error, Result};
use crate::sps::{
AvcSpsInfo, HevcSpsInfo, decode_avc_sps, decode_hevc_sps, rfc6381_avc1, rfc6381_hvc1,
};
use alloc::string::String;
use alloc::vec::Vec;
use broadcast_common::Serialize;
/// H.265 `nal_unit_type` for a sequence parameter set (`SPS_NUT`) — ITU-T H.265
/// Table 7-1 (type 33).
pub(crate) const HEVC_SPS_NUT: u8 = 33;
// ---------------------------------------------------------------------------
// AVC: SPS, PPS, and SPSExt NAL units (sequenceParameterSetNALUnit)
// ---------------------------------------------------------------------------
/// A single AVC sequence parameter set (SPS) NAL unit — raw bytes.
#[derive(Debug, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct AvcSps(pub Vec<u8>);
impl AvcSps {
/// Decode the SPS fields needed for codec configuration.
///
/// Returns profile, level, dimensions, chroma, bit-depth, and
/// frame-type information.
pub fn decode(&self) -> Result<AvcSpsInfo> {
decode_avc_sps(&self.0)
}
/// Build the RFC 6381 codec string (e.g. `"avc1.4D400D"`).
pub fn rfc6381(&self) -> Result<String> {
let info = self.decode()?;
Ok(rfc6381_avc1(
info.profile_idc,
info.constraint_flags,
info.level_idc,
))
}
}
/// A single AVC picture parameter set (PPS) NAL unit — raw bytes.
#[derive(Debug, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct AvcPps(pub Vec<u8>);
/// A single AVC sequence parameter set extension NAL unit — raw bytes.
#[derive(Debug, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct AvcSpsExt(pub Vec<u8>);
// ---------------------------------------------------------------------------
// HEVC: typed NAL array entry
// ---------------------------------------------------------------------------
/// A single HEVC NAL unit in the decoder config record arrays.
///
/// Equivalent to the per-array loop: `nalUnitLength + nalUnit`.
#[derive(Debug, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct HevcNalUnit(pub Vec<u8>);
impl HevcNalUnit {
const LENGTH_FIELD_SIZE: usize = 2;
/// Build a new HEVC NAL unit from raw bytes.
pub fn new(data: Vec<u8>) -> Self {
Self(data)
}
/// Decode the SPS fields if this NAL unit is an SPS (NAL unit type 33).
///
/// Returns `None` if the NAL unit type is not SPS.
pub fn decode_sps(&self) -> Result<Option<HevcSpsInfo>> {
if self.0.len() < 2 {
return Ok(None);
}
let nal_type = (self.0[0] >> 1) & 0x3F;
if nal_type != HEVC_SPS_NUT {
return Ok(None);
}
decode_hevc_sps(&self.0).map(Some)
}
/// Build the RFC 6381 `hvc1.…` codec string if this is an SPS NAL unit.
pub fn rfc6381(&self) -> Result<Option<String>> {
if let Some(info) = self.decode_sps()? {
Ok(Some(rfc6381_hvc1(&info)))
} else {
Ok(None)
}
}
}
impl Serialize for HevcNalUnit {
type Error = Error;
fn serialized_len(&self) -> usize {
Self::LENGTH_FIELD_SIZE + self.0.len()
}
fn serialize_into(&self, buf: &mut [u8]) -> Result<usize> {
let need = self.serialized_len();
if buf.len() < need {
return Err(Error::OutputBufferTooSmall {
need,
have: buf.len(),
});
}
let len = broadcast_common::len::fit_u16(self.0.len(), "nalUnitLength")?;
buf[..2].copy_from_slice(&len.to_be_bytes());
buf[2..need].copy_from_slice(&self.0);
Ok(need)
}
}
/// One HEVC NAL array in the decoder config record.
///
/// Corresponds to one iteration of the `numOfArrays` loop in
/// `HEVCDecoderConfigurationRecord` (ISO/IEC 14496-15:2017 §8.3.3).
#[derive(Debug, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct HevcNalArray {
/// `array_completeness` flag — all NALs of this type are in the array.
pub array_completeness: bool,
/// `NAL_unit_type` — restricted to VPS/SPS/PPS/prefix SEI/suffix SEI.
pub nal_unit_type: u8,
/// The NAL units in this array.
pub nalus: Vec<HevcNalUnit>,
}
impl HevcNalArray {
/// Create a new HEVC NAL array.
pub fn new(array_completeness: bool, nal_unit_type: u8, nalus: Vec<HevcNalUnit>) -> Self {
Self {
array_completeness,
nal_unit_type,
nalus,
}
}
}
impl Serialize for HevcNalArray {
type Error = Error;
fn serialized_len(&self) -> usize {
// header: 1 byte (array_completeness|reserved(1)|nal_unit_type(6)) + 2 bytes numNalus
3 + self.nalus.iter().map(|n| n.serialized_len()).sum::<usize>()
}
fn serialize_into(&self, buf: &mut [u8]) -> Result<usize> {
let need = self.serialized_len();
if buf.len() < need {
return Err(Error::OutputBufferTooSmall {
need,
have: buf.len(),
});
}
let mut cursor = 0usize;
// First byte: [array_completeness(1), reserved(1)=0, NAL_unit_type(6)]
let first_byte =
(if self.array_completeness { 0x80u8 } else { 0u8 }) | (self.nal_unit_type & 0x3F);
buf[cursor] = first_byte;
cursor += 1;
// numNalus as u16
let count = broadcast_common::len::fit_u16(self.nalus.len(), "numNalus")?;
buf[cursor..cursor + 2].copy_from_slice(&count.to_be_bytes());
cursor += 2;
for nalu in &self.nalus {
cursor += nalu.serialize_into(&mut buf[cursor..])?;
}
Ok(cursor)
}
}
#[cfg(test)]
mod tests {
use super::*;
/// A NAL unit of 65 536 bytes cannot fit `HevcNalUnit`'s 16-bit
/// `nalUnitLength` field (#1129): unfixed, `(len as u16)` silently
/// wrapped 65536 to 0 while the full-length payload was still copied.
#[test]
fn hevc_nal_unit_oversized_length_errors() {
let nalu = HevcNalUnit(alloc::vec![0xAAu8; 65536]);
let err = nalu.try_to_bytes().unwrap_err();
assert!(
matches!(
err,
Error::FieldOverflow(broadcast_common::len::FieldOverflow {
field: "nalUnitLength",
..
})
),
"expected FieldOverflow for nalUnitLength, got {err:?}"
);
}
/// The boundary: exactly 65 535 bytes (u16::MAX) still round-trips.
#[test]
fn hevc_nal_unit_max_length_round_trips() {
let nalu = HevcNalUnit(alloc::vec![0xAAu8; 65535]);
let bytes = nalu.try_to_bytes().unwrap();
assert_eq!(u16::from_be_bytes([bytes[0], bytes[1]]), 65535);
}
/// 65 536 NAL units in one array cannot fit `HevcNalArray`'s 16-bit
/// `numNalus` field (#1129): unfixed, `.len() as u16` wrapped.
#[test]
fn hevc_nal_array_oversized_count_errors() {
let arr = HevcNalArray {
array_completeness: false,
nal_unit_type: 33,
nalus: (0..65536).map(|_| HevcNalUnit(alloc::vec![0x42])).collect(),
};
let err = arr.try_to_bytes().unwrap_err();
assert!(
matches!(
err,
Error::FieldOverflow(broadcast_common::len::FieldOverflow {
field: "numNalus",
..
})
),
"expected FieldOverflow for numNalus, got {err:?}"
);
}
/// The boundary: exactly 65 535 NAL units still round-trips.
#[test]
fn hevc_nal_array_max_count_round_trips() {
let arr = HevcNalArray {
array_completeness: false,
nal_unit_type: 33,
nalus: (0..65535).map(|_| HevcNalUnit(alloc::vec![0x42])).collect(),
};
let bytes = arr.try_to_bytes().unwrap();
assert_eq!(u16::from_be_bytes([bytes[1], bytes[2]]), 65535);
}
}