Port of storytold/filmcraft#1952, reviewed and approved there before the
decoder moved to craft-libs. 4:2:2 streams that use no range-extension
coding tools (what cameras and libx265 write) now decode:
- chroma geometry from the SPS chroma format (ChromaFormat shifts) in the
picture store, intra, inter, transform tree, deblocking and SAO;
- Table 8-3 IntraPredModeC mapping for ChromaArrayType 2;
- stacked chroma transform blocks with their second cbf flags;
- chroma QP = Min(qPi, 51) for non-4:2:0 (Table 8-10 applies to 4:2:0 only);
- chroma motion vectors scaled per axis;
- a PPS that scales SAO offsets (a RExt tool) is refused as unsupported.
Tests: 22 libx265 4:2:2 fixtures (8- and 10-bit) compared sample-exactly
with ffmpeg, the Table 8-3 derivation, and the SAO offset scale check.
* craft-video: HEVC decoder from FilmCraft (`hevc-decode` feature)
FilmCraft's crates/hevc at 4c0d2ad7 becomes craft_video::hevc::decode. The encoder moves to
hevc/encode and is still exported from craft_video::hevc. Feature hevc now turns on hevc-decode
and hevc-encode, so either half can be built without the other.
craft_video::budget (the picture memory budget from DeckCraft's bitstream crate) is added for the
next commit. craft-video is built at opt-level 3 in the dev profile, as FilmCraft built its
codecs.
* craft-video: HEVC decoder hardening from DeckCraft's copy
- The picture store (DPB, current picture, pictures in flight) is checked against a memory
budget before a picture is allocated; Decoder::set_memory_budget.
- configure_hvcc checks every array before handling any NAL: only VPS, SPS, PPS and SEI arrays,
each NAL header agreeing with its array type. A picture slice in the record starts no picture.
- init_qp_minus26, slice_qp_delta and delta_chroma_log2_weight_denom are range checked before
the additions that overflowed on Exp-Golomb values near the i32 limits.
- A picture job sets up its picture state inside the panic guard.
Melchi Aaron Zedek
Dylan M. Taylor