Closes the deblock matrix: adds the four bS=4 intra-strength loop
filters used at I-MB edges (and other boundaries where H.264
§8.7.2.1 forces boundary strength to 4). After this PR fourier
covers all 8 standard 8-bit 4:2:0 deblock combinations:
bS<4 bS=4
----- -----
luma_v ✓ (cycle 8 QPU) ✓ (CPU)
luma_h ✓ (CPU, PR #9) ✓ (CPU)
chrm_v ✓ (CPU, PR #10) ✓ (CPU)
chrm_h ✓ (CPU, PR #10) ✓ (CPU)
Scope:
- 4 new kernel enums (LV_INTRA=13, LH_INTRA=14, CV_INTRA=15,
CH_INTRA=16), all → CPU substrate in the recipe table.
- 4 new public dispatch fns + 4 recipe wrappers (defined via two
DEFINE_INTRA_DISPATCH / DEFINE_INTRA_RECIPE macros to keep the
boilerplate tight).
- 4 new extern decls for the vendored
ff_h264_{v,h}_loop_filter_{luma,chroma}_intra_neon symbols.
- C reference: tests/h264_intra_loop_filter_ref.c covers all four
orientations. Algorithm per H.264 §8.7.2.3:
Luma: per-side strong/weak filter selector
strong_p = (|p2-p0| < β) AND (|p0-q0| < (α>>2)+2)
strong_q = (|q2-q0| < β) AND (|p0-q0| < (α>>2)+2)
Strong updates p0/p1/p2 (and mirror); weak updates p0 only.
Chroma: always weak, only p0/q0 updated.
- daedalus_h264_deblock_meta is REUSED for intra dispatches; the
tc0[] field is ignored (bS=4 hardcodes the strength). Callers
can build a single edge list and route by kernel without an
extra struct.
- Test refactor: an intra_test_spec table + run_intra_test helper
drives all four orientations through one harness, keeping the
new test surface compact (~50 LOC for 4 kernels vs ~200 if each
had its own test_deblock_*_intra fn).
Verified on hertz (Pi 5 / V3D 7.1):
$ ./build/test_api_h264
=== Phase 8a API smoke: H.264 kernels via recipe dispatch ===
...
H.264 deblock luma v intra: 1024/1024 bytes bit-exact (100.0000%)
H.264 deblock luma h intra: 1024/1024 bytes bit-exact (100.0000%)
H.264 deblock chroma v intra: 256/256 bytes bit-exact (100.0000%)
H.264 deblock chroma h intra: 256/256 bytes bit-exact (100.0000%)
...
All 11 H.264 kernels bit-exact PASS — the deblock matrix is closed.
The bit-exact match on first try is meaningful for these kernels:
the strong/weak filter selector + per-side asymmetry would have
surfaced any sign / shift / rounding mistake immediately. The
C reference is now a usable spec checkpoint for the eventual QPU
shader work.
QPU shader follow-up: not in this PR. The intra path's 3-cell
per-side update + strong/weak branch is structurally more complex
than the bS<4 path that already has a V shader (v3d_h264deblock.spv).
Per the prior R-band logic for deblock, intra edges are < 20% of
total deblock work at typical bit-rates, so NEON-only at ~ 10 ns/edge
fits comfortably in the budget.
claude-noether
9b1c106dc5