mc10 (¼-H), mc30 (¾-H), mc01 (¼-V), mc03 (¾-V). Each is the
corresponding half-pel filter (mc20 or mc02) with one extra L2
rounded-average step against an integer-source pixel at the tail:
mc10[r,c] = avg(clip255(mc20(s)), s[r, c ])
mc30[r,c] = avg(clip255(mc20(s)), s[r, c+1])
mc01[r,c] = avg(clip255(mc02(s)), s[r, c ])
mc03[r,c] = avg(clip255(mc02(s)), s[r+1, c ])
Each shader is ~45 lines (mc20-/mc02-pattern + 1 L2 line).
CMake foreach loop generates the 4 SPV compile rules. Dispatch
helper `dispatch_h264_qpel_axis_qpu` shares plumbing across all 4
(axis flag selects src_max bounds: H reads cols -2..+10, V reads
rows -2..+10). DEFINE_QPEL_AXIS_QPU + DEFINE_QPEL_DISPATCH_QPU
macros collapse ~200 LOC of boilerplate.
Recipe table flips DAEDALUS_KERNEL_H264_QPEL_MC{10,30,01,03} from
CPU to QPU.
Verified on hertz:
$ ./build/test_api_h264 | grep "qpel mc[01230]"
H.264 qpel mc10: 2048/2048 bytes bit-exact (100.0000%)
H.264 qpel mc30: 2048/2048 bytes bit-exact (100.0000%)
H.264 qpel mc01: 2048/2048 bytes bit-exact (100.0000%)
H.264 qpel mc03: 2048/2048 bytes bit-exact (100.0000%)
(+ mc20/mc02/mc22 anchors from previous PRs)
Qpel QPU coverage:
put_ mc20 ✓ mc02 ✓ mc22 ✓ (3 anchors)
mc10 ✓ mc30 ✓ mc01 ✓ mc03 ✓ (4 quarter-axis, THIS PR)
mc11/12/13/21/23/31/32/33 — CPU NEON (8 diagonals)
avg_ all 15 positions — CPU NEON
7 of 15 useful put_ positions now on QPU. The 8 diagonals each
compose two half-pel results via L2; can land via dedicated kernels
or by chaining existing anchor dispatches (the latter would need
the L2 step as a fourth dispatch — probably cheaper to write
dedicated 8x diagonal shaders).
claude-noether