Two acts:
Act 1 (β alone): all 5 libva codecs returned all-zero. MPEG-2 was a
regression (pre-β it worked); HEVC was unchanged (kernel returns
DQBUF FLAG_ERROR pre AND post β — same Phase 3 baseline showed it).
Root cause: ffmpeg-vaapi-copy passes surfaces_count=0 to vaCreateContext
per iter6 context.c:262 comment; my β walk of surfaces_ids[] was a
no-op → destination_planes_count stayed 0 → surface_bind_slot no-op
→ all-zero readback.
Act 2 (Commit D): cache format-uniform CAPTURE geometry in driver_data;
walk surface_heap in CreateContext; lazy-fill in CreateSurfaces2 when
fmt_valid is set; invalidate in DestroyContext. Restores MPEG-2 to
pre-β state and unlocks VP9.
Per Phase 1 criteria: criterion 1 PARTIAL (VP9 of HEVC+VP9+VP8);
criteria 2-4 PASS.
Bug 5 (NEW): HEVC libva DQBUF FLAG_ERROR — pre-existing kernel
rejection; β's OUTPUT format fix didn't address it. Transitive proof
at iter2 verified control payload shape but kernel still rejects;
some other V4L2 protocol contract aspect differs from kdirect.
Bug 6 (NEW): VP8 libva produces non-zero output with real content
(74.8% zero + 256 unique bytes incl. keyframe pixels at `93 8e 8a 89...`)
but diverges from kdirect. Decode runs; output mismatch likely
slot-rotation or partial-fill bug.
VP9 is iter5b-β's only clean PASS. Architecture-wise β succeeded:
no α'-style failure mode possible (no in-CreateSurfaces2 destructive
teardown), and the CRIT-1+CRIT-2 fixes from Phase 5 v2 review held.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
