claude-noether
df787a6cc2
Iteration 2 closes with all 5 Phase 1 boolean-correctness criteria
green. Third codec passes — campaign scoreboard 2/5 → 3/5 (H.264
in T4, MPEG-2 in iter1, HEVC in iter2). Loop terminates per
feedback_dev_process.md Phase 8.
Notable: ZERO Phase 7 → Phase 4 loopbacks needed. Phase 5 review
caught all 3 would-be loopback triggers in advance (data_byte_offset
rename, dpb.rps→index-arrays semantics, pic_order_cnt_val rename).
This is the dev-process ideal: review catches bugs before
implementation lands; verification confirms contract.
What landed:
Code (libva-v4l2-request-fourier master 229d6d1 → 8d71e20):
cca539d iter2 Phase 6 commit A: config.c break for HEVCMain case
8d71e20 iter2 Phase 6 commit B: rewrite h265.c against new V4L2
stateless HEVC API (6 files, 463 ins, 236 del)
Both authored as Claude (noether) per feedback_gitea_as_claude_noether.md.
Campaign docs (fresnel-fourier):
6e8c970 iter2 Phase 0 + Phase 1 lock
b3ba157 iter2 Phase 2 situation analysis (6 bugs)
d35a247 iter2 Phase 3 baselines (substrate post-pacman-Syu + HEVC anchor)
348736e iter2 Phase 4 plan (10 contract clauses)
9eae068 iter2 Phase 5 sonnet review (3 Critical UAPI errors caught)
05b4bd5 iter2 Phase 7 verification (5/5 GREEN)
[this commit] iter2 Phase 8 close
Lesson L1 distilled to memory (extension of iter1 entry):
feedback_review_empirical_over_theoretical.md updated with
Direction 2 corollary. Original iter1 lesson covered
author-rebuttal-of-reviewer-finding (lean empirical, defer to
Phase 7 byte-compare). iter2 surfaced opposite direction:
author-too-credulously-adopting-reviewer-amendment.
Concrete iter2 instance: Phase 5 S1 suggested
picture->pic_fields.bits.uniform_spacing_flag exists in VAAPI as
source for V4L2_HEVC_PPS_FLAG_UNIFORM_SPACING. I adopted into
amended plan without verifying. Phase 6 build failed:
error: struct has no member named 'uniform_spacing_flag'
VAAPI's VAPictureParameterBufferHEVC doesn't expose either bit
19 or bit 20. Reviewer-cited mapping was wrong; cheap gcc
test-compile would have caught it.
Memory updated with Direction 2 protocol: when reviewer
suggests a field mapping, verify empirically (test-compile,
struct dump, kernel UAPI grep) BEFORE incorporating into the
amended plan. Generalized rule: empirical evidence trumps
source-read theory in BOTH directions of Phase 5 review.
Backlog items deferred (campaign-internal, not durable memory):
B6 — VAAPI ↔ V4L2 SPS field-fidelity gaps:
sps_max_num_reorder_pics (post-fix=0, baseline=2),
sps_max_latency_increase_plus1 (post-fix=0, baseline=4),
possibly PPS bit 12 ENTROPY_CODING_SYNC_ENABLED.
VAAPI doesn't expose; FFmpeg parses from bitstream directly.
Operational impact NIL (Phase 7 Criterion 4 byte-identical
pixel pass). Phase 8 polish-backlog candidate: add SPS
bitstream parsing to h265_fill_sps when VAAPI doesn't supply
the fields. Probably low ROI — kernel HEVC handler tolerates
0 values for the BBB fixture. Defer until a real-world consumer
surfaces a fixture that breaks on this.
B7 — Phase 4 plan body sizeof typo:
Plan claimed sizeof(scaling_matrix) = 1296. Empirical = 1000
bytes. Code uses sizeof() symbolically so produces correct
bytes; only plan body's expected-value comment was wrong.
Phase 7 byte-compare structural check caught it. Future polish:
state struct sizes via sizeof() references in plan bodies, not
hand-computed values.
iter1 carryover backlog (still deferred):
B3 latent surface-reuse bug — picture.c:287 h264.matrix_set=false
hits union byte 240. For HEVC: byte 240 lands in h265.picture.
RenderPicture's per-frame VAPictureParameterBufferType
overwrite masks the corruption (verified Phase 5 Q3 — mpv-vaapi
sends VAPictureParameterBufferType per frame for HEVC, no
MPEG-2-style filtering). Iter2+ Phase 4 cross-cutting candidate.
B4 context.c H.264 device-init log noise (rkvdec accepts both
H.264 + HEVC controls cleanly; on hantro both EINVAL with
cosmetic log). Iter2 added a 2nd batched call for HEVC; same
(void) swallow pattern. Cosmetic.
B5 vbv_buffer_size 1MB vs 1.31MB (MPEG-2-only; not exercised by
HEVC).
Phase 4 cross-cutting work items collected:
- VIDIOC_EXPBUF + DMA_BUF_IOCTL_SYNC for vaDeriveImage cache-stale
fix (still applies to all codecs)
- V4L2 device-discovery probe (still applies)
- picture.c BeginPicture profile-aware reset (B3)
- context.c H.264+HEVC device-init log suppression (B4)
- mpeg2 vbv_buffer_size negotiation polish (B5)
- h265 SPS bitstream-parse fidelity polish (B6)
Campaign roadmap (codec iterations remaining):
iter3: VP8 on hantro — implement vp8.c. Smaller scope than iter2;
predicting closer to iter1 MPEG-2 in size. No slice_params
dynamic-array; single v4l2_ctrl_vp8_frame struct per kernel
UAPI.
iter4: VP9 on rkvdec — implement vp9.c. Largest control surface
remaining.
Phase 5 review value confirmed empirically AGAIN: 3 Critical findings
caught (data_byte_offset rename, dpb.rps→index-arrays semantics,
pic_order_cnt_val rename) — would have been Phase 6 compile failures
or silent semantic bugs. Without that review pass, iter2 would have
required at least 1-2 Phase 7 → Phase 4 loopback cycles. Reviews
are never skippable per global ~/.claude/CLAUDE.md rule; iter2
exemplifies why.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
fresnel-fourier
TL;DR
Peer campaign to libva-multiplanar, targeting fresnel (Pinebook Pro / Rockchip RK3399) instead of ohm (PineTab2 / RK3566). Same deliverable shape — make libva-v4l2-request-fourier work end-to-end, for production VA-API consumers — but on a different SoC with a different (and broader) V4L2 decoder surface.
The libva backend fork itself (libva-v4l2-request-fourier) is shared: it lives at ../libva-multiplanar/libva-v4l2-request-fourier/. This campaign does not nest a second copy. Code-side work that turns out to be RK3399-specific lands either as #ifdef/runtime-detected paths inside that fork's master or, if scope diverges sharply, on a feature branch — Phase 2 source-read of each iteration decides.
Origin
libva-multiplanar reached iter5-close on 2026-05-05 with the ohm path solid: hantro (rk3568-vpu DT compatible) decodes H.264 to NV12 dmabufs end-to-end, three iterations of bugs fixed, mpv --hwdec=vaapi smooth, firefox-fourier RDD-sandboxed Firefox engages the backend without MOZ_DISABLE_RDD_SANDBOX=1, chromium-fourier 149 confirmed as the regression-check consumer.
That campaign's README explicitly names fresnel (RK3399) and ampere/boltzmann (RK3588) as "future iterations after ohm path is solid" (libva-multiplanar/README.md:87). fresnel-fourier is the formal peer campaign for the RK3399 leg of that promise.
Topology choice (LOCKED 2026-05-07): peer campaign, not child of libva-multiplanar. Each runs its own 8(+1) phase loop. Cross-link only — fresnel-fourier results do not gate libva-multiplanar's Phase 8 close (which already happened iteration-by-iteration on ohm).
Hardware target
fresnel — Pinebook Pro laptop. See reference_fresnel_kernel_constraints.md for the custom-OC-kernel discipline (don't let pacman -Syu clobber the OC DTB) and project_fresnel.md for fleet placement.
| Property | Value |
|---|---|
| SoC | Rockchip RK3399 (2× Cortex-A72 + 4× Cortex-A53) |
| GPU | Mali-T860 MP4 (Midgard, panfrost) |
| Decoder block 1 | rkvdec (/dev/video3) — H.264 + HEVC + VP9 |
| Decoder block 2 | hantro-vpu-dec (rk3399-vpu-dec, /dev/video5) — MPEG-2 + VP8 (RK3399 hantro does not advertise H.264; corrected 2026-05-07 from empirical V4L2 enumeration — see phase0_evidence/2026-05-07/v4l2_inventory_findings.md) |
| Encoder block | hantro-vpu-enc (/dev/video4) — JPEG only |
| OS | EndeavourOS-ARM (Arch derivative; same pacman + marfrit-packages mechanism as ohm) |
| Kernel | linux-eos-arm 6.19.9-99 — CONFIG_FTRACE=y, CONFIG_FUNCTION_TRACER=y, CONFIG_DYNAMIC_FTRACE=y, CONFIG_TRACING=y verified 2026-05-07. No rebuild needed for trace work. |
The decode-side surface area is genuinely broader than ohm. ohm has hantro (H.264 + MPEG-2 + VP8) and an rkvdec block whose mainline rkvdec2/vdpu346 driver isn't merged. fresnel has hantro (MPEG-2 + VP8 only — empirical, see correction note in the table above) plus a fully-driven mainline rkvdec covering H.264 + HEVC + VP9. So this campaign exercises codecs (HEVC, VP9) the libva-v4l2-request-fourier fork has never run on real hardware to date, and there is exactly one decoder bind for H.264 (rkvdec) — no two-block routing decision.
GPU side: panfrost on Mali-T860 (Midgard) is a different generation than ohm's Mali-G52 (Bifrost). KWin / Mesa / panfrost stack regressions or wins on T860 are not assumed to track G52 — the kwin-fourier verdict from fourier_attribution doesn't transfer for free.
Scope (LOCKED 2026-05-07 in phase0_findings.md)
In scope:
- libva-v4l2-request-fourier backend exercised on fresnel V4L2 decode nodes (
rkvdec+hantro-vpu-dec). - Codecs: everything decode-capable — H.264 + HEVC + VP9 (via rkvdec) + MPEG-2 + VP8 (via hantro-vpu-dec). This is the explicit broadening from libva-multiplanar's H.264-first locked scope.
- Test consumers:
vainfo,mpv --hwdec=vaapi, Firefox viamedia.ffmpeg.vaapi.enabled, chromium-fourier 149 (regression check). - Phase 1 success criterion (matching libva-multiplanar): boolean correctness — "libva accepted + providing access to hardware decoder for each codec." Performance metrics deferred.
- Phase 0 task 1: recover fresnel from the SDDM greeter crash-loop (per
~/.claude/plans/dynamic-forging-piglet.md). Recovery is bookkept as substrate work inside this campaign, not as a separate prereq.
Out of scope:
- Front-end libva (API library). Backend only.
- Other hardware (ohm + ampere/boltzmann are libva-multiplanar's iterations).
- AV1 (no decoder block on RK3399 supports it).
- Performance metrics — fresnel CPU/GPU benchmarking is a separate iteration after correctness lands.
cros-codecsRust replacement (peruser_stance_rust.md).- Bootlin / Collabora upstreaming default-deferred (per
feedback_no_upstream.md). Same discipline as libva-multiplanar. - KWin / panfrost / Mali-T860 work — orthogonal until proven otherwise; a parallel
kwin-fourier-fresnelcampaign would be a separate decision.
Process
8(+1) phase loop per feedback_dev_process.md. Phase 0 substrate is in phase0_findings.md. Phase 5 review uses the sonnet-architect subagent pattern (Plan with model: sonnet).
In-session-acquired data discipline per feedback_replicate_baseline_first.md: libva-multiplanar's ohm-side measurements are reference history, not threshold sources for fresnel-fourier cells.
Predecessor work this campaign builds on
../libva-multiplanar/— five closed iterations on ohm. Read in order:README.md— current state, codec scope, file map.phase8_iteration5_close.md— most recent close. The iter5-end backend is the substrate fresnel-fourier starts from.phase0_findings.md(andphase0_findings_iter[2-5].md) — locked-scope precedent for codec breadth and consumer matrix on ohm; useful frame-of-reference when locking fresnel-side scope.phase8_iteration1_close.md— iter1 surface-export DMA-BUF lifecycle race + multi-resolution cache + 64-pitch alignment bugs. Likely re-surface candidates on RK3399.
../libva-multiplanar/libva-v4l2-request-fourier/— the fork itself. 12 commits ahead of bootlin tip plus iter1..iter5 work.git logfor the actual landing record.~/.claude/plans/dynamic-forging-piglet.md— fresnel SDDM greeter crash diagnosis + recovery plan. Phase 0 task 1 picks up from here.~/src/fourier_attribution/— ohm-only attribution matrix. The chromium-fourier WHEAT-but-fragile verdict and Cell E (vanilla Chromium 149 control) item are ohm-side context, not fresnel data.
External reference (carry-over from libva-multiplanar):
- Mozilla bug 1833354 / 1965646 (Firefox HW decode on RK35xx via libva-v4l2-request).
- Bootlin upstream
bootlin/libva-v4l2-request— dormant since 2021. - Linux kernel
drivers/staging/media/rkvdec/— RK3399 rkvdec H.264/HEVC/VP9 control protocol reference. - Linux kernel
drivers/media/platform/verisilicon/hantro_*— RK3399-vpu-dec MPEG-2/H.264/VP8 control protocol reference.
Repository layout
~/src/fresnel-fourier/ <- this campaign (its own git repo)
├── README.md <- this file
├── phase0_findings.md <- locked research question + Phase 0 work list
├── (worklist.md, phase[2-8]*.md as phases land)
└── (the libva fork is NOT here — see ../libva-multiplanar/libva-v4l2-request-fourier/)
The campaign repo and the fork repo stay separate. fresnel-fourier commits its findings here; code changes to the backend land on the fork's master (or a branch named per the iteration if scope diverges from libva-multiplanar's ohm-side master).
Operator-facing repo URL: git.reauktion.de/marfrit/fresnel-fourier — created empty during scaffolding, no push until first iteration finds something worth publishing.
Non-upstreaming default
Inherited from libva-multiplanar / feedback_no_upstream.md. Patches must be aligned to upstream in syntax and semantics; PR/MR/bug-report only on explicit operator instruction.
Build infrastructure
distcc/cross-build path is the existing fleet: aarch64crosscompiler LXD on data, tesla LXD on hertz, dcc1 on dcw3. See reference_distcc_kernel_builds.md for invocation. Per the locked Phase 0 answer for libva-multiplanar (item 9), no distcc for libva builds — libva is small and links fast, hand-build on fresnel directly. Same default applies here unless a specific reason emerges.
For chromium-fourier 149 / firefox-fourier rebuilds against fresnel-side findings, the boltzmann LXD container path from libva-multiplanar iter3 is reusable.