claude-noether
dc6937868a
Iteration 1 closes with all five Phase 1 boolean-correctness criteria
green. Second codec passes — campaign scoreboard 1/5 → 2/5 (H.264
in T4, MPEG-2 in iter1). Loop terminates per
feedback_dev_process.md Phase 8.
What landed:
Code (libva-v4l2-request-fourier master 65969da..229d6d1):
e7dad7a iter1 Phase 6 commit A: config.c break for MPEG-2 cases
5fe873c iter1 Phase 6 commit B: rewrite mpeg2.c against new V4L2 stateless API
3aab187 iter1 Phase 6 commit C: delete staging-era include/mpeg2-ctrls.h
229d6d1 iter1 Phase 6 commit D: drop missed mpeg2-ctrls.h include from context.c (fix-forward)
All four authored as Claude (noether) per feedback_gitea_as_claude_noether.md.
Campaign docs (fresnel-fourier):
f720c77 iter1 Phase 0 + Phase 1 lock
cc55a6e iter1 Phase 2 situation analysis (3 bugs)
b9625af iter1 Phase 3 baseline measurements (4 baselines)
3e996d0 iter1 Phase 4 plan (6 contract clauses)
0e2e1c2 iter1 Phase 5 sonnet review (6 findings, 4 amendments)
ec9133a iter1 Phase 7 verification (5/5 GREEN)
[this commit] iter1 Phase 8 close
Three lessons distilled to durable memory:
L1 — feedback_header_deletion_check.md
Phase 2 grep audit found 2 of 3 include sites for the
staging-era mpeg2-ctrls.h header; build broke on Commit C
delete because of context.c:42. Rule: when removing a header,
let the compiler enumerate includes authoritatively (clean
rebuild after include-removal patches, before git rm). Grep
is a hint; the compiler is the authority.
L2 — feedback_review_empirical_over_theoretical.md
Phase 5 reviewer S2 flagged a numerical mismatch in
vbv_buffer_size between Baseline C (1.31 MB) and predicted
post-fix (1 MB). I rejected with confident source-read
reasoning (slot->size = sizeimage = matches). Phase 7
byte-compare empirically showed the reviewer was right —
post-fix produces 1 MB, not 1.31 MB. Operational impact nil
(kernel ignores the field), but my Phase 5 rebuttal had a
source-read gap. Rule: when a reviewer cites a concrete
numerical discrepancy, defer to Phase 7 byte-compare; don't
reject on source-read alone.
L3 — feedback_rockchip_pixel_verify_path.md
Iter1 + T4 (H.264) both empirically confirm: libva backend's
vaDeriveImage / cached-mmap readback returns all-zero NV12
on RK3399 — same iter1 patch-0011 cache-coherency bug class
observed on RK3568. Pixel verification must use DMA-BUF GL
import (mpv --vo=image, ffmpeg-v4l2request DRM_PRIME +
hwdownload). NOT ffmpeg-vaapi+hwdownload (cache-stale on
Rockchip). Codec-agnostic; applies to all 5 codecs in
campaign scope.
Backlog items deferred (campaign-internal, not durable memory):
B1: V4L2 /dev/videoN numbering shuffles across reboots
(rkvdec moved video3+media1 → video1+media0 between
Phase 0/3 and Phase 7). Backend should probe /dev/media*
for driver match. Iter2+ Phase 4 cross-cutting candidate.
B2: mpv --hwdec=vaapi-copy silently filters MPEG-2 out before
libva is loaded. mpv --hwdec=vaapi (DMA-BUF) DOES engage.
Phase 1 criterion 3 ended up anchored on ffmpeg-direct.
Mpv-side investigation as separate follow-up.
B3: Latent surface-reuse bug — picture.c:287 h264.matrix_set
reset writes byte 240 of params union, lands inside
mpeg2.iqmatrix.chroma_intra_quantiser_matrix[20] (verified
via offsetof on fresnel via gcc + libva). Per-frame
RenderPicture overwrites this byte for ffmpeg-vaapi flows
that send VAIQMatrixBufferType every frame. Latent for
VAAPI clients that reuse a surface without re-sending
IQMatrix. Iter2+ candidate.
B4: src/context.c:142-155 H.264 device-init runs unconditionally
on every CreateContext, EINVALs on hantro. Intentional
best-effort but request_log fires "Unable to set
control(s)" cosmetically. Suppress-log candidate, low
priority.
B5: vbv_buffer_size = SOURCE_SIZE_MAX (1 MB) rather than
negotiated sizeimage. Kernel ignores. Polish candidate.
Phase 4 cross-cutting work items collected:
- Add VIDIOC_EXPBUF + DMA_BUF_IOCTL_SYNC to libva backend
image-export (fixes L3's vaDeriveImage cache-stale bug for
all codecs).
- V4L2 device-discovery probe (fixes B1).
- Picture.c BeginPicture profile-aware reset (fixes B3).
- Context.c H.264 device-init log suppression (fixes B4).
Campaign roadmap (codec iterations remaining):
iter2: HEVC on rkvdec — re-enable h265.c in build, audit against
rkvdec kernel HEVC contract.
iter3: VP8 on hantro — implement vp8.c.
iter4: VP9 on rkvdec — implement vp9.c (largest control surface).
Phase 5 review S2 historical-record correction: Phase 5 reviewer
was numerically right about vbv_buffer_size. My Phase 5 rebuttal
in phase5_iter1_review.md was empirically wrong. Acknowledged in
phase7_iter1_verification.md and phase8_iteration1_close.md;
Phase 5 doc preserved as-is for the historical record.
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.