claude-noether
d5d4beb64d
distilled, 0 Phase 7 → Phase 4 loopbacks
iter3 = VP8 on hantro-vpu-dec via libva-v4l2-request-fourier on
RK3399 (fresnel / Pinebook Pro). Fourth codec to ship.
Final state:
Fork tip: e1aca9c (post iter2 close 8d71e20 + 4 commits)
Phase 1 criteria: 5/5 GREEN (4 direct + 1 transitive)
LOC delta: +373 across 7 files (2 new + 5 modified)
Phase 7 → Phase 4 loopbacks: 0
Phase 6 fix-forwards: 1 (Commit D buffer.c allow-list)
Phase 5 review findings: 4 Critical, all empirically validated
Lessons distilled to memory (3 NEW entries):
feedback_hw_decode_engagement_check.md
Mandatory HW engagement check before claiming criterion-4
HW=SW PASS. mpv silently falls back to SW for some codec/
backend combos. Use lsof/strace/mpv -v/ffmpeg log to verify
HW path actually engaged. Established by user catch
mid-Phase-7: initial criterion-4 PASS was vacuous SW=SW.
reference_dmabuf_resv_blocker.md
Cross-campaign blocker. RK3399 hantro CAPTURE → libva
readback returns all-zero pages (videobuf2 missing
dma_resv release fence + panfrost no IOMMU_CACHE).
Tracked at git.reauktion.de/marfrit/dmabuf-modifier-triage/
issues/2. vb2_dma_resv kernel patches in flight (RFC v2,
2026-04 linux-media). Use transitive proof until patches
land: backend payload == kernel-direct payload AND
kernel-direct decode == SW reference.
feedback_runtime_enumerates_allowlists.md
Sibling to feedback_header_deletion_check.md. When ADDING
new enum values (buffer types, profiles, ioctls), grep
misses switch-default-rejection sites. Runtime enumerates
authoritatively — let fix-forward catch what grep missed.
Established by Phase 6 Commit D fix-forward: Phase 2 source-
read claimed buffer.c was type-agnostic; runtime enumerated
the explicit allow-list switch on first vaCreateBuffer.
Phase 5 amendments empirically validated (all 4 Critical correct):
C1 first_part_header_bits = slice->macroblock_offset → 6550 ✓
C2 first_part_size = partition_size[0]+ceil(macroblock_offset/8)
→ 22742 ✓ (= 21923 + 819, exact match for Phase 3 anchor)
C3 VAProbabilityBufferType (not VAProbabilityDataBufferType)
→ compiled clean post-Commit-D
C4 (int8_t) cast (not (s8)) → compiled clean Commit B first try
Estimated savings without Phase 5 review: 2 Phase 6 compile-fail/
fix-forward cycles (C3 + C4) + 1 Phase 7 → Phase 4 loopback (C1
+ C2 hardware-DMA-offset bug, would have produced visible-but-
corrupt output). Actual cost with review: 1 fix-forward (Commit
D, +1 LOC, was a Phase 2 source-read miss outside Phase 5 scope).
Cross-cutting backlog updates:
iter3-Q1 first_part_header_bits → CLOSED by Phase 5 C1
iter3-flags-anomaly bit 0x40 → not iter3 scope; kernel ignores
iter3-criterion-4-readback → blocked on dmabuf-modifier-triage
iter1; transitive proof used
iter3-mpv-vp8-fallback → mpv 0.41.0 falls back to SW for VP8;
consumer-side, not backend; verify
via chrome-fourier when convenient
Inherited backlog (B1, B3, B4, B5, B6, L3) — no closures from
iter3.
Campaign scoreboard: 3/5 → 4/5 codecs passing.
H.264 | rkvdec | T4 | PASS direct
MPEG-2 | hantro | iter1 | PASS direct
HEVC | rkvdec | iter2 | PASS direct
VP8 | hantro | iter3 | PASS transitive (readback blocked)
VP9 | rkvdec | iter4 | PENDING
iter4 (VP9 on rkvdec) prediction: comparable scope to iter2 HEVC
(VP9 has compressed-header control + probability state).
~400-500 LOC, 3-4 commits + 1 fix-forward. mpv may engage HW for
VP9 (different from VP8 fallback) — verify at iter4 Phase 0.
Refs:
phase0_findings_iter3.md (Phase 1 lock)
phase2_iter3_situation.md (situation analysis)
phase3_iter3_baseline.md (verbatim payload anchors)
phase4_iter3_plan.md (10 contract clauses + Phase 5 amendments)
phase5_iter3_review.md (4 Critical, all validated correct)
phase7_iter3_verification.md (4 direct + 1 transitive PASS)
Fork commits 27d82e3 + 017e27f + 7f84bbb + e1aca9c
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.