claude-noether
6e8c970c1d
Iteration 2 of the campaign 8(+1)-phase loop opens following iter1
close (dc69378). Per phase0_evidence/2026-05-07/cross_validator_
traces.md suggested ordering, iter2 attacks HEVC Main on rkvdec —
the kernel + driver path is verified working (cross-validator sweep
exit 0); broken link is the libva backend at five distinct sites:
src/config.c HEVCMain case fall-through (analogous to iter1 Bug 1)
src/picture.c HEVCMain explicit UNSUPPORTED_PROFILE reject (NEW)
src/h265.c uncompiled in build (presumably staging-era CIDs;
Phase 2 source-read decides scope of rewrite)
include/hevc-ctrls.h staging-era local header (deferred from
iter1 Phase 5 Nit 6; iter2 closes the loop)
src/meson.build h265.c commented out (re-enable)
Plus possible novel issues vs iter1's MPEG-2 work:
- HEVC has 10 stateless control IDs vs MPEG-2's 3 (much larger
rewrite if h265.c uses staging-era API)
- HEVC slice_params is dynamic-array (kernel rkvdec accepts up
to 600 entries) — different submission shape vs MPEG-2 single-
struct or H.264 fixed-shape
- HEVC SCALING_MATRIX is conditional (only when scaling_list_
enabled in SPS); mapping VAIQMatrixBufferHEVC to V4L2 control
- HEVC ENTRY_POINT_OFFSETS is in kernel surface (tile/slice
resync) but campaign fixture doesn't use tiles — defer
Locked research question:
Make HEVC Main the third codec to pass boolean-correctness on
fresnel via libva-v4l2-request-fourier — mpv --hwdec=vaapi
bbb_720p10s_hevc.mp4 engages backend cleanly and DMA-BUF GL
import yields HW pixels byte-identical to SW reference for the
same frames.
Phase 1 success criterion (5 boolean checks, all must pass):
1. vainfo enumerates VAProfileHEVCMain on rkvdec env binding
(regression check; already passes today).
2. vaCreateConfig(VAProfileHEVCMain, VLD) returns VA_STATUS_
SUCCESS. (Pre-iter2: VA_STATUS_ERROR_UNSUPPORTED_PROFILE.)
3. ffmpeg -hwaccel vaapi -i bbb_720p10s_hevc.mp4 -frames:v 5
-f null - exits 0 cleanly with no Failed-to-create-decode-
configuration lines and no S_EXT_CTRLS EINVAL on HEVC
controls. (Phase 1 criterion 3 anchored on ffmpeg-direct,
mirroring iter1 Phase 5 Q4 amendment for codecs mpv may
filter out.)
4. mpv --hwdec=vaapi --vo=image at +02s seek: 2 distinct frames
hash-equal to SW reference, hash-differ from each other (real
motion). DMA-BUF GL import path per memory feedback_rockchip_
pixel_verify_path.md (NOT ffmpeg-vaapi+hwdownload, which is
cache-stale on RK3399 for both H.264 and MPEG-2 per iter1
Phase 6/7 findings).
5. iter1 MPEG-2 + T4 H.264 reference hashes BOTH still match
(regression check on prior-iteration cells):
MPEG-2 +02s: HW1=6e7873030dbf... HW2=ccc7ce08810d...
H.264 +30s: HW1=f623d5f7a416... HW2=7d7bc6f2146d...
Substrate carry-over:
- libva-v4l2-request-fourier master tip post-iter1-close
(commits e7dad7a..229d6d1 stack on iter8 65969da).
- bbb_720p10s_hevc.mp4 fixture (620 KB, HEVC Main, 1280x720,
24fps, 10s, yuv420p; provenance phase0_evidence/2026-05-07/
test_fixtures.md).
- Cross-validator anchor: phase0_evidence/2026-05-07/
cross_validator/hevc/ — 14 S_EXT_CTRLS + 5 QUERY_EXT_CTRL
(HEVC slice_params dynamic-array introspection unique among
the 5 codecs) + 4 REQUEST_ALLOC.
- Memory carries forward: feedback_gitea_as_claude_noether,
feedback_no_session_termination_attempts, feedback_header_
deletion_check (iter1 lesson L1 — apply to hevc-ctrls.h
deletion), feedback_review_empirical_over_theoretical
(iter1 lesson L2 — apply to Phase 5 review responses),
feedback_rockchip_pixel_verify_path (iter1 lesson L3 —
DMA-BUF GL is the verifier, NOT cached-mmap).
Out-of-scope (LOCKED): VP9/VP8 (later iterations); HEVC Main 10
(silicon support unverified); HEVC Main Still Picture; performance
metrics; long-duration HEVC stress; tile / wavefront parallel
processing (ENTRY_POINT_OFFSETS); Phase 4 cross-cutting backlog
(B1 device-discovery, B3 BeginPicture profile-aware reset, B4
context.c log suppression, B5 vbv_buffer_size negotiation, L3
vaDeriveImage cache-stale fix); chromium-fourier 149 install;
src/context.c changes; upstream engagement.
Predecessor open questions:
- iter1 B3 latent surface-reuse bug (picture.c:287
h264.matrix_set=false hits union byte 240) — for HEVC, the
union member is params.h265.{picture,slice,iqmatrix,
iqmatrix_set}. params.h265 layout differs from params.mpeg2.
Phase 2 source-read action item: verify whether byte 240 lands
in a meaningful HEVC field. If so, iter2 may need to address
even though MPEG-2 didn't.
Phase 2 source-read targets (queued for next phase):
- src/h265.c (~267 lines) — current state, target API
- src/picture.c:204-206 (the explicit HEVC reject)
- src/config.c:55-69 (confirm HEVCMain fall-through)
- src/surface.h:103-108 (params.h265 struct)
- include/hevc-ctrls.h (staging-era; identify CID/struct refs)
- src/meson.build (commented-out h265.c)
- linux/v4l2-controls.h:2110+ (modern HEVC stateless UAPI)
- drivers/staging/media/rkvdec/rkvdec_hevc.c (rkvdec contract)
- libavcodec/v4l2_request_hevc.c (FFmpeg reference impl)
- va/va_dec_hevc.h (VAAPI HEVC buffer structs)
Predicted iter2 close shape: similar pattern to iter1 (config
break + h265.c new-API rewrite + header delete + meson re-enable
+ picture.c reject removal). Larger code change than iter1
(predicting 250-400 lines for h265.c rewrite vs iter1's ~120 lines
for mpeg2.c). One novel construct (slice_params dynamic-array)
worth Phase 4 contract-clause-level attention. Expect Phase 6
takes longer than iter1; Phase 7 harness re-uses iter1's pattern.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
158 lines
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158 lines
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# Iteration 2 — Phase 0 (substrate / motivation / inventory) → Phase 1 lock
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Opens 2026-05-08 immediately after iter1 close ([`phase8_iteration1_close.md`](phase8_iteration1_close.md), commit `dc69378`). Per `feedback_dev_process.md` Phase 0, this document captures iter2's locked research question + substrate + scope, ending with the Phase 1 measurable success criterion.
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## Locked research question (iteration 2)
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> **"Make HEVC Main the third codec to pass boolean-correctness on fresnel via the libva-v4l2-request-fourier path — `mpv --hwdec=vaapi bbb_720p10s_hevc.mp4` engages the backend cleanly and DMA-BUF GL import yields HW pixels byte-identical to a software-decoded reference for the same frames."**
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Pass/fail (boolean):
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1. **Profile enumeration regression check.** `vainfo` with the rkvdec env binding (`LIBVA_V4L2_REQUEST_VIDEO_PATH=/dev/video<N>`, `LIBVA_V4L2_REQUEST_MEDIA_PATH=/dev/media<M>` where `N`/`M` are this-boot's rkvdec node numbers — see device-numbering caveat below) continues to list `VAProfileHEVCMain`. (The enumerator already advertises HEVCMain unconditionally on rkvdec, gated only by the V4L2 `V4L2_PIX_FMT_HEVC_SLICE` format probe; this exists to confirm iter2 work doesn't strip the enumeration.)
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2. **Config creation succeeds.** `vaCreateConfig(VAProfileHEVCMain, VAEntrypointVLD)` returns `VA_STATUS_SUCCESS`. (Today returns `12 = VA_STATUS_ERROR_UNSUPPORTED_PROFILE` per [`phase0_evidence/2026-05-07/cross_validator_traces.md`](phase0_evidence/2026-05-07/cross_validator_traces.md) — same fall-through bug iter1 fixed for MPEG-2.)
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3. **End-to-end decode engages the backend.** `ffmpeg -hwaccel vaapi -i ~/fourier-test/bbb_720p10s_hevc.mp4 -frames:v 5 -f null -` (with rkvdec env binding) shows the libva chain in stderr, libva trace shows `vaCreateConfig SUCCESS`, no `Failed to create decode configuration`, no `EINVAL` from `VIDIOC_S_EXT_CTRLS`, exits 0. (Phase 1 criterion #3 wording is ffmpeg-direct, mirroring iter1 Phase 5 Q4 amendment — mpv `--hwdec=vaapi-copy` may also silently filter HEVC out before libva is loaded; ffmpeg-direct exercises the path. mpv-driven testing follows in criterion #4 via DMA-BUF GL.)
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4. **Cache-safe pixel verification matches SW reference.** `mpv --hwdec=vaapi --vo=image --frames=2 --start=00:00:02` against `bbb_720p10s_hevc.mp4` and the equivalent `--hwdec=no` SW run produce JPEGs whose `sha256sum` outputs match for both frame 1 and frame 2. Frames 1 and 2 must hash-differ between each other (real motion content, not solid color) AND hash-equal across HW vs SW. Per [`memory/feedback_rockchip_pixel_verify_path.md`](../../.claude/projects/-home-mfritsche-src-fresnel-fourier/memory/feedback_rockchip_pixel_verify_path.md): DMA-BUF GL is the cache-coherency-safe verifier; do NOT use ffmpeg-vaapi+hwdownload (vaDeriveImage cache-stale class returns all-zero on RK3399).
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5. **Regression check on iter1 MPEG-2 AND T4 H.264.** Both prior-iteration boolean cells continue to pass:
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- MPEG-2 hashes at +02s seek still `6e7873030dbf...` and `ccc7ce08810d...` (iter1 Phase 7 reference).
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- T4 H.264 hashes at +30s seek still `f623d5f7...` and `7d7bc6f2...` (iter1 Phase 7 + T4 reference).
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Iter2 must not regress either codec.
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A clean iter2 close has all five checks green. Anything less loops back to Phase 4 per `feedback_dev_process.md` Phase 7 → Phase 4 edge.
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## Mechanism the question targets
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Phase 0 cross-validator sweep ([`phase0_evidence/2026-05-07/cross_validator_traces.md`](phase0_evidence/2026-05-07/cross_validator_traces.md)) established the kernel + rkvdec driver path works for HEVC: `ffmpeg -hwaccel v4l2request -i bbb_720p10s_hevc.mp4 -frames:v 2 -f null - = exit 0`. So the broken link is the libva backend. From iter1 Phase 2 source-read of the master tip:
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- `src/config.c:55-69` `RequestCreateConfig` — `case VAProfileHEVCMain:` falls through to `default:` returning `VA_STATUS_ERROR_UNSUPPORTED_PROFILE`. iter1 added a `break;` for the MPEG-2 cases; HEVC stays in the fall-through bucket.
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- `src/picture.c:204-206` `codec_set_controls` — `case VAProfileHEVCMain:` explicitly returns `VA_STATUS_ERROR_UNSUPPORTED_PROFILE` with the comment `/* Fourier-local: HEVC stripped, no HW support on RK3566. */`. The "no HW support on RK3566" rationale was for ohm (PineTab2 RK3566/RK3568) at libva-multiplanar iter5 close; on RK3399 fresnel rkvdec, HEVC IS supported in silicon (cross-validator confirms).
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- `src/meson.build` — `# 'h265.c'` is commented out in the `sources` list. Re-enable.
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- `src/h265.c` — uncompiled today; likely uses staging-era control IDs from `include/hevc-ctrls.h` (analogous to mpeg2.c using staging-era `mpeg2-ctrls.h` before iter1). The new mainline kernel UAPI for HEVC stateless controls lives at `include/uapi/linux/v4l2-controls.h:2110+` with control IDs `V4L2_CID_STATELESS_HEVC_{SPS,PPS,SLICE_PARAMS,SCALING_MATRIX,DECODE_PARAMS,DECODE_MODE,START_CODE,ENTRY_POINT_OFFSETS,EXT_SPS_ST_RPS,EXT_SPS_LT_RPS}` (10 control IDs total — substantially more than MPEG-2's 3).
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- `include/hevc-ctrls.h` — local fork header, staging-era. iter1 Phase 5 Nit 6 deferred this deletion; iter2 closes that loop.
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iter2 likely encounters **four bugs** structurally analogous to iter1, plus possibly more:
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- **B1 (analogous to iter1 Bug 1)**: config.c HEVCMain case fall-through. Fix shape: 3-line `break;` addition.
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- **B2 (analogous to iter1 Bug 2)**: src/h265.c using staging-era CIDs. Fix shape: rewrite against the new V4L2_CID_STATELESS_HEVC_* split API. Larger than iter1's mpeg2.c rewrite because HEVC has 10 control IDs vs MPEG-2's 3.
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- **B3 (analogous to iter1 Bug 3)**: `include/hevc-ctrls.h` is the staging-era local header. Fix shape: delete the file; verify no remaining includes via clean rebuild after include-removal patches (per [`memory/feedback_header_deletion_check.md`](../../.claude/projects/-home-mfritsche-src-fresnel-fourier/memory/feedback_header_deletion_check.md) — grep alone is insufficient).
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- **B4 (NEW)**: picture.c::codec_set_controls explicitly returns UNSUPPORTED_PROFILE for HEVCMain. Fix shape: replace the explicit reject with a dispatch to `h265_set_controls`.
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- **B5 (meson)**: src/meson.build comments out `h265.c`. Fix shape: uncomment.
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Plus possibly:
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- **B6**: VAAPI VAPicture/VASlice/VAIQMatrix HEVC structs may not map 1:1 to the new V4L2 control structs. Phase 2 source-read of `<va/va_dec_hevc.h>` + the kernel UAPI HEVC structs will identify any mismatches.
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- **B7**: HEVC slice_params is a dynamic-array control (kernel UAPI `v4l2-controls.h:2117` `V4L2_CID_STATELESS_HEVC_SLICE_PARAMS` is per-slice; rkvdec accepts up to 600 entries per Phase 0 v4l2-ctl inventory). The libva backend must accumulate per-slice params and submit them as a dynamic-array. Different shape from H.264 (which uses single VASliceParameter per RenderPicture call) and MPEG-2 (which doesn't have slice params at all in the new API).
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Phase 4 plan must cite the contract before patching (`feedback_dev_process.md` Phase 6 contract-before-code): read kernel `drivers/staging/media/rkvdec/rkvdec_hevc.c` (the rkvdec HEVC driver source), read FFmpeg downstream `libavcodec/v4l2_request_hevc.c`, read mainline `include/uapi/linux/v4l2-controls.h:2110+`, state the HEVC control-submission contract explicitly before any code lands.
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## Predecessor carry-over (iter1 → iter2)
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### State that carries forward (re-verified at iter2 open)
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- **Hardware**: fresnel RK3399, kernel `6.19.9-99-eos-arm`. ftrace + tracing enabled. mpv 0.41.0 stock, ffmpeg n8.1-13 (Kwiboo branch), libva 1.23.0.
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- **rkvdec node**: Phase 7 verified `/dev/video1` + `/dev/media0` on the boot of 2026-05-08 morning. **Caveat**: V4L2 `/dev/videoN` numbering shuffles across reboots (per iter1 Phase 8 backlog B1). iter2 binding cells should re-verify `v4l2-ctl --info` at session start. Long-term fix candidate: backend-side device-discovery probe (Phase 4 cross-cutting, not iter2).
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- **Decoder formats** (rkvdec, from [`phase0_evidence/2026-05-07/v4l2_inventory.txt`](phase0_evidence/2026-05-07/v4l2_inventory.txt)): OUTPUT_MPLANE = `S265` (HEVC Parsed Slice Data) + `S264` (H.264) + `VP9F` (VP9). CAPTURE_MPLANE = `NV12`.
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- **Stateless control payloads** kernel exposes (rkvdec, HEVC): `hevc_sequence_parameter_set` (`0x00a40a90`), `hevc_picture_parameter_set` (`0x00a40a91`), `hevc_slice_parameters` (`0x00a40a92`, dynamic-array max 600 elems), `hevc_scaling_matrix` (`0x00a40a93`), `hevc_decode_parameters` (`0x00a40a94`), `hevc_decode_mode` (`0x00a40a95`, menu, FRAME_BASED only), `hevc_start_code` (`0x00a40a96`, menu, ANNEX_B only).
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- **HEVC profile menu** (rkvdec): Main, Main Still Picture, Main 10. RK3399 silicon support for Main 10 (10-bit) is unverified; iter2 fixture is 8-bit Main only.
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- **Backend build state**: libva-v4l2-request-fourier master tip post-iter1-close, including:
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- iter1 commits: `e7dad7a` (config.c break) + `5fe873c` (mpeg2.c rewrite) + `3aab187` (delete include/mpeg2-ctrls.h) + `229d6d1` (commit D fix-forward).
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- iter1's MPEG-2 path is a working reference for the patch shape (config.c break + new-API rewrite + header delete + grep-audit incompleteness fix).
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- `src/h265.c` is **already in the source tree** (267 lines per Phase 0 inventory) — Phase 2 will audit whether it uses staging-era or modern API. If staging-era, rewrite is the bulk of iter2 work. If somehow already on modern API, the work is much smaller.
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- **Test fixture**: `~/fourier-test/bbb_720p10s_hevc.mp4` on fresnel (620 KB, HEVC Main, 1280×720@24fps, yuv420p, 10s, generated 2026-05-07 23:34 from H.264 master via libx265 ultrafast). Provenance: [`phase0_evidence/2026-05-07/test_fixtures.md`](phase0_evidence/2026-05-07/test_fixtures.md).
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- **Reference fixtures for regression**: `~/fourier-test/bbb_1080p30_h264.mp4` (T4 reference) and `~/fourier-test/bbb_720p10s_mpeg2.ts` (iter1 reference).
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- **iter1 + T4 reference hashes for regression criterion 5**:
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- H.264 (T4) at +30s: HW frame 1 `f623d5f7a41697f67dd227275c6f1b21ffc257f65626d32fde8229357f8764c9`, frame 2 `7d7bc6f2146dda8b2d223bba622c4b9fbe9674181ff1e02afe286b620342e0a8`.
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- MPEG-2 (iter1) at +02s: HW frame 1 `6e7873030dbf0403c67f35dd106ebef3c7909a0fd12433b82ad758e7fee9f092`, frame 2 `ccc7ce08810d4a96e9ba7a19f4f95bbf6cc861bda9337604b5c668ad52bef7de`.
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- **Cross-validator anchor**: ffmpeg-v4l2request HEVC contract from [`phase0_evidence/2026-05-07/cross_validator/hevc/`](phase0_evidence/2026-05-07/cross_validator/hevc/). 14 `S_EXT_CTRLS`, 5 `QUERY_EXT_CTRL` (HEVC slice_params dynamic-array introspection — unique among the 5 codecs), 4 `MEDIA_IOC_REQUEST_ALLOC`. 60 ftrace v4l2 events for 2 frames.
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- **Cache-safe verify path**: `mpv --hwdec=vaapi --vo=image` (DMA-BUF GL import). Confirmed for H.264 (T4) and MPEG-2 (iter1 Phase 7); iter2 expects the same path to work for HEVC.
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### Data that does NOT carry forward (re-acquire if needed)
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- ohm/RK3568 hantro HEVC behavior — there is none; RK3568 hantro doesn't decode HEVC. RK3399 rkvdec is the first time the libva-v4l2-request-fourier fork sees HEVC on real hardware. Reference history: zero.
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- libva-multiplanar iter1-iter5 close docs' "HEVC stripped" disposition — that was an ohm-side build-cleanly decision, not an empirical "HEVC doesn't work" finding. iter2 reverses the strip.
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### Open questions inherited from iter1 close
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- **B3 latent surface-reuse bug** ([`phase8_iteration1_close.md`](phase8_iteration1_close.md) backlog): `picture.c:287` `params.h264.matrix_set = false` writes union byte 240, lands inside `mpeg2.iqmatrix.chroma_intra_quantiser_matrix[20]`. For HEVC, the union member is `params.h265.{picture, slice, iqmatrix, iqmatrix_set}`. The `params.h265` struct layout differs from `params.mpeg2` (per [`src/surface.h:90-109`](../libva-multiplanar/libva-v4l2-request-fourier/src/surface.h)). iter2 should verify whether byte 240 lands inside `h265.iqmatrix` or elsewhere; if it lands in a meaningful HEVC field, the latent bug becomes acute for iter2's binding cells. **Phase 2 source-read action item**.
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- **Phase 4 cross-cutting work items** (vaDeriveImage fix, V4L2 device-discovery, BeginPicture profile-aware reset, context.c log suppression): not iter2 scope; iter2 works around them via DMA-BUF GL verify path and re-checked device numbers.
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## Tooling and measurement-instrument inventory (live verification)
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Re-verified at iter2 open (carries forward from iter1, all proven working):
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- `strace -ff -tt -y -v -e trace=ioctl,openat,close` — captures V4L2 + media-request ioctl sequence per thread.
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- `LIBVA_TRACE` environment variable — captures vaCreate/vaQuery/vaInitialize call traces with status return codes.
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- `sudo sh -c "echo 1 > /sys/kernel/tracing/events/v4l2/enable"` — captures kernel v4l2 tracepoints (qbuf/dqbuf events).
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- `mpv --hwdec=vaapi --vo=image` — cache-coherency-safe pixel verifier (DMA-BUF GL import).
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- `ffmpeg -hwaccel v4l2request` — independent V4L2 client cross-validator (different code path than libva).
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- Backend build harness on fresnel: `ninja -C ~/src/libva-v4l2-request-fourier/build && sudo ninja -C build install`.
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- Empirical HEVC decode of `bbb_720p10s_hevc.mp4` via ffmpeg-v4l2request DRM_PRIME path — proven works in cross-validator sweep.
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iter2 will likely add per-source debug `printf`/`fprintf(stderr, ...)` instrumentation in `src/h265.c` during Phase 6. That instrumentation is iter2-internal scratch; clean sweep at iter2 close per Phase 5 review precedent.
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## In-scope (LOCKED 2026-05-08 for iteration 2)
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- libva-v4l2-request-fourier backend HEVC Main path on rkvdec.
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- `src/config.c::RequestCreateConfig` — add `break;` for `VAProfileHEVCMain` case (analogous to iter1 Commit A pattern for MPEG-2).
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- `src/picture.c::codec_set_controls` — replace the explicit `case VAProfileHEVCMain: return UNSUPPORTED_PROFILE` with a dispatch to `h265_set_controls`.
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- `src/h265.c` — Phase 2 source-read decides the scope: if it uses staging-era CIDs, full rewrite against new split API. If somehow already modern, the audit produces a delta. Plus any fixes needed for VAAPI ↔ V4L2 control struct mapping (slice_params dynamic-array semantics, scaling_matrix conditional, decode_params per-frame).
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- `include/hevc-ctrls.h` — DELETE (iter1 Phase 5 Nit 6 deferred this; iter2 closes the loop). Apply [`memory/feedback_header_deletion_check.md`](../../.claude/projects/-home-mfritsche-src-fresnel-fourier/memory/feedback_header_deletion_check.md) discipline: drop `#include` from all callsites + clean rebuild + then `git rm`.
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- `src/meson.build` — uncomment `'h265.c'` in the sources list.
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- iter2 binding-cell test harness: re-run iter1's Phase 7 5-criterion harness substituting HEVC fixture, plus iter1's MPEG-2 + T4 H.264 regression checks.
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- Cache-safe pixel verify must use DMA-BUF GL import (not vaDeriveImage), per memory `feedback_rockchip_pixel_verify_path.md`.
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## Out-of-scope (LOCKED 2026-05-08 for iteration 2)
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- VP9, VP8 work (iter3/iter4).
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- HEVC Main 10 (10-bit). Silicon support unverified; campaign codec scope is 8-bit yuv420p.
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- HEVC Main Still Picture profile (rkvdec advertises it via the menu, but the campaign fixture is Main, not Main Still Picture; defer).
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- Performance metrics (Phase 1+ separate iteration).
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- Long-duration HEVC stress (>10s).
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- HEVC tile / wavefront parallel processing (`ENTRY_POINT_OFFSETS` is in the kernel surface but the campaign fixture doesn't use tiles; defer).
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- Phase 4 cross-cutting backlog items B1 (V4L2 device-discovery), B3 (BeginPicture profile-aware reset), B4 (context.c log suppression), B5 (vbv_buffer_size negotiation), L3 (vaDeriveImage cache-stale fix). All carry forward from iter1; not iter2 scope.
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- chromium-fourier 149 install on fresnel (carry-over from iter1 deferred).
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- `src/context.c` — no changes (the H.264 device-init unconditional-EINVAL is auxiliary noise per iter1 Phase 7; benign for HEVC binding cells).
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- Upstream Linux engagement (per `feedback_no_upstream.md`). Kernel-side works; nothing to file.
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## Phase 1 success criterion (LOCKED 2026-05-08)
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The five Pass/fail bullets at the top of this document are the iter2 success criterion. Phase 3 baseline measurements feed Phase 4 plan; Phase 7 verification re-runs all five against the patched backend.
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If Phase 3 baseline reveals the chosen criterion is the wrong target (Phase 3 → Phase 1 loopback per `feedback_dev_process.md`), the criterion will be rewritten and re-locked. Plausible reasons that would trigger the loopback:
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- The HEVC fixture is malformed in a way that exposes a fixture-side bug rather than a backend-side bug. (Mitigation: ffmpeg-v4l2request decodes the same fixture cleanly per Phase 0 cross-validator sweep, so this is unlikely.)
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- HEVC slice_params dynamic-array semantics on rkvdec require a different submission shape than expected (e.g., per-slice `S_EXT_CTRLS` vs single batched submission with a slice_params array). Phase 3 baseline of ffmpeg-v4l2request HEVC trace will resolve.
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- mpv `--hwdec=vaapi` (DMA-BUF) ALSO filters HEVC out (Phase 5 Q4 amendment for iter1 ended up being non-blocking because mpv-vaapi engages MPEG-2; we'll see if HEVC behaves the same). Mitigation: fall-forward to ffmpeg-v4l2request DRM_PRIME + hwdownload pixel verify (we know that works; criterion holds, harness adapts).
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- VAAPI HEVC consumer pattern requires VAEncSliceParameterBufferType to be sent in some specific order; iter1 didn't have to handle this. Phase 2 source-read will identify.
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The other four Phase 1 criteria (vainfo enumeration, vaCreateConfig success, ffmpeg-direct exit 0, MPEG-2+T4 regression) hold as locked — no adjustment expected.
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## Phase 2 source-read targets
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For the upcoming Phase 2 situation analysis:
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||
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- `src/h265.c` (entire file, ~267 lines) — current state, what API it targets, what VAAPI buffers it reads, what V4L2 controls it submits.
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- `src/picture.c:204-206` — the explicit HEVC reject; verify the surrounding context.
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- `src/config.c:55-69` — confirm HEVC fall-through (already inspected during iter1 Phase 2; nothing should have changed).
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- `src/surface.h:103-108` (`params.h265` struct) — VAAPI HEVC buffers in the surface union.
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- `include/hevc-ctrls.h` (entire file) — staging-era definitions; identify which CIDs and structs are referenced from `src/h265.c`.
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- `src/meson.build` — confirm `h265.c` commented out; identify any conditional compile flags.
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- Kernel UAPI `<linux/v4l2-controls.h>` lines 2110+ — modern HEVC stateless control IDs and struct layouts.
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- Linux mainline kernel `drivers/staging/media/rkvdec/rkvdec_hevc.c` — the rkvdec HEVC driver source. Specifically: which controls are mandatory, which are optional, what's the slice_params dynamic-array contract, what's the decode_params contract.
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- FFmpeg downstream `libavcodec/v4l2_request_hevc.c` — independent V4L2 client implementation. Submission shape, per-slice params batching, scaling_matrix conditionality.
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- VAAPI `<va/va_dec_hevc.h>` — VAAPI HEVC buffer struct definitions (especially `VAPictureParameterBufferHEVC`, `VASliceParameterBufferHEVC` (and any 422/444 ext variants), `VAIQMatrixBufferHEVC`).
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||
|
||
## What "iteration 2 close" looks like
|
||
|
||
A clean iter2 close per `feedback_dev_process.md` Phase 8:
|
||
|
||
- All 5 Phase 1 criteria green.
|
||
- `phase8_iteration2_close.md` summarizing the bug, contract, fix, binding-cell numbers.
|
||
- Third-codec passing on the campaign-level scoreboard: 2/5 → 3/5.
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||
- Memory entries distilled for any new lessons (iter1 produced 3; iter2 may produce 0 if the work mirrors iter1's MPEG-2 pattern cleanly, or more if HEVC surfaces novel issues).
|
||
- Debug-instrumentation sweep at close.
|
||
- Phase 5 sonnet-architect review pass signed off.
|
||
- Commits all authored as `claude-noether` per [`memory/feedback_gitea_as_claude_noether.md`](../../.claude/projects/-home-mfritsche-src-fresnel-fourier/memory/feedback_gitea_as_claude_noether.md).
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||
- `include/hevc-ctrls.h` deleted (closing iter1 Phase 5 Nit 6).
|
||
- `src/h265.c` re-enabled in `src/meson.build`, modernized against new V4L2 stateless API, dispatched correctly from picture.c.
|
||
|
||
Predicted iter2 difficulty vs iter1: similar shape (config break + new-API rewrite + header delete + grep-audit completeness), larger scope (10 control IDs vs 3), one novel construct (slice_params dynamic-array). Expect Phase 6 to take longer than iter1 (~120 lines mpeg2.c rewrite vs probably 250-400 lines for h265.c). Phase 7 verification harness re-uses iter1's pattern verbatim.
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