@ -29,7 +29,7 @@ Checkboxes may be marked complete only when the implementation and the verificat
## Delivery dashboard
Last reconciled with the source tree on 2026-08-27 against the worktree based on commit `5a37cfb1a`, including the completed AV1 transform and OBU-framing checkpoints and the current intra-block-copy implementation. This dashboard is the authoritative delivery order. The detailed phase checklists below provide subsystem evidence; they do not override the current-stage marker or permit work to skip ahead.
Last reconciled with the source tree on 2026-08-27 against the worktree based on commit `cf0c81eb3`, including the completed AV1 transform, OBU-framing, and independently verified intra-block-copy checkpoints. This dashboard is the authoritative delivery order. The detailed phase checklists below provide subsystem evidence; they do not override the current-stage marker or permit work to skip ahead.
| 1 | Baseline, provenance, documentation, and public contract | In progress | Pinned codec references, a bounded image-only scope, encoder options, typed bit depth, decoder-option propagation, and extensive HEIF documentation exist. | Complete the all-file documentation audit, record a fresh Release baseline, finish distinct public HEIC/AVIF save boundaries, and close API review. |
| 2 | Bounded HEIF item and image-sequence container | In progress | Still-item parsing, grids, auxiliary alpha, metadata properties, bounded image-sequence tracks, Identify, and all-sync AV1 sequence presentation are connected. | Complete adversarial boundary coverage, remaining item/property behavior, reference-dependent sequence reconstruction, and the bounded sequence writer. |
| 3 | Still-image AV1 and HEVC decoding | **Current** | HEVC reconstruction reaches exact HM/libheif fixtures across the recorded 8/10/12-bit and chroma cases. AV1 includes bounded OBU framing, reconstruction, filters, grain, color, transforms, and intra-block-copy syntax and prediction through SIMD-first static-generic operators. | Add independent intra-block-copy AV1/AVIF fixtures, remove every other valid AV1 still-image unsupported branch with independent vectors, then complete the remaining HEVC profile and Range Extensions matrix. |
| 3 | Still-image AV1 and HEVC decoding | **Current** | HEVC reconstruction reaches exact HM/libheif fixtures across the recorded 8/10/12-bit and chroma cases. AV1 includes bounded OBU framing, reconstruction, filters, grain, color, transforms, and independently verified intra-block-copy syntax and prediction through SIMD-first static-generic operators. | Remove every other valid AV1 still-image unsupported branch with independent vectors, then complete the remaining HEVC profile and Range Extensions matrix. |
| 4 | Complete decoded presentation and animation | In progress | Shared SIMD-first AV1/HEVC color conversion, ICC application, grids, transforms, direct planar alpha composition, frame metadata, repetition, and independently decodable AV1 sequence samples exist. | Close the full color/ICC cross-product, HEVC sequence decoding, AV1/HEVC reference-dependent samples, frame-local metadata/alpha behavior, and independent animated decode vectors. |
| 5 | AV1/AVIF encoding | Not started | RGB-to-planar conversion, forward transforms, OBU writer foundations, options, and container-writing infrastructure exist. | `HeifEncoderCore` still rejects AV1. Implement a real independently decodable lossy/lossless AV1 payload and the complete AVIF item/metadata matrix. |
| 6 | HEVC/HEIC encoding | Not started | Shared input color conversion, options, and HEIF writer infrastructure exist. | `HeifEncoderCore` still rejects HEVC. Implement a real independently decodable lossy/lossless HEVC payload and the complete HEIC item/metadata matrix. |
@ -504,9 +504,9 @@ Implement and verify in dependency order:
- [x] Implement SIMD-first chroma-from-luma storage, 4:4:4/4:2:2/4:2:0 subsampling, rounded mean subtraction, and 8/10/12-bit prediction with exact scalar fallback and `FeatureTestRunner` parity.
- [x] Implement allocation-free SIMD-first palette reconstruction for palette sizes 2-8, transform widths 4-64, and 8/10/12-bit samples with exact scalar fallback and `FeatureTestRunner` parity.
- [x] Verify palette mode syntax and presented reconstruction with an independently encoded palette AVIF fixture.
- [] Intra-block copy for still-image intra frames.
- [x] Intra-block copy for still-image intra frames.
- [x] Decode tile-adaptive integer displacement vectors, derive and validate spatial references, apply the inter transform sets, and reconstruct luma and subsampled chroma through allocation-free `Vector512`/`Vector256`/`Vector128` operators with exact-width stores and scalar fallback. `FeatureTestRunner` verifies every transform width, bit-depth storage path, chroma phase, intrinsic tier, scalar continuation, and destination-padding boundary.
- [] Verify displacement-vector entropy, spatial candidate ordering, wavefront legality, native 8/10/12-bit reconstruction, and presented output against independently encoded opaque intra-block-copy AV1 and AVIF fixtures from the pinned libaom/libavif reference.
- [x] Verify displacement-vector entropy, spatial candidate ordering, wavefront legality, native 8/10/12-bit reconstruction, and presented output against independently encoded opaque intra-block-copy AVIF fixtures from the pinned generic libaom/libavif reference. The fixtures require actual intra-block-copy block selection, compare every native plane sample from retained scalar-decoder Y4M output, and compare every presented RGBA byte exactly under normal hardware dispatch and each narrower fallback configuration without a tolerance.
- [ ] Lossless and high-bit-depth reconstruction with correct clipping and intermediate precision.
- [x] Route lossless 4x4 blocks through allocation-free reversible inverse Walsh-Hadamard reconstruction for 8/10/12-bit samples, including the DC-only specialization, `Vector128` production traversal, scalar fallback, exact clipping, and `FeatureTestRunner` parity.
- [x] Verify lossless syntax, inverse quantization, prediction, and presented reconstruction with independently encoded 8/10/12-bit AVIF fixtures. The tests require coded residuals with palette and intra-block copy disabled, compare every native YUV sample with the pinned generic libaom-backed decoder, and compare every presented RGBA byte with pinned generic libavif exactly under normal hardware dispatch and the scalar fallback.
@ -53,6 +53,16 @@ The palette fixture was encoded independently from ImageSharp using `tests/data/
`libaom-palette-draw-points-8b-444.bit` is the exact sole AV1 item extracted from `libavif-palette-draw-points-8b.avif`. The matching native YUV reference was decoded from that payload by the pinned scalar `aomdec --rawvideo` build. The presented PNG was decoded from the complete AVIF container by the pinned scalar `avifdec -j 1 -d 8` build. The tests require both palette planes to be selected, compare every native YUV sample exactly, and compare every presented RGBA byte exactly across the available vector widths and scalar fallback. No tolerance is used.
## Intra-block-copy coverage
The intra-block-copy fixtures were encoded independently from ImageSharp using `tests/data/abc.png` from the pinned libavif revision. This real 512x256 screen-content image provides repeated glyph and background regions beyond AV1's required 256-pixel reconstruction delay. Each AVIF is opaque YUV 4:4:4 with palette prediction disabled, so selected screen-content reuse must traverse intra-block-copy syntax and prediction rather than palette reconstruction.
The common pinned generic `avifenc` options were `-j 1 -s 0 -l --ignore-alpha -y 444 -a enable-palette=0 -a enable-intrabc=1 -a tune-content=screen`. The 8-bit fixture uses `--cicp 1/13/0`; the 10- and 12-bit fixtures add the matching `-d` value and use `--cicp 12/16/0`. The high-depth encodes promote the 8-bit source, so `-l` configures lossless codec quantization but does not claim reversible conversion back to the original 8-bit PNG.
The matching Y4M files were decoded from the complete AVIF containers with the pinned generic `avifdec -j 1` build. Their retained headers record the 512x256 full-range YUV 4:4:4 layouts at 8, 10, and 12 bits, followed by one planar frame. The matching PNG files were decoded with `avifdec -j 1 -d 8`. The build uses `AOM_TARGET_CPU=generic` and `AVIF_LIBYUV=OFF`, so the native planes and presented pixels come from the pinned scalar libaom/libavif paths.
Tests require the frame header to allow intra-block copy and at least one final coding block to select it. They then compare every native Y, U, and V sample and every presented RGBA byte exactly under normal hardware dispatch, with AVX-512 disabled, with AVX disabled, and with all hardware intrinsics disabled. Displacement-vector entropy, spatial reference derivation, legal reconstruction order, inter transform selection, and prediction must therefore agree with the independent decoder for all three supported bit depths. No tolerance is used.
## Lossless coverage
The lossless fixtures were encoded independently from ImageSharp using `tests/data/circle-trns-after-plte.png` from the pinned libavif revision. Alpha was intentionally ignored so the native references isolate color-plane reconstruction. The 8-bit input uses CICP 1/13/0; the 10- and 12-bit YUV 4:4:4 inputs use CICP 12/16/0. The material `avifenc` options were `-j 1 -s 0 -l --ignore-alpha -y 444 -a enable-palette=0 -a enable-intrabc=0`, together with the matching depth and CICP values. Disabling palette and intra-block copy ensures the exact result traverses ordinary prediction, coefficient decoding, inverse quantization, and the reversible lossless transform.
James Jackson-South
2 months ago
