@ -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 2026-08-30 against production checkpoint `fcd16c862`. Committed checkpoints include the AV1 transform architecture, OBU framing, tile partitioning, mode information, segmentation, delta quantization, transform-size selection, coefficient decoding, inverse quantization, inverse transforms, complete intra prediction, intra-block copy, official extreme-displacement intra-block-copy conformance, the 12-profile reconstruction matrix, corrected twelve-bit inverse-transform SIMD arithmetic, layered-item properties, layered reference/header/CDF/motion-field state, inter-frame intra blocks, SIMD-first translational prediction, complete single-reference inter reconstruction, compound reference trees and modes, paired reference-MV derivation, reference-dependent bounded sequence decoding, allocation-free SIMD-first equal averaging, selected inter-intra prediction, selectable compound blending, OBMC, scaled-reference reconstruction, local warped prediction, non-translational global prediction, official motion-vector conformance, official spatial- and temporal-layer default-operating-point conformance, official active-film-grain and monochrome sequence conformance, selected spatial-layer presentation, progressive color and auxiliary-alpha conformance, pinned-HM HEVC CABAC verification, pinned-HM HEVC coding-tree traversal verification, official HEVC intra-prediction verification, official HEVC residual-reconstruction verification, HEVC parallel slice decoding, and bounded HEVC supplemental presentation and metadata handling. 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 2026-08-30 against production checkpoint `9d7348efd`. Committed checkpoints include the AV1 transform architecture, OBU framing, tile partitioning, mode information, segmentation, delta quantization, transform-size selection, coefficient decoding, inverse quantization, inverse transforms, complete intra prediction, intra-block copy, official extreme-displacement intra-block-copy conformance, the 12-profile reconstruction matrix, corrected twelve-bit inverse-transform SIMD arithmetic, layered-item properties, layered reference/header/CDF/motion-field state, inter-frame intra blocks, SIMD-first translational prediction, complete single-reference inter reconstruction, compound reference trees and modes, paired reference-MV derivation, reference-dependent bounded sequence decoding, allocation-free SIMD-first equal averaging, selected inter-intra prediction, selectable compound blending, OBMC, scaled-reference reconstruction, local warped prediction, non-translational global prediction, official motion-vector conformance, official spatial- and temporal-layer default-operating-point conformance, official active-film-grain and monochrome sequence conformance, selected spatial-layer presentation, progressive color and auxiliary-alpha conformance, pinned-HM HEVC CABAC verification, pinned-HM HEVC coding-tree traversal verification, official HEVC intra-prediction verification, official HEVC residual-reconstruction verification, HEVC parallel slice decoding, bounded HEVC supplemental presentation and metadata handling, and the complete independently coded HEVC Range Extensions native-plane profile/tool matrix. 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.
Commit `a0d1b5af56acb3a3a9aebb29c916d1b36cd49367` restores the established JPEG color-converter operator architecture throughout the HEIF implementation. `Av1ForwardTransformer` owns its nested one-dimensional contract and all twelve concrete forward transform operators; `Av1Inverse2dTransformer` owns the corresponding inverse contract and operators; and `Av1InverseTransformer` owns the byte and high-bit-depth reconstruction-output operators. Each contract lives in the owner's `.Operator.cs`, while every semantic transform with a shared traversal has its own `<Owner>.<Semantic>Operator.cs` partial-family file and implements concrete scalar and SIMD overload bodies without a forwarding semantic core. The same owner-and-partial-file rule now covers HEVC inverse transforms and intra prediction, AV1 and HEVC deblocking, AV1 CDEF, and HEVC transform-skip reconstruction. Vector-width and sample-storage adapters that are not semantic dispatch operators are named `Operations`; no operator type is named after a hardware width, no static contract uses CRTP, no source file groups multiple concrete semantic operator structs, and no semantic operator remains top-level. Roslynk reports zero compiler errors, both Release source targets build with zero warnings and errors, and 736 focused `net10.0` transform, loop-filter, prediction, reconstruction, transfer-function, and film-grain cases pass without failures or skips through the existing `FeatureTestRunner` coverage. All 56 new C# paths resolve to the existing `csharp` diff driver without an attributes change, and `git diff --check` is clean.
@ -43,6 +43,8 @@ Commit `97538abd29cb69df0ecf3e30a4ee3b40b586c070` closes the independently coded
Commit `fcd16c862c437e3249c7e693012c717512985163` closes the bounded HEVC supplemental-presentation checkpoint. The item parser now consumes prefix-SEI messages in access-unit order, supports extended payload types and sizes, skips unknown payloads, rejects misplaced prefix messages and malformed trailing bits, and maps pinned-HM display orientation, no-display, mastering-display color volume, content light level, alternative transfer characteristics, ambient viewing environment, and content color volume into the bounded ImageSharp result. Codec orientation is applied after item scaling and auxiliary-alpha composition but before container crop, rotation, and mirroring, so a real public HEIC with alpha matches its independent reference PNG at every final RGBA sample after the injected transform. Metadata conflicts and no-display fail at the item boundary, while optional video timing, persistence, and post-processing messages without an ImageSharp still-image result or exposed metadata mapping remain intentionally ignored. `FeatureTestRunner` verifies normal and scalar presentation paths through an 8 KiB constrained tracked allocator with balanced exactly-once returns. All 195 focused HEVC cases pass without failures or skips, both Release source targets build with zero warnings and errors, Roslynk reports zero compiler errors, scoped StyleCop and whitespace verification are clean, `.gitattributes` is unchanged, and `git diff --check` is clean.
Commit `9d7348efd6496b54cef7ec27e42352641439c400` completes the independently coded HEVC Range Extensions native-plane profile and tool matrix. Twenty-five selected official H.265.1 pictures extend the existing ten Sony GENERAL pictures with Main RExt and High Throughput RExt coverage for cross-component prediction, unequal luma/chroma precision, persistent Rice adaptation, extended precision, PCM, transform-skip contexts, chroma-angle adjustment, coding-unit chroma-QP adjustment, tiles, wavefront entry points, and CABAC bypass alignment. Every selected Y, Cb, and Cr plane matches its normative decoded-picture-hash SEI or a first reference picture whose complete output matches the archive's published MD5. The matrix exposed and corrected PCM sample restoration from signaled PCM precision to reconstructed component precision and the chroma-deblocking rule that excludes slice and coding-unit chroma-QP adjustments from `tc` derivation; dead per-coding-unit deblocking-offset storage was removed. The exact 25-case matrix and all 220 focused HEVC cases pass in `net10.0` Release, both Release source targets build with zero warnings and errors, Roslynk reports zero compiler errors, all 24 retained fixture SHA-256 values and staged LFS pointers match the documented existing attributes, `.gitattributes` is unchanged, and `git diff --check` is clean. This checkpoint proves native reconstruction for the independently coded Phase 4 scope; it does not prove the separate every-profile HEIC container-presentation exit gate.
Commit `1c58d855f70b024170ced9eb0a7005f0f9c955ad` records the complete official motion-vector conformance checkpoint. The official IVF has SHA-1 `F064290D7FCD3B3DE19020E8AEC6C43C88D3A505`, matching the pinned libaom test-data manifest, and SHA-256 `222A9050059B254DAB17CFB802FF829C778E3F93AF18961A622C8268576C1395`; its pinned-libaom Y4M has SHA-256 `D97AC78C81782CF1507549368047769DC677DBE205706458D1EE9C807DE6EC78`. Both source targets build with zero warnings and errors, the `net10.0` test-project analyzer build completes with zero errors and 1,014 pre-existing repository warnings, Roslynk reports zero compiler errors, 3,985 focused `net10.0` cases pass without failures or skips, and `git diff --check` is clean.
Commit `019ac5648b4380a6ff4865072c96fde29ce09fad` records the complete selected-spatial-layer presentation checkpoint. An essential `lsel` selecting the genuine 40x40 base layer of the committed 40x40-to-80x80 progressive AVIF returns that exact pinned-libaom native reconstruction, then scales its YUV444 planes to the 80x80 `ispe` extent before color conversion and matches pinned libavif's RGBA output exactly. Retained reconstructed planes remain at coded dimensions; presentation planes use group-safe allocator-owned rows and are returned exactly once under a 1,024-byte constrained allocator. Portable `Vector128` and scalar two-times filters match pinned libyuv edge, quarter-sample, and rounding results at 8 and 12 bits through `FeatureTestRunner`. Both source targets build with zero warnings and errors, the `net10.0` test-project analyzer build completes with zero errors and 1,014 pre-existing repository warnings, Roslynk reports zero compiler errors, 156 focused reconstruction and color cases pass without failures or skips, and `git diff --check` is clean.
@ -81,15 +83,15 @@ Status meanings:
- **Not started:** supporting primitives may exist, but the production format path is absent.
- **Current:** the only work item that should be advanced before taking the next queued item.
Current development stage: **Stage 4 — complete HEVC still-image decoding.** The AV1 still-image exit gate is complete across the exact 12-profile matrix, layered reference-dependent items, every connected normative reconstruction tool, official quantizer and size boundaries, constrained allocation, and pinned native and presentation output. The bounded HEVC item-local syntax, allocator-backed decoder lifecycle, CABAC arithmetic and context state, coding-tree traversal, intra prediction, residual reconstruction, in-loop filtering, tiles, wavefront entry points, dependent slices, entry-point offset handling, and supplemental presentation and metadata are implemented and verified through pinned-HM tables and analysis, official native-plane output, real HEIC payloads, constrained allocation, constructor failure, public presentation cases, and SIMD/scalar feature isolation. The next dependency is the remaining exact HEVC profile and Range Extensions matrix. Neither AV1 nor HEVC production encoding is implemented.
Current development stage: **Stage 4 — complete HEVC still-image decoding.** The AV1 still-image exit gate is complete across the exact 12-profile matrix, layered reference-dependent items, every connected normative reconstruction tool, official quantizer and size boundaries, constrained allocation, and pinned native and presentation output. The bounded HEVC item-local syntax, allocator-backed decoder lifecycle, CABAC arithmetic and context state, coding-tree traversal, intra prediction, residual reconstruction, in-loop filtering, tiles, wavefront entry points, dependent slices, entry-point offset handling, supplemental presentation and metadata, and independently coded Range Extensions native-plane profile/tool matrix are implemented and verified through pinned-HM tables and analysis, official native-plane output, real HEIC payloads, constrained allocation, constructor failure, public presentation cases, and SIMD/scalar feature isolation. The next dependency is independently encoded HEIC container-presentation evidence across every exposed profile and required Range Extensions tool. Neither AV1 nor HEVC production encoding is implemented.
Immediate checkpoint: **current — complete the remaining HEVC profile and Range Extensions matrix.** Establish exact native-plane and presentation evidence for 8/10/12-bit monochrome, 4:2:0, 4:2:2, and 4:4:4 across every exposed HEVC profile and required Range Extensions tool before closing the Phase 4 decoder exit gate.
Immediate checkpoint: **current — close the HEVC container-presentation matrix.** Retain or independently produce genuine HEIC files across every exposed profile and required Range Extensions tool, preserve the completed exact native-plane oracle, and compare final ImageSharp presentation with an independent HEIF decoder before closing the Phase 4 decoder exit gate.
| Order | Delivery stage | State | Delivered state | Gate that remains open |
| --- | --- | --- | --- | --- |
| 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** | AV1 still-image decoding has passed its complete exact native/presentation profile, layered-item, normative-tool, official-sequence, constrained-allocation, and SIMD-fallback exit gate. HEVC item-local syntax, lifecycle, CABAC, coding-tree traversal, intra prediction, residual reconstruction, in-loop filtering, tiles, wavefront entry points, dependent slices, entry-point offsets, and bounded supplemental presentation and metadata pass the recorded pinned-HM, native-plane, public-presentation, constrained-allocation, and scalar/SIMD evidence. | Close the remaining exact HEVC profile and Range Extensions matrix. |
| 3 | Still-image AV1 and HEVC decoding | **Current** | AV1 still-image decoding has passed its complete exact native/presentation profile, layered-item, normative-tool, official-sequence, constrained-allocation, and SIMD-fallback exit gate. HEVC item-local syntax, lifecycle, CABAC, coding-tree traversal, intra prediction, residual reconstruction, in-loop filtering, tiles, wavefront entry points, dependent slices, entry-point offsets, bounded supplemental presentation and metadata, and the independently coded Range Extensions native-plane profile/tool matrix pass the recorded pinned-HM, official-plane, constrained-allocation, and scalar/SIMD evidence. | Close the remaining genuine-HEIC presentation matrix across every exposed profile and required Range Extensions tool. |
| 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. |
@ -149,7 +151,7 @@ Immediate checkpoint: **current — complete the remaining HEVC profile and Rang
- [x] Verify HEVC CABAC arithmetic and every required context transition against pinned HM tables and complete production slices.
- [x] Complete coding-tree, coding-unit, prediction-unit, and transform-unit traversal across every permitted size and partition mode. Eight official ITU first pictures compare exactly with pinned-HM native planes, pinned HM matches every archive complete-sequence MD5 and every RQT decoded-picture hash SEI, analyser output proves the recorded coding and transform sizes and partition alternatives, and all 150 focused HEVC decoder cases pass in Release. Commit `66d1f3c41b0baeaa98726b57d5feaeba50874f16` records the checkpoint.
- [x] Complete HEVC intra prediction for every luma and chroma mode, including strong intra smoothing and constrained prediction rules. The official `IPRED_B_Nokia_3` native output and independently coded first `CIP_A_Panasonic_3` picture match pinned HM, all 149 focused HEVC decoder cases pass in Release, and commit `9bc5b9842` records the checkpoint.
- [ ] **Current:** complete the remaining exact HEVC native-plane profile and Range Extensions matrix, then close Phase 4 still-image decoding.
- [ ] **Current:** complete the genuine-HEIC presentation matrix across every exposed HEVC profile and required Range Extensions tool, then close Phase 4 still-image decoding.
- [ ] Close shared decoded presentation, ICC, alpha, grid, transform, metadata, and animated AV1/HEVC decode gates.
- [ ] Implement and independently verify real AV1/AVIF still encoding.
- [ ] Implement and independently verify real HEVC/HEIC still encoding.
@ -183,7 +185,7 @@ Performance, allocation, documentation, and independent test work are part of ea
- [x] Compare native HEVC planes byte-for-byte with HM 18 output for four item payloads extracted from independently produced HEIC files: two 8-bit 4:2:0 grid tiles, a cropped 8-bit 4:2:0 grid tile, and an 8-bit 4:4:4 wavefront tile.
- [x] Compare complete HEIC presentation output exactly with libheif 1.23.1 and libde265 1.1.1 for single images, multi-tile grids, an auxiliary alpha image, ICC-bearing images, 4:2:0, and 4:4:4 output. Keep the exact HM native-plane tests as the independent codec-reconstruction oracle.
- [x] Add permanent official HEVC 8/10/12-bit monochrome, 4:2:0, 4:2:2, and 4:4:4 fixtures with exact native-plane references and published per-plane digests. All 10 first pictures from the Sony GENERAL RExt conformance streams match every Y, Cb, and Cr sample with normal SIMD dispatch and with all hardware intrinsics disabled.
- [] Extend the permanent HEVC matrix to every exposed profile and each Range Extensions tool not individually isolated by the Sony GENERAL streams, with exact native-plane references from HM or another independent decoder.
- [x] Extend the permanent HEVC matrix to every exposed profile and each Range Extensions tool not individually isolated by the Sony GENERAL streams, with exact native-plane references from HM or another independent decoder. Commit `9d7348efd6496b54cef7ec27e42352641439c400` records 25 additional official-picture cases, exact profile/tool signaling, exact native-plane hashes, the PCM precision and chroma-deblocking corrections, both zero-warning Release source builds, all 220 focused HEVC cases, verified existing LFS attributes and fixture hashes, zero Roslynk compiler errors, and clean `git diff --check`.
- [x] Implement the shared SIMD-first YUV/CICP paths in both directions for AV1 and HEVC bit depths, chroma formats, ranges, matrix coefficients, transfer functions, color primaries, and chroma positions, with scalar fallback only after the available vector widths are exhausted.
- [ ] Complete the independently generated AV1 and HEVC conformance matrix for every supported color-signaling combination before closing the Phase 5 color exit gate.
- [x] Apply ICC conversion only after the SIMD YUV/CICP stage, alpha composition, grid assembly, and presentation transforms have produced the presented RGB image; retain ImageSharp's shared ICC converter and optimize reusable bulk kernels rather than creating a HEIF-specific color-management implementation.
@ -406,7 +408,7 @@ This table is intentionally incomplete. Add a row before each additional AV1 or
## Current implementation assessment
This assessment was reconciled with the source tree on 2026-08-29, including production checkpoint `e1a764b8f2e8a8db98a003fb3b913213f40084db`. Unless a result is stated explicitly, each item is a source-inspection finding rather than a verified interoperability claim.
This assessment was reconciled with the source tree on 2026-08-30, including production checkpoint `9d7348efd6496b54cef7ec27e42352641439c400`. Unless a result is stated explicitly, each item is a source-inspection finding rather than a verified interoperability claim.
### Public integration
@ -430,16 +432,16 @@ This assessment was reconciled with the source tree on 2026-08-29, including pro
- Decode now resolves `cdsc`-associated Exif and `application/rdf+xml` XMP items for the primary still image, validates the declared Exif TIFF-header offset, and attaches the payloads through ImageSharp's existing profile types before presentation transforms. Independent AVIF, HEIC, and HIF metadata fixtures and Identify-time profile reporting remain required.
- ICC and `nclx` CICP color properties are now associated with the presented color item instead of global parser state, validated, and exposed on Decode and Identify through the existing ImageSharp profiles. AV1 decode requires specified sequence-header fields and the range flag to match `nclx`, uses the property only for fields the bitstream leaves unspecified, and exposes the effective sequence-header CICP description when no property is present. Independent libavif fixtures verify exact ICC byte preservation, observable non-sRGB conversion, canonical-sRGB compaction, non-sRGB compact preservation, and metadata skipping for primary, grid, alpha-composited, and every presented sequence frame; the alpha vector also verifies that ICC conversion does not alter composed alpha. Identify-time bitstream fallback, independent CICP vectors, and HEVC integration remain required.
- Pixel aspect ratio now preserves the complete unsigned spacing pair, affects Decode and Identify through ImageSharp's existing unitless resolution metadata, and follows quarter-turn presentation rotation. Independent grid, rotation, and maximum-spacing fixtures remain required.
- AV1 codec configuration is now retained per `av01` image item rather than in decoder-global state. Decode requires the property, validates its fixed record against the item's sequence header and any associated `pixi` channel depths, and requires matching configurations across grid tiles. Identify now reports the configuration's 8/10/12-bit precision and monochrome shape. The optional `configOBUs` sequence is bounded and validated, including its mandatory size fields, first-position/at-most-one sequence-header rule, the image item's exactly-one sequence-header rule, and exact comparison of a repeated configuration header with the item header. Content light-level and mastering-display color-volume information are decoded from the bounded `clli` and `mdcv` image properties and matching AV1 HDR metadata OBUs, with the representations' distinct fixed-point precision, grid/property precedence, and `SkipMetadata` behavior preserved. The still-image `cclv`, `amve`, `reve`, and `ndwt` properties preserve content-volume, ambient-viewing, mastering-environment, and diffuse-white descriptions without importing their video-SEI or sample-entry state models. Independent fixtures and encoder preservation remain required. HEVC `hvcC` is associated with each `hvc1` image item, structurally validated through its VPS/SPS/PPS arrays, and used to report encoded precision and monochrome shape. The bounded decoder reconstructs exact native planes for the verified 8-bit 4:2:0 and 4:4:4 item payloads; the remaining profile, bit-depth, chroma-layout, and Range Extensions matrix is not yet established.
- AV1 codec configuration is now retained per `av01` image item rather than in decoder-global state. Decode requires the property, validates its fixed record against the item's sequence header and any associated `pixi` channel depths, and requires matching configurations across grid tiles. Identify now reports the configuration's 8/10/12-bit precision and monochrome shape. The optional `configOBUs` sequence is bounded and validated, including its mandatory size fields, first-position/at-most-one sequence-header rule, the image item's exactly-one sequence-header rule, and exact comparison of a repeated configuration header with the item header. Content light-level and mastering-display color-volume information are decoded from the bounded `clli` and `mdcv` image properties and matching AV1 HDR metadata OBUs, with the representations' distinct fixed-point precision, grid/property precedence, and `SkipMetadata` behavior preserved. The still-image `cclv`, `amve`, `reve`, and `ndwt` properties preserve content-volume, ambient-viewing, mastering-environment, and diffuse-white descriptions without importing their video-SEI or sample-entry state models. Independent fixtures and encoder preservation remain required. HEVC `hvcC` is associated with each `hvc1` image item, structurally validated through its VPS/SPS/PPS arrays, and used to report encoded precision and monochrome shape. The bounded decoder reconstructs exact native planes for the complete independently coded 8/10/12-bit monochrome, 4:2:0, 4:2:2, and 4:4:4 Range Extensions profile/tool matrix; genuine HEIC container-presentation evidence across that complete matrix remains open.
- Several image-item properties and relationships remain missing or parsed without fully affecting output.
- Identify and decode now use the same bounded metadata parser and both validate the complete leading file type box. The parsed state is still mutable and Identify does not yet report the complete bit depth, color, profile, or transform model.
### HEVC decoder and encoder
- `Heif4CharCode` recognizes `hvc1` image items, `HevcCodecConfiguration` validates and associates the bounded `hvcC` property, Identify reports its HEVC precision and monochrome shape, and `HeifCompressionFactory` registers the bounded HEVC still-image decoder.
- The HEVC path validates NAL headers and RBSP escaping, links `hvcC` VPS/SPS/PPS structures through Range Extensions, parses one length-delimited base-layer IDR picture, and reconstructs its complete intra-coded coding tree. It includes CABAC, transform traversal, coefficient decoding, intra prediction, inverse quantization and transform, PCM, deblocking, sample-adaptive offset, and allocator-owned native `ushort` planes for monochrome, 4:2:0, 4:2:2, 4:4:4, separate-color-plane, and 8-through-16-bit samples. The item adapter converts the SPS conformance window directly through the shared pooled SIMD-first H.273 pipeline and preserves the effective container-or-VUI CICP description. Four real item payloads match HM 18 native planes exactly, and the first pictures from 10 official Sony GENERAL Range Extensions streams match every 8/10/12-bit monochrome, 4:2:0, 4:2:2, and 4:4:4 sample with normal and forced-scalar dispatch. Complete images covering grids, auxiliary alpha, ICC, 4:2:0, and 4:4:4 presentation also match independent libheif output exactly. Profiles and Range Extensions tools not isolated by that matrix, plus the complete color matrix, remain open.
- The HEVC path validates NAL headers and RBSP escaping, links `hvcC` VPS/SPS/PPS structures through Range Extensions, parses one length-delimited base-layer IDR picture, and reconstructs its complete intra-coded coding tree. It includes CABAC, transform traversal, coefficient decoding, intra prediction, inverse quantization and transform, PCM, deblocking, sample-adaptive offset, and allocator-owned native `ushort` planes for monochrome, 4:2:0, 4:2:2, 4:4:4, separate-color-plane, and 8-through-16-bit samples. The item adapter converts the SPS conformance window directly through the shared pooled SIMD-first H.273 pipeline and preserves the effective container-or-VUI CICP description. Four real item payloads match HM 18 native planes exactly, ten official Sony GENERAL pictures cover the 8/10/12-bit chroma-layout boundary, and 25 additional official pictures cover every exposed independently coded Range Extensions profile and required tool with exact native-plane hashes. Complete images covering grids, auxiliary alpha, ICC, 4:2:0, and 4:4:4 presentation also match independent libheif output exactly. Genuine HEIC presentation across the complete profile/tool matrix and the complete color matrix remain open.
- There is no HEVC encoder. `HeifEncoderCore` rejects `HeifCompressionMethod.Hevc`; the separately selected legacy JPEG path emits a generic HEIF/HIF-style JPEG image item and does not provide HEIC output.
- Permanent HEVC conformance tests compare extracted item planes exactly with HM output and complete presented images exactly with pinned libheif/libde265 reference PNGs. The fixtures do not yet cover the complete exposed profile matrix.
- Permanent HEVC conformance tests compare extracted item planes exactly with HM output or normative decoded-picture hashes and complete presented images exactly with pinned libheif/libde265 reference PNGs. Native-plane fixtures cover the complete independently coded exposed profile/tool matrix; genuine HEIC presentation fixtures do not yet cover that complete matrix.
### AV1 decoder
@ -460,7 +462,7 @@ This assessment was reconciled with the source tree on 2026-08-29, including pro
- Loop-restoration unit parsing records tile-local switchable/Wiener/self-guided filter selections and coefficients in frame-owned plane grids, including super-resolution-adjusted unit corners and the corrected conditional 64x64-superblock unit-size bit. The active restoration stage implements the normative unit geometry, striped deblocked boundaries, Wiener filtering, self-guided projection, and 8/10/12-bit clipping. Self-guided filtering now follows libaom's summed-area-table, coefficient-grid, alternating-row radius-two, full radius-one, and projection stages through AVX2 and cross-platform 128-bit traversals with one exact scalar fallback and caller-owned scratch. Independently encoded fixtures cover active Wiener and self-guided reconstruction and exact AVIF presentation at every supported bit depth. An independent direct-window definition covers all sixteen self-guided parameter sets, narrow and odd processing units, both vector-tail widths, padded strides, and the scalar fallback. Combined active-restoration and super-resolution fixtures cover 4:2:0, 4:2:2, and 4:4:4 at 8, 10, and 12 bits, including restoration-unit boundaries and clipped chroma transform traversal. Other normative independently decodable still-image syntax paths still contain `NotImplementedException` or equivalent unsupported branches. Tile-local palette CDF adaptation is present; the remaining still-image frame-context behavior requires a separate source audit without introducing sequence playback state.
- The frame buffer now establishes two-byte native sample storage, logical plane rows, and sample-unit block strides for 10/12-bit frames. The active intra-prediction, inverse-transform, and block-reconstruction path selects native 16-bit samples for 10/12-bit frames and has focused pipeline wiring coverage. Chroma-from-luma storage, 4:4:4/4:2:2/4:2:0 subsampling, rounded mean subtraction, U/V sharing, and 8/10/12-bit prediction now traverse AVX2 and cross-platform `Vector128` paths before an exact scalar fallback. `FeatureTestRunner` verifies every tier against independent fixed-point definitions across every supported block width; independently encoded high-bit-depth and chroma-from-luma AVIF conformance files are still required.
- `Av1YuvConverter` now consumes the signaled full or limited range, every non-reserved AV1 H.273 matrix coefficient, transfer characteristics where the matrix definition requires them, subsampling, and chroma sample position for 8, 10, and 12-bit output. Its high-bit-depth decode and encode paths use allocator-backed `Rgb48` rows and the existing `PixelOperations<TPixel>` conversions, avoiding the former eight-bit intermediate. Encoder conversion covers monochrome, YUV 4:2:0, 4:2:2, and 4:4:4 with libavif-compatible box averaging. Identity, full/limited-range YCgCo, the fixed non-constant-luminance matrices, both fixed and chromaticity-derived constant/non-constant-luminance systems, SMPTE ST 2085, and PQ/HLG ICtCp are active in both directions. Independent vectors for every matrix, transfer, range, bit depth, sampling layout, and chroma position remain required before the complete color matrix is externally verified.
- Forward and inverse transforms use operation-owned workspace, explicit sequential fixed storage, and stateless static-generic operator structs for every valid DCT, ADST, and identity size. Named configuration factories keep the encoder's three shifts and variable cosine precision separate from the decoder's two shifts, fixed 12-bit cosine precision, and 8/10/12-bit clamp ranges. Forward traversal shares one libaom-shaped stage network across scalar, `Vector128`, `Vector256`, and `Vector512`; inverse production traversal uses the verified scalar, `Vector128`, and `Vector256` tiers. Lossless segments now bypass the DCT pipeline and apply the reversible four-by-four inverse Walsh-Hadamard transform through the same byte/high-bit-depth output operators, with a `Vector128` production path and caller-workspace scalar fallback. The focused Release matrix passes across the `FeatureTestRunner` hardware configurations, and the production transform benchmarks report zero allocation. The separately audited 12-bit inverse ADST4, Identity4, and Identity16 widening correction remains open, so the complete Phase 3 transform correctness gate is not closed.
- Forward and inverse transforms use operation-owned workspace, explicit sequential fixed storage, and stateless static-generic operator structs for every valid DCT, ADST, and identity size. Named configuration factories keep the encoder's three shifts and variable cosine precision separate from the decoder's two shifts, fixed 12-bit cosine precision, and 8/10/12-bit clamp ranges. Forward traversal shares one libaom-shaped stage network across scalar, `Vector128`, `Vector256`, and `Vector512`; inverse production traversal uses the verified scalar, `Vector128`, and `Vector256` tiers. Lossless segments now bypass the DCT pipeline and apply the reversible four-by-four inverse Walsh-Hadamard transform through the same byte/high-bit-depth output operators, with a `Vector128` production path and caller-workspace scalar fallback. The focused Release matrix passes across the `FeatureTestRunner` hardware configurations, and the production transform benchmarks report zero allocation. Commit `ef93d584511055f8e91e8d801662c44a5b0984d9` records the separately audited 12-bit inverse ADST4, Identity4, and Identity16 widening correction and closes the Phase 3 transform correctness gate.
- Core intra prediction, chroma-from-luma, palette reconstruction, and nonlinear self-guided restoration now use SIMD-first operator or packed-kernel architectures with exact scalar fallbacks. Self-guided restoration dispatches portably through `Vector256`, `Vector128`, and scalar tiers; AVX2-only gather and scan operations remain local fast paths within the 256-bit implementation. `FeatureTestRunner` verifies AVX2, portable AVX-only 256-bit, 128-bit, and scalar execution. No namespace, file, or type name exposes SIMD width, ISA, storage, or bit depth. Transform traversal is already SIMD-first, while normative super-resolution and Wiener horizontal products reuse ImageSharp's cross-platform adjacent multiply/add SIMD helper with exact scalar fallbacks.
### AV1 encoder
@ -479,7 +481,7 @@ This assessment was reconciled with the source tree on 2026-08-29, including pro
### Tests
- HEVC coverage includes exact native-plane comparison with HM output, exact complete-image comparison with pinned libheif/libde265 references, and the 10 official Sony GENERAL Range Extensions first-picture fixtures across 8/10/12-bit monochrome, 4:2:0, 4:2:2, and 4:4:4 reconstruction. The remaining exposed profiles and individual Range Extensions tools still need exact independent vectors.
- HEVC coverage includes exact native-plane comparison with HM output or normative decoded-picture hashes, exact complete-image comparison with pinned libheif/libde265 references, ten official Sony GENERAL pictures across the 8/10/12-bit chroma-layout boundary, and 25 additional official Range Extensions pictures across every exposed independently coded profile and required tool. The remaining Phase 4 evidence is genuine HEIC presentation across that complete profile/tool matrix.
- AV1 has focused bitstream, prediction, entropy, reconstruction, filter, film-grain, color, and transform coverage, plus real libavif inputs. A real two-layer libavif-derived OBU stream verifies the bounded frame lifecycle, retained-slot occupancy, resolved inter references, and `frame_size_with_refs` dimensions through a fake tile lifecycle. The corrected progressive color item then verifies its production single-reference inter branch against exact pinned-libaom native planes and pinned-libavif presentation. The pinned 19-frame YUV444 sequence separately reaches production equal-average compound reconstruction after every preceding reference sample and matches its final native and presented references exactly. A real palette stream truncated inside its tile entropy payload verifies libaom-equivalent overflow/trailing-bit rejection and decoder-session recovery. The committed equal-average checkpoint passes 119 direct focused cases plus three `FeatureTestRunner` cases, zero-warning `net10.0` and `net11.0` source builds, a zero-error test-project analyzer build with pre-existing repository warnings, allocator lifetime validation, and `git diff --check`. Four additional pinned sequences reach distance-weighted, both wedge signs, both difference-mask orientations, and smooth and wedge inter-intra reconstruction with exact final native and presented output. Commit `864b11ad9791d3254a38691246270c569001b5a1` records the selectable-compound checkpoint after both source targets, the test-project analyzer build, 25 direct focused cases, six `FeatureTestRunner` cases, constrained allocation, exactly-once tracked returns, and `git diff --check` passed. Commit `59a4fbad5ed3bc7c34331c4bdc65acc7acde3f04` adds exact traced OBMC sequence evidence, subsampled direct reconstruction, constrained allocation, both source builds, the analyzer build, 14 direct cases, the normal/scalar `FeatureTestRunner` comparison, and clean staged `git diff --check`. Commit `8f57c29b250b4291f034b31c1ea3de3fa3345467` adds a genuine size-changing layered AVIF, exact retained-base and final native planes, exact final presentation, active inter deblocking, constrained allocation, normal/scalar dispatch, direct 8/10/12-bit block reconstruction, and 87 passing focused cases. The local-warp checkpoint adds a genuine two-frame 256x256 bounded AVIF with many traced `WARPED_CAUSAL` blocks, exact pinned multi-sample projection, exact final native and presentation comparisons, constrained allocation, normal/scalar `FeatureTestRunner` dispatch, direct 8/10/12-bit predictor parity, zero-warning source builds, and 86 passing focused cases. Valid still-image syntax paths still contain explicit unsupported branches, so the independent AV1 decode matrix is not complete.
- Local-warp fixture provenance is pinned to libavif `062e582e8afda88e6baf988fdcf046a801efa0f5` and libaom `03087864cf4bea6abb0d28f95cf7843511413d8f`. A deterministic two-frame limited-range YUV444 grid sequence was encoded with `avifenc -j 1 -s 0 -q 60 -a color:enable-warped-motion=1 -a color:enable-global-motion=0 -a color:enable-obmc=0`. SHA-256 values are `990BAC4AD443005C217B0DA4FCCFA9ADFB3AA147AD06C85F9A655A4433E9E8A7` for the AVIF, `984B2815CEE0C05FDE26430F150A21B5C993141E25BA1ED4FDE09372DB64AC13` for the pinned-libaom frame-1 Y4M, and `4490D62FB6679378E92CACA48427359091AD2106BE49FC1A3848F78BE03BEEB1` for the pinned-libavif frame-1 PNG.
- Scaled-reference fixture provenance is pinned to libavif `062e582e8afda88e6baf988fdcf046a801efa0f5` and libaom `03087864cf4bea6abb0d28f95cf7843511413d8f`. The source is libavif `tests/data/webp_logo_animated.y4m`, encoded as two layered YUV444 inputs with `avifenc -j 1 -q 90 --layered --scaling-mode:u 1/2 <input> --scaling-mode:u 1/1 <input> <output>`. The resulting item contains a 701-byte 40x40 base layer followed by a 1,494-byte 80x80 dependent layer. SHA-256 values are `EB239F31EC8DBF5E97AD6F52670FCA6497AE2A933822CFE724C75F66AAA2520B` for the AVIF, `B7E30E04A935414A517BAA2DF06AB756DA18BA7C291220D9D7C063297761AE82` for the 2,195-byte logical AV1 payload, `873DC1AB5623910FBF8053CBF684399F4F3BDDBA4110492E3E11DE86E01FEC1B` for the 4,800-byte pinned-libaom base YUV, `964F4D85A79FC10EEB3722E2C9DA3415083E1EB8C2611FE154946FA55E2171ED` for the pinned-libaom final Y4M, and `DC4C6DBE6BD92C5FCE1E3E23700AFA603EF04ED02EDD336213EBBA1E3BD84BA0` for the pinned-libavif final PNG.
@ -714,7 +716,7 @@ Implement and verify in dependency order:
- [x] Supplemental enhancement information that changes ImageSharp still-image presentation or metadata exposed by ImageSharp. Commit `fcd16c862c437e3249c7e693012c717512985163` records pinned-HM syntax for display orientation, no-display, mastering-display color volume, content light level, alternative transfer characteristics, ambient viewing environment, and content color volume; complete production ordering across scaling, auxiliary alpha, codec orientation, and container transforms; exact independent RGBA comparison; malformed and conflicting metadata rejection; constrained exactly-once allocation; normal/scalar `FeatureTestRunner` coverage; all 195 focused HEVC cases; both zero-warning Release source builds; zero Roslynk compiler errors; clean scoped StyleCop and whitespace verification; an unchanged `.gitattributes`; and clean `git diff --check`.
- [x] Establish exact HM 18 native-plane conformance for four real 8-bit item payloads covering 4:2:0, 4:4:4, cropping, multiple grid positions, and wavefront entry points.
- [x] Establish exact independent presentation verification for single images, grids, auxiliary alpha, ICC, 4:2:0, and 4:4:4 output without weakening the exact native-plane codec oracle.
- [ ] **Current:** establish exact native-plane conformance for 8/10/12-bit monochrome, 4:2:0, 4:2:2, and 4:4:4 across every exposed HEVC profile and required Range Extensions tool.
- [x] Establish exact native-plane conformance for 8/10/12-bit monochrome, 4:2:0, 4:2:2, and 4:4:4 across every exposed HEVC profile and required Range Extensions tool. Commit `9d7348efd6496b54cef7ec27e42352641439c400` records 25 additional official H.265.1 independently coded pictures, exact profile/tool assertions and native-plane hashes, the PCM precision and chroma-deblocking corrections, all 220 focused HEVC cases, both zero-warning Release source builds, zero Roslynk compiler errors, verified fixture hashes and existing LFS pointers without an attributes change, and clean `git diff --check`.
Each subsystem keeps a specification-shaped scalar oracle derived from the HEVC specification and the pinned implementation reference, while production hot paths are designed SIMD-first with scalar fallback. No valid syntax in the exposed HEIC profiles may terminate in an unsupported branch or silently omit a normative reconstruction stage.
@ -899,7 +901,7 @@ The dashboard and immediate execution queue define the remaining critical path.
- [x] Complete progressive color and auxiliary-alpha verification through exact native and presentation comparisons, every required `FeatureTestRunner` fallback, and constrained tracked allocation.
- [x] Correct the audited 12-bit inverse ADST4, Identity4, and Identity16 arithmetic through exact pinned boundary vectors and SIMD/scalar feature isolation.
- [x] Remove every other unsupported valid AV1 still-image syntax path and prove the complete AVIF decode matrix with independent inputs and scalar/SIMD parity. Commit `2219edbc91edb6a2d905f1221a45207eb2719abc` closes Phase 3.
- [ ] **Current:** close Phase 4 with the remaining HEVC profile and Range Extensions native-plane and presentation evidence.
- [ ] **Current:** close Phase 4 with genuine HEIC presentation evidence across every exposed profile and required Range Extensions tool; the native-plane matrix is complete.
- [ ] Close Phase 5 and the decode portion of the bounded sequence ledger: color, ICC, alpha, grids, presentation transforms, reference-dependent samples, and complete animated AVIF/HEIC decode.
- [ ] Close the still-image portions of Phases 0, 1, and 2 that remain as release gates: documentation, provenance, public format boundaries, API review, parser hardening, and malformed-input coverage.
- [ ] Complete Phase 6 with a real AV1 encoder and independent AVIF cross-decode across every public option and metadata combination.
James Jackson-South
4 days ago