diff --git a/HEIF_IMPLEMENTATION_PLAN.md b/HEIF_IMPLEMENTATION_PLAN.md
index 0b3a418f1..0e799d82b 100644
--- a/HEIF_IMPLEMENTATION_PLAN.md
+++ b/HEIF_IMPLEMENTATION_PLAN.md
@@ -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 2026-08-29 against production checkpoint `03737411e62155df8e998c37475ceeebf4f053bf`. Committed checkpoints include the AV1 transform architecture, OBU framing, 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, selected spatial-layer presentation, and progressive color and auxiliary-alpha conformance. 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 2026-08-29 against production checkpoint `15613b01c0bc098fd9926b886216558e0d26eff9`. Committed checkpoints include the AV1 transform architecture, OBU framing, 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 sequence conformance, selected spatial-layer presentation, and progressive color and auxiliary-alpha conformance. 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 `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.
@@ -49,6 +49,8 @@ Commit `a5e4cc6cc6cf87ee02b41cfe4ca71d1ef3411ed7` records the official one-spati
Commit `03737411e62155df8e998c37475ceeebf4f053bf` records the official two-spatial-layer, two-temporal-layer L2T2 checkpoint. The manifest-matching 119,907-byte IVF and pinned-libaom Y4M prove all eight 1280x720 YUV420 frames exactly under normal and scalar dispatch; constrained tracked allocation verifies balanced exactly-once returns. The existing decoder required no production correction. The scoped test-project analyzer build completes with zero errors and 1,011 repository warnings, Roslynk reports zero compiler errors, both focused cases pass without failures or skips, and `git diff --check` is clean.
+Commit `15613b01c0bc098fd9926b886216558e0d26eff9` records the official ten-frame active-film-grain checkpoint. The manifest-matching 28,634-byte IVF and pinned-libaom grained Y4M prove every displayed 352x288 YUV420 frame exactly under normal and scalar dispatch; the differing skip-grain digest and explicit coverage prove synthesis is active. The checkpoint corrected the AV1 default loop-filter reference-delta order so Golden is -1 and Backward is 0, restoring exact dependent-frame deblocking before display-only grain. Constrained tracked allocation returns every allocation exactly once. Both Release source targets build with zero warnings and errors, the scoped test-project analyzer build completes with zero errors and 1,011 repository warnings, Roslynk reports zero compiler errors, 28 focused cases pass without failures or skips, and `git diff --check` is clean.
+
Status meanings:
- **Complete:** the implementation and its phase exit evidence are recorded.
@@ -59,7 +61,7 @@ Status meanings:
Current development stage: **Stage 3 — complete AV1 still-image decoding.** The decoder retains reference/header/CDF/motion-field state, derives frame-level skip-mode references, consumes temporal segment prediction, decodes intra-coded blocks inside inter frames, and reconstructs translational single-reference, compound, inter-intra, OBMC, scaled-reference, local warped, and non-translational global prediction before residual traversal. Commit `1c58d855f70b024170ced9eb0a7005f0f9c955ad` adds exact official four-frame coverage through all ordinary inter modes, all three motion modes, every regular/smooth/sharp dual-filter pair, sub-8x8 chroma prediction, and no-round compound intermediates. Commit `019ac5648b4380a6ff4865072c96fde29ce09fad` adds exact selected-layer native reconstruction and scaled presentation. Neither AV1 nor HEVC production encoding is implemented.
-Immediate checkpoint: **verification complete; commit pending — official ten-frame active-film-grain AV1 sequence.** All ten displayed 352x288 YUV420 frames match the pinned-libaom grained output exactly under normal and scalar dispatch, active synthesis is explicit, and constrained tracked allocation returns every allocation exactly once. The fixture exposed a swapped AV1 default loop-filter delta: Golden now defaults to -1 and Backward to 0, restoring normative dependent-frame deblocking before display-only grain synthesis. A direct default-table regression, adjacent deblocking/CDEF cases, retained-reference and presentation ownership, both zero-warning Release source builds, the zero-error test-project analyzer build with 1,011 repository warnings, zero Roslynk compiler errors, 28 focused cases, documentation review, and `git diff --check` pass. Only the checkpoint commit remains open.
+Immediate checkpoint: **verification complete; commit pending — official eight-bit monochrome AV1 sequence.** The 10,000-byte official IVF matches the pinned manifest and all ten displayed 320x180 luma planes match pinned libaom exactly under normal and scalar dispatch. The shared compact-sequence oracle now validates native YUV400 without manufacturing chroma planes, while every prior YUV420 caller remains exact. A 2 KiB constrained tracked allocator returns every allocation exactly once. The existing decoder required no production correction. Both Release source targets build with zero warnings and errors, the scoped test-project analyzer build completes with zero errors and 1,011 repository warnings, Roslynk reports zero compiler errors, all 17 official-sequence cases pass without failures or skips, and `git diff --check` is clean. Only the checkpoint commit remains open.
| Order | Delivery stage | State | Delivered state | Gate that remains open |
| --- | --- | --- | --- | --- |
@@ -612,8 +614,9 @@ Implement and verify in dependency order:
- [x] Decode the official two-spatial-layer L2T1 sequence at its default operating point. The 159,037-byte IVF has manifest-matching SHA-1 `E14825F50FF845B8A6932C64CB254007A0B5E3A1` and SHA-256 `D65824E8E7C19BC958DB810D728B2132B513B5A93CB5F99CA3D7995E19A226E1`; its pinned-libaom Y4M has SHA-256 `7A427631ECBF144F435AA4612F1201415FB1A9BCF9A67BA010AEF830B0C3AB81`. All eight 1280x720 YUV420 frames match exactly under normal and scalar dispatch, and an 8 KiB constrained tracked allocator verifies balanced exactly-once returns. The existing decoder required no production correction. Both Release source targets build with zero warnings and errors, the scoped test-project analyzer build completes with zero errors and 1,011 repository warnings, Roslynk reports zero compiler errors, and all five focused compact-sequence cases pass without failures or skips.
- [x] Decode the official one-spatial-layer, two-temporal-layer L1T2 sequence at its default operating point. The 48,883-byte IVF has manifest-matching SHA-1 `E94687EB0E90179B3800B6D5E11EB7E9BFB34EEC` and SHA-256 `EADE696AB60415D476E1D2A489EC2CCCD24D5EAAADFA4559C6488B7932274C5E`; its pinned-libaom Y4M has SHA-256 `4012DE2D4AFD095E7BB68EAE18B50B0674781BB4971CECABC0E5471E63373ED3`. All eight 640x360 YUV420 frames match exactly under normal/scalar dispatch, and an 8 KiB constrained tracked allocator verifies balanced exactly-once returns. The existing decoder required no production correction. The scoped test-project analyzer build completes with zero errors and 1,011 repository warnings, Roslynk reports zero compiler errors, and both focused cases pass without failures or skips.
- [x] Decode the official two-spatial-layer, two-temporal-layer L2T2 sequence at its default operating point. The 119,907-byte IVF has manifest-matching SHA-1 `32EF2F14EE9CB11A24A22934F4C065E926E5D236` and SHA-256 `14257D5FD3901581DBEB88133378CD79D50EA32506ADB729909AB56B4A52AF3C`; its pinned-libaom Y4M has SHA-256 `1ABB981CFF76BA9557DA437B258D8A95FCA755DED8E3949D857E8388AB1D6AE3`. All eight 1280x720 YUV420 frames match exactly under normal/scalar dispatch, and an 8 KiB constrained tracked allocator verifies balanced exactly-once returns. The existing decoder required no production correction. The scoped test-project analyzer build completes with zero errors and 1,011 repository warnings, Roslynk reports zero compiler errors, and both focused cases pass without failures or skips.
- - [ ] **Verification complete; commit pending:** decode the official ten-frame active-film-grain sequence. The 28,634-byte IVF has manifest-matching SHA-1 `11BB40026103182C23A88133EDAFCA369E5575E2` and SHA-256 `BA3EDD82A58414F009E1C821B947EC8DE4E0420F33803CA7BFEA39AF6AEEA155`; its pinned-libaom grained Y4M has SHA-256 `C71958DE496A949D12E819190F240BD56010E5AD57D8A0D55903BF380A9E0C26`, while pinned libaom's skip-grain output differs with SHA-256 `9E0762A82E582E854AFF2DC61EBA1E48C0F1D41BBC21E5C896573DA3BB2F1200`. All ten displayed 352x288 YUV420 frames match exactly under normal/scalar dispatch; active synthesis, dependent retained-reference reconstruction, and 2 KiB constrained tracked allocation with exactly-once returns pass. The fixture corrected the AV1 default loop-filter reference deltas from a swapped Golden/Backward pair to the normative `[1, 0, 0, 0, -1, 0, -1, -1]` order. Both Release source targets build with zero warnings and errors, the scoped test-project analyzer build completes with zero errors and 1,011 repository warnings, Roslynk reports zero compiler errors, 28 focused cases pass without failures or skips, documentation review is complete, and `git diff --check` is clean.
-- [ ] Lossless and high-bit-depth reconstruction with correct clipping and intermediate precision.
+ - [x] Decode the official ten-frame active-film-grain sequence. The 28,634-byte IVF has manifest-matching SHA-1 `11BB40026103182C23A88133EDAFCA369E5575E2` and SHA-256 `BA3EDD82A58414F009E1C821B947EC8DE4E0420F33803CA7BFEA39AF6AEEA155`; its pinned-libaom grained Y4M has SHA-256 `C71958DE496A949D12E819190F240BD56010E5AD57D8A0D55903BF380A9E0C26`, while pinned libaom's skip-grain output differs with SHA-256 `9E0762A82E582E854AFF2DC61EBA1E48C0F1D41BBC21E5C896573DA3BB2F1200`. All ten displayed 352x288 YUV420 frames match exactly under normal/scalar dispatch; active synthesis, dependent retained-reference reconstruction, and 2 KiB constrained tracked allocation with exactly-once returns pass. The fixture corrected the AV1 default loop-filter reference deltas from a swapped Golden/Backward pair to the normative `[1, 0, 0, 0, -1, 0, -1, -1]` order. Both Release source targets build with zero warnings and errors, the scoped test-project analyzer build completes with zero errors and 1,011 repository warnings, Roslynk reports zero compiler errors, 28 focused cases pass without failures or skips, documentation review is complete, and `git diff --check` is clean. Commit `15613b01c0bc098fd9926b886216558e0d26eff9` records the checkpoint.
+ - [ ] **Verification complete; commit pending:** decode the official eight-bit monochrome sequence. The 10,000-byte IVF has manifest-matching SHA-1 `A17584012187CD886B64F8CB0F35BFD8D762F9DC` and SHA-256 `3DCC2A3C181F74788BD9575D94F0862D9E914415AC358A4DA4ED7D904F0535B7`; its ten-frame 576,000-byte pinned-libaom luma reference has SHA-256 `6A4F8A68366E801D60A14C00BE6EA88A861B1B631D86DEF8A8DB65EFB6B06FA8`. All ten displayed 320x180 native YUV400 frames match exactly under normal/scalar dispatch, the shared compact-sequence oracle keeps every prior YUV420 fixture exact, and a 2 KiB constrained tracked allocator verifies balanced exactly-once returns. The existing decoder required no production correction. Both Release source targets build with zero warnings and errors, the scoped test-project analyzer build completes with zero errors and 1,011 repository warnings, Roslynk reports zero compiler errors, all 17 official-sequence cases pass without failures or skips, documentation review is complete, and `git diff --check` is clean.
+- [x] 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.
- [x] Deblocking loop filter.
diff --git a/tests/ImageSharp.Tests/Formats/Heif/Av1/Av1ReconstructionConformanceTests.cs b/tests/ImageSharp.Tests/Formats/Heif/Av1/Av1ReconstructionConformanceTests.cs
index a4831e3c9..52483bb52 100644
--- a/tests/ImageSharp.Tests/Formats/Heif/Av1/Av1ReconstructionConformanceTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Heif/Av1/Av1ReconstructionConformanceTests.cs
@@ -236,6 +236,21 @@ public class Av1ReconstructionConformanceTests
///
private const int OfficialFilmGrainFixtureFrameCount = 10;
+ ///
+ /// The width of the official libaom eight-bit monochrome sequence.
+ ///
+ private const int OfficialMonochromeFixtureWidth = 320;
+
+ ///
+ /// The height of the official libaom eight-bit monochrome sequence.
+ ///
+ private const int OfficialMonochromeFixtureHeight = 180;
+
+ ///
+ /// The number of frames in the official libaom eight-bit monochrome sequence.
+ ///
+ private const int OfficialMonochromeFixtureFrameCount = 10;
+
///
/// The coverage bit representing tile-local adaptive CDF updates.
///
@@ -1475,6 +1490,58 @@ public class Av1ReconstructionConformanceTests
Assert.NotEqual(0, coverage & FilmGrainCoverage);
}
+ ///
+ /// Verifies the official eight-bit monochrome sequence against exact pinned-libaom native output under normal and
+ /// scalar dispatch.
+ ///
+ [Fact]
+ public void DecodeOfficialMonochromeSequenceMatchesPinnedLibaomReference()
+ => FeatureTestRunner.RunWithHwIntrinsicsFeature(
+ ValidateOfficialMonochromeFixture,
+ ReconstructionConfigurations);
+
+ ///
+ /// Verifies the official eight-bit monochrome sequence through constrained tracked allocation.
+ ///
+ [Fact]
+ [ValidateDisposedMemoryAllocations]
+ public void DecodeOfficialMonochromeSequenceWithConstrainedAllocator()
+ {
+ TestMemoryAllocator allocator = new() { BufferCapacityInBytes = 2_048 };
+ allocator.EnableNonThreadSafeLogging();
+ Configuration configuration = Configuration.Default.Clone();
+ configuration.MemoryAllocator = allocator;
+
+ ValidateOfficialCompactSequence(
+ configuration,
+ TestImages.Heif.Av1OfficialMonochromeSequence,
+ TestImages.Heif.Av1OfficialMonochromeSequenceNativeReference,
+ OfficialMonochromeFixtureFrameCount,
+ OfficialMonochromeFixtureWidth,
+ OfficialMonochromeFixtureHeight,
+ Av1ColorFormat.Yuv400);
+
+ Assert.Equal(allocator.AllocationLog.Count, allocator.ReturnLog.Count);
+ Assert.All(
+ allocator.AllocationLog,
+ allocation => Assert.Single(
+ allocator.ReturnLog,
+ returned => returned.AllocationId == allocation.AllocationId));
+ }
+
+ ///
+ /// Decodes the official eight-bit monochrome sequence.
+ ///
+ private static void ValidateOfficialMonochromeFixture()
+ => ValidateOfficialCompactSequence(
+ Configuration.Default,
+ TestImages.Heif.Av1OfficialMonochromeSequence,
+ TestImages.Heif.Av1OfficialMonochromeSequenceNativeReference,
+ OfficialMonochromeFixtureFrameCount,
+ OfficialMonochromeFixtureWidth,
+ OfficialMonochromeFixtureHeight,
+ Av1ColorFormat.Yuv400);
+
///
/// Decodes one compact official IVF sequence, compares every native sample, and returns its active frame-state
/// coverage mask.
@@ -1485,12 +1552,15 @@ public class Av1ReconstructionConformanceTests
string nativeReferencePath,
int expectedFrameCount,
int expectedWidth = OfficialMotionVectorFixtureWidth,
- int expectedHeight = OfficialMotionVectorFixtureHeight)
+ int expectedHeight = OfficialMotionVectorFixtureHeight,
+ Av1ColorFormat expectedColorFormat = Av1ColorFormat.Yuv420)
{
byte[] ivf = TestFile.Create(fixturePath).Bytes;
byte[] nativeReference = TestFile.Create(nativeReferencePath).Bytes;
- byte[] y4mFileHeader =
- Encoding.ASCII.GetBytes($"YUV4MPEG2 W{expectedWidth} H{expectedHeight} F30:1 Ip C420jpeg\n");
+ bool hasY4mHeaders = expectedColorFormat != Av1ColorFormat.Yuv400;
+ ReadOnlySpan y4mFileHeader = hasY4mHeaders
+ ? Encoding.ASCII.GetBytes($"YUV4MPEG2 W{expectedWidth} H{expectedHeight} F30:1 Ip C420jpeg\n")
+ : [];
ReadOnlySpan y4mFrameHeader = "FRAME\n"u8;
@@ -1504,13 +1574,16 @@ public class Av1ReconstructionConformanceTests
expectedFrameCount,
checked((int)BinaryPrimitives.ReadUInt32LittleEndian(ivf.AsSpan(24, 4))));
- Assert.True(nativeReference.AsSpan().StartsWith(y4mFileHeader));
+ if (hasY4mHeaders)
+ {
+ Assert.True(nativeReference.AsSpan().StartsWith(y4mFileHeader));
+ }
int ivfOffset = 32;
int nativeOffset = y4mFileHeader.Length;
- int nativeFrameLength =
- (expectedWidth * expectedHeight) +
- (2 * (expectedWidth >> 1) * (expectedHeight >> 1));
+ int nativeFrameLength = expectedColorFormat == Av1ColorFormat.Yuv400
+ ? expectedWidth * expectedHeight
+ : (expectedWidth * expectedHeight) + (2 * (expectedWidth >> 1) * (expectedHeight >> 1));
int coverage = 0;
using Av1Decoder decoder = new(configuration);
@@ -1526,10 +1599,14 @@ public class Av1ReconstructionConformanceTests
ivfOffset += payloadLength;
Assert.Equal(expectedWidth, frame.Width);
Assert.Equal(expectedHeight, frame.Height);
- Assert.True(nativeReference.AsSpan(nativeOffset).StartsWith(y4mFrameHeader));
- nativeOffset += y4mFrameHeader.Length;
+ if (hasY4mHeaders)
+ {
+ Assert.True(nativeReference.AsSpan(nativeOffset).StartsWith(y4mFrameHeader));
+ nativeOffset += y4mFrameHeader.Length;
+ }
Av1FrameBuffer frameBuffer = Assert.IsType>(decoder.FrameBuffer);
+ Assert.Equal(expectedColorFormat, frameBuffer.ColorFormat);
AssertNativePlanesEqual(
decoder,
frameBuffer,
diff --git a/tests/ImageSharp.Tests/TestImages.cs b/tests/ImageSharp.Tests/TestImages.cs
index 75f7cf1b6..ec35c95aa 100644
--- a/tests/ImageSharp.Tests/TestImages.cs
+++ b/tests/ImageSharp.Tests/TestImages.cs
@@ -1406,6 +1406,8 @@ public static class TestImages
public const string Av1OfficialSpatialTemporalLayerSequenceNativeReference = "Heif/Av1/Conformance/libaom-av1-1-b8-22-svc-L2T2-libaom.y4m";
public const string Av1OfficialFilmGrainSequence = "Heif/Av1/Conformance/libaom-av1-1-b8-23-film-grain-50.ivf";
public const string Av1OfficialFilmGrainSequenceNativeReference = "Heif/Av1/Conformance/libaom-av1-1-b8-23-film-grain-50-libaom.y4m";
+ public const string Av1OfficialMonochromeSequence = "Heif/Av1/Conformance/libaom-av1-1-b8-24-monochrome.ivf";
+ public const string Av1OfficialMonochromeSequenceNativeReference = "Heif/Av1/Conformance/libaom-av1-1-b8-24-monochrome-libaom.yuv";
public const string Av1Cdef8BitPayload = "Heif/Av1/Conformance/libaom-cdef-kodim23-8b.bit";
public const string Av1Cdef8BitReference = "Heif/Av1/Conformance/libaom-cdef-kodim23-8b-libaom.yuv";
public const string Av1Cdef8BitAvif = "Heif/Av1/Conformance/libavif-cdef-kodim23-8b.avif";
diff --git a/tests/Images/Input/Heif/Av1/Conformance/libaom-av1-1-b8-24-monochrome-libaom.yuv b/tests/Images/Input/Heif/Av1/Conformance/libaom-av1-1-b8-24-monochrome-libaom.yuv
new file mode 100644
index 000000000..fef4d4611
--- /dev/null
+++ b/tests/Images/Input/Heif/Av1/Conformance/libaom-av1-1-b8-24-monochrome-libaom.yuv
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:6a4f8a68366e801d60a14c00be6ea88a861b1b631d86def8a8db65efb6b06fa8
+size 576000
diff --git a/tests/Images/Input/Heif/Av1/Conformance/libaom-av1-1-b8-24-monochrome.ivf b/tests/Images/Input/Heif/Av1/Conformance/libaom-av1-1-b8-24-monochrome.ivf
new file mode 100644
index 000000000..573787737
--- /dev/null
+++ b/tests/Images/Input/Heif/Av1/Conformance/libaom-av1-1-b8-24-monochrome.ivf
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:3dcc2a3c181f74788bd9575d94f0862d9e914415ac358a4da4ed7d904f0535b7
+size 10000