Fix AV1 encoder mode info mapping

HEIF_IMPLEMENTATION_PLAN.md

@@ -821,6 +821,7 @@ Encoder verification contract:
 - [~] Current-libaom `av1_quantize_fp_no_qmatrix` arithmetic is implemented as a closed generic forward-quantizer family with Vector512, Vector256, Vector128, and scalar paths, raster-order output, coded 64-point coefficient limits, and scan-order EOB selection. Transform search, coefficient optimization, and lossless behavior remain.
 - [ ] Implement real rate-distortion selection and make quality and effort change work, size, and output quality.
 - [~] The tile writer now publishes one packed coefficient context per covered 4x4 edge unit and derives luma/chroma skip plus DC-sign contexts from the complete transform edges using current-libaom units. Complete tile traversal, initialized picture state, and verified CDF update behavior remain.
+- [~] Encoder mode information now uses a frame-owned reference grid over its contiguous allocation, matching current libaom's `mi_grid_base` and `mi_alloc` ownership without per-block tail copies. Signed relative neighbor lookup, 4x4-unit addressing, and mutable selected skip syntax have focused contracts; complete mode decision still remains.
 - [ ] Implement legal deblocking, CDEF, restoration, super-resolution, and film-grain signaling decisions.
 - [~] The coefficient symbol encoder now reuses tile-lifetime level and context workspaces instead of allocating per transform. Every remaining encoder fragment must be audited before it becomes active.
 - [~] The planar conversion, forward transform, and forward quantizer use descending SIMD dispatch: Vector512, Vector256, Vector128, then scalar. Apply the same rule to every later hot-path family.

src/ImageSharp/Formats/Heif/Av1/Tiling/Av1EncoderBlockModeInfo.cs

@@ -11,44 +11,34 @@ namespace SixLabors.ImageSharp.Formats.Heif.Av1.Tiling;
 internal class Av1EncoderBlockModeInfo
 {
     /// <summary>
-    /// Gets the encoded block size.
+    /// Gets or sets the encoded block size.
     /// </summary>
-    public Av1BlockSize BlockSize { get; }
+    public Av1BlockSize BlockSize { get; set; }
 
     /// <summary>
-    /// Gets the selected luma prediction mode.
+    /// Gets or sets the partition type that produced the block.
     /// </summary>
-    public Av1PredictionMode PredictionMode { get; }
+    public Av1PartitionType PartitionType { get; set; }
 
     /// <summary>
-    /// Gets the partition type that produced the block.
+    /// Gets or sets a value indicating whether residual coefficients are omitted for the block.
     /// </summary>
-    public Av1PartitionType PartitionType { get; }
+    public bool Skip { get; set; }
 
     /// <summary>
-    /// Gets the selected chroma prediction mode.
+    /// Gets or sets a value indicating whether compound skip mode is selected.
     /// </summary>
-    public Av1ChromaPredictionMode UvPredictionMode { get; }
+    public bool SkipMode { get; set; }
 
     /// <summary>
-    /// Gets a value indicating whether residual coefficients are omitted for the block.
+    /// Gets or sets a value indicating whether intra block copy is selected.
     /// </summary>
-    public bool Skip { get; } = true;
+    public bool UseIntraBlockCopy { get; set; }
 
     /// <summary>
-    /// Gets a value indicating whether compound skip mode is selected.
+    /// Gets or sets the segmentation identifier assigned to the block.
     /// </summary>
-    public bool SkipMode { get; } = true;
+    public int SegmentId { get; set; }
-
-    /// <summary>
-    /// Gets a value indicating whether intra block copy is selected.
-    /// </summary>
-    public bool UseIntraBlockCopy { get; } = true;
-
-    /// <summary>
-    /// Gets the segmentation identifier assigned to the block.
-    /// </summary>
-    public int SegmentId { get; }
 
     /// <summary>
     /// Gets or sets the transform-tree depth selected for the block.

src/ImageSharp/Formats/Heif/Av1/Tiling/Av1MacroBlockD.cs

@@ -9,23 +9,14 @@ namespace SixLabors.ImageSharp.Formats.Heif.Av1.Tiling;
 internal class Av1MacroBlockD
 {
     /// <summary>
-    /// Stores the mode-information entries exposed through <see cref="ModeInfo"/>.
+    /// Stores the frame's mode-information reference grid.
     /// </summary>
-    private Av1ModeInfo[] modeInfo = [];
+    private Av1ModeInfo[] modeInfoGrid = [];
 
     /// <summary>
-    /// Gets or sets the mode-information entries for the current block and its mapped neighbors.
+    /// Stores the current block's linear position in <see cref="modeInfoGrid"/>.
     /// </summary>
-    public required ReadOnlySpan<Av1ModeInfo> ModeInfo
+    private int modeInfoIndex;
-    {
-        get => this.modeInfo;
-        set
-        {
-            // A span cannot be retained by the class, so preserve the selected map entries in owned storage.
-            this.modeInfo = new Av1ModeInfo[value.Length];
-            value.CopyTo(this.modeInfo);
-        }
-    }
 
     /// <summary>
     /// Gets or sets the tile containing the current block.
@@ -86,4 +77,22 @@ internal class Av1MacroBlockD
     /// Gets or sets a value indicating whether this block is the second half of a rectangular partition.
     /// </summary>
     public bool IsSecondRectangle { get; set; }
+
+    /// <summary>
+    /// Selects the current entry in the frame-owned mode-information reference grid.
+    /// </summary>
+    /// <param name="grid">The frame-owned mode-information reference grid.</param>
+    /// <param name="index">The current block's linear grid index.</param>
+    public void SetModeInfoGrid(Av1ModeInfo[] grid, int index)
+    {
+        this.modeInfoGrid = grid;
+        this.modeInfoIndex = index;
+    }
+
+    /// <summary>
+    /// Gets a mode-information entry relative to the current block.
+    /// </summary>
+    /// <param name="offset">The signed linear offset from the current block.</param>
+    /// <returns>The mapped neighboring or current entry.</returns>
+    public Av1ModeInfo GetRelativeModeInfo(int offset) => this.modeInfoGrid[this.modeInfoIndex + offset];
 }

src/ImageSharp/Formats/Heif/Av1/Tiling/Av1MacroBlockModeInfo.cs

@@ -13,11 +13,6 @@ internal class Av1MacroBlockModeInfo
     /// </summary>
     public required Av1EncoderBlockModeInfo Block { get; set; }
 
-    /// <summary>
-    /// Gets or sets the luma palette decisions for the block.
-    /// </summary>
-    public required Av1PaletteLumaModeInfo Palette { get; set; }
-
     /// <summary>
     /// Gets or sets the constrained directional enhancement filter strength for the block.
     /// </summary>

src/ImageSharp/Formats/Heif/Av1/Tiling/Av1PaletteLumaModeInfo.cs

@@ -1,11 +0,0 @@
-// Copyright (c) Six Labors.
-// Licensed under the Six Labors Split License.
-
-namespace SixLabors.ImageSharp.Formats.Heif.Av1.Tiling;
-
-/// <summary>
-/// Reserves encoder-side state for AV1 luma palette mode decisions.
-/// </summary>
-internal class Av1PaletteLumaModeInfo
-{
-}

src/ImageSharp/Formats/Heif/Av1/Tiling/Av1PictureControlSet.cs

@@ -1,8 +1,6 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-using System;
-
 namespace SixLabors.ImageSharp.Formats.Heif.Av1.Tiling;
 
 /// <summary>
@@ -51,14 +49,14 @@ internal class Av1PictureControlSet
     public required byte[] SegmentationNeighborMap { get; set; }
 
     /// <summary>
-    /// Gets the frame grid that maps each 4x4 position to its mode-information span.
+    /// Gets or sets the frame grid that maps each 4x4 position to its mode-information entry.
     /// </summary>
-    public Av1ModeInfo[][] ModeInfoGrid { get; } = [];
+    public required Av1ModeInfo[] ModeInfoGrid { get; set; }
 
     /// <summary>
     /// Gets or sets the contiguous mode-information storage addressed by <see cref="ModeInfoGrid"/>.
     /// </summary>
-    public required Av1ModeInfo[] Mip { get; set; }
+    public required Av1ModeInfo[] ModeInfoAllocation { get; set; }
 
     /// <summary>
     /// Gets or sets the row stride of <see cref="ModeInfoGrid"/> in 4x4 mode-information units.
@@ -76,51 +74,29 @@ internal class Av1PictureControlSet
     public required int[][] CdefPreset { get; set; }
 
     /// <summary>
-    /// Gets the mode-information span mapped to a frame position.
+    /// Gets the mode-information entry mapped to a frame position.
     /// </summary>
     /// <param name="position">The frame position in 4x4 mode-information units.</param>
-    /// <returns>The mode-information span beginning at the position.</returns>
+    /// <returns>The mapped mode-information entry.</returns>
-    public Span<Av1ModeInfo> GetFromModeInfoGrid(Point position)
+    public Av1ModeInfo GetFromModeInfoGrid(Point position)
         => this.ModeInfoGrid[(position.Y * this.ModeInfoStride) + position.X];
 
-    /// <summary>
-    /// Maps a frame position to the supplied mode-information span.
-    /// </summary>
-    /// <param name="position">The frame position in 4x4 mode-information units.</param>
-    /// <param name="span">The mode-information entries to map.</param>
-    public void SetModeInfoGridRow(Point position, ReadOnlySpan<Av1ModeInfo> span)
-        => this.SetModeInfoGridRow((position.Y * this.ModeInfoStride) + position.X, span);
-
-    /// <summary>
-    /// Maps a linear grid offset to the supplied mode-information span.
-    /// </summary>
-    /// <param name="offset">The linear grid offset.</param>
-    /// <param name="span">The mode-information entries to map.</param>
-    public void SetModeInfoGridRow(int offset, ReadOnlySpan<Av1ModeInfo> span)
-    {
-        // Grid entries own their arrays because the source span can refer to temporary traversal state.
-        this.ModeInfoGrid[offset] = new Av1ModeInfo[span.Length];
-        span.CopyTo(this.ModeInfoGrid[offset]);
-    }
-
     /// <summary>
     /// Gets the macroblock mode information at a block origin and refreshes its grid mapping.
     /// </summary>
-    /// <param name="blockOrigin">The block origin in 4x4 mode-information units.</param>
+    /// <param name="modeInfoPosition">The block position in 4x4 mode-information units.</param>
     /// <returns>The macroblock mode information at the origin.</returns>
-    public Av1MacroBlockModeInfo GetMacroBlockModeInfo(Point blockOrigin)
+    public Av1MacroBlockModeInfo GetMacroBlockModeInfo(Point modeInfoPosition)
     {
         int modeInfoStride = this.ModeInfoStride;
-        int offset = (blockOrigin.Y * modeInfoStride) + blockOrigin.X;
+        int offset = (modeInfoPosition.Y * modeInfoStride) + modeInfoPosition.X;
 
-        // Rectangular mode-decision blocks can replace grid entries. Restore the entry from the
+        // The grid stores references into the contiguous mode-info allocation, matching libaom's
-        // contiguous backing store, whose index is halved when 4x4 blocks are globally disabled.
+        // mi_grid_base/mi_alloc ownership without copying a tail for every coded block.
         int disallow4x4 = this.Disallow4x4AllFrames ? 1 : 0;
-        int mipOffset = ((blockOrigin.Y >> disallow4x4) * (modeInfoStride >> disallow4x4)) + (blockOrigin.X >> disallow4x4);
+        int allocationOffset = ((modeInfoPosition.Y >> disallow4x4) * (modeInfoStride >> disallow4x4)) + (modeInfoPosition.X >> disallow4x4);
-        this.SetModeInfoGridRow(offset, ((Span<Av1ModeInfo>)this.Mip)[mipOffset..]);
+        Av1ModeInfo modeInfo = this.ModeInfoAllocation[allocationOffset];
-
+        this.ModeInfoGrid[offset] = modeInfo;
-        // The first mapped entry owns the macroblock state for the entire block.
-        Av1ModeInfo modeInfo = this.ModeInfoGrid[offset][0];
         return modeInfo.MacroBlockModeInfo;
     }
 

src/ImageSharp/Formats/Heif/Av1/Tiling/Av1TileWriter.cs

@@ -364,26 +364,26 @@ internal partial class Av1TileWriter
         Av1BlockGeometry blockGeometry = Av1BlockGeometryFactory.GetBlockGeometryByModeDecisionScanIndex(blk_ptr.ModeDecisionScanIndex);
         Point blockOrigin = Point.Add(entropyCodingContext.SuperblockOrigin, (Size)blockGeometry.Origin);
         Av1BlockSize blockSize = blockGeometry.BlockSize;
-        Av1MacroBlockModeInfo macroBlockModeInfo = pcs.GetMacroBlockModeInfo(blockOrigin);
+        int mi_row = blockOrigin.Y >> Av1Constants.ModeInfoSizeLog2;
+        int mi_col = blockOrigin.X >> Av1Constants.ModeInfoSizeLog2;
+        int mi_stride = pcs.Parent.Common.ModeInfoStride;
+        int offset = (mi_row * mi_stride) + mi_col;
+        Point modeInfoPosition = new(mi_col, mi_row);
+        Av1MacroBlockModeInfo macroBlockModeInfo = pcs.GetMacroBlockModeInfo(modeInfoPosition);
         bool skipWritingCoefficients = macroBlockModeInfo.Block.Skip;
         entropyCodingContext.MacroBlockModeInfo = macroBlockModeInfo;
 
         bool skip_mode = macroBlockModeInfo.Block.SkipMode;
 
         Guard.MustBeLessThan((int)blockSize, (int)Av1BlockSize.AllSizes, nameof(blockSize));
-        int mi_row = blockOrigin.Y >> Av1Constants.ModeInfoSizeLog2;
+        blk_ptr.MacroBlock.SetModeInfoGrid(pcs.ModeInfoGrid, offset);
-        int mi_col = blockOrigin.X >> Av1Constants.ModeInfoSizeLog2;
-        int mi_stride = pcs.Parent.Common.ModeInfoStride;
-        int offset = (mi_row * mi_stride) + mi_col;
-        Point modeInfoPosition = new(mi_col, mi_row);
-        blk_ptr.MacroBlock.ModeInfo = pcs.ModeInfoGrid[offset];
         blk_ptr.MacroBlock.Tile = new Av1TileInfo(tb_ptr.TileInfo);
         blk_ptr.MacroBlock.IsUpAvailable = modeInfoPosition.Y > tb_ptr.TileInfo.ModeInfoRowStart;
         blk_ptr.MacroBlock.IsLeftAvailable = modeInfoPosition.X > tb_ptr.TileInfo.ModeInfoColumnStart;
 
         if (blk_ptr.MacroBlock.IsUpAvailable)
         {
-            blk_ptr.MacroBlock.AboveMacroBlock = blk_ptr.MacroBlock.ModeInfo[-mi_stride].MacroBlockModeInfo;
+            blk_ptr.MacroBlock.AboveMacroBlock = blk_ptr.MacroBlock.GetRelativeModeInfo(-mi_stride).MacroBlockModeInfo;
         }
         else
         {
@@ -392,7 +392,7 @@ internal partial class Av1TileWriter
 
         if (blk_ptr.MacroBlock.IsLeftAvailable)
         {
-            blk_ptr.MacroBlock.LeftMacroBlock = blk_ptr.MacroBlock.ModeInfo[-1].MacroBlockModeInfo;
+            blk_ptr.MacroBlock.LeftMacroBlock = blk_ptr.MacroBlock.GetRelativeModeInfo(-1).MacroBlockModeInfo;
         }
         else
         {
@@ -600,12 +600,12 @@ internal partial class Av1TileWriter
         if (xd.IsLeftAvailable)
         {
             // Key-frame neighbors are intra blocks, so their luma modes directly select the context class.
-            intraLumaLeftMode = xd.ModeInfo[-1].MacroBlockModeInfo.Block.Mode;
+            intraLumaLeftMode = xd.GetRelativeModeInfo(-1).MacroBlockModeInfo.Block.Mode;
         }
 
         if (xd.IsUpAvailable)
         {
-            intraLumaTopMode = xd.ModeInfo[-xd.ModeInfoStride].MacroBlockModeInfo.Block.Mode;
+            intraLumaTopMode = xd.GetRelativeModeInfo(-xd.ModeInfoStride).MacroBlockModeInfo.Block.Mode;
         }
 
         above_ctx = IntraModeContextLookup[(int)intraLumaTopMode];
@@ -738,7 +738,8 @@ internal partial class Av1TileWriter
         Av1NeighborArrayUnit<byte> cr_dc_sign_level_coeff_na = pcs.CrDcSignLevelCoefficientNeighbors[tile_idx];
         Av1NeighborArrayUnit<byte> cb_dc_sign_level_coeff_na = pcs.CbDcSignLevelCoefficientNeighbors[tile_idx];
         Av1BlockGeometry blk_geom = Av1BlockGeometryFactory.GetBlockGeometryByModeDecisionScanIndex(blk_ptr.ModeDecisionScanIndex);
-        Av1MacroBlockModeInfo mbmi = pcs.GetMacroBlockModeInfo(blockOrigin);
+        Point modeInfoPosition = blockOrigin >> Av1Constants.ModeInfoSizeLog2;
+        Av1MacroBlockModeInfo mbmi = pcs.GetMacroBlockModeInfo(modeInfoPosition);
         bool skip_coeff = mbmi.Block.Skip;
 
         // Store the block-size split mask across the edges that future partition symbols can observe.
@@ -843,7 +844,7 @@ internal partial class Av1TileWriter
 
         // int m = ~((1 << (6 - Av1Constants.ModeInfoSizeLog2)) - 1);
         // cm->mi_grid_visible[(mi_row & m) * cm->mi_stride + (mi_col & m)];
-        Av1ModeInfo mi = pcs.GetFromModeInfoGrid(modeInfoPosition)[0];
+        Av1ModeInfo mi = pcs.GetFromModeInfoGrid(modeInfoPosition);
 
         // Each superblock begins with all contained 64x64 filter units unassigned.
         if ((modeInfoPosition.Y & (scs.SequenceHeader.SuperblockModeInfoSize - 1)) == 0 &&
@@ -897,11 +898,12 @@ internal partial class Av1TileWriter
         // Prediction cannot cross tile boundaries even when frame mode information exists there.
         macroBlock.IsUpAvailable = modeInfoPosition.Y > tile.ModeInfoRowStart;
         macroBlock.IsLeftAvailable = modeInfoPosition.X > tile.ModeInfoColumnStart;
-        macroBlock.ModeInfo = pcs.GetFromModeInfoGrid(modeInfoPosition);
+        int modeInfoIndex = (modeInfoPosition.Y * modeInfoStride) + modeInfoPosition.X;
+        macroBlock.SetModeInfoGrid(pcs.ModeInfoGrid, modeInfoIndex);
 
         if (macroBlock.IsUpAvailable)
         {
-            macroBlock.AboveMacroBlock = macroBlock.ModeInfo[-modeInfoStride].MacroBlockModeInfo;
+            macroBlock.AboveMacroBlock = macroBlock.GetRelativeModeInfo(-modeInfoStride).MacroBlockModeInfo;
         }
         else
         {
@@ -910,7 +912,7 @@ internal partial class Av1TileWriter
 
         if (macroBlock.IsLeftAvailable)
         {
-            macroBlock.LeftMacroBlock = macroBlock.ModeInfo[-1].MacroBlockModeInfo;
+            macroBlock.LeftMacroBlock = macroBlock.GetRelativeModeInfo(-1).MacroBlockModeInfo;
         }
         else
         {

tests/ImageSharp.Tests/Formats/Heif/Av1/Av1CoefficientsEntropyTests.cs

@@ -4,6 +4,7 @@
 using System.Buffers;
 using SixLabors.ImageSharp.Formats.Heif.Av1;
 using SixLabors.ImageSharp.Formats.Heif.Av1.Entropy;
+using SixLabors.ImageSharp.Formats.Heif.Av1.OpenBitstreamUnit;
 using SixLabors.ImageSharp.Formats.Heif.Av1.Prediction;
 using SixLabors.ImageSharp.Formats.Heif.Av1.Tiling;
 using SixLabors.ImageSharp.Formats.Heif.Av1.Transform;
@@ -72,6 +73,113 @@ public class Av1CoefficientsEntropyTests
         Assert.Equal(expectedSkipContext, context.SkipContext);
     }
 
+    [Theory]
+    [InlineData(false, 2, 1, 6, 6)]
+    [InlineData(true, 2, 2, 10, 3)]
+    public void PictureControlSetMapsModeInfoAllocationByReference(
+        bool disallow4x4,
+        int column,
+        int row,
+        int gridOffset,
+        int allocationOffset)
+    {
+        Av1ModeInfo expected = CreateModeInfo(Av1PredictionMode.Paeth);
+        Av1ModeInfo[] allocation = new Av1ModeInfo[8];
+        allocation[allocationOffset] = expected;
+        Av1PictureControlSet picture = new()
+        {
+            PartitionContexts = [],
+            LuminanceDcSignLevelCoefficientNeighbors = [],
+            CrDcSignLevelCoefficientNeighbors = [],
+            CbDcSignLevelCoefficientNeighbors = [],
+            TransformFunctionContexts = [],
+            Sequence = new Av1SequenceControlSet { SequenceHeader = new ObuSequenceHeader() },
+            Parent = new Av1PictureParentControlSet
+            {
+                Common = new Av1EncoderCommon
+                {
+                    FrameSize = new ObuFrameSize(),
+                    TilesInfo = new ObuTileGroupHeader()
+                },
+                FrameHeader = new ObuFrameHeader(),
+                PreviousQIndex = [],
+                SuperblockGeometry = []
+            },
+            SegmentationNeighborMap = [],
+            ModeInfoGrid = new Av1ModeInfo[16],
+            ModeInfoAllocation = allocation,
+            ModeInfoStride = 4,
+            Disallow4x4AllFrames = disallow4x4,
+            CdefPreset = []
+        };
+
+        Av1MacroBlockModeInfo result = picture.GetMacroBlockModeInfo(new Point(column, row));
+
+        Assert.Same(expected.MacroBlockModeInfo, result);
+        Assert.Same(expected, picture.ModeInfoGrid[gridOffset]);
+    }
+
+    [Fact]
+    public void MacroBlockReadsNeighborsRelativeToCurrentGridEntry()
+    {
+        Av1ModeInfo above = CreateModeInfo(Av1PredictionMode.Vertical);
+        Av1ModeInfo left = CreateModeInfo(Av1PredictionMode.Horizontal);
+        Av1ModeInfo current = CreateModeInfo(Av1PredictionMode.DC);
+        Av1ModeInfo[] grid = new Av1ModeInfo[9];
+        grid[1] = above;
+        grid[3] = left;
+        grid[4] = current;
+        ObuTileGroupHeader tiles = new()
+        {
+            TileColumnCount = 1,
+            TileRowCount = 1
+        };
+
+        tiles.TileColumnStartModeInfo[1] = 3;
+        tiles.TileRowStartModeInfo[1] = 3;
+        ObuFrameHeader frameHeader = new()
+        {
+            ModeInfoColumnCount = 3,
+            ModeInfoRowCount = 3,
+            TilesInfo = tiles
+        };
+
+        Av1MacroBlockD macroBlock = new() { Tile = new Av1TileInfo(0, 0, frameHeader) };
+        macroBlock.SetModeInfoGrid(grid, 4);
+
+        Assert.Same(left, macroBlock.GetRelativeModeInfo(-1));
+        Assert.Same(above, macroBlock.GetRelativeModeInfo(-3));
+        Assert.Same(current, macroBlock.GetRelativeModeInfo(0));
+    }
+
+    [Fact]
+    public void EncoderBlockModeInfoStoresSelectedSyntax()
+    {
+        Av1EncoderBlockModeInfo modeInfo = new();
+
+        Assert.False(modeInfo.Skip);
+        Assert.False(modeInfo.SkipMode);
+        Assert.False(modeInfo.UseIntraBlockCopy);
+
+        modeInfo.Skip = true;
+        modeInfo.SkipMode = true;
+        modeInfo.UseIntraBlockCopy = true;
+        modeInfo.BlockSize = Av1BlockSize.Block16x16;
+        modeInfo.PartitionType = Av1PartitionType.Split;
+        modeInfo.SegmentId = 3;
+        modeInfo.Mode = Av1PredictionMode.Smooth;
+        modeInfo.UvMode = Av1ChromaPredictionMode.Smooth;
+
+        Assert.True(modeInfo.Skip);
+        Assert.True(modeInfo.SkipMode);
+        Assert.True(modeInfo.UseIntraBlockCopy);
+        Assert.Equal(Av1BlockSize.Block16x16, modeInfo.BlockSize);
+        Assert.Equal(Av1PartitionType.Split, modeInfo.PartitionType);
+        Assert.Equal(3, modeInfo.SegmentId);
+        Assert.Equal(Av1PredictionMode.Smooth, modeInfo.Mode);
+        Assert.Equal(Av1ChromaPredictionMode.Smooth, modeInfo.UvMode);
+    }
+
     [Fact]
     public void RoundTripZeroEndOfBlock()
     {
@@ -277,6 +385,15 @@ public class Av1CoefficientsEntropyTests
         }
     }
 
+    private static Av1ModeInfo CreateModeInfo(Av1PredictionMode mode)
+        => new()
+        {
+            MacroBlockModeInfo = new Av1MacroBlockModeInfo
+            {
+                Block = new Av1EncoderBlockModeInfo { Mode = mode }
+            }
+        };
+
     public static TheoryData<int> GetTransformTypes()
     {
         TheoryData<int> result = [];