More bug fixes

src/ImageSharp/Formats/Heif/Av1/Av1Constants.cs

@@ -145,6 +145,14 @@ internal static class Av1Constants
 
     public const int CoefficientBaseRange = 12;
 
+    public const int MaxTransformSize = 1 << 6;
+
+    public const int MaxTransformSizeUnit = MaxTransformSize >> 2;
+
+    public const int CoefficientContextBitCount = 6;
+
+    public const int CoefficientContextMask = (1 << CoefficientContextBitCount) - 1;
+
     public const int TransformPadHorizontalLog2 = 2;
 
     public const int TransformPadHorizontal = 1 << TransformPadHorizontalLog2;
@@ -153,16 +161,8 @@ internal static class Av1Constants
 
     public const int TransformPadEnd = 16;
 
-    public const int CoefficientContextBitCount = 6;
-
-    public const int CoefficientContextMask = (1 << CoefficientContextBitCount) - 1;
-
     public const int TransformPad2d = ((MaxTransformSize + TransformPadHorizontal) * (MaxTransformSize + TransformPadVertical)) + TransformPadEnd;
 
-    public const int MaxTransformSize = 1 << 6;
-
-    public const int MaxTransformSizeUnit = MaxTransformSize >> 2;
-
     public const int TransformPadTop = 2;
 
     public const int BaseRangeSizeMinus1 = 3;

src/ImageSharp/Formats/Heif/Av1/OpenBitstreamUnit/ObuReader.cs

@@ -369,10 +369,10 @@ internal class ObuReader
         }
 
         // Video related flags removed
-        sequenceHeader.Use128x128SuperBlock = reader.ReadBoolean();
-        sequenceHeader.SuperBlockSize = sequenceHeader.Use128x128SuperBlock ? Av1BlockSize.Block128x128 : Av1BlockSize.Block64x64;
-        sequenceHeader.ModeInfoSize = sequenceHeader.Use128x128SuperBlock ? 32 : 16;
-        sequenceHeader.SuperBlockSizeLog2 = sequenceHeader.Use128x128SuperBlock ? 7 : 6;
+        sequenceHeader.Use128x128Superblock = reader.ReadBoolean();
+        sequenceHeader.SuperblockSize = sequenceHeader.Use128x128Superblock ? Av1BlockSize.Block128x128 : Av1BlockSize.Block64x64;
+        sequenceHeader.SuperblockModeInfoSize = sequenceHeader.Use128x128Superblock ? 32 : 16;
+        sequenceHeader.SuperblockSizeLog2 = sequenceHeader.Use128x128Superblock ? 7 : 6;
         sequenceHeader.EnableFilterIntra = reader.ReadBoolean();
         sequenceHeader.EnableIntraEdgeFilter = reader.ReadBoolean();
 
@@ -701,7 +701,7 @@ internal class ObuReader
         int superBlockColumnCount;
         int superBlockRowCount;
         int superBlockShift;
-        if (sequenceHeader.Use128x128SuperBlock)
+        if (sequenceHeader.Use128x128Superblock)
         {
             superBlockColumnCount = (frameInfo.ModeInfoColumnCount + 31) >> 5;
             superBlockRowCount = (frameInfo.ModeInfoRowCount + 31) >> 5;
@@ -1579,7 +1579,7 @@ internal class ObuReader
         if (usesLoopRestoration)
         {
             uint loopRestorationShift = reader.ReadLiteral(1);
-            if (sequenceHeader.Use128x128SuperBlock)
+            if (sequenceHeader.Use128x128Superblock)
             {
                 loopRestorationShift++;
             }

src/ImageSharp/Formats/Heif/Av1/OpenBitstreamUnit/ObuSequenceHeader.cs

@@ -37,13 +37,13 @@ internal class ObuSequenceHeader
 
     public int MaxFrameHeight { get; set; }
 
-    public bool Use128x128SuperBlock { get; set; }
+    public bool Use128x128Superblock { get; set; }
 
-    public Av1BlockSize SuperBlockSize { get; set; }
+    public Av1BlockSize SuperblockSize { get; set; }
 
-    public int ModeInfoSize { get; set; }
+    public int SuperblockModeInfoSize { get; set; }
 
-    public int SuperBlockSizeLog2 { get; set; }
+    public int SuperblockSizeLog2 { get; set; }
 
     public int FilterIntraLevel { get; set; }
 

src/ImageSharp/Formats/Heif/Av1/OpenBitstreamUnit/ObuWriter.cs

@@ -91,7 +91,7 @@ internal class ObuWriter
         writer.WriteLiteral((uint)sequenceHeader.MaxFrameHeight - 1, sequenceHeader.FrameHeightBits);
 
         // Video related flags removed
-        writer.WriteBoolean(sequenceHeader.Use128x128SuperBlock);
+        writer.WriteBoolean(sequenceHeader.Use128x128Superblock);
         writer.WriteBoolean(sequenceHeader.EnableFilterIntra);
         writer.WriteBoolean(sequenceHeader.EnableIntraEdgeFilter);
 
@@ -223,7 +223,7 @@ internal class ObuWriter
         int superBlockColumnCount;
         int superBlockRowCount;
         int superBlockShift;
-        if (sequenceHeader.Use128x128SuperBlock)
+        if (sequenceHeader.Use128x128Superblock)
         {
             superBlockColumnCount = (frameInfo.ModeInfoColumnCount + 31) >> 5;
             superBlockRowCount = (frameInfo.ModeInfoRowCount + 31) >> 5;

src/ImageSharp/Formats/Heif/Av1/Tiling/Av1FrameBuffer.cs

@@ -33,7 +33,7 @@ internal class Av1FrameBuffer
     public Av1FrameBuffer(ObuSequenceHeader sequenceHeader)
     {
         // init_main_frame_ctxt
-        int superblockSizeLog2 = sequenceHeader.SuperBlockSizeLog2;
+        int superblockSizeLog2 = sequenceHeader.SuperblockSizeLog2;
         int superblockAlignedWidth = Av1Math.AlignPowerOf2(sequenceHeader.MaxFrameWidth, superblockSizeLog2);
         int superblockAlignedHeight = Av1Math.AlignPowerOf2(sequenceHeader.MaxFrameHeight, superblockSizeLog2);
         this.superblockColumnCount = superblockAlignedWidth >> superblockSizeLog2;

src/ImageSharp/Formats/Heif/Av1/Tiling/Av1ParseAboveNeighbor4x4Context.cs

@@ -8,30 +8,24 @@ namespace SixLabors.ImageSharp.Formats.Heif.Av1.Symbol;
 
 internal class Av1ParseAboveNeighbor4x4Context
 {
-    /* Buffer holding the transform sizes of the previous 4x4 block row. */
-    private readonly int[] aboveTransformWidth;
-
-    /* Buffer holding the partition context of the previous 4x4 block row. */
-    private int[] abovePartitionWidth;
-
     /* Buffer holding the sign of the DC coefficients and the
        cumulative sum of the coefficient levels of the above 4x4
        blocks corresponding to the current super block row. */
-    private int[][] aboveContext = new int[Av1Constants.MaxPlanes][];
+    private readonly int[][] aboveContext = new int[Av1Constants.MaxPlanes][];
 
     /* Buffer holding the seg_id_predicted of the previous 4x4 block row. */
-    private int[] aboveSegmentIdPredictionContext;
+    private readonly int[] aboveSegmentIdPredictionContext;
 
     /* Value of base colors for Y, U, and V */
-    private int[][] abovePaletteColors = new int[Av1Constants.MaxPlanes][];
+    private readonly int[][] abovePaletteColors = new int[Av1Constants.MaxPlanes][];
 
-    private int[] aboveCompGroupIndex;
+    private readonly int[] aboveCompGroupIndex;
 
     public Av1ParseAboveNeighbor4x4Context(int planesCount, int modeInfoColumnCount)
     {
         int wide64x64Count = Av1BlockSize.Block64x64.Get4x4WideCount();
-        this.aboveTransformWidth = new int[modeInfoColumnCount];
-        this.abovePartitionWidth = new int[modeInfoColumnCount];
+        this.AboveTransformWidth = new int[modeInfoColumnCount];
+        this.AbovePartitionWidth = new int[modeInfoColumnCount];
         for (int i = 0; i < planesCount; i++)
         {
             this.aboveContext[i] = new int[modeInfoColumnCount];
@@ -42,25 +36,32 @@ internal class Av1ParseAboveNeighbor4x4Context
         this.aboveCompGroupIndex = new int[modeInfoColumnCount];
     }
 
-    public int[] AbovePartitionWidth => this.abovePartitionWidth;
+    /// <summary>
+    /// Gets a buffer holding the partition context of the previous 4x4 block row.
+    /// </summary>
+    public int[] AbovePartitionWidth { get; }
 
-    public int[] AboveTransformWidth => this.aboveTransformWidth;
+    /// <summary>
+    /// Gets a buffer holding the transform sizes of the previous 4x4 block row.
+    /// </summary>
+    public int[] AboveTransformWidth { get; }
 
     public int[] GetContext(int plane) => this.aboveContext[plane];
 
-    public void Clear(ObuSequenceHeader sequenceHeader)
+    public void Clear(ObuSequenceHeader sequenceHeader, int modeInfoColumnStart, int modeInfoColumnEnd)
     {
         int planeCount = sequenceHeader.ColorConfig.ChannelCount;
-        Array.Fill(this.aboveTransformWidth, Av1TransformSize.Size64x64.GetWidth());
-        Array.Fill(this.abovePartitionWidth, 0);
+        int width = modeInfoColumnEnd - modeInfoColumnStart;
+        Array.Fill(this.AboveTransformWidth, Av1TransformSize.Size64x64.GetWidth(), 0, width);
+        Array.Fill(this.AbovePartitionWidth, 0, 0, width);
         for (int i = 0; i < planeCount; i++)
         {
-            Array.Fill(this.aboveContext[i], 0);
-            Array.Fill(this.abovePaletteColors[i], 0);
+            Array.Fill(this.aboveContext[i], 0, 0, width);
+            Array.Fill(this.abovePaletteColors[i], 0, 0, width);
         }
 
-        Array.Fill(this.aboveSegmentIdPredictionContext, 0);
-        Array.Fill(this.aboveCompGroupIndex, 0);
+        Array.Fill(this.aboveSegmentIdPredictionContext, 0, 0, width);
+        Array.Fill(this.aboveCompGroupIndex, 0, 0, width);
     }
 
     public void UpdatePartition(Point modeInfoLocation, Av1TileInfo tileLoc, Av1BlockSize subSize, Av1BlockSize blockSize)
@@ -70,7 +71,7 @@ internal class Av1ParseAboveNeighbor4x4Context
         int value = Av1PartitionContext.GetAboveContext(subSize);
         for (int i = 0; i < bw; i++)
         {
-            this.abovePartitionWidth[startIndex + i] = value;
+            this.AbovePartitionWidth[startIndex + i] = value;
         }
     }
 
@@ -84,7 +85,7 @@ internal class Av1ParseAboveNeighbor4x4Context
             transformWidth = n4w << Av1Constants.ModeInfoSizeLog2;
         }
 
-        Array.Fill(this.aboveTransformWidth, transformWidth, startIndex, n4w);
+        Array.Fill(this.AboveTransformWidth, transformWidth, startIndex, n4w);
     }
 
     internal void ClearContext(int plane, int offset, int length)

src/ImageSharp/Formats/Heif/Av1/Tiling/Av1ParseLeftNeighbor4x4Context.cs

@@ -8,31 +8,23 @@ namespace SixLabors.ImageSharp.Formats.Heif.Av1.Symbol;
 
 internal class Av1ParseLeftNeighbor4x4Context
 {
-    /* Buffer holding the transform sizes of the left 4x4 blocks corresponding
-         to the current super block row. */
-    private readonly int[] leftTransformHeight;
-
-    /* Buffer holding the partition context of the left 4x4 blocks corresponding
-     to the current super block row. */
-    private int[] leftPartitionHeight;
-
     /* Buffer holding the sign of the DC coefficients and the
        cumulative sum of the coefficient levels of the left 4x4
        blocks corresponding to the current super block row. */
-    private int[][] leftContext = new int[Av1Constants.MaxPlanes][];
+    private readonly int[][] leftContext = new int[Av1Constants.MaxPlanes][];
 
     /* Buffer holding the seg_id_predicted of the previous 4x4 block row. */
-    private int[] leftSegmentIdPredictionContext;
+    private readonly int[] leftSegmentIdPredictionContext;
 
     /* Value of base colors for Y, U, and V */
-    private int[][] leftPaletteColors = new int[Av1Constants.MaxPlanes][];
+    private readonly int[][] leftPaletteColors = new int[Av1Constants.MaxPlanes][];
 
-    private int[] leftCompGroupIndex;
+    private readonly int[] leftCompGroupIndex;
 
     public Av1ParseLeftNeighbor4x4Context(int planesCount, int superblockModeInfoSize)
     {
-        this.leftTransformHeight = new int[superblockModeInfoSize];
-        this.leftPartitionHeight = new int[superblockModeInfoSize];
+        this.LeftTransformHeight = new int[superblockModeInfoSize];
+        this.LeftPartitionHeight = new int[superblockModeInfoSize];
         for (int i = 0; i < planesCount; i++)
         {
             this.leftContext[i] = new int[superblockModeInfoSize];
@@ -43,23 +35,33 @@ internal class Av1ParseLeftNeighbor4x4Context
         this.leftCompGroupIndex = new int[superblockModeInfoSize];
     }
 
-    public int[] LeftPartitionHeight => this.leftPartitionHeight;
+    /// <summary>
+    /// Gets a buffer holding the partition context of the left 4x4 blocks corresponding
+    /// to the current super block row.
+    /// </summary>
+    public int[] LeftPartitionHeight { get; }
 
-    public int[] LeftTransformHeight => this.leftTransformHeight;
+    /// <summary>
+    /// Gets a buffer holding the transform sizes of the left 4x4 blocks corresponding
+    /// to the current super block row.
+    /// </summary>
+    public int[] LeftTransformHeight { get; }
 
     public void Clear(ObuSequenceHeader sequenceHeader)
     {
+        int blockCount = sequenceHeader.SuperblockModeInfoSize;
         int planeCount = sequenceHeader.ColorConfig.ChannelCount;
-        Array.Fill(this.leftTransformHeight, Av1TransformSize.Size64x64.GetHeight());
-        Array.Fill(this.leftPartitionHeight, 0);
+        int neighbor4x4Count = sequenceHeader.SuperblockModeInfoSize;
+        Array.Fill(this.LeftTransformHeight, Av1TransformSize.Size64x64.GetHeight(), 0, blockCount);
+        Array.Fill(this.LeftPartitionHeight, 0, 0, blockCount);
         for (int i = 0; i < planeCount; i++)
         {
-            Array.Fill(this.leftContext[i], 0);
-            Array.Fill(this.leftPaletteColors[i], 0);
+            Array.Fill(this.leftContext[i], 0, 0, blockCount);
+            Array.Fill(this.leftPaletteColors[i], 0, 0, blockCount);
         }
 
-        Array.Fill(this.leftSegmentIdPredictionContext, 0);
-        Array.Fill(this.leftCompGroupIndex, 0);
+        Array.Fill(this.leftSegmentIdPredictionContext, 0, 0, blockCount);
+        Array.Fill(this.leftCompGroupIndex, 0, 0, blockCount);
     }
 
     public void UpdatePartition(Point modeInfoLocation, Av1SuperblockInfo superblockInfo, Av1BlockSize subSize, Av1BlockSize blockSize)
@@ -69,7 +71,7 @@ internal class Av1ParseLeftNeighbor4x4Context
         int value = Av1PartitionContext.GetLeftContext(subSize);
         for (int i = 0; i < bh; i++)
         {
-            this.leftPartitionHeight[startIndex + i] = value;
+            this.LeftPartitionHeight[startIndex + i] = value;
         }
     }
 
@@ -83,8 +85,8 @@ internal class Av1ParseLeftNeighbor4x4Context
             transformHeight = n4h << Av1Constants.ModeInfoSizeLog2;
         }
 
-        DebugGuard.MustBeLessThanOrEqualTo(startIndex + n4h, this.leftTransformHeight.Length, nameof(startIndex));
-        Array.Fill(this.leftTransformHeight, transformHeight, startIndex, n4h);
+        DebugGuard.MustBeLessThanOrEqualTo(startIndex + n4h, this.LeftTransformHeight.Length, nameof(startIndex));
+        Array.Fill(this.LeftTransformHeight, transformHeight, startIndex, n4h);
     }
 
     internal void ClearContext(int plane, int offset, int length)

src/ImageSharp/Formats/Heif/Av1/Tiling/Av1TileDecoder.cs

@@ -54,11 +54,11 @@ internal class Av1TileDecoder : IAv1TileDecoder
         // Hard code number of threads to 1 for now.
         int planesCount = sequenceHeader.ColorConfig.IsMonochrome ? 1 : Av1Constants.MaxPlanes;
         int superblockColumnCount =
-            Av1Math.AlignPowerOf2(sequenceHeader.MaxFrameWidth, sequenceHeader.SuperBlockSizeLog2) >> sequenceHeader.SuperBlockSizeLog2;
-        int modeInfoWideColumnCount = superblockColumnCount * sequenceHeader.ModeInfoSize;
-        modeInfoWideColumnCount = Av1Math.AlignPowerOf2(modeInfoWideColumnCount, sequenceHeader.SuperBlockSizeLog2 - 2);
+            Av1Math.AlignPowerOf2(sequenceHeader.MaxFrameWidth, sequenceHeader.SuperblockSizeLog2) >> sequenceHeader.SuperblockSizeLog2;
+        int modeInfoWideColumnCount = superblockColumnCount * sequenceHeader.SuperblockModeInfoSize;
+        modeInfoWideColumnCount = Av1Math.AlignPowerOf2(modeInfoWideColumnCount, sequenceHeader.SuperblockSizeLog2 - 2);
         this.aboveNeighborContext = new Av1ParseAboveNeighbor4x4Context(planesCount, modeInfoWideColumnCount);
-        this.leftNeighborContext = new Av1ParseLeftNeighbor4x4Context(planesCount, sequenceHeader.ModeInfoSize);
+        this.leftNeighborContext = new Av1ParseLeftNeighbor4x4Context(planesCount, sequenceHeader.SuperblockModeInfoSize);
         this.tusCount = new int[Av1Constants.MaxPlanes][];
         this.tusCount[0] = new int[this.FrameBuffer.ModeInfoCount];
         this.tusCount[1] = new int[this.FrameBuffer.ModeInfoCount];
@@ -78,7 +78,11 @@ internal class Av1TileDecoder : IAv1TileDecoder
         int tileColumnIndex = tileNum % this.FrameInfo.TilesInfo.TileColumnCount;
         int tileRowIndex = tileNum / this.FrameInfo.TilesInfo.TileColumnCount;
 
-        this.aboveNeighborContext.Clear(this.SequenceHeader);
+        int modeInfoColumnStart = this.FrameInfo.TilesInfo.TileColumnStartModeInfo[tileColumnIndex];
+        int modeInfoColumnEnd = this.FrameInfo.TilesInfo.TileColumnStartModeInfo[tileColumnIndex + 1];
+        int modeInfoRowStart = this.FrameInfo.TilesInfo.TileRowStartModeInfo[tileRowIndex];
+        int modeInfoRowEnd = this.FrameInfo.TilesInfo.TileRowStartModeInfo[tileRowIndex + 1];
+        this.aboveNeighborContext.Clear(this.SequenceHeader, modeInfoColumnStart, modeInfoColumnEnd);
         this.ClearLoopFilterDelta();
         int planesCount = this.SequenceHeader.ColorConfig.ChannelCount;
 
@@ -98,15 +102,15 @@ internal class Av1TileDecoder : IAv1TileDecoder
         }
 
         Av1TileInfo tileInfo = new(tileRowIndex, tileColumnIndex, this.FrameInfo);
-        Av1BlockSize superBlockSize = this.SequenceHeader.Use128x128SuperBlock ? Av1BlockSize.Block128x128 : Av1BlockSize.Block64x64;
+        Av1BlockSize superBlockSize = this.SequenceHeader.Use128x128Superblock ? Av1BlockSize.Block128x128 : Av1BlockSize.Block64x64;
         int superBlock4x4Size = superBlockSize.Get4x4WideCount();
-        for (int row = this.FrameInfo.TilesInfo.TileRowStartModeInfo[tileRowIndex]; row < this.FrameInfo.TilesInfo.TileRowStartModeInfo[tileRowIndex + 1]; row += this.SequenceHeader.ModeInfoSize)
+        for (int row = modeInfoRowStart; row < modeInfoRowEnd; row += this.SequenceHeader.SuperblockModeInfoSize)
         {
-            int superBlockRow = row << Av1Constants.ModeInfoSizeLog2 >> this.SequenceHeader.SuperBlockSizeLog2;
+            int superBlockRow = row << Av1Constants.ModeInfoSizeLog2 >> this.SequenceHeader.SuperblockSizeLog2;
             this.leftNeighborContext.Clear(this.SequenceHeader);
-            for (int column = this.FrameInfo.TilesInfo.TileColumnStartModeInfo[tileColumnIndex]; column < this.FrameInfo.TilesInfo.TileColumnStartModeInfo[tileColumnIndex + 1]; column += this.SequenceHeader.ModeInfoSize)
+            for (int column = modeInfoColumnStart; column < modeInfoColumnEnd; column += this.SequenceHeader.SuperblockModeInfoSize)
             {
-                int superBlockColumn = column << Av1Constants.ModeInfoSizeLog2 >> this.SequenceHeader.SuperBlockSizeLog2;
+                int superBlockColumn = column << Av1Constants.ModeInfoSizeLog2 >> this.SequenceHeader.SuperblockSizeLog2;
                 Point superblockPosition = new(superBlockColumn, superBlockRow);
                 Av1SuperblockInfo superblockInfo = this.FrameBuffer.GetSuperblock(superblockPosition);
 
@@ -162,6 +166,7 @@ internal class Av1TileDecoder : IAv1TileDecoder
         int quarterBlock4x4Size = halfBlock4x4Size >> 1;
         bool hasRows = (modeInfoLocation.Y + halfBlock4x4Size) < this.FrameInfo.ModeInfoRowCount;
         bool hasColumns = (modeInfoLocation.X + halfBlock4x4Size) < this.FrameInfo.ModeInfoColumnCount;
+        int ctx = this.GetPartitionPlaneContext(modeInfoLocation, blockSize, tileInfo, superblockInfo);
         Av1PartitionType partitionType = Av1PartitionType.Split;
         if (blockSize < Av1BlockSize.Block8x8)
         {
@@ -169,20 +174,17 @@ internal class Av1TileDecoder : IAv1TileDecoder
         }
         else if (hasRows && hasColumns)
         {
-            int ctx = this.GetPartitionPlaneContext(modeInfoLocation, blockSize, tileInfo, superblockInfo);
             partitionType = reader.ReadPartitionType(ctx);
         }
         else if (hasColumns)
         {
-            int ctx = this.GetPartitionPlaneContext(modeInfoLocation, blockSize, tileInfo, superblockInfo);
-            bool splitOrHorizontal = reader.ReadSplitOrHorizontal(blockSize, ctx);
-            partitionType = splitOrHorizontal ? Av1PartitionType.Split : Av1PartitionType.Horizontal;
+            bool splitOrVertical = reader.ReadSplitOrVertical(blockSize, ctx);
+            partitionType = splitOrVertical ? Av1PartitionType.Split : Av1PartitionType.Horizontal;
         }
         else if (hasRows)
         {
-            int ctx = this.GetPartitionPlaneContext(modeInfoLocation, blockSize, tileInfo, superblockInfo);
-            bool splitOrVertical = reader.ReadSplitOrVertical(blockSize, ctx);
-            partitionType = splitOrVertical ? Av1PartitionType.Split : Av1PartitionType.Vertical;
+            bool splitOrHorizontal = reader.ReadSplitOrHorizontal(blockSize, ctx);
+            partitionType = splitOrHorizontal ? Av1PartitionType.Split : Av1PartitionType.Vertical;
         }
 
         Av1BlockSize subSize = partitionType.GetBlockSubSize(blockSize);
@@ -1204,27 +1206,6 @@ internal class Av1TileDecoder : IAv1TileDecoder
         return (aboveEntropyContext ? 1 : 0) + (leftEntropyContext ? 1 : 0);
     }
 
-    private void Reconstruct(int plane, int startX, int startY, Av1TransformSize transformSize) => throw new NotImplementedException();
-
-    private int Coefficients(int plane, int startX, int startY, Av1TransformSize transformSize) => throw new NotImplementedException();
-
-    private void PredictChromaFromLuma(int plane, int startX, int startY, Av1TransformSize transformSize) => throw new NotImplementedException();
-
-    /// <summary>
-    /// 7.11.2. Intra prediction process.
-    /// </summary>
-    private void PredictIntra(int plane, int startX, int startY, bool leftAvailable, bool upAvailable, bool haveAboveRight, bool haveBelowLeft, Av1PredictionMode mode, int log2Width, int log2Height) => throw new NotImplementedException();
-
-    private void PredictPalette(int plane, int startX, int startY, int x, int y, Av1TransformSize transformSize) => throw new NotImplementedException();
-
-    /// <summary>
-    /// Page 65, below 5.11.5. Decode block syntax.
-    /// </summary>
-    private static void ResetBlockContext(int rowIndex, int columnIndex, Av1BlockSize blockSize)
-    {
-        // TODO: Do we still need this method.
-    }
-
     /// <summary>
     /// 5.11.15. TX size syntax.
     /// </summary>
@@ -1236,7 +1217,7 @@ internal class Av1TileDecoder : IAv1TileDecoder
             return Av1TransformSize.Size4x4;
         }
 
-        if (modeInfo.BlockSize > Av1BlockSize.Block4x4 && allowSelect && this.FrameInfo.TransformMode == Transform.Av1TransformMode.Select)
+        if (modeInfo.BlockSize > Av1BlockSize.Block4x4 && allowSelect && this.FrameInfo.TransformMode == Av1TransformMode.Select)
         {
             return this.ReadSelectedTransformSize(ref reader, partitionInfo, superblockInfo, tileInfo);
         }
@@ -1719,7 +1700,7 @@ internal class Av1TileDecoder : IAv1TileDecoder
         if (partitionInfo.CdefStrength[r][c] == -1)
         {
             partitionInfo.CdefStrength[r][c] = reader.ReadLiteral(this.FrameInfo.CdefParameters.BitCount);
-            if (this.SequenceHeader.SuperBlockSize == Av1BlockSize.Block128x128)
+            if (this.SequenceHeader.SuperblockSize == Av1BlockSize.Block128x128)
             {
                 int w4 = partitionInfo.ModeInfo.BlockSize.Get4x4WideCount();
                 int h4 = partitionInfo.ModeInfo.BlockSize.Get4x4HighCount();
@@ -1736,7 +1717,7 @@ internal class Av1TileDecoder : IAv1TileDecoder
 
     private void ReadDeltaLoopFilter(ref Av1SymbolDecoder reader, Av1PartitionInfo partitionInfo)
     {
-        Av1BlockSize superBlockSize = this.SequenceHeader.Use128x128SuperBlock ? Av1BlockSize.Block128x128 : Av1BlockSize.Block64x64;
+        Av1BlockSize superBlockSize = this.SequenceHeader.Use128x128Superblock ? Av1BlockSize.Block128x128 : Av1BlockSize.Block64x64;
         if (this.FrameInfo.DeltaLoopFilterParameters.IsPresent ||
             (partitionInfo.ModeInfo.BlockSize == superBlockSize && partitionInfo.ModeInfo.Skip))
         {
@@ -1790,14 +1771,14 @@ internal class Av1TileDecoder : IAv1TileDecoder
 
     private void ReadDeltaQuantizerIndex(ref Av1SymbolDecoder reader, Av1PartitionInfo partitionInfo)
     {
-        Av1BlockSize superBlockSize = this.SequenceHeader.Use128x128SuperBlock ? Av1BlockSize.Block128x128 : Av1BlockSize.Block64x64;
+        Av1BlockSize superBlockSize = this.SequenceHeader.Use128x128Superblock ? Av1BlockSize.Block128x128 : Av1BlockSize.Block64x64;
         if (!this.FrameInfo.DeltaQParameters.IsPresent ||
             (partitionInfo.ModeInfo.BlockSize == superBlockSize && partitionInfo.ModeInfo.Skip))
         {
             return;
         }
 
-        if (partitionInfo.ModeInfo.BlockSize != this.SequenceHeader.SuperBlockSize || !partitionInfo.ModeInfo.Skip)
+        if (partitionInfo.ModeInfo.BlockSize != this.SequenceHeader.SuperblockSize || !partitionInfo.ModeInfo.Skip)
         {
             int deltaQuantizerAbsolute = reader.ReadDeltaQuantizerAbsolute();
             if (deltaQuantizerAbsolute == Av1Constants.DeltaQuantizerSmall)
@@ -1834,15 +1815,17 @@ internal class Av1TileDecoder : IAv1TileDecoder
         return xPos && yPos;
     }*/
 
-    private int GetPartitionPlaneContext(Point location, Av1BlockSize blockSize, Av1TileInfo tileLoc, Av1SuperblockInfo superblockInfo)
+    private int GetPartitionPlaneContext(Point location, Av1BlockSize blockSize, Av1TileInfo tileInfo, Av1SuperblockInfo superblockInfo)
     {
         // Maximum partition point is 8x8. Offset the log value occordingly.
-        int aboveCtx = this.aboveNeighborContext.AbovePartitionWidth[location.X - tileLoc.ModeInfoColumnStart];
+        int aboveCtx = this.aboveNeighborContext.AbovePartitionWidth[location.X - tileInfo.ModeInfoColumnStart];
         int leftCtx = this.leftNeighborContext.LeftPartitionHeight[(location.Y - superblockInfo.Position.Y) & Av1PartitionContext.Mask];
         int blockSizeLog = blockSize.Get4x4WidthLog2() - Av1BlockSize.Block8x8.Get4x4WidthLog2();
         int above = (aboveCtx >> blockSizeLog) & 0x1;
         int left = (leftCtx >> blockSizeLog) & 0x1;
-        return (left * 2) + above + (blockSizeLog * PartitionProbabilitySet);
+        DebugGuard.IsTrue(blockSize.Get4x4WidthLog2() == blockSize.Get4x4HeightLog2(), "Blocks should be square");
+        DebugGuard.MustBeGreaterThanOrEqualTo(blockSizeLog, 0, nameof(blockSizeLog));
+        return ((left << 1) + above) + (blockSizeLog * PartitionProbabilitySet);
     }
 
     private void UpdatePartitionContext(Point modeInfoLocation, Av1TileInfo tileLoc, Av1SuperblockInfo superblockInfo, Av1BlockSize subSize, Av1BlockSize blockSize, Av1PartitionType partition)