Extend AV1 partition search through 32x32

src/ImageSharp/Formats/Heif/Av1/Pipeline/Av1EncoderModeDecisionWorkspace.cs

@@ -18,7 +18,7 @@ internal readonly ref struct Av1EncoderModeDecisionWorkspace<TSample>
     /// <summary>
     /// The largest coding-block dimension evaluated directly by the current partition search.
     /// </summary>
-    public const int MaximumBlockDimension = 16;
+    public const int MaximumBlockDimension = 32;
 
     /// <summary>
     /// The maximum number of samples in one directly evaluated coding block.
@@ -49,8 +49,7 @@ internal readonly ref struct Av1EncoderModeDecisionWorkspace<TSample>
         2 * (MaximumBlockDimension >> Av1Constants.ModeInfoSizeLog2) * sizeof(byte) / sizeof(int);
 
     private const int TransientStorageOffset = TransformContextStorageOffset + TransformContextStorageLength;
-    private const int ChromaFromLumaSampleCount =
-        Av1ChromaFromLumaContext.BufferLine * MaximumBlockDimension;
+    private const int ChromaFromLumaSampleCount = Av1ChromaFromLumaContext.BufferLength;
 
     private const int ChromaFromLumaSampleStorageLength = ChromaFromLumaSampleCount * sizeof(short) / sizeof(int);
     private const int ChromaFromLumaBlueRateOffset = ChromaFromLumaSampleStorageLength;

src/ImageSharp/Formats/Heif/Av1/Pipeline/Av1IntraSuperblockEncoder.ModeDecision.cs

@@ -183,7 +183,10 @@ internal static partial class Av1IntraSuperblockEncoder
             Av1BlockSize blockSize,
             Av1PartitionType preparedPartition)
         {
-            if (blockSize is not Av1BlockSize.Block8x8 and not Av1BlockSize.Block16x16)
+            bool searchPartition = blockSize is Av1BlockSize.Block8x8 or Av1BlockSize.Block16x16 ||
+                (this.effort == 10 && blockSize == Av1BlockSize.Block32x32);
+
+            if (!searchPartition)
             {
                 return preparedPartition;
             }

tests/ImageSharp.Tests/Formats/Heif/Av1/Av1EncoderFrameTests.cs

@@ -274,6 +274,46 @@ public class Av1EncoderFrameTests
         Assert.Equal(new Size(Size, Size), decoded.Size);
     }
 
+    [Fact]
+    public void EncodeEffortTenSelectsThirtyTwoByThirtyTwoBlocks()
+    {
+        const int Size = 64;
+        using Image<Rgba32> source = new(Size, Size);
+        for (int y = 0; y < Size; y++)
+        {
+            Span<Rgba32> row = source.Frames.RootFrame.PixelBuffer.DangerousGetRowSpan(y);
+            for (int x = 0; x < Size; x++)
+            {
+                row[x] = new Rgba32(128, 128, 128);
+            }
+        }
+
+        using MemoryStream stream = new();
+        _ = Av1FrameEncoder.Encode(
+            Configuration.Default,
+            source.Frames.RootFrame,
+            stream,
+            CreateColorConfig(Av1BitDepth.EightBit, Av1ColorFormat.Yuv400),
+            qIndex: 4,
+            effort: 10);
+
+        byte[] payload = stream.ToArray();
+        using Av1Decoder decoder = new(Configuration.Default);
+        using Image<Rgba32> decoded = decoder.Decode<Rgba32>(payload);
+        Av1FrameInfo frameInfo = Assert.IsType<Av1FrameInfo>(decoder.FrameInfo);
+        for (int modeInfoY = 0; modeInfoY < 16; modeInfoY++)
+        {
+            for (int modeInfoX = 0; modeInfoX < 16; modeInfoX++)
+            {
+                Assert.Equal(
+                    Av1BlockSize.Block32x32,
+                    frameInfo.GetModeInfoAt(new Point(modeInfoX, modeInfoY)).BlockSize);
+            }
+        }
+
+        Assert.Equal(new Size(Size, Size), decoded.Size);
+    }
+
     [Theory]
     [InlineData(EightBit)]
     [InlineData(TenBit)]