mirror of https://github.com/SixLabors/ImageSharp
James Jackson-South
1 month ago
6 changed files with 473 additions and 194 deletions
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// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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using System; |
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using SixLabors.ImageSharp.Formats.Heif.Av1.Transform; |
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namespace SixLabors.ImageSharp.Formats.Heif.Av1.Prediction; |
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/// <summary>
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/// Determines whether extended intra-prediction references have already been reconstructed.
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/// </summary>
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internal static class Av1IntraReferenceAvailability |
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{ |
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/// <summary>
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/// Determines whether every bottom-left reference sample required by a transform is already reconstructed.
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/// </summary>
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/// <param name="superblockSize">The sequence superblock size.</param>
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/// <param name="blockSize">The containing block size in the current plane's geometry.</param>
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/// <param name="modeInfoRow">The containing block row in 4-by-4 mode-information units.</param>
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/// <param name="modeInfoColumn">The containing block column in 4-by-4 mode-information units.</param>
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/// <param name="bottomAvailable">A value indicating whether the required rows remain inside the frame and tile.</param>
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/// <param name="haveLeft">A value indicating whether reconstructed samples exist immediately to the left.</param>
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/// <param name="partition">The partition type that determines reconstruction order.</param>
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/// <param name="transformSize">The transform size whose extended edge is required.</param>
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/// <param name="blockModeInfoRowOffset">The transform row offset within the containing block.</param>
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/// <param name="blockModeInfoColumnOffset">The transform column offset within the containing block.</param>
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/// <param name="subX">The horizontal chroma subsampling shift.</param>
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/// <param name="subY">The vertical chroma subsampling shift.</param>
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/// <returns><see langword="true"/> when the bottom-left reference extension is available; otherwise, <see langword="false"/>.</returns>
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public static bool HasBottomLeft(Av1BlockSize superblockSize, Av1BlockSize blockSize, int modeInfoRow, int modeInfoColumn, bool bottomAvailable, bool haveLeft, Av1PartitionType partition, Av1TransformSize transformSize, int blockModeInfoRowOffset, int blockModeInfoColumnOffset, int subX, int subY) |
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{ |
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if (!bottomAvailable || !haveLeft) |
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{ |
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return false; |
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} |
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// A 128-wide block is reconstructed as two 64-wide regions in raster order,
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// so the right half can consume references that already belong to the left half.
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if (blockSize.GetWidth() > 64 && blockModeInfoColumnOffset > 0) |
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{ |
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int block64WidthInUnits = Av1BlockSize.Block64x64.Get4x4WideCount(); |
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int planeBlockWidthInUnits64 = block64WidthInUnits >> subX; |
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int columnOffset64 = blockModeInfoColumnOffset % planeBlockWidthInUnits64; |
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if (columnOffset64 == 0) |
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{ |
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// We are at the left edge of top-right or bottom-right 64x* block.
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int block64HeightInUnits = Av1BlockSize.Block64x64.Get4x4HighCount(); |
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int planeBlockHeightInUnits64 = block64HeightInUnits >> subY; |
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int rowOffset64 = blockModeInfoRowOffset % planeBlockHeightInUnits64; |
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int planeBlockHeightInUnits = Math.Min(blockSize.Get4x4HighCount() >> subY, planeBlockHeightInUnits64); |
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// Check if all bottom-left pixels are in the left 64x* block (which is
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// already coded).
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return rowOffset64 + transformSize.Get4x4HighCount() < planeBlockHeightInUnits; |
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} |
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} |
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if (blockModeInfoColumnOffset > 0) |
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{ |
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// Bottom-left pixels are in the bottom-left block, which is not available.
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return false; |
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} |
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else |
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{ |
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int blockHeightInUnits = blockSize.GetHeight() >> Av1TransformSize.Size4x4.GetBlockHeightLog2(); |
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int planeBlockHeightInUnits = Math.Max(blockHeightInUnits >> subY, 1); |
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int bottomLeftUnitCount = transformSize.Get4x4HighCount(); |
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// All bottom-left pixels are in the left block, which is already available.
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if (blockModeInfoRowOffset + bottomLeftUnitCount < planeBlockHeightInUnits) |
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{ |
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return true; |
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} |
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int blockWidthInModeInfoLog2 = blockSize.Get4x4WidthLog2(); |
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int blockHeightInModeInfoLog2 = blockSize.Get4x4HeightLog2(); |
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int superblockModeInfoSize = superblockSize.Get4x4HighCount(); |
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int blockRowInSuperblock = (modeInfoRow & (superblockModeInfoSize - 1)) >> blockHeightInModeInfoLog2; |
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int blockColumnInSuperblock = (modeInfoColumn & (superblockModeInfoSize - 1)) >> blockWidthInModeInfoLog2; |
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// Leftmost column of superblock: so bottom-left pixels maybe in the left
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// and/or bottom-left superblocks. But only the left superblock is
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// available, so check if all required pixels fall in that superblock.
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if (blockColumnInSuperblock == 0) |
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{ |
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int blockStartRowOffset = blockRowInSuperblock << (blockHeightInModeInfoLog2 + Av1Constants.ModeInfoSizeLog2 - Av1TransformSize.Size4x4.GetBlockWidthLog2()) >> subY; |
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int rowOffsetInSuperblock = blockStartRowOffset + blockModeInfoRowOffset; |
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int superblockHeightInUnits = superblockModeInfoSize >> subY; |
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return rowOffsetInSuperblock + bottomLeftUnitCount < superblockHeightInUnits; |
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} |
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// Bottom row of superblock (and not the leftmost column): so bottom-left
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// pixels fall in the bottom superblock, which is not available yet.
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if (((blockRowInSuperblock + 1) << blockHeightInModeInfoLog2) >= superblockModeInfoSize) |
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{ |
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return false; |
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} |
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// General case (neither leftmost column nor bottom row): check if the
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// bottom-left block is coded before the current block.
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int thisBlockIndex = ((blockRowInSuperblock + 0) << (Av1Constants.MaxSuperBlockSizeLog2 - Av1Constants.ModeInfoSizeLog2 - blockWidthInModeInfoLog2)) + blockColumnInSuperblock + 0; |
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return Av1BottomRightTopLeftConstants.HasBottomLeft(partition, blockSize, thisBlockIndex); |
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} |
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} |
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/// <summary>
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/// Determines whether every top-right reference sample required by a transform is already reconstructed.
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/// </summary>
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/// <param name="superblockSize">The sequence superblock size.</param>
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/// <param name="blockSize">The containing block size in the current plane's geometry.</param>
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/// <param name="modeInfoRow">The containing block row in 4-by-4 mode-information units.</param>
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/// <param name="modeInfoColumn">The containing block column in 4-by-4 mode-information units.</param>
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/// <param name="haveTop">A value indicating whether reconstructed samples exist immediately above.</param>
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/// <param name="rightAvailable">A value indicating whether the required columns remain inside the frame and tile.</param>
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/// <param name="partition">The partition type that determines reconstruction order.</param>
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/// <param name="transformSize">The transform size whose extended edge is required.</param>
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/// <param name="blockModeInfoRowOffset">The transform row offset within the containing block.</param>
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/// <param name="blockModeInfoColumnOffset">The transform column offset within the containing block.</param>
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/// <param name="subX">The horizontal chroma subsampling shift.</param>
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/// <param name="subY">The vertical chroma subsampling shift.</param>
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/// <returns><see langword="true"/> when the top-right reference extension is available; otherwise, <see langword="false"/>.</returns>
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public static bool HasTopRight(Av1BlockSize superblockSize, Av1BlockSize blockSize, int modeInfoRow, int modeInfoColumn, bool haveTop, bool rightAvailable, Av1PartitionType partition, Av1TransformSize transformSize, int blockModeInfoRowOffset, int blockModeInfoColumnOffset, int subX, int subY) |
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{ |
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if (!haveTop || !rightAvailable) |
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{ |
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return false; |
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} |
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int blockWideInUnits = blockSize.GetWidth() >> 2; |
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int planeBlockWidthInUnits = Math.Max(blockWideInUnits >> subX, 1); |
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int topRightUnitCount = transformSize.Get4x4WideCount(); |
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if (blockModeInfoRowOffset > 0) |
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{ |
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// Transforms below the first row obtain their top edge from the containing block,
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// so only the reconstructed width to their right constrains availability.
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if (blockSize.GetWidth() > 64) |
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{ |
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// Special case: For 128x128 blocks, the transform unit whose
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// top-right corner is at the center of the block does in fact have
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// pixels available at its top-right corner.
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int block64WidthInUnits = Av1BlockSize.Block64x64.Get4x4WideCount(); |
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int block64HeightInUnits = Av1BlockSize.Block64x64.Get4x4HighCount(); |
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if (blockModeInfoRowOffset == block64HeightInUnits >> subY && |
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blockModeInfoColumnOffset + topRightUnitCount == block64WidthInUnits >> subX) |
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{ |
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return true; |
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} |
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int planeBlockWidthInUnits64 = block64WidthInUnits >> subX; |
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int blockModeInfoColumnOffset64 = blockModeInfoColumnOffset % planeBlockWidthInUnits64; |
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return blockModeInfoColumnOffset64 + topRightUnitCount < planeBlockWidthInUnits64; |
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} |
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return blockModeInfoColumnOffset + topRightUnitCount < planeBlockWidthInUnits; |
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} |
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else |
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{ |
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// All top-right pixels are in the block above, which is already available.
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if (blockModeInfoColumnOffset + topRightUnitCount < planeBlockWidthInUnits) |
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{ |
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return true; |
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} |
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int blockWidthInModeInfoLog2 = blockSize.Get4x4WidthLog2(); |
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int blockHeightInModeInfeLog2 = blockSize.Get4x4HeightLog2(); |
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int superBlockModeInfoSize = superblockSize.Get4x4HighCount(); |
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int blockRowInSuperblock = (modeInfoRow & (superBlockModeInfoSize - 1)) >> blockHeightInModeInfeLog2; |
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int blockColumnInSuperBlock = (modeInfoColumn & (superBlockModeInfoSize - 1)) >> blockWidthInModeInfoLog2; |
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// Top row of superblock: so top-right pixels are in the top and/or
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// top-right superblocks, both of which are already available.
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if (blockRowInSuperblock == 0) |
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{ |
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return true; |
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} |
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// Rightmost column of superblock (and not the top row): so top-right pixels
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// fall in the right superblock, which is not available yet.
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if (((blockColumnInSuperBlock + 1) << blockWidthInModeInfoLog2) >= superBlockModeInfoSize) |
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{ |
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return false; |
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} |
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// General case (neither top row nor rightmost column): check if the
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// top-right block is coded before the current block.
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int thisBlockIndex = ((blockRowInSuperblock + 0) << (Av1Constants.MaxSuperBlockSizeLog2 - Av1Constants.ModeInfoSizeLog2 - blockWidthInModeInfoLog2)) + blockColumnInSuperBlock + 0; |
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return Av1BottomRightTopLeftConstants.HasTopRight(partition, blockSize, thisBlockIndex); |
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} |
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} |
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} |
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