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Paragraph 13.4: Parse probabilities

pull/1147/head
Brian Popow 6 years ago
parent
ab743a1d3d
commit
9444fe251e
6 changed files with 417 additions and 16 deletions
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  1. 18
      src/ImageSharp/Formats/WebP/VP8BandProbas.cs
  2. 25
      src/ImageSharp/Formats/WebP/Vp8BitReader.cs
  3. 23
      src/ImageSharp/Formats/WebP/Vp8Proba.cs
  4. 18
      src/ImageSharp/Formats/WebP/Vp8ProbaArray.cs
  5. 296
      src/ImageSharp/Formats/WebP/WebPConstants.cs
  6. 53
      src/ImageSharp/Formats/WebP/WebPDecoderCore.cs

18
src/ImageSharp/Formats/WebP/VP8BandProbas.cs
View File

@ -0,0 +1,18 @@
// Copyright (c) Six Labors and contributors.
// Licensed under the Apache License, Version 2.0.
namespace SixLabors.ImageSharp.Formats.WebP
{
/// <summary>
/// All the probabilities associated to one band.
/// </summary>
internal class Vp8BandProbas
{
public Vp8BandProbas()
{
this.Probabilities = new Vp8ProbaArray[WebPConstants.NumCtx];
}
public Vp8ProbaArray[] Probabilities { get; }
}
}

25
src/ImageSharp/Formats/WebP/Vp8BitReader.cs
View File

@ -46,23 +46,19 @@ namespace SixLabors.ImageSharp.Formats.WebP
/// </summary>
private long pos;
public int Pos { get { return (int)pos; } }
/// <summary>
/// Initializes a new instance of the <see cref="Vp8BitReader"/> class.
/// </summary>
/// <param name="inputStream">The input stream to read from.</param>
/// <param name="imageDataSize">The raw image data size in bytes.</param>
/// <param name="memoryAllocator">Used for allocating memory during reading data from the stream.</param>
public Vp8BitReader(Stream inputStream, uint imageDataSize, MemoryAllocator memoryAllocator)
/// <param name="startPos">Start index in the data array. Defaults to 0.</param>
public Vp8BitReader(Stream inputStream, uint imageDataSize, MemoryAllocator memoryAllocator, int startPos = 0)
{
this.ReadImageDataFromStream(inputStream, (int)imageDataSize, memoryAllocator);
this.range = 255 - 1;
this.value = 0;
this.bits = -8; // to load the very first 8bits.
this.eof = false;
this.pos = 0;
this.LoadNewBytes();
this.InitBitreader(startPos);
}
public int GetBit(int prob)
@ -124,6 +120,17 @@ namespace SixLabors.ImageSharp.Formats.WebP
return this.ReadValue(1) != 0 ? -value : value;
}
private void InitBitreader(int pos = 0)
{
this.range = 255 - 1;
this.value = 0;
this.bits = -8; // to load the very first 8bits.
this.eof = false;
this.pos = 0;
this.LoadNewBytes();
}
private void LoadNewBytes()
{
if (this.pos < this.Data.Length)

23
src/ImageSharp/Formats/WebP/Vp8Proba.cs
View File

@ -0,0 +1,23 @@
// Copyright (c) Six Labors and contributors.
// Licensed under the Apache License, Version 2.0.
namespace SixLabors.ImageSharp.Formats.WebP
{
/// <summary>
/// Data for all frame-persistent probabilities.
/// </summary>
internal class Vp8Proba
{
private const int MbFeatureTreeProbs = 3;
public Vp8Proba()
{
this.Segments = new uint[MbFeatureTreeProbs];
this.Bands = new Vp8BandProbas[WebPConstants.NumTypes, WebPConstants.NumBands];
}
public uint[] Segments { get; }
public Vp8BandProbas[,] Bands { get; }
}
}

18
src/ImageSharp/Formats/WebP/Vp8ProbaArray.cs
View File

@ -0,0 +1,18 @@
// Copyright (c) Six Labors and contributors.
// Licensed under the Apache License, Version 2.0.
namespace SixLabors.ImageSharp.Formats.WebP
{
/// <summary>
/// Probabilities associated to one of the contexts.
/// </summary>
internal class Vp8ProbaArray
{
public Vp8ProbaArray()
{
this.Probabilities = new uint[WebPConstants.NumProbas];
}
public uint[] Probabilities { get; }
}
}

296
src/ImageSharp/Formats/WebP/WebPConstants.cs
View File

@ -5,6 +5,9 @@ using System.Collections.Generic;
namespace SixLabors.ImageSharp.Formats.WebP
{
/// <summary>
/// Constants used for decoding VP8 and VP8L bitstreams.
/// </summary>
internal static class WebPConstants
{
/// <summary>
@ -105,11 +108,25 @@ namespace SixLabors.ImageSharp.Formats.WebP
NumDistanceCodes
};
// VP8 constants
// VP8 constants from here on
public const int NumMbSegments = 4;
public const int MaxNumPartitions = 8;
public const int NumTypes = 4;
public const int NumBands = 8;
public const int NumProbas = 11;
public const int NumCtx = 3;
// Paragraph 9.9
public static readonly int[] Bands =
{
0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7, 0
};
// Paragraph 14.1
public static readonly int[] DcTable =
{
@ -152,10 +169,281 @@ namespace SixLabors.ImageSharp.Formats.WebP
249, 254, 259, 264, 269, 274, 279, 284
};
// Paragraph 9.9
public static readonly int[] Bands =
// Paragraph 13
public static readonly byte[,,,] CoeffsUpdateProba =
{
0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7, 0
{ { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 176, 246, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 223, 241, 252, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 249, 253, 253, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 244, 252, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 234, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 253, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 246, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 239, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 254, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 248, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 251, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 251, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 254, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 254, 253, 255, 254, 255, 255, 255, 255, 255, 255 },
{ 250, 255, 254, 255, 254, 255, 255, 255, 255, 255, 255 },
{ 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
}
},
{ { { 217, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 225, 252, 241, 253, 255, 255, 254, 255, 255, 255, 255 },
{ 234, 250, 241, 250, 253, 255, 253, 254, 255, 255, 255 }
},
{ { 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 223, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 238, 253, 254, 254, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 248, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 249, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 253, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 247, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 252, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 253, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 254, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 250, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
}
},
{ { { 186, 251, 250, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 234, 251, 244, 254, 255, 255, 255, 255, 255, 255, 255 },
{ 251, 251, 243, 253, 254, 255, 254, 255, 255, 255, 255 }
},
{ { 255, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 236, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 251, 253, 253, 254, 254, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 254, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
}
},
{ { { 248, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 250, 254, 252, 254, 255, 255, 255, 255, 255, 255, 255 },
{ 248, 254, 249, 253, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 253, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 246, 253, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 252, 254, 251, 254, 254, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 254, 252, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 248, 254, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 253, 255, 254, 254, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 251, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 245, 251, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 253, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 251, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 252, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 252, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 249, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 255, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 250, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
},
{ { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
{ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
}
}
};
// Paragraph 13.5: Default Token Probability Table.
public static readonly byte[,,,] DefaultCoeffsProba =
{
{
{ { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
{ 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
{ 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 }
},
{ { 253, 136, 254, 255, 228, 219, 128, 128, 128, 128, 128 },
{ 189, 129, 242, 255, 227, 213, 255, 219, 128, 128, 128 },
{ 106, 126, 227, 252, 214, 209, 255, 255, 128, 128, 128 }
},
{ { 1, 98, 248, 255, 236, 226, 255, 255, 128, 128, 128 },
{ 181, 133, 238, 254, 221, 234, 255, 154, 128, 128, 128 },
{ 78, 134, 202, 247, 198, 180, 255, 219, 128, 128, 128 },
},
{ { 1, 185, 249, 255, 243, 255, 128, 128, 128, 128, 128 },
{ 184, 150, 247, 255, 236, 224, 128, 128, 128, 128, 128 },
{ 77, 110, 216, 255, 236, 230, 128, 128, 128, 128, 128 },
},
{ { 1, 101, 251, 255, 241, 255, 128, 128, 128, 128, 128 },
{ 170, 139, 241, 252, 236, 209, 255, 255, 128, 128, 128 },
{ 37, 116, 196, 243, 228, 255, 255, 255, 128, 128, 128 }
},
{ { 1, 204, 254, 255, 245, 255, 128, 128, 128, 128, 128 },
{ 207, 160, 250, 255, 238, 128, 128, 128, 128, 128, 128 },
{ 102, 103, 231, 255, 211, 171, 128, 128, 128, 128, 128 }
},
{ { 1, 152, 252, 255, 240, 255, 128, 128, 128, 128, 128 },
{ 177, 135, 243, 255, 234, 225, 128, 128, 128, 128, 128 },
{ 80, 129, 211, 255, 194, 224, 128, 128, 128, 128, 128 }
},
{ { 1, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
{ 246, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
{ 255, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 }
}
},
{
{ { 198, 35, 237, 223, 193, 187, 162, 160, 145, 155, 62 },
{ 131, 45, 198, 221, 172, 176, 220, 157, 252, 221, 1 },
{ 68, 47, 146, 208, 149, 167, 221, 162, 255, 223, 128 }
},
{ { 1, 149, 241, 255, 221, 224, 255, 255, 128, 128, 128 },
{ 184, 141, 234, 253, 222, 220, 255, 199, 128, 128, 128 },
{ 81, 99, 181, 242, 176, 190, 249, 202, 255, 255, 128 }
},
{ { 1, 129, 232, 253, 214, 197, 242, 196, 255, 255, 128 },
{ 99, 121, 210, 250, 201, 198, 255, 202, 128, 128, 128 },
{ 23, 91, 163, 242, 170, 187, 247, 210, 255, 255, 128 }
},
{ { 1, 200, 246, 255, 234, 255, 128, 128, 128, 128, 128 },
{ 109, 178, 241, 255, 231, 245, 255, 255, 128, 128, 128 },
{ 44, 130, 201, 253, 205, 192, 255, 255, 128, 128, 128 }
},
{ { 1, 132, 239, 251, 219, 209, 255, 165, 128, 128, 128 },
{ 94, 136, 225, 251, 218, 190, 255, 255, 128, 128, 128 },
{ 22, 100, 174, 245, 186, 161, 255, 199, 128, 128, 128 }
},
{ { 1, 182, 249, 255, 232, 235, 128, 128, 128, 128, 128 },
{ 124, 143, 241, 255, 227, 234, 128, 128, 128, 128, 128 },
{ 35, 77, 181, 251, 193, 211, 255, 205, 128, 128, 128 }
},
{ { 1, 157, 247, 255, 236, 231, 255, 255, 128, 128, 128 },
{ 121, 141, 235, 255, 225, 227, 255, 255, 128, 128, 128 },
{ 45, 99, 188, 251, 195, 217, 255, 224, 128, 128, 128 }
},
{ { 1, 1, 251, 255, 213, 255, 128, 128, 128, 128, 128 },
{ 203, 1, 248, 255, 255, 128, 128, 128, 128, 128, 128 },
{ 137, 1, 177, 255, 224, 255, 128, 128, 128, 128, 128 }
}
},
{ { { 253, 9, 248, 251, 207, 208, 255, 192, 128, 128, 128 },
{ 175, 13, 224, 243, 193, 185, 249, 198, 255, 255, 128 },
{ 73, 17, 171, 221, 161, 179, 236, 167, 255, 234, 128 }
},
{ { 1, 95, 247, 253, 212, 183, 255, 255, 128, 128, 128 },
{ 239, 90, 244, 250, 211, 209, 255, 255, 128, 128, 128 },
{ 155, 77, 195, 248, 188, 195, 255, 255, 128, 128, 128 }
},
{ { 1, 24, 239, 251, 218, 219, 255, 205, 128, 128, 128 },
{ 201, 51, 219, 255, 196, 186, 128, 128, 128, 128, 128 },
{ 69, 46, 190, 239, 201, 218, 255, 228, 128, 128, 128 }
},
{ { 1, 191, 251, 255, 255, 128, 128, 128, 128, 128, 128 },
{ 223, 165, 249, 255, 213, 255, 128, 128, 128, 128, 128 },
{ 141, 124, 248, 255, 255, 128, 128, 128, 128, 128, 128 }
},
{ { 1, 16, 248, 255, 255, 128, 128, 128, 128, 128, 128 },
{ 190, 36, 230, 255, 236, 255, 128, 128, 128, 128, 128 },
{ 149, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
},
{ { 1, 226, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
{ 247, 192, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
{ 240, 128, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
},
{ { 1, 134, 252, 255, 255, 128, 128, 128, 128, 128, 128 },
{ 213, 62, 250, 255, 255, 128, 128, 128, 128, 128, 128 },
{ 55, 93, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
},
{ { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
{ 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
{ 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 }
}
},
{
{ { 202, 24, 213, 235, 186, 191, 220, 160, 240, 175, 255 },
{ 126, 38, 182, 232, 169, 184, 228, 174, 255, 187, 128 },
{ 61, 46, 138, 219, 151, 178, 240, 170, 255, 216, 128 }
},
{ { 1, 112, 230, 250, 199, 191, 247, 159, 255, 255, 128 },
{ 166, 109, 228, 252, 211, 215, 255, 174, 128, 128, 128 },
{ 39, 77, 162, 232, 172, 180, 245, 178, 255, 255, 128 }
},
{ { 1, 52, 220, 246, 198, 199, 249, 220, 255, 255, 128 },
{ 124, 74, 191, 243, 183, 193, 250, 221, 255, 255, 128 },
{ 24, 71, 130, 219, 154, 170, 243, 182, 255, 255, 128 }
},
{ { 1, 182, 225, 249, 219, 240, 255, 224, 128, 128, 128 },
{ 149, 150, 226, 252, 216, 205, 255, 171, 128, 128, 128 },
{ 28, 108, 170, 242, 183, 194, 254, 223, 255, 255, 128 }
},
{ { 1, 81, 230, 252, 204, 203, 255, 192, 128, 128, 128 },
{ 123, 102, 209, 247, 188, 196, 255, 233, 128, 128, 128 },
{ 20, 95, 153, 243, 164, 173, 255, 203, 128, 128, 128 }
},
{ { 1, 222, 248, 255, 216, 213, 128, 128, 128, 128, 128 },
{ 168, 175, 246, 252, 235, 205, 255, 255, 128, 128, 128 },
{ 47, 116, 215, 255, 211, 212, 255, 255, 128, 128, 128 }
},
{ { 1, 121, 236, 253, 212, 214, 255, 255, 128, 128, 128 },
{ 141, 84, 213, 252, 201, 202, 255, 219, 128, 128, 128 },
{ 42, 80, 160, 240, 162, 185, 255, 205, 128, 128, 128 }
},
{ { 1, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
{ 244, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
{ 238, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
}
}
};
}
}

53
src/ImageSharp/Formats/WebP/WebPDecoderCore.cs
View File

@ -373,8 +373,9 @@ namespace SixLabors.ImageSharp.Formats.WebP
// Paragraph 9.3: Parse the segment header.
var vp8SegmentHeader = new Vp8SegmentHeader();
var proba = new Vp8Proba();
vp8SegmentHeader.UseSegment = bitReader.ReadBool();
bool hasValue = false;
bool hasValue;
if (vp8SegmentHeader.UseSegment)
{
vp8SegmentHeader.UpdateMap = bitReader.ReadBool();
@ -398,10 +399,18 @@ namespace SixLabors.ImageSharp.Formats.WebP
if (vp8SegmentHeader.UpdateMap)
{
// TODO: Read VP8Proba
for (int s = 0; s < proba.Segments.Length; ++s)
{
hasValue = bitReader.ReadBool();
proba.Segments[s] = hasValue ? bitReader.ReadValue(8) : 255;
}
}
}
}
else
{
vp8SegmentHeader.UpdateMap = false;
}
// Paragraph 9.4: Parse the filter specs.
var vp8FilterHeader = new Vp8FilterHeader();
@ -442,8 +451,13 @@ namespace SixLabors.ImageSharp.Formats.WebP
int numPartsMinusOne = (1 << (int)bitReader.ReadValue(2)) - 1;
int lastPart = numPartsMinusOne;
// TODO: check if we have enough data available here, throw exception if not
int partStart = bitReader.Pos + (lastPart * 3);
for (int p = 0; p < lastPart; ++p)
{
// int psize = sz[0] | (sz[1] << 8) | (sz[2] << 16);
}
// Paragraph 9.6: Dequantization Indices
// Paragraph 9.6: Dequantization Indices.
int baseQ0 = (int)bitReader.ReadValue(7);
hasValue = bitReader.ReadBool();
int dqy1Dc = hasValue ? bitReader.ReadSignedValue(4) : 0;
@ -499,6 +513,39 @@ namespace SixLabors.ImageSharp.Formats.WebP
m.UvQuant = q + dquvAc;
}
// Ignore the value of update_proba
bitReader.ReadBool();
// Parse probabilities.
for (int t = 0; t < WebPConstants.NumTypes; ++t)
{
for (int b = 0; b < WebPConstants.NumBands; ++b)
{
for (int c = 0; c < WebPConstants.NumCtx; ++c)
{
for (int p = 0; p < WebPConstants.NumProbas; ++p)
{
var prob = WebPConstants.CoeffsUpdateProba[t, b, c, p];
int v = bitReader.GetBit(prob) == 0 ? (int)bitReader.ReadValue(8) : WebPConstants.DefaultCoeffsProba[t, b, c, p];
proba.Bands[t, b].Probabilities[c].Probabilities[p] = (uint)v;
}
}
}
for (int b = 0; b < 16 + 1; ++b)
{
// TODO: This needs to be reviewed and fixed.
// proba->bands_ptr_[t][b] = &proba->bands_[t][kBands[b]];
}
}
// TODO: those values needs to be stored somewhere
bool useSkipProba = bitReader.ReadBool();
if (useSkipProba)
{
var skipP = bitReader.ReadValue(8);
}
return new WebPImageInfo()
{
Width = width,

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