mirror of https://github.com/SixLabors/ImageSharp
James Jackson-South
2 weeks ago
8 changed files with 302 additions and 65 deletions
@ -1,105 +1,166 @@ |
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// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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using SixLabors.ImageSharp.Formats.Heif.Av1.OpenBitstreamUnit; |
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namespace SixLabors.ImageSharp.Formats.Heif.Av1; |
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/// <summary>
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/// Represents the decoder configuration fields stored in an AV1 codec-configuration property.
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/// Contains the image-description fields stored in an AV1 codec-configuration item property.
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/// </summary>
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internal struct Av1CodecConfiguration |
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internal sealed class Av1CodecConfiguration |
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{ |
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/// <summary>
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/// Initializes a new instance of the <see cref="Av1CodecConfiguration"/> struct from an AV1 codec-configuration payload.
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/// The optional open bitstream units following the fixed four-byte configuration record.
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/// </summary>
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private readonly byte[] configObus; |
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/// <summary>
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/// Initializes a new instance of the <see cref="Av1CodecConfiguration"/> class from an AV1 codec-configuration
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/// item-property payload.
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/// </summary>
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/// <param name="boxBuffer">The configuration payload beginning with the marker and version fields.</param>
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public Av1CodecConfiguration(Span<byte> boxBuffer) |
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{ |
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if (boxBuffer.Length < 4) |
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{ |
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throw new InvalidImageContentException("The AV1 codec configuration is truncated."); |
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} |
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Av1BitStreamReader reader = new(boxBuffer); |
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uint marker = reader.ReadLiteral(1); |
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uint version = reader.ReadLiteral(7); |
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if (marker != 1 || version != 1) |
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{ |
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throw new InvalidImageContentException("The AV1 codec configuration has an invalid marker or version."); |
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} |
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this.Marker = (byte)reader.ReadLiteral(1); |
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this.Version = (byte)reader.ReadLiteral(7); |
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this.SeqProfile = (byte)reader.ReadLiteral(3); |
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this.SeqLevelIdx0 = (byte)reader.ReadLiteral(5); |
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this.SeqTier0 = (byte)reader.ReadLiteral(1); |
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this.HighBitdepth = (byte)reader.ReadLiteral(1); |
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this.SequenceProfile = (byte)reader.ReadLiteral(3); |
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this.SequenceLevelIndex = (byte)reader.ReadLiteral(5); |
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this.SequenceTier = reader.ReadLiteral(1) == 1; |
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this.HighBitDepth = reader.ReadLiteral(1) == 1; |
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this.TwelveBit = reader.ReadLiteral(1) == 1; |
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this.MonoChrome = reader.ReadLiteral(1) == 1; |
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this.IsMonochrome = reader.ReadLiteral(1) == 1; |
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this.ChromaSubsamplingX = reader.ReadLiteral(1) == 1; |
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this.ChromaSubsamplingY = reader.ReadLiteral(1) == 1; |
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this.ChromaSamplePosition = (byte)reader.ReadLiteral(2); |
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if (this.SequenceProfile > (byte)ObuSequenceProfile.Professional |
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|| (this.TwelveBit && !this.HighBitDepth) |
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|| this.ChromaSamplePosition == (byte)ObuChromoSamplePosition.Reserved) |
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{ |
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throw new InvalidImageContentException("The AV1 codec configuration contains invalid image-description fields."); |
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} |
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// 3 bits are reserved.
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reader.ReadLiteral(3); |
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if (reader.ReadLiteral(3) != 0) |
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{ |
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throw new InvalidImageContentException("The AV1 codec configuration has nonzero reserved bits."); |
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} |
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this.InitialPresentationDelayPresent = reader.ReadLiteral(1) == 1; |
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if (this.InitialPresentationDelayPresent) |
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bool hasInitialPresentationDelay = reader.ReadLiteral(1) == 1; |
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uint delayOrReserved = reader.ReadLiteral(4); |
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if (!hasInitialPresentationDelay && delayOrReserved != 0) |
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{ |
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byte initialPresentationDelayMinusOne = (byte)reader.ReadLiteral(4); |
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this.InitialPresentationDelay = (byte)(initialPresentationDelayMinusOne + 1); |
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throw new InvalidImageContentException("The AV1 codec configuration has a nonzero reserved delay field."); |
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} |
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} |
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/// <summary>
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/// Gets the one-bit configuration marker.
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/// </summary>
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public byte Marker { get; } |
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// The delay syntax is consumed to validate the fixed record, but it describes sample presentation and has
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// no meaning for the independently presented image item supported by this bounded container implementation.
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this.configObus = boxBuffer[4..].ToArray(); |
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} |
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/// <summary>
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/// Gets the codec-configuration record version.
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/// Gets the sequence profile declared for the coded image.
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/// </summary>
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public byte Version { get; } |
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public byte SequenceProfile { get; } |
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/// <summary>
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/// Gets the sequence profile declared by the configuration record.
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/// Gets the first operating point's sequence-level index.
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/// </summary>
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public byte SeqProfile { get; } |
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public byte SequenceLevelIndex { get; } |
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/// <summary>
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/// Gets the first operating point's sequence level index.
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/// Gets a value indicating whether the first operating point uses the high tier.
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/// </summary>
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public byte SeqLevelIdx0 { get; } |
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public bool SequenceTier { get; } |
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/// <summary>
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/// Gets the first operating point's sequence tier flag.
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/// Gets a value indicating whether the coded image uses more than eight bits per sample.
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/// </summary>
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public byte SeqTier0 { get; } |
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public bool HighBitDepth { get; } |
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/// <summary>
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/// Gets the high-bit-depth flag.
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/// Gets a value indicating whether the coded image uses twelve bits per sample.
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/// </summary>
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public byte HighBitdepth { get; } |
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public bool TwelveBit { get; } |
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/// <summary>
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/// Gets a value indicating whether the sequence uses twelve-bit samples.
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/// Gets the coded image sample precision in bits.
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/// </summary>
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public bool TwelveBit { get; } |
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public int BitDepth => this.TwelveBit ? 12 : this.HighBitDepth ? 10 : 8; |
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/// <summary>
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/// Gets a value indicating whether the sequence contains only a luma plane.
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/// Gets a value indicating whether the coded image contains only a luma plane.
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/// </summary>
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public bool MonoChrome { get; } |
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public bool IsMonochrome { get; } |
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/// <summary>
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/// Gets a value indicating whether chroma is horizontally subsampled.
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/// Gets a value indicating whether the coded image's chroma planes are horizontally subsampled.
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/// </summary>
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public bool ChromaSubsamplingX { get; } |
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/// <summary>
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/// Gets a value indicating whether chroma is vertically subsampled.
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/// Gets a value indicating whether the coded image's chroma planes are vertically subsampled.
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/// </summary>
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public bool ChromaSubsamplingY { get; } |
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/// <summary>
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/// Gets the chroma sample-position code.
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/// Gets the position of vertically subsampled chroma samples relative to luma samples.
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/// </summary>
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public byte ChromaSamplePosition { get; } |
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/// <summary>
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/// Gets a value indicating whether an initial presentation delay is declared.
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/// Gets the optional configuration open bitstream units following the fixed record.
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/// </summary>
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public bool InitialPresentationDelayPresent { get; } |
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public ReadOnlyMemory<byte> ConfigObus => this.configObus; |
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/// <summary>
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/// Gets the initial presentation delay in decoded frames, or zero when no delay is declared.
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/// Determines whether another item configuration describes the same coded-image sample layout.
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/// </summary>
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public byte InitialPresentationDelay { get; } |
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/// <param name="other">The configuration to compare.</param>
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/// <returns><see langword="true"/> when every fixed image-description field is equal.</returns>
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public bool HasMatchingImageConfiguration(Av1CodecConfiguration other) |
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=> this.SequenceProfile == other.SequenceProfile |
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&& this.SequenceLevelIndex == other.SequenceLevelIndex |
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&& this.SequenceTier == other.SequenceTier |
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&& this.HighBitDepth == other.HighBitDepth |
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&& this.TwelveBit == other.TwelveBit |
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&& this.IsMonochrome == other.IsMonochrome |
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&& this.ChromaSubsamplingX == other.ChromaSubsamplingX |
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&& this.ChromaSubsamplingY == other.ChromaSubsamplingY |
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&& this.ChromaSamplePosition == other.ChromaSamplePosition; |
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/// <summary>
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/// Validates the configuration fields against the sequence header that describes the coded image item.
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/// </summary>
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/// <param name="sequenceHeader">The decoded AV1 sequence header.</param>
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public void Validate(ObuSequenceHeader sequenceHeader) |
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{ |
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ObuOperatingPoint operatingPoint = sequenceHeader.OperatingPoint[0]; |
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ObuColorConfig colorConfig = sequenceHeader.ColorConfig; |
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bool highBitDepth = colorConfig.BitDepth is Av1BitDepth.TenBit or Av1BitDepth.TwelveBit; |
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bool twelveBit = colorConfig.BitDepth == Av1BitDepth.TwelveBit; |
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if (this.SequenceProfile != (byte)sequenceHeader.SequenceProfile |
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|| this.SequenceLevelIndex != operatingPoint.SequenceLevelIndex |
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|| this.SequenceTier != (operatingPoint.SequenceTier != 0) |
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|| this.HighBitDepth != highBitDepth |
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|| this.TwelveBit != twelveBit |
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|| this.IsMonochrome != colorConfig.IsMonochrome |
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|| this.ChromaSubsamplingX != colorConfig.SubSamplingX |
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|| this.ChromaSubsamplingY != colorConfig.SubSamplingY |
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|| this.ChromaSamplePosition != (byte)colorConfig.ChromaSamplePosition) |
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{ |
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throw new InvalidImageContentException("The AV1 item configuration does not match its sequence header."); |
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} |
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} |
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} |
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