mirror of https://github.com/SixLabors/ImageSharp
James Jackson-South
1 week ago
6 changed files with 531 additions and 3 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.Buffers.Binary; |
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namespace SixLabors.ImageSharp.Formats.Heif.Hevc; |
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/// <summary>
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/// Contains the image-description fields and parameter-set arrays stored in an HEVC codec-configuration item
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/// property.
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/// </summary>
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internal sealed class HevcCodecConfiguration |
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{ |
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/// <summary>
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/// The NAL-unit arrays carried by the codec-configuration property.
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/// </summary>
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private readonly HevcNalUnitArray[] nalUnitArrays; |
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/// <summary>
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/// Initializes a new instance of the <see cref="HevcCodecConfiguration"/> class from an HEVC
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/// codec-configuration item-property payload.
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/// </summary>
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/// <param name="data">The complete bounded configuration payload.</param>
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public HevcCodecConfiguration(ReadOnlySpan<byte> data) |
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{ |
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const int fixedRecordLength = 23; |
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if (data.Length < fixedRecordLength) |
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{ |
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throw new InvalidImageContentException("The HEVC codec configuration is truncated."); |
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} |
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int offset = 0; |
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if (data[offset++] != 1) |
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{ |
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throw new InvalidImageContentException("The HEVC codec configuration has an unsupported version."); |
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} |
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byte profile = data[offset++]; |
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this.GeneralProfileSpace = (byte)(profile >> 6); |
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this.GeneralTierFlag = (profile & 0x20) != 0; |
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this.GeneralProfileIdc = (byte)(profile & 0x1F); |
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this.GeneralProfileCompatibilityFlags = BinaryPrimitives.ReadUInt32BigEndian(data[offset..]); |
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offset += 4; |
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this.GeneralConstraintIndicatorFlags = ((ulong)BinaryPrimitives.ReadUInt32BigEndian(data[offset..]) << 16) |
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| BinaryPrimitives.ReadUInt16BigEndian(data[(offset + 4)..]); |
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offset += 6; |
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this.GeneralLevelIdc = data[offset++]; |
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ushort spatialSegmentation = BinaryPrimitives.ReadUInt16BigEndian(data[offset..]); |
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offset += 2; |
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byte parallelism = data[offset++]; |
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byte chromaFormat = data[offset++]; |
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byte lumaBitDepth = data[offset++]; |
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byte chromaBitDepth = data[offset++]; |
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if ((spatialSegmentation & 0xF000) != 0xF000 |
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|| (parallelism & 0xFC) != 0xFC |
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|| (chromaFormat & 0xFC) != 0xFC |
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|| (lumaBitDepth & 0xF8) != 0xF8 |
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|| (chromaBitDepth & 0xF8) != 0xF8) |
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{ |
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throw new InvalidImageContentException("The HEVC codec configuration has invalid reserved bits."); |
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} |
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this.ChromaFormat = (byte)(chromaFormat & 3); |
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this.BitDepthLuma = 8 + (lumaBitDepth & 7); |
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this.BitDepthChroma = 8 + (chromaBitDepth & 7); |
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// Average frame rate and temporal-layer signaling describe timed samples. Consume those fixed-record fields
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// to reach the image item's NAL length width without retaining playback state in the still-image model.
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offset += 2; |
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byte temporalAndLengthFields = data[offset++]; |
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this.NalUnitLengthSize = (temporalAndLengthFields & 3) + 1; |
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int arrayCount = data[offset++]; |
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this.nalUnitArrays = new HevcNalUnitArray[arrayCount]; |
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Span<bool> seenNalUnitTypes = stackalloc bool[64]; |
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for (int arrayIndex = 0; arrayIndex < arrayCount; arrayIndex++) |
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{ |
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if (data.Length - offset < 3) |
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{ |
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throw new InvalidImageContentException("The HEVC codec configuration contains a truncated NAL-unit array header."); |
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} |
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byte arrayHeader = data[offset++]; |
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if ((arrayHeader & 0x40) != 0) |
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{ |
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throw new InvalidImageContentException("The HEVC codec configuration NAL-unit array has a nonzero reserved bit."); |
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} |
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bool isComplete = (arrayHeader & 0x80) != 0; |
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byte nalUnitType = (byte)(arrayHeader & 0x3F); |
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if (seenNalUnitTypes[nalUnitType]) |
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{ |
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throw new InvalidImageContentException($"The HEVC codec configuration contains more than one array for NAL-unit type {nalUnitType}."); |
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} |
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seenNalUnitTypes[nalUnitType] = true; |
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int nalUnitCount = BinaryPrimitives.ReadUInt16BigEndian(data[offset..]); |
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offset += 2; |
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ReadOnlyMemory<byte>[] nalUnits = new ReadOnlyMemory<byte>[nalUnitCount]; |
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for (int nalUnitIndex = 0; nalUnitIndex < nalUnitCount; nalUnitIndex++) |
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{ |
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if (data.Length - offset < 2) |
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{ |
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throw new InvalidImageContentException("The HEVC codec configuration contains a truncated NAL-unit length."); |
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} |
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int nalUnitLength = BinaryPrimitives.ReadUInt16BigEndian(data[offset..]); |
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offset += 2; |
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if (nalUnitLength < 2 || nalUnitLength > data.Length - offset) |
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{ |
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throw new InvalidImageContentException("The HEVC codec configuration contains an invalid NAL-unit length."); |
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} |
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ReadOnlySpan<byte> nalUnit = data.Slice(offset, nalUnitLength); |
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byte actualNalUnitType = (byte)((nalUnit[0] >> 1) & 0x3F); |
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// The two-byte HEVC NAL header repeats the array's type. temporal_id_plus1 cannot be zero because
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// zero is reserved to make header damage detectable before any parameter syntax is consumed.
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if ((nalUnit[0] & 0x80) != 0 || (nalUnit[1] & 7) == 0 || actualNalUnitType != nalUnitType) |
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{ |
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throw new InvalidImageContentException("The HEVC codec configuration contains an invalid NAL-unit header."); |
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} |
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nalUnits[nalUnitIndex] = nalUnit.ToArray(); |
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offset += nalUnitLength; |
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} |
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this.nalUnitArrays[arrayIndex] = new HevcNalUnitArray(nalUnitType, isComplete, nalUnits); |
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} |
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if (offset != data.Length) |
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{ |
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throw new InvalidImageContentException("The HEVC codec configuration contains unexpected trailing data."); |
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} |
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} |
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/// <summary>
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/// Gets the profile namespace declared by the coded image.
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/// </summary>
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public byte GeneralProfileSpace { get; } |
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/// <summary>
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/// Gets a value indicating whether the coded image uses the high tier.
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/// </summary>
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public bool GeneralTierFlag { get; } |
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/// <summary>
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/// Gets the profile identifier declared by the coded image.
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/// </summary>
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public byte GeneralProfileIdc { get; } |
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/// <summary>
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/// Gets the profile-compatibility flags declared by the coded image.
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/// </summary>
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public uint GeneralProfileCompatibilityFlags { get; } |
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/// <summary>
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/// Gets the 48-bit profile-constraint flags declared by the coded image.
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/// </summary>
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public ulong GeneralConstraintIndicatorFlags { get; } |
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/// <summary>
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/// Gets the level identifier declared by the coded image.
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/// </summary>
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public byte GeneralLevelIdc { get; } |
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/// <summary>
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/// Gets the coded chroma format, where zero denotes monochrome and one through three denote 4:2:0, 4:2:2,
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/// and 4:4:4 respectively.
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/// </summary>
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public byte ChromaFormat { get; } |
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/// <summary>
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/// Gets the coded luma sample precision in bits.
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/// </summary>
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public int BitDepthLuma { get; } |
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/// <summary>
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/// Gets the coded chroma sample precision in bits.
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/// </summary>
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public int BitDepthChroma { get; } |
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/// <summary>
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/// Gets the maximum coded color-component precision in bits.
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/// </summary>
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public int BitDepth => this.IsMonochrome ? this.BitDepthLuma : Math.Max(this.BitDepthLuma, this.BitDepthChroma); |
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/// <summary>
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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 IsMonochrome => this.ChromaFormat == 0; |
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/// <summary>
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/// Gets the number of bytes used by each length-delimited NAL unit in the associated image item.
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/// </summary>
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public int NalUnitLengthSize { get; } |
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/// <summary>
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/// Gets the bounded NAL-unit arrays carried by the codec-configuration property.
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/// </summary>
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public IReadOnlyList<HevcNalUnitArray> NalUnitArrays => this.nalUnitArrays; |
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/// <summary>
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/// Validates the associated pixel-information property against the coded luma and chroma sample precisions.
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/// </summary>
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/// <param name="channelBitDepths">The per-channel precisions associated with the HEVC image item.</param>
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public void ValidateChannelBitDepths(ReadOnlySpan<byte> channelBitDepths) |
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{ |
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int expectedChannelCount = this.IsMonochrome ? 1 : 3; |
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if (channelBitDepths.Length != expectedChannelCount || channelBitDepths[0] != this.BitDepthLuma) |
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{ |
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throw new InvalidImageContentException("The HEVC item pixel information does not match its codec configuration."); |
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} |
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for (int channel = 1; channel < channelBitDepths.Length; channel++) |
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{ |
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if (channelBitDepths[channel] != this.BitDepthChroma) |
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{ |
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throw new InvalidImageContentException("The HEVC item pixel information does not match its codec configuration."); |
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} |
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} |
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} |
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/// <summary>
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/// Determines whether another configuration describes the same coded-image sample layout.
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/// </summary>
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/// <param name="other">The configuration to compare.</param>
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/// <returns><see langword="true"/> when the profile, level, chroma format, and sample precisions match.</returns>
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public bool HasMatchingImageConfiguration(HevcCodecConfiguration other) |
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=> this.GeneralProfileSpace == other.GeneralProfileSpace |
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&& this.GeneralTierFlag == other.GeneralTierFlag |
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&& this.GeneralProfileIdc == other.GeneralProfileIdc |
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&& this.GeneralProfileCompatibilityFlags == other.GeneralProfileCompatibilityFlags |
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&& this.GeneralConstraintIndicatorFlags == other.GeneralConstraintIndicatorFlags |
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&& this.GeneralLevelIdc == other.GeneralLevelIdc |
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&& this.ChromaFormat == other.ChromaFormat |
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&& this.BitDepthLuma == other.BitDepthLuma |
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&& this.BitDepthChroma == other.BitDepthChroma; |
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} |
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/// <summary>
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/// Contains every configuration NAL unit declared for one HEVC NAL-unit type.
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/// </summary>
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internal sealed class HevcNalUnitArray |
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{ |
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/// <summary>
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/// Initializes a new instance of the <see cref="HevcNalUnitArray"/> class.
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/// </summary>
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/// <param name="nalUnitType">The six-bit HEVC NAL-unit type.</param>
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/// <param name="isComplete">A value indicating whether the array contains every NAL unit of this type.</param>
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/// <param name="nalUnits">The complete bounded NAL units, including their two-byte headers.</param>
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public HevcNalUnitArray(byte nalUnitType, bool isComplete, ReadOnlyMemory<byte>[] nalUnits) |
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{ |
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this.NalUnitType = nalUnitType; |
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this.IsComplete = isComplete; |
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this.NalUnits = nalUnits; |
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} |
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/// <summary>
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/// Gets the six-bit HEVC NAL-unit type shared by every entry in the array.
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/// </summary>
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public byte NalUnitType { get; } |
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/// <summary>
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/// Gets a value indicating whether the array contains every NAL unit of this type for the coded image.
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/// </summary>
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public bool IsComplete { get; } |
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/// <summary>
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/// Gets the complete NAL units, including their two-byte HEVC headers.
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/// </summary>
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public IReadOnlyList<ReadOnlyMemory<byte>> NalUnits { get; } |
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} |
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