mirror of https://github.com/SixLabors/ImageSharp
James Jackson-South
1 week ago
5 changed files with 431 additions and 0 deletions
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// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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namespace SixLabors.ImageSharp.Formats.Heif.Hevc; |
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/// <summary>
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/// Contains the general HEVC profile, tier, constraint, and level description declared by a parameter set.
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/// </summary>
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internal sealed class HevcProfileTierLevel |
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{ |
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/// <summary>
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/// Initializes a new instance of the <see cref="HevcProfileTierLevel"/> class.
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/// </summary>
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/// <param name="reader">The parameter-set raw byte sequence payload reader.</param>
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/// <param name="maxSubLayersMinusOne">The highest declared temporal sublayer index.</param>
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/// <exception cref="InvalidImageContentException">
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/// The profile-tier-level syntax is truncated or contains nonzero reserved bits.
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/// </exception>
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public HevcProfileTierLevel(ref HevcBitReader reader, int maxSubLayersMinusOne) |
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{ |
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DebugGuard.MustBeBetweenOrEqualTo(maxSubLayersMinusOne, 0, 6, nameof(maxSubLayersMinusOne)); |
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this.ProfileSpace = (byte)reader.ReadBits(2); |
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this.TierFlag = reader.ReadFlag(); |
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this.ProfileIdc = (byte)reader.ReadBits(5); |
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this.ProfileCompatibilityFlags = reader.ReadBits(32); |
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// The configuration record carries these 48 bits verbatim. Preserve their exact ordering so the
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// parameter set can be checked without reinterpreting profile-specific constraint layouts.
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this.ConstraintIndicatorFlags = ((ulong)reader.ReadBits(16) << 32) | reader.ReadBits(32); |
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this.LevelIdc = (byte)reader.ReadBits(8); |
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Span<bool> subLayerProfilePresent = stackalloc bool[6]; |
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Span<bool> subLayerLevelPresent = stackalloc bool[6]; |
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for (int subLayer = 0; subLayer < maxSubLayersMinusOne; subLayer++) |
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{ |
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subLayerProfilePresent[subLayer] = reader.ReadFlag(); |
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subLayerLevelPresent[subLayer] = reader.ReadFlag(); |
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} |
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if (maxSubLayersMinusOne > 0) |
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{ |
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for (int subLayer = maxSubLayersMinusOne; subLayer < 8; subLayer++) |
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{ |
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if (reader.ReadBits(2) != 0) |
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{ |
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throw new InvalidImageContentException("The HEVC profile-tier-level syntax has nonzero reserved bits."); |
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} |
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} |
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} |
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for (int subLayer = 0; subLayer < maxSubLayersMinusOne; subLayer++) |
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{ |
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if (subLayerProfilePresent[subLayer]) |
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{ |
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// A sublayer profile repeats the fixed 88-bit profile and constraint structure. It is consumed
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// for alignment but not retained because one still-image item has no temporal playback model.
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reader.ReadBits(2); |
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reader.ReadFlag(); |
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reader.ReadBits(5); |
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reader.ReadBits(32); |
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reader.ReadBits(16); |
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reader.ReadBits(32); |
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} |
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if (subLayerLevelPresent[subLayer]) |
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{ |
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reader.ReadBits(8); |
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} |
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} |
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} |
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/// <summary>
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/// Gets the namespace of the declared profile identifier.
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/// </summary>
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public byte ProfileSpace { get; } |
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/// <summary>
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/// Gets a value indicating whether the high tier is declared.
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/// </summary>
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public bool TierFlag { get; } |
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/// <summary>
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/// Gets the five-bit profile identifier.
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/// </summary>
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public byte ProfileIdc { get; } |
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/// <summary>
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/// Gets the profile-compatibility flags.
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/// </summary>
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public uint ProfileCompatibilityFlags { get; } |
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/// <summary>
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/// Gets the 48-bit profile-constraint flags.
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/// </summary>
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public ulong ConstraintIndicatorFlags { get; } |
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/// <summary>
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/// Gets the eight-bit level identifier.
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/// </summary>
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public byte LevelIdc { get; } |
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/// <summary>
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/// Determines whether this parameter-set description is compatible with an image item's codec-configuration
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/// property.
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/// </summary>
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/// <param name="configuration">The associated HEVC codec configuration.</param>
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/// <returns><see langword="true"/> when the general profile, tier, compatibility, and level fields match.</returns>
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public bool Matches(HevcCodecConfiguration configuration) |
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=> this.ProfileSpace == configuration.GeneralProfileSpace |
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&& this.TierFlag == configuration.GeneralTierFlag |
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&& this.ProfileIdc == configuration.GeneralProfileIdc |
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&& this.ProfileCompatibilityFlags == configuration.GeneralProfileCompatibilityFlags |
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&& this.LevelIdc == configuration.GeneralLevelIdc; |
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} |
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@ -0,0 +1,251 @@ |
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// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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namespace SixLabors.ImageSharp.Formats.Heif.Hevc; |
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/// <summary>
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/// Contains the bounded HEVC video-parameter-set fields required to validate and decode one still-image item.
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/// </summary>
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internal sealed class HevcVideoParameterSet |
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{ |
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/// <summary>
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/// Initializes a new instance of the <see cref="HevcVideoParameterSet"/> class.
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/// </summary>
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/// <param name="nalUnit">The decoded video-parameter-set NAL unit.</param>
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/// <exception cref="InvalidImageContentException">
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/// The NAL unit is not a supported, conforming base-layer video parameter set.
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/// </exception>
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public HevcVideoParameterSet(HevcNalUnit nalUnit) |
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{ |
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const byte videoParameterSetNalUnitType = 32; |
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if (nalUnit.Header.NalUnitType != videoParameterSetNalUnitType |
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|| nalUnit.Header.LayerId != 0 |
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|| nalUnit.Header.TemporalId != 0) |
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{ |
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throw new InvalidImageContentException("The HEVC video parameter set has an invalid NAL-unit header."); |
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} |
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HevcBitReader reader = new(nalUnit.Rbsp.Span); |
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this.Id = (byte)reader.ReadBits(4); |
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bool baseLayerInternal = reader.ReadFlag(); |
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bool baseLayerAvailable = reader.ReadFlag(); |
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if (!baseLayerInternal || !baseLayerAvailable) |
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{ |
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throw new InvalidImageContentException("The HEVC video parameter set does not make its base layer available."); |
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} |
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int maxLayersMinusOne = (int)reader.ReadBits(6); |
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if (maxLayersMinusOne != 0) |
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{ |
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// HEIF auxiliary images are separate image items. Importing an HEVC multilayer selection model would
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// exceed the one-presented-image contract and is not part of the exposed still-picture profiles.
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throw new InvalidImageContentException("Layered HEVC video parameter sets are not supported for still-image items."); |
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} |
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int maxSubLayersMinusOne = (int)reader.ReadBits(3); |
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if (maxSubLayersMinusOne > 6) |
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{ |
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throw new InvalidImageContentException("The HEVC video parameter set declares too many temporal sublayers."); |
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} |
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this.MaxSubLayers = maxSubLayersMinusOne + 1; |
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this.TemporalIdNestingFlag = reader.ReadFlag(); |
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if (maxSubLayersMinusOne == 0 && !this.TemporalIdNestingFlag) |
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{ |
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throw new InvalidImageContentException("The HEVC video parameter set has invalid temporal nesting."); |
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} |
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if (reader.ReadBits(16) != ushort.MaxValue) |
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{ |
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throw new InvalidImageContentException("The HEVC video parameter set has invalid reserved bits."); |
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} |
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this.ProfileTierLevel = new HevcProfileTierLevel(ref reader, maxSubLayersMinusOne); |
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bool subLayerOrderingInfoPresent = reader.ReadFlag(); |
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int firstOrderingSubLayer = subLayerOrderingInfoPresent ? 0 : maxSubLayersMinusOne; |
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for (int subLayer = firstOrderingSubLayer; subLayer <= maxSubLayersMinusOne; subLayer++) |
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{ |
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uint maxDecodedPictureBufferingMinusOne = reader.ReadUnsignedExpGolomb(); |
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uint maxNumReorderPictures = reader.ReadUnsignedExpGolomb(); |
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reader.ReadUnsignedExpGolomb(); |
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if (maxNumReorderPictures > maxDecodedPictureBufferingMinusOne) |
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{ |
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throw new InvalidImageContentException("The HEVC video parameter set has invalid sublayer ordering limits."); |
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} |
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} |
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uint maxLayerId = reader.ReadBits(6); |
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uint numLayerSetsMinusOne = reader.ReadUnsignedExpGolomb(); |
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if (maxLayerId != 0 || numLayerSetsMinusOne != 0) |
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{ |
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throw new InvalidImageContentException("HEVC layer sets are not supported for still-image items."); |
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} |
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bool timingInfoPresent = reader.ReadFlag(); |
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if (timingInfoPresent) |
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{ |
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// Timing and hypothetical-reference-decoder values are required for bit alignment but do not describe
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// the pixels of the one image item, so they are deliberately consumed without retained playback state.
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reader.ReadBits(32); |
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reader.ReadBits(32); |
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if (reader.ReadFlag()) |
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{ |
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reader.ReadUnsignedExpGolomb(); |
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} |
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uint hrdParameterCount = reader.ReadUnsignedExpGolomb(); |
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if (hrdParameterCount > 1024) |
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{ |
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throw new InvalidImageContentException("The HEVC video parameter set declares too many HRD parameter sets."); |
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} |
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bool nalHrdParametersPresent = false; |
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bool vclHrdParametersPresent = false; |
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bool subPictureHrdParametersPresent = false; |
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for (uint hrdIndex = 0; hrdIndex < hrdParameterCount; hrdIndex++) |
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{ |
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uint layerSetIndex = reader.ReadUnsignedExpGolomb(); |
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if (layerSetIndex != 0) |
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{ |
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throw new InvalidImageContentException("The HEVC HRD parameters reference an unsupported layer set."); |
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} |
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bool commonInformationPresent = hrdIndex == 0 || reader.ReadFlag(); |
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SkipHrdParameters( |
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ref reader, |
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commonInformationPresent, |
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maxSubLayersMinusOne, |
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ref nalHrdParametersPresent, |
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ref vclHrdParametersPresent, |
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ref subPictureHrdParametersPresent); |
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} |
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} |
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if (reader.ReadFlag()) |
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{ |
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while (reader.HasMoreRbspData()) |
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{ |
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reader.ReadFlag(); |
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} |
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} |
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reader.ReadRbspTrailingBits(); |
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} |
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/// <summary>
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/// Gets the four-bit video-parameter-set identifier.
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/// </summary>
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public byte Id { get; } |
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/// <summary>
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/// Gets the declared number of temporal sublayers.
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/// </summary>
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public int MaxSubLayers { get; } |
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/// <summary>
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/// Gets a value indicating whether temporal identifiers are nested.
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/// </summary>
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public bool TemporalIdNestingFlag { get; } |
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/// <summary>
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/// Gets the general profile, tier, constraint, and level description.
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/// </summary>
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public HevcProfileTierLevel ProfileTierLevel { get; } |
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/// <summary>
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/// Consumes hypothetical-reference-decoder syntax without adding playback state to the still-image model.
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/// </summary>
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/// <param name="reader">The video-parameter-set raw byte sequence payload reader.</param>
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/// <param name="commonInformationPresent">Whether common HRD flags are coded for this parameter set.</param>
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/// <param name="maxSubLayersMinusOne">The highest declared temporal sublayer index.</param>
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/// <param name="nalHrdParametersPresent">The effective NAL HRD presence flag.</param>
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/// <param name="vclHrdParametersPresent">The effective VCL HRD presence flag.</param>
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/// <param name="subPictureHrdParametersPresent">The effective sub-picture HRD presence flag.</param>
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/// <exception cref="InvalidImageContentException">The HRD syntax is truncated or exceeds its registered bounds.</exception>
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private static void SkipHrdParameters( |
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ref HevcBitReader reader, |
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bool commonInformationPresent, |
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int maxSubLayersMinusOne, |
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ref bool nalHrdParametersPresent, |
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ref bool vclHrdParametersPresent, |
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ref bool subPictureHrdParametersPresent) |
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{ |
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if (commonInformationPresent) |
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{ |
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nalHrdParametersPresent = reader.ReadFlag(); |
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vclHrdParametersPresent = reader.ReadFlag(); |
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subPictureHrdParametersPresent = false; |
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if (nalHrdParametersPresent || vclHrdParametersPresent) |
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{ |
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subPictureHrdParametersPresent = reader.ReadFlag(); |
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if (subPictureHrdParametersPresent) |
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{ |
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reader.ReadBits(8); |
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reader.ReadBits(5); |
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reader.ReadFlag(); |
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reader.ReadBits(5); |
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} |
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reader.ReadBits(4); |
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reader.ReadBits(4); |
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if (subPictureHrdParametersPresent) |
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{ |
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reader.ReadBits(4); |
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} |
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reader.ReadBits(5); |
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reader.ReadBits(5); |
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reader.ReadBits(5); |
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} |
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} |
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for (int subLayer = 0; subLayer <= maxSubLayersMinusOne; subLayer++) |
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{ |
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bool fixedPictureRateGeneral = reader.ReadFlag(); |
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bool fixedPictureRateWithinCvs = fixedPictureRateGeneral || reader.ReadFlag(); |
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bool lowDelayHrd = false; |
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if (fixedPictureRateWithinCvs) |
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{ |
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reader.ReadUnsignedExpGolomb(); |
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} |
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else |
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{ |
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lowDelayHrd = reader.ReadFlag(); |
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} |
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uint cpbCountMinusOne = 0; |
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if (!lowDelayHrd) |
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{ |
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cpbCountMinusOne = reader.ReadUnsignedExpGolomb(); |
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if (cpbCountMinusOne > 31) |
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{ |
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throw new InvalidImageContentException("The HEVC HRD syntax declares too many coded-picture buffers."); |
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} |
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} |
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for (int hrdKind = 0; hrdKind < 2; hrdKind++) |
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{ |
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bool parametersPresent = hrdKind == 0 ? nalHrdParametersPresent : vclHrdParametersPresent; |
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if (!parametersPresent) |
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{ |
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continue; |
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} |
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for (uint cpbIndex = 0; cpbIndex <= cpbCountMinusOne; cpbIndex++) |
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{ |
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reader.ReadUnsignedExpGolomb(); |
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reader.ReadUnsignedExpGolomb(); |
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if (subPictureHrdParametersPresent) |
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{ |
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reader.ReadUnsignedExpGolomb(); |
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reader.ReadUnsignedExpGolomb(); |
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} |
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reader.ReadFlag(); |
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} |
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} |
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} |
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} |
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} |
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