| | | 1 | | using System; |
| | | 2 | | using System.Buffers.Binary; |
| | | 3 | | using Jellyfin.MediaEncoding.Keyframes.Matroska.Models; |
| | | 4 | | using NEbml.Core; |
| | | 5 | | |
| | | 6 | | namespace Jellyfin.MediaEncoding.Keyframes.Matroska.Extensions; |
| | | 7 | | |
| | | 8 | | /// <summary> |
| | | 9 | | /// Extension methods for the <see cref="EbmlReader"/> class. |
| | | 10 | | /// </summary> |
| | | 11 | | internal static class EbmlReaderExtensions |
| | | 12 | | { |
| | | 13 | | /// <summary> |
| | | 14 | | /// Traverses the current container to find the element with <paramref name="identifier"/> identifier. |
| | | 15 | | /// </summary> |
| | | 16 | | /// <param name="reader">An instance of <see cref="EbmlReader"/>.</param> |
| | | 17 | | /// <param name="identifier">The element identifier.</param> |
| | | 18 | | /// <returns>A value indicating whether the element was found.</returns> |
| | | 19 | | internal static bool FindElement(this EbmlReader reader, ulong identifier) |
| | 0 | 20 | | { |
| | 0 | 21 | | while (reader.ReadNext()) |
| | 0 | 22 | | { |
| | 0 | 23 | | if (reader.ElementId.EncodedValue == identifier) |
| | 0 | 24 | | { |
| | 0 | 25 | | return true; |
| | | 26 | | } |
| | 0 | 27 | | } |
| | | 28 | | |
| | 0 | 29 | | return false; |
| | 0 | 30 | | } |
| | | 31 | | |
| | | 32 | | /// <summary> |
| | | 33 | | /// Reads the current position in the file as an unsigned integer converted from binary. |
| | | 34 | | /// </summary> |
| | | 35 | | /// <param name="reader">An instance of <see cref="EbmlReader"/>.</param> |
| | | 36 | | /// <returns>The unsigned integer.</returns> |
| | | 37 | | internal static uint ReadUIntFromBinary(this EbmlReader reader) |
| | 0 | 38 | | { |
| | 0 | 39 | | var buffer = new byte[4]; |
| | 0 | 40 | | reader.ReadBinary(buffer, 0, 4); |
| | 0 | 41 | | return BinaryPrimitives.ReadUInt32BigEndian(buffer); |
| | 0 | 42 | | } |
| | | 43 | | |
| | | 44 | | /// <summary> |
| | | 45 | | /// Reads from the start of the file to retrieve the SeekHead segment. |
| | | 46 | | /// </summary> |
| | | 47 | | /// <param name="reader">An instance of <see cref="EbmlReader"/>.</param> |
| | | 48 | | /// <returns>Instance of <see cref="SeekHead"/>.</returns> |
| | | 49 | | internal static SeekHead ReadSeekHead(this EbmlReader reader) |
| | 0 | 50 | | { |
| | 0 | 51 | | reader = reader ?? throw new ArgumentNullException(nameof(reader)); |
| | | 52 | | |
| | 0 | 53 | | if (reader.ElementPosition != 0) |
| | 0 | 54 | | { |
| | 0 | 55 | | throw new InvalidOperationException("File position must be at 0"); |
| | | 56 | | } |
| | | 57 | | |
| | | 58 | | // Skip the header |
| | 0 | 59 | | if (!reader.FindElement(MatroskaConstants.SegmentContainer)) |
| | 0 | 60 | | { |
| | 0 | 61 | | throw new InvalidOperationException("Expected a segment container"); |
| | | 62 | | } |
| | | 63 | | |
| | 0 | 64 | | reader.EnterContainer(); |
| | | 65 | | |
| | 0 | 66 | | long? tracksPosition = null; |
| | 0 | 67 | | long? cuesPosition = null; |
| | 0 | 68 | | long? infoPosition = null; |
| | | 69 | | // The first element should be a SeekHead otherwise we'll have to search manually |
| | 0 | 70 | | if (!reader.FindElement(MatroskaConstants.SeekHead)) |
| | 0 | 71 | | { |
| | 0 | 72 | | throw new InvalidOperationException("Expected a SeekHead"); |
| | | 73 | | } |
| | | 74 | | |
| | 0 | 75 | | reader.EnterContainer(); |
| | 0 | 76 | | while (reader.FindElement(MatroskaConstants.Seek)) |
| | 0 | 77 | | { |
| | 0 | 78 | | reader.EnterContainer(); |
| | 0 | 79 | | reader.ReadNext(); |
| | 0 | 80 | | var type = (ulong)reader.ReadUIntFromBinary(); |
| | 0 | 81 | | switch (type) |
| | | 82 | | { |
| | | 83 | | case MatroskaConstants.Tracks: |
| | 0 | 84 | | reader.ReadNext(); |
| | 0 | 85 | | tracksPosition = (long)reader.ReadUInt(); |
| | 0 | 86 | | break; |
| | | 87 | | case MatroskaConstants.Cues: |
| | 0 | 88 | | reader.ReadNext(); |
| | 0 | 89 | | cuesPosition = (long)reader.ReadUInt(); |
| | 0 | 90 | | break; |
| | | 91 | | case MatroskaConstants.Info: |
| | 0 | 92 | | reader.ReadNext(); |
| | 0 | 93 | | infoPosition = (long)reader.ReadUInt(); |
| | 0 | 94 | | break; |
| | | 95 | | } |
| | | 96 | | |
| | 0 | 97 | | reader.LeaveContainer(); |
| | | 98 | | |
| | 0 | 99 | | if (tracksPosition.HasValue && cuesPosition.HasValue && infoPosition.HasValue) |
| | 0 | 100 | | { |
| | 0 | 101 | | break; |
| | | 102 | | } |
| | 0 | 103 | | } |
| | | 104 | | |
| | 0 | 105 | | reader.LeaveContainer(); |
| | | 106 | | |
| | 0 | 107 | | if (!tracksPosition.HasValue || !cuesPosition.HasValue || !infoPosition.HasValue) |
| | 0 | 108 | | { |
| | 0 | 109 | | throw new InvalidOperationException("SeekHead is missing or does not contain Info, Tracks and Cues positions |
| | | 110 | | } |
| | | 111 | | |
| | 0 | 112 | | return new SeekHead(infoPosition.Value, tracksPosition.Value, cuesPosition.Value); |
| | 0 | 113 | | } |
| | | 114 | | |
| | | 115 | | /// <summary> |
| | | 116 | | /// Reads from SegmentContainer to retrieve the Info segment. |
| | | 117 | | /// </summary> |
| | | 118 | | /// <param name="reader">An instance of <see cref="EbmlReader"/>.</param> |
| | | 119 | | /// <param name="position">The position of the info segment relative to the Segment container.</param> |
| | | 120 | | /// <returns>Instance of <see cref="Info"/>.</returns> |
| | | 121 | | internal static Info ReadInfo(this EbmlReader reader, long position) |
| | 0 | 122 | | { |
| | 0 | 123 | | reader.ReadAt(position); |
| | | 124 | | |
| | 0 | 125 | | double? duration = null; |
| | 0 | 126 | | reader.EnterContainer(); |
| | | 127 | | // Mandatory element |
| | 0 | 128 | | reader.FindElement(MatroskaConstants.TimestampScale); |
| | 0 | 129 | | var timestampScale = reader.ReadUInt(); |
| | | 130 | | |
| | 0 | 131 | | if (reader.FindElement(MatroskaConstants.Duration)) |
| | 0 | 132 | | { |
| | 0 | 133 | | duration = reader.ReadFloat(); |
| | 0 | 134 | | } |
| | | 135 | | |
| | 0 | 136 | | reader.LeaveContainer(); |
| | | 137 | | |
| | 0 | 138 | | return new Info((long)timestampScale, duration); |
| | 0 | 139 | | } |
| | | 140 | | |
| | | 141 | | /// <summary> |
| | | 142 | | /// Enters the Tracks segment and reads all tracks to find the specified type. |
| | | 143 | | /// </summary> |
| | | 144 | | /// <param name="reader">Instance of <see cref="EbmlReader"/>.</param> |
| | | 145 | | /// <param name="tracksPosition">The relative position of the tracks segment.</param> |
| | | 146 | | /// <param name="type">The track type identifier.</param> |
| | | 147 | | /// <returns>The first track number with the specified type.</returns> |
| | | 148 | | /// <exception cref="InvalidOperationException">Stream type is not found.</exception> |
| | | 149 | | internal static ulong FindFirstTrackNumberByType(this EbmlReader reader, long tracksPosition, ulong type) |
| | 0 | 150 | | { |
| | 0 | 151 | | reader.ReadAt(tracksPosition); |
| | | 152 | | |
| | 0 | 153 | | reader.EnterContainer(); |
| | 0 | 154 | | while (reader.FindElement(MatroskaConstants.TrackEntry)) |
| | 0 | 155 | | { |
| | 0 | 156 | | reader.EnterContainer(); |
| | | 157 | | // Mandatory element |
| | 0 | 158 | | reader.FindElement(MatroskaConstants.TrackNumber); |
| | 0 | 159 | | var trackNumber = reader.ReadUInt(); |
| | | 160 | | |
| | | 161 | | // Mandatory element |
| | 0 | 162 | | reader.FindElement(MatroskaConstants.TrackType); |
| | 0 | 163 | | var trackType = reader.ReadUInt(); |
| | | 164 | | |
| | 0 | 165 | | reader.LeaveContainer(); |
| | 0 | 166 | | if (trackType == MatroskaConstants.TrackTypeVideo) |
| | 0 | 167 | | { |
| | 0 | 168 | | reader.LeaveContainer(); |
| | 0 | 169 | | return trackNumber; |
| | | 170 | | } |
| | 0 | 171 | | } |
| | | 172 | | |
| | 0 | 173 | | reader.LeaveContainer(); |
| | | 174 | | |
| | 0 | 175 | | throw new InvalidOperationException($"No stream with type {type} found"); |
| | 0 | 176 | | } |
| | | 177 | | } |