cellar                                                         S. Lhomme
Internet-Draft
Intended status: Standards Track                               M. Bunkus
Expires: May 27, 2017
                                                                 D. Rice
                                                       November 23, 2016


                                Matroska
                    draft-lhomme-cellar-matroska-01

Abstract

   This document defines the Matroska audiovisual container, including
   definitions of its structural Elements, as well as its terminology,
   vocabulary, and application.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 27, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   9
   2.  Status of this document . . . . . . . . . . . . . . . . . . .  10
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   5.  Notations and Conventions . . . . . . . . . . . . . . . . . .  10
   6.  Basis in EBML . . . . . . . . . . . . . . . . . . . . . . . .  11
     6.1.  Added Constaints on EBML  . . . . . . . . . . . . . . . .  11
     6.2.  Matroska Design . . . . . . . . . . . . . . . . . . . . .  11
       6.2.1.  Language Codes  . . . . . . . . . . . . . . . . . . .  11
       6.2.2.  Physical Types  . . . . . . . . . . . . . . . . . . .  11
       6.2.3.  Block Structure . . . . . . . . . . . . . . . . . . .  12
       6.2.4.  Lacing  . . . . . . . . . . . . . . . . . . . . . . .  14
   7.  Matroska Schema . . . . . . . . . . . . . . . . . . . . . . .  19
     7.1.  Matroska Additions to Schema Element Attributes . . . . .  19
     7.2.  Matroska Schema . . . . . . . . . . . . . . . . . . . . .  20
       7.2.1.  Segment Element . . . . . . . . . . . . . . . . . . .  20
       7.2.2.  SeekHead Element  . . . . . . . . . . . . . . . . . .  20
       7.2.3.  Seek Element  . . . . . . . . . . . . . . . . . . . .  21
       7.2.4.  SeekID Element  . . . . . . . . . . . . . . . . . . .  21
       7.2.5.  SeekPosition Element  . . . . . . . . . . . . . . . .  21
       7.2.6.  Info Element  . . . . . . . . . . . . . . . . . . . .  22
       7.2.7.  SegmentUID Element  . . . . . . . . . . . . . . . . .  22
       7.2.8.  SegmentFilename Element . . . . . . . . . . . . . . .  23
       7.2.9.  PrevUID Element . . . . . . . . . . . . . . . . . . .  23
       7.2.10. PrevFilename Element  . . . . . . . . . . . . . . . .  23
       7.2.11. NextUID Element . . . . . . . . . . . . . . . . . . .  24
       7.2.12. NextFilename Element  . . . . . . . . . . . . . . . .  24
       7.2.13. SegmentFamily Element . . . . . . . . . . . . . . . .  25
       7.2.14. ChapterTranslate Element  . . . . . . . . . . . . . .  25
       7.2.15. ChapterTranslateEditionUID Element  . . . . . . . . .  25
       7.2.16. ChapterTranslateCodec Element . . . . . . . . . . . .  26
       7.2.17. ChapterTranslateID Element  . . . . . . . . . . . . .  26
       7.2.18. TimecodeScale Element . . . . . . . . . . . . . . . .  26
       7.2.19. Duration Element  . . . . . . . . . . . . . . . . . .  27
       7.2.20. DateUTC Element . . . . . . . . . . . . . . . . . . .  27
       7.2.21. Title Element . . . . . . . . . . . . . . . . . . . .  28
       7.2.22. MuxingApp Element . . . . . . . . . . . . . . . . . .  28
       7.2.23. WritingApp Element  . . . . . . . . . . . . . . . . .  28
       7.2.24. Cluster Element . . . . . . . . . . . . . . . . . . .  29
       7.2.25. Timecode Element  . . . . . . . . . . . . . . . . . .  29
       7.2.26. SilentTracks Element  . . . . . . . . . . . . . . . .  29
       7.2.27. SilentTrackNumber Element . . . . . . . . . . . . . .  30
       7.2.28. Position Element  . . . . . . . . . . . . . . . . . .  30
       7.2.29. PrevSize Element  . . . . . . . . . . . . . . . . . .  30
       7.2.30. SimpleBlock Element . . . . . . . . . . . . . . . . .  31
       7.2.31. BlockGroup Element  . . . . . . . . . . . . . . . . .  31



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       7.2.32. Block Element . . . . . . . . . . . . . . . . . . . .  31
       7.2.33. BlockVirtual Element  . . . . . . . . . . . . . . . .  32
       7.2.34. BlockAdditions Element  . . . . . . . . . . . . . . .  32
       7.2.35. BlockMore Element . . . . . . . . . . . . . . . . . .  33
       7.2.36. BlockAddID Element  . . . . . . . . . . . . . . . . .  33
       7.2.37. BlockAdditional Element . . . . . . . . . . . . . . .  33
       7.2.38. BlockDuration Element . . . . . . . . . . . . . . . .  34
       7.2.39. ReferencePriority Element . . . . . . . . . . . . . .  34
       7.2.40. ReferenceBlock Element  . . . . . . . . . . . . . . .  35
       7.2.41. ReferenceVirtual Element  . . . . . . . . . . . . . .  35
       7.2.42. CodecState Element  . . . . . . . . . . . . . . . . .  35
       7.2.43. DiscardPadding Element  . . . . . . . . . . . . . . .  36
       7.2.44. Slices Element  . . . . . . . . . . . . . . . . . . .  36
       7.2.45. TimeSlice Element . . . . . . . . . . . . . . . . . .  36
       7.2.46. LaceNumber Element  . . . . . . . . . . . . . . . . .  37
       7.2.47. FrameNumber Element . . . . . . . . . . . . . . . . .  37
       7.2.48. BlockAdditionID Element . . . . . . . . . . . . . . .  38
       7.2.49. Delay Element . . . . . . . . . . . . . . . . . . . .  38
       7.2.50. SliceDuration Element . . . . . . . . . . . . . . . .  38
       7.2.51. ReferenceFrame Element  . . . . . . . . . . . . . . .  39
       7.2.52. ReferenceOffset Element . . . . . . . . . . . . . . .  39
       7.2.53. ReferenceTimeCode Element . . . . . . . . . . . . . .  39
       7.2.54. EncryptedBlock Element  . . . . . . . . . . . . . . .  40
       7.2.55. Tracks Element  . . . . . . . . . . . . . . . . . . .  40
       7.2.56. TrackEntry Element  . . . . . . . . . . . . . . . . .  41
       7.2.57. TrackNumber Element . . . . . . . . . . . . . . . . .  41
       7.2.58. TrackUID Element  . . . . . . . . . . . . . . . . . .  41
       7.2.59. TrackType Element . . . . . . . . . . . . . . . . . .  42
       7.2.60. FlagEnabled Element . . . . . . . . . . . . . . . . .  42
       7.2.61. FlagDefault Element . . . . . . . . . . . . . . . . .  43
       7.2.62. FlagForced Element  . . . . . . . . . . . . . . . . .  43
       7.2.63. FlagLacing Element  . . . . . . . . . . . . . . . . .  44
       7.2.64. MinCache Element  . . . . . . . . . . . . . . . . . .  44
       7.2.65. MaxCache Element  . . . . . . . . . . . . . . . . . .  44
       7.2.66. DefaultDuration Element . . . . . . . . . . . . . . .  45
       7.2.67. DefaultDecodedFieldDuration Element . . . . . . . . .  45
       7.2.68. TrackTimecodeScale Element  . . . . . . . . . . . . .  45
       7.2.69. TrackOffset Element . . . . . . . . . . . . . . . . .  46
       7.2.70. MaxBlockAdditionID Element  . . . . . . . . . . . . .  46
       7.2.71. Name Element  . . . . . . . . . . . . . . . . . . . .  47
       7.2.72. Language Element  . . . . . . . . . . . . . . . . . .  47
       7.2.73. CodecID Element . . . . . . . . . . . . . . . . . . .  47
       7.2.74. CodecPrivate Element  . . . . . . . . . . . . . . . .  48
       7.2.75. CodecName Element . . . . . . . . . . . . . . . . . .  48
       7.2.76. AttachmentLink Element  . . . . . . . . . . . . . . .  48
       7.2.77. CodecSettings Element . . . . . . . . . . . . . . . .  49
       7.2.78. CodecInfoURL Element  . . . . . . . . . . . . . . . .  49
       7.2.79. CodecDownloadURL Element  . . . . . . . . . . . . . .  49



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       7.2.80. CodecDecodeAll Element  . . . . . . . . . . . . . . .  50
       7.2.81. TrackOverlay Element  . . . . . . . . . . . . . . . .  50
       7.2.82. CodecDelay Element  . . . . . . . . . . . . . . . . .  51
       7.2.83. SeekPreRoll Element . . . . . . . . . . . . . . . . .  51
       7.2.84. TrackTranslate Element  . . . . . . . . . . . . . . .  51
       7.2.85. TrackTranslateEditionUID Element  . . . . . . . . . .  52
       7.2.86. TrackTranslateCodec Element . . . . . . . . . . . . .  52
       7.2.87. TrackTranslateTrackID Element . . . . . . . . . . . .  52
       7.2.88. Video Element . . . . . . . . . . . . . . . . . . . .  53
       7.2.89. FlagInterlaced Element  . . . . . . . . . . . . . . .  53
       7.2.90. FieldOrder Element  . . . . . . . . . . . . . . . . .  54
       7.2.91. StereoMode Element  . . . . . . . . . . . . . . . . .  54
       7.2.92. AlphaMode Element . . . . . . . . . . . . . . . . . .  55
       7.2.93. OldStereoMode Element . . . . . . . . . . . . . . . .  55
       7.2.94. PixelWidth Element  . . . . . . . . . . . . . . . . .  55
       7.2.95. PixelHeight Element . . . . . . . . . . . . . . . . .  56
       7.2.96. PixelCropBottom Element . . . . . . . . . . . . . . .  56
       7.2.97. PixelCropTop Element  . . . . . . . . . . . . . . . .  57
       7.2.98. PixelCropLeft Element . . . . . . . . . . . . . . . .  57
       7.2.99. PixelCropRight Element  . . . . . . . . . . . . . . .  57
       7.2.100. DisplayWidth Element . . . . . . . . . . . . . . . .  58
       7.2.101. DisplayHeight Element  . . . . . . . . . . . . . . .  58
       7.2.102. DisplayUnit Element  . . . . . . . . . . . . . . . .  58
       7.2.103. AspectRatioType Element  . . . . . . . . . . . . . .  59
       7.2.104. ColourSpace Element  . . . . . . . . . . . . . . . .  59
       7.2.105. GammaValue Element . . . . . . . . . . . . . . . . .  60
       7.2.106. FrameRate Element  . . . . . . . . . . . . . . . . .  60
       7.2.107. Colour Element . . . . . . . . . . . . . . . . . . .  60
       7.2.108. MatrixCoefficients Element . . . . . . . . . . . . .  61
       7.2.109. BitsPerChannel Element . . . . . . . . . . . . . . .  61
       7.2.110. ChromaSubsamplingHorz Element  . . . . . . . . . . .  61
       7.2.111. ChromaSubsamplingVert Element  . . . . . . . . . . .  62
       7.2.112. CbSubsamplingHorz Element  . . . . . . . . . . . . .  62
       7.2.113. CbSubsamplingVert Element  . . . . . . . . . . . . .  63
       7.2.114. ChromaSitingHorz Element . . . . . . . . . . . . . .  63
       7.2.115. ChromaSitingVert Element . . . . . . . . . . . . . .  63
       7.2.116. Range Element  . . . . . . . . . . . . . . . . . . .  64
       7.2.117. TransferCharacteristics Element  . . . . . . . . . .  64
       7.2.118. Primaries Element  . . . . . . . . . . . . . . . . .  65
       7.2.119. MaxCLL Element . . . . . . . . . . . . . . . . . . .  65
       7.2.120. MaxFALL Element  . . . . . . . . . . . . . . . . . .  65
       7.2.121. MasteringMetadata Element  . . . . . . . . . . . . .  66
       7.2.122. PrimaryRChromaticityX Element  . . . . . . . . . . .  66
       7.2.123. PrimaryRChromaticityY Element  . . . . . . . . . . .  66
       7.2.124. PrimaryGChromaticityX Element  . . . . . . . . . . .  67
       7.2.125. PrimaryGChromaticityY Element  . . . . . . . . . . .  67
       7.2.126. PrimaryBChromaticityX Element  . . . . . . . . . . .  67
       7.2.127. PrimaryBChromaticityY Element  . . . . . . . . . . .  68



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       7.2.128. WhitePointChromaticityX Element  . . . . . . . . . .  68
       7.2.129. WhitePointChromaticityY Element  . . . . . . . . . .  68
       7.2.130. LuminanceMax Element . . . . . . . . . . . . . . . .  69
       7.2.131. LuminanceMin Element . . . . . . . . . . . . . . . .  69
       7.2.132. Audio Element  . . . . . . . . . . . . . . . . . . .  70
       7.2.133. SamplingFrequency Element  . . . . . . . . . . . . .  70
       7.2.134. OutputSamplingFrequency Element  . . . . . . . . . .  70
       7.2.135. Channels Element . . . . . . . . . . . . . . . . . .  71
       7.2.136. ChannelPositions Element . . . . . . . . . . . . . .  71
       7.2.137. BitDepth Element . . . . . . . . . . . . . . . . . .  72
       7.2.138. TrackOperation Element . . . . . . . . . . . . . . .  72
       7.2.139. TrackCombinePlanes Element . . . . . . . . . . . . .  72
       7.2.140. TrackPlane Element . . . . . . . . . . . . . . . . .  73
       7.2.141. TrackPlaneUID Element  . . . . . . . . . . . . . . .  73
       7.2.142. TrackPlaneType Element . . . . . . . . . . . . . . .  73
       7.2.143. TrackJoinBlocks Element  . . . . . . . . . . . . . .  74
       7.2.144. TrackJoinUID Element . . . . . . . . . . . . . . . .  74
       7.2.145. TrickTrackUID Element  . . . . . . . . . . . . . . .  75
       7.2.146. TrickTrackSegmentUID Element . . . . . . . . . . . .  75
       7.2.147. TrickTrackFlag Element . . . . . . . . . . . . . . .  75
       7.2.148. TrickMasterTrackUID Element  . . . . . . . . . . . .  76
       7.2.149. TrickMasterTrackSegmentUID Element . . . . . . . . .  76
       7.2.150. ContentEncodings Element . . . . . . . . . . . . . .  76
       7.2.151. ContentEncoding Element  . . . . . . . . . . . . . .  77
       7.2.152. ContentEncodingOrder Element . . . . . . . . . . . .  77
       7.2.153. ContentEncodingScope Element . . . . . . . . . . . .  78
       7.2.154. ContentEncodingType Element  . . . . . . . . . . . .  78
       7.2.155. ContentCompression Element . . . . . . . . . . . . .  79
       7.2.156. ContentCompAlgo Element  . . . . . . . . . . . . . .  79
       7.2.157. ContentCompSettings Element  . . . . . . . . . . . .  79
       7.2.158. ContentEncryption Element  . . . . . . . . . . . . .  80
       7.2.159. ContentEncAlgo Element . . . . . . . . . . . . . . .  80
       7.2.160. ContentEncKeyID Element  . . . . . . . . . . . . . .  81
       7.2.161. ContentSignature Element . . . . . . . . . . . . . .  81
       7.2.162. ContentSigKeyID Element  . . . . . . . . . . . . . .  81
       7.2.163. ContentSigAlgo Element . . . . . . . . . . . . . . .  82
       7.2.164. ContentSigHashAlgo Element . . . . . . . . . . . . .  82
       7.2.165. Cues Element . . . . . . . . . . . . . . . . . . . .  82
       7.2.166. CuePoint Element . . . . . . . . . . . . . . . . . .  83
       7.2.167. CueTime Element  . . . . . . . . . . . . . . . . . .  83
       7.2.168. CueTrackPositions Element  . . . . . . . . . . . . .  83
       7.2.169. CueTrack Element . . . . . . . . . . . . . . . . . .  84
       7.2.170. CueClusterPosition Element . . . . . . . . . . . . .  84
       7.2.171. CueRelativePosition Element  . . . . . . . . . . . .  85
       7.2.172. CueDuration Element  . . . . . . . . . . . . . . . .  85
       7.2.173. CueBlockNumber Element . . . . . . . . . . . . . . .  85
       7.2.174. CueCodecState Element  . . . . . . . . . . . . . . .  86
       7.2.175. CueReference Element . . . . . . . . . . . . . . . .  86



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       7.2.176. CueRefTime Element . . . . . . . . . . . . . . . . .  86
       7.2.177. CueRefCluster Element  . . . . . . . . . . . . . . .  87
       7.2.178. CueRefNumber Element . . . . . . . . . . . . . . . .  87
       7.2.179. CueRefCodecState Element . . . . . . . . . . . . . .  88
       7.2.180. Attachments Element  . . . . . . . . . . . . . . . .  88
       7.2.181. AttachedFile Element . . . . . . . . . . . . . . . .  88
       7.2.182. FileDescription Element  . . . . . . . . . . . . . .  89
       7.2.183. FileName Element . . . . . . . . . . . . . . . . . .  89
       7.2.184. FileMimeType Element . . . . . . . . . . . . . . . .  89
       7.2.185. FileData Element . . . . . . . . . . . . . . . . . .  90
       7.2.186. FileUID Element  . . . . . . . . . . . . . . . . . .  90
       7.2.187. FileReferral Element . . . . . . . . . . . . . . . .  90
       7.2.188. FileUsedStartTime Element  . . . . . . . . . . . . .  91
       7.2.189. FileUsedEndTime Element  . . . . . . . . . . . . . .  91
       7.2.190. Chapters Element . . . . . . . . . . . . . . . . . .  91
       7.2.191. EditionEntry Element . . . . . . . . . . . . . . . .  92
       7.2.192. EditionUID Element . . . . . . . . . . . . . . . . .  92
       7.2.193. EditionFlagHidden Element  . . . . . . . . . . . . .  92
       7.2.194. EditionFlagDefault Element . . . . . . . . . . . . .  93
       7.2.195. EditionFlagOrdered Element . . . . . . . . . . . . .  93
       7.2.196. ChapterAtom Element  . . . . . . . . . . . . . . . .  94
       7.2.197. ChapterUID Element . . . . . . . . . . . . . . . . .  94
       7.2.198. ChapterStringUID Element . . . . . . . . . . . . . .  94
       7.2.199. ChapterTimeStart Element . . . . . . . . . . . . . .  95
       7.2.200. ChapterTimeEnd Element . . . . . . . . . . . . . . .  95
       7.2.201. ChapterFlagHidden Element  . . . . . . . . . . . . .  95
       7.2.202. ChapterFlagEnabled Element . . . . . . . . . . . . .  96
       7.2.203. ChapterSegmentUID Element  . . . . . . . . . . . . .  96
       7.2.204. ChapterSegmentEditionUID Element . . . . . . . . . .  97
       7.2.205. ChapterPhysicalEquiv Element . . . . . . . . . . . .  97
       7.2.206. ChapterTrack Element . . . . . . . . . . . . . . . .  98
       7.2.207. ChapterTrackNumber Element . . . . . . . . . . . . .  98
       7.2.208. ChapterDisplay Element . . . . . . . . . . . . . . .  98
       7.2.209. ChapString Element . . . . . . . . . . . . . . . . .  99
       7.2.210. ChapLanguage Element . . . . . . . . . . . . . . . .  99
       7.2.211. ChapCountry Element  . . . . . . . . . . . . . . . . 100
       7.2.212. ChapProcess Element  . . . . . . . . . . . . . . . . 100
       7.2.213. ChapProcessCodecID Element . . . . . . . . . . . . . 100
       7.2.214. ChapProcessPrivate Element . . . . . . . . . . . . . 101
       7.2.215. ChapProcessCommand Element . . . . . . . . . . . . . 101
       7.2.216. ChapProcessTime Element  . . . . . . . . . . . . . . 101
       7.2.217. ChapProcessData Element  . . . . . . . . . . . . . . 102
       7.2.218. Tags Element . . . . . . . . . . . . . . . . . . . . 102
       7.2.219. Tag Element  . . . . . . . . . . . . . . . . . . . . 103
       7.2.220. Targets Element  . . . . . . . . . . . . . . . . . . 103
       7.2.221. TargetTypeValue Element  . . . . . . . . . . . . . . 103
       7.2.222. TargetType Element . . . . . . . . . . . . . . . . . 104
       7.2.223. TagTrackUID Element  . . . . . . . . . . . . . . . . 104



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       7.2.224. TagEditionUID Element  . . . . . . . . . . . . . . . 104
       7.2.225. TagChapterUID Element  . . . . . . . . . . . . . . . 105
       7.2.226. TagAttachmentUID Element . . . . . . . . . . . . . . 105
       7.2.227. SimpleTag Element  . . . . . . . . . . . . . . . . . 106
       7.2.228. TagName Element  . . . . . . . . . . . . . . . . . . 106
       7.2.229. TagLanguage Element  . . . . . . . . . . . . . . . . 106
       7.2.230. TagDefault Element . . . . . . . . . . . . . . . . . 107
       7.2.231. TagString Element  . . . . . . . . . . . . . . . . . 107
       7.2.232. TagBinary Element  . . . . . . . . . . . . . . . . . 108
   8.  Beginning of File . . . . . . . . . . . . . . . . . . . . . . 108
   9.  Block Timecodes . . . . . . . . . . . . . . . . . . . . . . . 108
   10. Default decoded field duration  . . . . . . . . . . . . . . . 109
   11. Default Values  . . . . . . . . . . . . . . . . . . . . . . . 109
   12. DRM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
   13. Encryption  . . . . . . . . . . . . . . . . . . . . . . . . . 110
   14. Image cropping  . . . . . . . . . . . . . . . . . . . . . . . 110
   15. Matroska version indicators . . . . . . . . . . . . . . . . . 110
   16. Mime Types  . . . . . . . . . . . . . . . . . . . . . . . . . 111
   17. Octet . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
   18. Overlay Track . . . . . . . . . . . . . . . . . . . . . . . . 111
   19. Position References . . . . . . . . . . . . . . . . . . . . . 111
   20. Raw Timecode  . . . . . . . . . . . . . . . . . . . . . . . . 112
   21. Linked Segments . . . . . . . . . . . . . . . . . . . . . . . 112
     21.1.  Hard Linking . . . . . . . . . . . . . . . . . . . . . . 112
     21.2.  Soft Linking . . . . . . . . . . . . . . . . . . . . . . 113
     21.3.  Medium Linking . . . . . . . . . . . . . . . . . . . . . 113
   22. Timecode Types  . . . . . . . . . . . . . . . . . . . . . . . 114
   23. TimecodeScale . . . . . . . . . . . . . . . . . . . . . . . . 114
   24. TimecodeScale Rounding  . . . . . . . . . . . . . . . . . . . 114
   25. Track Flags . . . . . . . . . . . . . . . . . . . . . . . . . 116
     25.1.  Default flag . . . . . . . . . . . . . . . . . . . . . . 116
     25.2.  Forced flag  . . . . . . . . . . . . . . . . . . . . . . 116
   26. TrackTimecodeScale  . . . . . . . . . . . . . . . . . . . . . 117
   27. Unknown elements  . . . . . . . . . . . . . . . . . . . . . . 118
   28. Multi-planar and 3D videos  . . . . . . . . . . . . . . . . . 119
   29. Track Operation . . . . . . . . . . . . . . . . . . . . . . . 119
   30. Matroska Element Ordering Guidelines  . . . . . . . . . . . . 120
     30.1.  Top-Level Elements . . . . . . . . . . . . . . . . . . . 120
     30.2.  CRC-32 . . . . . . . . . . . . . . . . . . . . . . . . . 120
     30.3.  SeekHead . . . . . . . . . . . . . . . . . . . . . . . . 121
     30.4.  Cues (index) . . . . . . . . . . . . . . . . . . . . . . 121
     30.5.  Info . . . . . . . . . . . . . . . . . . . . . . . . . . 121
     30.6.  Chapters . . . . . . . . . . . . . . . . . . . . . . . . 121
     30.7.  Attachments  . . . . . . . . . . . . . . . . . . . . . . 122
     30.8.  Tags . . . . . . . . . . . . . . . . . . . . . . . . . . 122
     30.9.  Optimum layout from a muxer  . . . . . . . . . . . . . . 122
     30.10. Optimum layout after editing tags  . . . . . . . . . . . 122
     30.11. Optimum layout with Cues at the front  . . . . . . . . . 123



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     30.12. Cluster Timecode . . . . . . . . . . . . . . . . . . . . 123
   31. CodecID . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
     31.1.  Video Codecs . . . . . . . . . . . . . . . . . . . . . . 124
     31.2.  Audio  . . . . . . . . . . . . . . . . . . . . . . . . . 127
     31.3.  Subtitle . . . . . . . . . . . . . . . . . . . . . . . . 132
     31.4.  Buttons  . . . . . . . . . . . . . . . . . . . . . . . . 133
     31.5.  Example 1 : basic chaptering . . . . . . . . . . . . . . 133
     31.6.  Example 2 : nested chapters  . . . . . . . . . . . . . . 134
       31.6.1.  The Micronauts "Bleep To Bleep"  . . . . . . . . . . 134
     31.7.  Edition and chapter flags  . . . . . . . . . . . . . . . 135
       31.7.1.  Chapter flags  . . . . . . . . . . . . . . . . . . . 135
       31.7.2.  Edition flags  . . . . . . . . . . . . . . . . . . . 136
     31.8.  Menu features  . . . . . . . . . . . . . . . . . . . . . 136
       31.8.1.  Matroska Script (0)  . . . . . . . . . . . . . . . . 136
       31.8.2.  DVD menu (1) . . . . . . . . . . . . . . . . . . . . 136
   32. Subtitles . . . . . . . . . . . . . . . . . . . . . . . . . . 138
   33. Images Subtitles  . . . . . . . . . . . . . . . . . . . . . . 139
   34. SRT Subtitles . . . . . . . . . . . . . . . . . . . . . . . . 142
   35. SSA/ASS Subtitles . . . . . . . . . . . . . . . . . . . . . . 142
   36. USF Subtitles . . . . . . . . . . . . . . . . . . . . . . . . 145
   37. WebVTT  . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
     37.1.  Storage of WebVTT in Matroska  . . . . . . . . . . . . . 146
       37.1.1.  CodecID: codec identification  . . . . . . . . . . . 146
       37.1.2.  CodecPrivate: storage of gloal WebVTT blocks . . . . 146
       37.1.3.  Storage of non-global WebVTT blocks  . . . . . . . . 146
       37.1.4.  Storage of Cues in Matroska blocks . . . . . . . . . 146
       37.1.5.  BlockAdditions: storing non-global WebVTT blocks,
                Cue Settings Lists and Cue identifiers . . . . . . . 146
     37.2.  Examples of transformation . . . . . . . . . . . . . . . 147
       37.2.1.  Example WebVTT file  . . . . . . . . . . . . . . . . 147
       37.2.2.  CodecPrivate . . . . . . . . . . . . . . . . . . . . 147
       37.2.3.  Storage of Cue 1 . . . . . . . . . . . . . . . . . . 147
       37.2.4.  Storage of Cue 2 . . . . . . . . . . . . . . . . . . 147
       37.2.5.  Storage of Cue 3 . . . . . . . . . . . . . . . . . . 147
       37.2.6.  Storage of Cue 4 . . . . . . . . . . . . . . . . . . 148
     37.3.  Storage of WebVTT in Matroska vs. WebM . . . . . . . . . 148
   38. Tagging . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
     38.1.  Why official tags matter . . . . . . . . . . . . . . . . 148
     38.2.  Tag translations . . . . . . . . . . . . . . . . . . . . 149
     38.3.  Tag Formatting . . . . . . . . . . . . . . . . . . . . . 149
     38.4.  Target types . . . . . . . . . . . . . . . . . . . . . . 150
     38.5.  Official tags  . . . . . . . . . . . . . . . . . . . . . 150
     38.6.  Notes  . . . . . . . . . . . . . . . . . . . . . . . . . 150
   39. Attachments . . . . . . . . . . . . . . . . . . . . . . . . . 151
     39.1.  Introduction . . . . . . . . . . . . . . . . . . . . . . 151
     39.2.  Cover Art  . . . . . . . . . . . . . . . . . . . . . . . 151
     39.3.  Font files . . . . . . . . . . . . . . . . . . . . . . . 152
   40. Matroska Streaming  . . . . . . . . . . . . . . . . . . . . . 152



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   41. File Access . . . . . . . . . . . . . . . . . . . . . . . . . 152
   42. Live Streaming  . . . . . . . . . . . . . . . . . . . . . . . 152
   43. Menu Specifications . . . . . . . . . . . . . . . . . . . . . 153
   44. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . 153
   45. Requirements  . . . . . . . . . . . . . . . . . . . . . . . . 153
     45.1.  Highlights/Hotspots  . . . . . . . . . . . . . . . . . . 153
     45.2.  Playback features  . . . . . . . . . . . . . . . . . . . 154
     45.3.  Player requirements  . . . . . . . . . . . . . . . . . . 155
   46. Working Graph . . . . . . . . . . . . . . . . . . . . . . . . 155
   47. Ideas . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
   48. Data Structure  . . . . . . . . . . . . . . . . . . . . . . . 155
     49.1.  URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 155
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . 159

1.  Introduction

   Matroska aims to become THE standard of multimedia container formats.
   It was derived from a project called MCF [1], but differentiates from
   it significantly because it is based on EBML [2] (Extensible Binary
   Meta Language), a binary derivative of XML.  EBML enables significant
   advantages in terms of future format extensibility, without breaking
   file support in old parsers.

   First, it is essential to clarify exactly "What an Audio/Video
   container is", to avoid any misunderstandings:

   o  It is NOT a video or audio compression format (codec)

   o  It is an envelope for which there can be many audio, video and
      subtitles streams, allowing the user to store a complete movie or
      CD in a single file.

   Matroska is designed with the future in mind.  It incorporates
   features like:

   o  Fast seeking in the file

   o  Chapter entries

   o  Full metadata (tags) support

   o  Selectable subtitle/audio/video streams

   o  Modularly expandable

   o  Error resilience (can recover playback even when the stream is
      damaged)




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   o  Streamable over the internet and local networks (HTTP, CIFS, FTP,
      etc)

   o  Menus (like DVDs have)

   Matroska is an open standards project.  This means for personal use
   it is absolutely free to use and that the technical specifications
   describing the bitstream are open to everybody, even to companies
   that would like to support it in their products.

2.  Status of this document

   This document is a work-in-progress specification defining the
   Matroska file format as part of the IETF Cellar working group [3].
   But since it's quite complete it is used as a reference for the
   development of libmatroska.  Legacy versions of the specification can
   be found here [4] (PDF doc by Alexander Noe -- outdated).

   For a simplified diagram of the layout of a Matroska file, see the
   Diagram page [5].

   A more refined and detailed version of the EBML specifications is
   being worked on here [6].

   The table found below is now generated from the "source" of the
   Matroska specification.  This XML file [7] is also used to generate
   the semantic data used in libmatroska and libmatroska2.  We encourage
   anyone to use and monitor its changes so your code is spec-proof and
   always up to date.

   Note that versions 1, 2 and 3 have been finalized.  Version 4 is
   currently work in progress.  There MAY be further additions to v4.

3.  Security Considerations

   Matroska inherits security considerations from EBML.  Other security
   considerations are to be determined.

4.  IANA Considerations

   To be determined.

5.  Notations and Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [8].




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6.  Basis in EBML

   Matroska is a Document Type of EBML (Extensible Binary Meta
   Language).  This specification is dependent on the EBML Specification
   [9].  For an understanding of Matroska's EBML Schema, see in
   particular the sections of the EBML Specification covering EBML
   Element Types [10], EBML Schema [11], and EBML Structure [12].

6.1.  Added Constaints on EBML

   As an EBML Document Type, Matroska adds the following constraints to
   the EBML specification.

   o  The "docType" of the "EBML Header" MUST be 'matroska'.

   o  The "EBMLMaxIDLength" of the "EBML Header" MUST be "4".

   o  The "EBMLMaxSizeLength" of the "EBML Header" MUST be "8" or less.

6.2.  Matroska Design

   All top-levels elements (Segment and direct sub-elements) are coded
   on 4 octets, i.e. class D elements.

6.2.1.  Language Codes

   Language codes can be either the 3 letters bibliographic ISO-639-2
   [13] form (like "fre" for french), or such a language code followed
   by a dash and a country code for specialities in languages (like
   "fre-ca" for Canadian French).  Country codes are the same as used
   for internet domains [14].

6.2.2.  Physical Types

   Each level can have different meanings for audio and video.  The
   ORIGINAL_MEDIUM tag can be used to specify a string for
   ChapterPhysicalEquiv = 60.  Here is the list of possible levels for
   both audio and video :













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   +----------------------+--------------+-----------+-----------------+
   | ChapterPhysicalEquiv | Audio        | Video     | Comment         |
   +----------------------+--------------+-----------+-----------------+
   | 70                   | SET /        | SET /     | the collection  |
   |                      | PACKAGE      | PACKAGE   | of different    |
   |                      |              |           | media           |
   | 60                   | CD / 12" /   | DVD / VHS | the physical    |
   |                      | 10" / 7" /   | /         | medium like a   |
   |                      | TAPE /       | LASERDISC | CD or a DVD     |
   |                      | MINIDISC /   |           |                 |
   |                      | DAT          |           |                 |
   | 50                   | SIDE         | SIDE      | when the        |
   |                      |              |           | original medium |
   |                      |              |           | (LP/DVD) has    |
   |                      |              |           | different sides |
   | 40                   | -            | LAYER     | another         |
   |                      |              |           | physical level  |
   |                      |              |           | on DVDs         |
   | 30                   | SESSION      | SESSION   | as found on CDs |
   |                      |              |           | and DVDs        |
   | 20                   | TRACK        | -         | as found on     |
   |                      |              |           | audio CDs       |
   | 10                   | INDEX        | -         | the first       |
   |                      |              |           | logical level   |
   |                      |              |           | of the          |
   |                      |              |           | side/medium     |
   +----------------------+--------------+-----------+-----------------+

6.2.3.  Block Structure

   Size = 1 + (1-8) + 4 + (4 + (4)) octets.  So from 6 to 21 octets.

   Bit 0 is the most significant bit.

   Frames using references SHOULD be stored in "coding order".  That
   means the references first and then the frames referencing them.  A
   consequence is that timecodes MAY NOT be consecutive.  But a frame
   with a past timecode MUST reference a frame already known, otherwise
   it's considered bad/void.

   There can be many Blocks in a BlockGroup provided they all have the
   same timecode.  It is used with different parts of a frame with
   different priorities.








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6.2.3.1.  Block Header

   +--------+--------+-------------------------------------------------+
   | Offset | Player | Description                                     |
   +--------+--------+-------------------------------------------------+
   | 0x00+  | MUST   | Track Number (Track Entry). It is coded in EBML |
   |        |        | like form (1 octet if the value is < 0x80, 2 if |
   |        |        | < 0x4000, etc) (most significant bits set to    |
   |        |        | increase the range).                            |
   | 0x01+  | MUST   | Timecode (relative to Cluster timecode, signed  |
   |        |        | int16)                                          |
   +--------+--------+-------------------------------------------------+

6.2.3.2.  Block Header Flags

   +--------+-----+--------+-------------------------------------------+
   | Offset | Bit | Player | Description                               |
   +--------+-----+--------+-------------------------------------------+
   | 0x03+  | 0-3 | -      | Reserved, set to 0                        |
   | 0x03+  | 4   | -      | Invisible, the codec SHOULD decode this   |
   |        |     |        | frame but not display it                  |
   | 0x03+  | 5-6 | MUST   | Lacing                                    |
   |        |     |        | *   00 : no lacing                        |
   |        |     |        | *   01 : Xiph lacing                      |
   |        |     |        | *   11 : EBML lacing                      |
   |        |     |        | *   10 : fixed-size lacing                |
   | 0x03+  | 7   | -      | not used                                  |
   +--------+-----+--------+-------------------------------------------+

6.2.3.3.  Laced Data

   When lacing bit is set.

   +--------+--------+-------------------------------------------------+
   | Offset | Player | Description                                     |
   +--------+--------+-------------------------------------------------+
   | 0x00   | MUST   | Number of frames in the lace-1 (uint8)          |
   | 0x01 / | MUST*  | Lace-coded size of each frame of the lace,      |
   | 0xXX   |        | except for the last one (multiple uint8). *This |
   |        |        | is not used with Fixed-size lacing as it is     |
   |        |        | calculated automatically from (total size of    |
   |        |        | lace) / (number of frames in lace).             |
   +--------+--------+-------------------------------------------------+

   For (possibly) Laced Data






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              +--------+--------+--------------------------+
              | Offset | Player | Description              |
              +--------+--------+--------------------------+
              | 0x00   | MUST   | Consecutive laced frames |
              +--------+--------+--------------------------+

6.2.4.  Lacing

   Lacing is a mechanism to save space when storing data.  It is
   typically used for small blocks of data (refered to as frames in
   matroska).  There are 3 types of lacing : the Xiph one inspired by
   what is found in the Ogg container, the EBML one which is the same
   with sizes coded differently and the fixed-size one where the size is
   not coded.  As an example is better than words...

   Let's say you want to store 3 frames of the same track.  The first
   frame is 800 octets long, the second is 500 octets long and the third
   is 1000 octets long.  As these data are small, you can store them in
   a lace to save space.  They will then be solved in the same block as
   follows:

6.2.4.1.  Xiph lacing

   o  Block head (with lacing bits set to 01)

   o  Lacing head: Number of frames in the lace -1, i.e. 2 (the 800 and
      500 octets one)

   o  Lacing sizes: only the 2 first ones will be coded, 800 gives
      255;255;255;35, 500 gives 255;245.  The size of the last frame is
      deduced from the total size of the Block.

   o  Data in frame 1

   o  Data in frame 2

   o  Data in frame 3

   A frame with a size multiple of 255 is coded with a 0 at the end of
   the size, for example 765 is coded 255;255;255;0.

6.2.4.2.  EBML lacing

   In this case the size is not coded as blocks of 255 bytes, but as a
   difference with the previous size and this size is coded as in EBML.
   The first size in the lace is unsigned as in EBML.  The others use a
   range shifting to get a sign on each value :




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   +----------------------------------+--------------------------------+
   | Bit Representation               | Value                          |
   +----------------------------------+--------------------------------+
   | 1xxx xxxx                        | value -(2^6-1) to 2^6-1 (ie 0  |
   |                                  | to 2^7-2 minus 2^6-1, half of  |
   |                                  | the range)                     |
   | 01xx xxxx  xxxx xxxx             | value -(2^13-1) to 2^13-1      |
   | 001x xxxx  xxxx xxxx  xxxx xxxx  | value -(2^20-1) to 2^20-1      |
   | 0001 xxxx  xxxx xxxx  xxxx xxxx  | value -(2^27-1) to 2^27-1      |
   | xxxx xxxx                        |                                |
   | 0000 1xxx  xxxx xxxx  xxxx xxxx  | value -(2^34-1) to 2^34-1      |
   | xxxx xxxx  xxxx xxxx             |                                |
   | 0000 01xx  xxxx xxxx  xxxx xxxx  | value -(2^41-1) to 2^41-1      |
   | xxxx xxxx  xxxx xxxx  xxxx xxxx  |                                |
   | 0000 001x  xxxx xxxx  xxxx xxxx  | value -(2^48-1) to 2^48-1      |
   | xxxx xxxx  xxxx xxxx  xxxx xxxx  |                                |
   | xxxx xxxx                        |                                |
   +----------------------------------+--------------------------------+

   o  Block head (with lacing bits set to 11)

   o  Lacing head: Number of frames in the lace -1, i.e. 2 (the 800 and
      400 octets one)

   o  Lacing sizes: only the 2 first ones will be coded, 800 gives 0x320
      0x4000 = 0x4320, 500 is coded as -300 : - 0x12C + 0x1FFF + 0x4000
      = 0x5ED3.  The size of the last frame is deduced from the total
      size of the Block.

   o  Data in frame 1

   o  Data in frame 2

   o  Data in frame 3

6.2.4.3.  Fixed-size lacing

   In this case only the number of frames in the lace is saved, the size
   of each frame is deduced from the total size of the Block.  For
   example, for 3 frames of 800 octets each :

   o  Block head (with lacing bits set to 10)

   o  Lacing head: Number of frames in the lace -1, i.e. 2

   o  Data in frame 1

   o  Data in frame 2



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   o  Data in frame 3

6.2.4.4.  SimpleBlock Structure

   The SimpleBlock is very inspired by the [Block
   structure](({{site.baseurl}}/index.html#block-structure).  The main
   differences are the added Keyframe flag and Discardable flag.
   Otherwise everything is the same.

   Size = 1 + (1-8) + 4 + (4 + (4)) octets.  So from 6 to 21 octets.

   Bit 0 is the most significant bit.

   Frames using references SHOULD be stored in "coding order".  That
   means the references first and then the frames referencing them.  A
   consequence is that timecodes MAY NOT be consecutive.  But a frame
   with a past timecode MUST reference a frame already known, otherwise
   it's considered bad/void.

   There can be many Blocks in a BlockGroup provided they all have the
   same timecode.  It is used with different parts of a frame with
   different priorities.

6.2.4.4.1.  SimpleBlock Header

   +--------+--------+-------------------------------------------------+
   | Offset | Player | Description                                     |
   +--------+--------+-------------------------------------------------+
   | 0x00+  | MUST   | Track Number (Track Entry). It is coded in EBML |
   |        |        | like form (1 octet if the value is < 0x80, 2 if |
   |        |        | < 0x4000, etc) (most significant bits set to    |
   |        |        | increase the range).                            |
   | 0x01+  | MUST   | Timecode (relative to Cluster timecode, signed  |
   |        |        | int16)                                          |
   +--------+--------+-------------------------------------------------+

6.2.4.4.2.  SimpleBlock Header Flags














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   +--------+-----+--------+-------------------------------------------+
   | Offset | Bit | Player | Description                               |
   +--------+-----+--------+-------------------------------------------+
   | 0x03+  | 0   | -      | Keyframe, set when the Block contains     |
   |        |     |        | only keyframes                            |
   | 0x03+  | 1-3 | -      | Reserved, set to 0                        |
   | 0x03+  | 4   | -      | Invisible, the codec SHOULD decode this   |
   |        |     |        | frame but not display it                  |
   | 0x03+  | 5-6 | MUST   | Lacing                                    |
   |        |     |        | *   00 : no lacing                        |
   |        |     |        | *   01 : Xiph lacing                      |
   |        |     |        | *   11 : EBML lacing                      |
   |        |     |        | *   10 : fixed-size lacing                |
   | 0x03+  | 7   | -      | Discardable, the frames of the Block can  |
   |        |     |        | be discarded during playing if needed     |
   +--------+-----+--------+-------------------------------------------+

6.2.4.5.  Laced Data

   When lacing bit is set.

   +--------+--------+-------------------------------------------------+
   | Offset | Player | Description                                     |
   +--------+--------+-------------------------------------------------+
   | 0x00   | MUST   | Number of frames in the lace-1 (uint8)          |
   | 0x01 / | MUST*  | Lace-coded size of each frame of the lace,      |
   | 0xXX   |        | except for the last one (multiple uint8). *This |
   |        |        | is not used with Fixed-size lacing as it is     |
   |        |        | calculated automatically from (total size of    |
   |        |        | lace) / (number of frames in lace).             |
   +--------+--------+-------------------------------------------------+

   For (possibly) Laced Data

              +--------+--------+--------------------------+
              | Offset | Player | Description              |
              +--------+--------+--------------------------+
              | 0x00   | MUST   | Consecutive laced frames |
              +--------+--------+--------------------------+

6.2.4.6.  EncryptedBlock Structure

   The EncryptedBlock is very inspired by the [SimpleBlock
   structure](({{site.baseurl}}/index.html#simpleblock_structure).  The
   main differences is that the raw data are Transformed.  That means
   the data after the lacing definition (if present) have been processed
   before put into the Block.  The laced sizes apply on the decoded




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   (Inverse Transform) data.  This size of the Transformed data MAY NOT
   match the size of the initial chunk of data.

   The other difference is that the number of frames in the lace are not
   saved if "no lacing" is specified (bits 5 and 6 set to 0).

   The Transformation is specified by a TransformID in the Block (MUST
   be the same for all frames within the EncryptedBlock).

   Size = 1 + (1-8) + 4 + (4 + (4)) octets.  So from 6 to 21 octets.

   Bit 0 is the most significant bit.

   Frames using references SHOULD be stored in "coding order".  That
   means the references first and then the frames referencing them.  A
   consequence is that timecodes MAY NOT be consecutive.  But a frame
   with a past timecode MUST reference a frame already known, otherwise
   it's considered bad/void.

   There can be many Blocks in a BlockGroup provided they all have the
   same timecode.  It is used with different parts of a frame with
   different priorities.

   | EncryptedBlock Header | | Offset | Player | Description | | 0x00+ |
   MUST | Track Number (Track Entry).  It is coded in EBML like form (1
   octet if the value is < 0x80, 2 if < 0x4000, etc) (most significant
   bits set to increase the range). | | 0x01+ | MUST | Timecode
   (relative to Cluster timecode, signed int16) | | 0x03+ | - |

   | Flags | | Bit | Player | Description | | 0 | - | Keyframe, set when
   the Block contains only keyframes | | 1-3 | - | Reserved, set to
   0 | | 4 | - | Invisible, the codec SHOULD decode this frame but not
   display it | | 5-6 | MUST | Lacing

   o  00 : no lacing

   o  01 : Xiph lacing

   o  11 : EBML lacing

   o  10 : fixed-size lacing

   | | 7 | - | Discardable, the frames of the Block can be discarded
   during playing if needed |

   | | Lace (when lacing bit is set) | | 0x00 | MUST* | Number of frames
   in the lace-1 (uint8) _Only available if bit 5 or bit 6 of the
   EncryptedBlock flag is set to one. | | 0x01 / 0xXX | MUST_ | Lace-



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   coded size of each frame of the lace, except for the last one
   (multiple uint8). *This is not used with Fixed-size lacing as it is
   calculated automatically from (total size of lace) / (number of
   frames in lace). | | (possibly) Laced Data | | 0x00 | MUST |
   TransformID (EBML coded integer value).  Value 0 = Null Transform | |
   0x01+ | MUST | Consecutive laced frames |

6.2.4.7.  Virtual Block

   The data in matroska is stored in coding order.  But that means if
   you seek to a particular point and a frame has been referenced far
   away, you won't know while playing and you might miss this frame
   (true for independent frames and overlapping of dependent frames).
   So the idea is to have a placeholder for the original frame in the
   timecode (display) order.

   The structure is a scaled down version of the normal Block [15].

   | Virtual Block Header | | Offset | Player | Description | | 0x00+ |
   MUST | Track Number (Track Entry).  It is coded in EBML like form (1
   octet if the value is < 0x80, 2 if < 0x4000, etc) (most significant
   bits set to increase the range). | | 0x01+ | MUST | Timecode
   (relative to Cluster timecode, signed int16) | | 0x03+ | - |

   | Flags | | Bit | Player | Description | | 7-0 | - | Reserved, set to
   0 |

   |

7.  Matroska Schema

   This specification includes an "EBML Schema" which defines the
   Elements and structure of Matroska as an EBML Document Type.  The
   EBML Schema defines every valid Matroska element in a manner defined
   by the EBML specification.

7.1.  Matroska Additions to Schema Element Attributes

   In addition to the EBML Schema definition provided by the EBML
   Specification, Matroska adds the following additional attributes:











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   +-----------+----------+--------------------------------------------+
   | attribute | required | definition                                 |
   | name      |          |                                            |
   +-----------+----------+--------------------------------------------+
   | webm      | No       | A boolean to express if the Matroska       |
   |           |          | Element is also supported within version 2 |
   |           |          | of the "webm" specification. Please        |
   |           |          | consider the webm specification [16] as    |
   |           |          | the authoritative on "webm".               |
   +-----------+----------+--------------------------------------------+

7.2.  Matroska Schema

   Here the definition of each Matroska Element is provided.

   % concatenate with Matroska EBML Schema converted to markdown %

7.2.1.  Segment Element

   name: "Segment"

   path: "1*1(\Segment)"

   id: "0x18538067"

   minOccurs: "1"

   type: "master"

   minver: "1"

   documentation: The Root Element that contains all other Top-Level
   Elements (Elements defined only at Level 1).  A Matroska file is
   composed of 1 Segment.

7.2.2.  SeekHead Element

   name: "SeekHead"

   path: "0*2(\Segment\SeekHead)"

   id: "0x114D9B74"

   maxOccurs: "2"

   type: "master"

   minver: "1"



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   documentation: Contains the position of other Top-Level Elements.

7.2.3.  Seek Element

   name: "Seek"

   path: "1*(\Segment\SeekHead\Seek)"

   id: "0x4DBB"

   minOccurs: "1"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   documentation: Contains a single seek entry to an EBML Element.

7.2.4.  SeekID Element

   name: "SeekID"

   path: "1*1(\Segment\SeekHead\Seek\SeekID)"

   id: "0x53AB"

   minOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: The binary ID corresponding to the Element name.

7.2.5.  SeekPosition Element

   name: "SeekPosition"

   path: "1*1(\Segment\SeekHead\Seek\SeekPosition)"

   id: "0x53AC"

   minOccurs: "1"

   type: "uinteger"




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   minver: "1"

   documentation: The position of the Element in the Segment in octets
   (0 = first level 1 Element).

7.2.6.  Info Element

   name: "Info"

   path: "1*(\Segment\Info)"

   id: "0x1549A966"

   minOccurs: "1"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   definition: Contains general information about the Segment.

7.2.7.  SegmentUID Element

   name: "SegmentUID"

   path: "0*1(\Segment\Info\SegmentUID)"

   id: "0x73A4"

   range: "not 0"

   size: "16"

   type: "binary"

   minver: "1"

   definition: A randomly generated unique ID to identify the Segment
   amongst many others (128 bits).

   usage notes: If the Segment is a part of a Linked Segment then this
   Element is REQUIRED.







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7.2.8.  SegmentFilename Element

   name: "SegmentFilename"

   path: "0*1(\Segment\Info\SegmentFilename)"

   id: "0x7384"

   type: "utf-8"

   minver: "1"

   definition: A filename corresponding to this Segment.

7.2.9.  PrevUID Element

   name: "PrevUID"

   path: "0*1(\Segment\Info\PrevUID)"

   id: "0x3CB923"

   size: "16"

   type: "binary"

   minver: "1"

   definition: A unique ID to identify the previous Segment of a Linked
   Segment (128 bits).

   usage notes: If the Segment is a part of a Linked Segment that uses
   Hard Linking then either the PrevUID or the NextUID Element is
   REQUIRED.  If a Segment contains a PrevUID but not a NextUID then it
   MAY be considered as the last Segment of the Linked Segment.  The
   PrevUID MUST NOT be equal to the SegmentUID.

7.2.10.  PrevFilename Element

   name: "PrevFilename"

   path: "0*1(\Segment\Info\PrevFilename)"

   id: "0x3C83AB"

   type: "utf-8"

   minver: "1"



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   definition: A filename corresponding to the file of the previous
   Linked Segment.

   usage notes: Provision of the previous filename is for display
   convenience, but PrevUID SHOULD be considered authoritative for
   identifying the previous Segment in a Linked Segment.

7.2.11.  NextUID Element

   name: "NextUID"

   path: "0*1(\Segment\Info\NextUID)"

   id: "0x3EB923"

   size: "16"

   type: "binary"

   minver: "1"

   definition: A unique ID to identify the next Segment of a Linked
   Segment (128 bits).

   usage notes: If the Segment is a part of a Linked Segment that uses
   Hard Linking then either the PrevUID or the NextUID Element is
   REQUIRED.  If a Segment contains a NextUID but not a PrevUID then it
   MAY be considered as the first Segment of the Linked Segment.  The
   NextUID MUST NOT be equal to the SegmentUID.

7.2.12.  NextFilename Element

   name: "NextFilename"

   path: "0*1(\Segment\Info\NextFilename)"

   id: "0x3E83BB"

   type: "utf-8"

   minver: "1"

   definition: A filename corresponding to the file of the next Linked
   Segment.

   usage notes: Provision of the next filename is for display
   convenience, but NextUID SHOULD be considered authoritative for
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7.2.13.  SegmentFamily Element

   name: "SegmentFamily"

   path: "0*(\Segment\Info\SegmentFamily)"

   id: "0x4444"

   maxOccurs: "unbounded"

   size: "16"

   type: "binary"

   minver: "1"

   definition: A randomly generated unique ID that all Segments of a
   Linked Segment MUST share (128 bits).

   usage notes: If the Segment is a part of a Linked Segment that uses
   Soft Linking then this Element is REQUIRED.

7.2.14.  ChapterTranslate Element

   name: "ChapterTranslate"

   path: "0*(\Segment\Info\ChapterTranslate)"

   id: "0x6924"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   documentation: A tuple of corresponding ID used by chapter codecs to
   represent this Segment.

7.2.15.  ChapterTranslateEditionUID Element

   name: "ChapterTranslateEditionUID"

   path: "0*(\Segment\Info\ChapterTranslate\ChapterTranslateEditionUID)"

   id: "0x69FC"

   maxOccurs: "unbounded"



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   type: "uinteger"

   minver: "1"

   documentation: Specify an edition UID on which this correspondance
   applies.  When not specified, it means for all editions found in the
   Segment.

7.2.16.  ChapterTranslateCodec Element

   name: "ChapterTranslateCodec"

   path: "1*1(\Segment\Info\ChapterTranslate\ChapterTranslateCodec)"

   id: "0x69BF"

   minOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: The chapter codec using this ID (0: Matroska Script,
   1: DVD-menu).

7.2.17.  ChapterTranslateID Element

   name: "ChapterTranslateID"

   path: "1*1(\Segment\Info\ChapterTranslate\ChapterTranslateID)"

   id: "0x69A5"

   minOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: The binary value used to represent this Segment in the
   chapter codec data.  The format depends on the ChapProcessCodecID
   used.

7.2.18.  TimecodeScale Element

   name: "TimecodeScale"

   path: "1*1(\Segment\Info\TimecodeScale)"



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   id: "0x2AD7B1"

   minOccurs: "1"

   default: "1000000"

   type: "uinteger"

   minver: "1"

   documentation: Timestamp scale in nanoseconds (1.000.000 means all
   timestamps in the Segment are expressed in milliseconds).

7.2.19.  Duration Element

   name: "Duration"

   path: "0*1(\Segment\Info\Duration)"

   id: "0x4489"

   range: "> 0x0p+0"

   type: "float"

   minver: "1"

   definition: Duration of the Segment in nanoseconds based on
   TimecodeScale.

7.2.20.  DateUTC Element

   name: "DateUTC"

   path: "0*1(\Segment\Info\DateUTC)"

   id: "0x4461"

   type: "date"

   minver: "1"

   documentation: The date and time that the Segment was created by the
   muxing application or library.







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7.2.21.  Title Element

   name: "Title"

   path: "0*1(\Segment\Info\Title)"

   id: "0x7BA9"

   type: "utf-8"

   minver: "1"

   documentation: General name of the Segment.

7.2.22.  MuxingApp Element

   name: "MuxingApp"

   path: "1*1(\Segment\Info\MuxingApp)"

   id: "0x4D80"

   minOccurs: "1"

   type: "utf-8"

   minver: "1"

   definition: Muxing application or library (example: "libmatroska-
   0.4.3").

   usage notes: Include the full name of the application or library
   followed by the version number.

7.2.23.  WritingApp Element

   name: "WritingApp"

   path: "1*1(\Segment\Info\WritingApp)"

   id: "0x5741"

   minOccurs: "1"

   type: "utf-8"

   minver: "1"




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   definition: Writing application (example: "mkvmerge-0.3.3").

   usage notes: Include the full name of the application followed by the
   version number.

7.2.24.  Cluster Element

   name: "Cluster"

   path: "0*(\Segment\Cluster)"

   id: "0x1F43B675"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   documentation: The Top-Level Element containing the (monolithic)
   Block structure.

7.2.25.  Timecode Element

   name: "Timecode"

   path: "1*1(\Segment\Cluster\Timecode)"

   id: "0xE7"

   minOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: Absolute timestamp of the cluster (based on
   TimecodeScale).

7.2.26.  SilentTracks Element

   name: "SilentTracks"

   path: "0*1(\Segment\Cluster\SilentTracks)"

   id: "0x5854"

   type: "master"



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   minver: "1"

   documentation: The list of tracks that are not used in that part of
   the stream.  It is useful when using overlay tracks on seeking or to
   decide what track to use.

7.2.27.  SilentTrackNumber Element

   name: "SilentTrackNumber"

   path: "0*(\Segment\Cluster\SilentTracks\SilentTrackNumber)"

   id: "0x58D7"

   maxOccurs: "unbounded"

   type: "uinteger"

   minver: "1"

   documentation: One of the track number that are not used from now on
   in the stream.  It could change later if not specified as silent in a
   further Cluster.

7.2.28.  Position Element

   name: "Position"

   path: "0*1(\Segment\Cluster\Position)"

   id: "0xA7"

   type: "uinteger"

   minver: "1"

   documentation: The Position of the Cluster in the Segment (0 in live
   broadcast streams).  It might help to resynchronise offset on damaged
   streams.

7.2.29.  PrevSize Element

   name: "PrevSize"

   path: "0*1(\Segment\Cluster\PrevSize)"

   id: "0xAB"




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   type: "uinteger"

   minver: "1"

   documentation: Size of the previous Cluster, in octets.  Can be
   useful for backward playing.

7.2.30.  SimpleBlock Element

   name: "SimpleBlock"

   path: "0*(\Segment\Cluster\SimpleBlock)"

   id: "0xA3"

   maxOccurs: "unbounded"

   type: "binary"

   minver: "2"

   documentation: Similar to Block but without all the extra
   information, mostly used to reduced overhead when no extra feature is
   needed. (see SimpleBlock Structure)

7.2.31.  BlockGroup Element

   name: "BlockGroup"

   path: "0*(\Segment\Cluster\BlockGroup)"

   id: "0xA0"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   documentation: Basic container of information containing a single
   Block or BlockVirtual, and information specific to that Block/
   VirtualBlock.

7.2.32.  Block Element

   name: "Block"

   path: "1*1(\Segment\Cluster\BlockGroup\Block)"



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   id: "0xA1"

   minOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: Block containing the actual data to be rendered and a
   timestamp relative to the Cluster Timecode. (see Block Structure)

7.2.33.  BlockVirtual Element

   name: "BlockVirtual"

   path: "0*1(\Segment\Cluster\BlockGroup\BlockVirtual)"

   id: "0xA2"

   type: "binary"

   minver: "0"

   maxver: "0"

   documentation: A Block with no data.  It MUST be stored in the stream
   at the place the real Block would be in display order. (see Block
   Virtual)

7.2.34.  BlockAdditions Element

   name: "BlockAdditions"

   path: "0*1(\Segment\Cluster\BlockGroup\BlockAdditions)"

   id: "0x75A1"

   type: "master"

   minver: "1"

   documentation: Contain additional blocks to complete the main one.
   An EBML parser that has no knowledge of the Block structure could
   still see and use/skip these data.







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7.2.35.  BlockMore Element

   name: "BlockMore"

   path: "1*(\Segment\Cluster\BlockGroup\BlockAdditions\BlockMore)"

   id: "0xA6"

   minOccurs: "1"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   documentation: Contain the BlockAdditional and some parameters.

7.2.36.  BlockAddID Element

   name: "BlockAddID"

   path: "1*1(\Segment\Cluster\BlockGroup\BlockAdditions\BlockMore\Block
   AddID)"

   id: "0xEE"

   minOccurs: "1"

   range: "not 0"

   default: "1"

   type: "uinteger"

   minver: "1"

   documentation: An ID to identify the BlockAdditional level.

7.2.37.  BlockAdditional Element

   name: "BlockAdditional"

   path: "1*1(\Segment\Cluster\BlockGroup\BlockAdditions\BlockMore\Block
   Additional)"

   id: "0xA5"




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   minOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: Interpreted by the codec as it wishes (using the
   BlockAddID).

7.2.38.  BlockDuration Element

   name: "BlockDuration"

   path: "0*1(\Segment\Cluster\BlockGroup\BlockDuration)"

   id: "0x9B"

   default: "DefaultDuration"

   type: "uinteger"

   minver: "1"

   documentation: The duration of the Block (based on TimecodeScale).
   This Element is mandatory when DefaultDuration is set for the track
   (but can be omitted as other default values).  When not written and
   with no DefaultDuration, the value is assumed to be the difference
   between the timestamp of this Block and the timestamp of the next
   Block in "display" order (not coding order).  This Element can be
   useful at the end of a Track (as there is not other Block available),
   or when there is a break in a track like for subtitle tracks.  When
   set to 0 that means the frame is not a keyframe.

7.2.39.  ReferencePriority Element

   name: "ReferencePriority"

   path: "1*1(\Segment\Cluster\BlockGroup\ReferencePriority)"

   id: "0xFA"

   minOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"



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   documentation: This frame is referenced and has the specified cache
   priority.  In cache only a frame of the same or higher priority can
   replace this frame.  A value of 0 means the frame is not referenced.

7.2.40.  ReferenceBlock Element

   name: "ReferenceBlock"

   path: "0*(\Segment\Cluster\BlockGroup\ReferenceBlock)"

   id: "0xFB"

   maxOccurs: "unbounded"

   type: "integer"

   minver: "1"

   documentation: Timestamp of another frame used as a reference (ie: B
   or P frame).  The timestamp is relative to the block it's attached
   to.

7.2.41.  ReferenceVirtual Element

   name: "ReferenceVirtual"

   path: "0*1(\Segment\Cluster\BlockGroup\ReferenceVirtual)"

   id: "0xFD"

   type: "integer"

   minver: "0"

   maxver: "0"

   documentation: Relative position of the data that would otherwise be
   in position of the virtual block.

7.2.42.  CodecState Element

   name: "CodecState"

   path: "0*1(\Segment\Cluster\BlockGroup\CodecState)"

   id: "0xA4"

   type: "binary"



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   minver: "2"

   documentation: The new codec state to use.  Data interpretation is
   private to the codec.  This information SHOULD always be referenced
   by a seek entry.

7.2.43.  DiscardPadding Element

   name: "DiscardPadding"

   path: "0*1(\Segment\Cluster\BlockGroup\DiscardPadding)"

   id: "0x75A2"

   type: "integer"

   minver: "4"

   documentation: Duration in nanoseconds of the silent data added to
   the Block (padding at the end of the Block for positive value, at the
   beginning of the Block for negative value).  The duration of
   DiscardPadding is not calculated in the duration of the TrackEntry
   and SHOULD be discarded during playback.

7.2.44.  Slices Element

   name: "Slices"

   path: "0*1(\Segment\Cluster\BlockGroup\Slices)"

   id: "0x8E"

   type: "master"

   minver: "1"

   documentation: Contains slices description.

7.2.45.  TimeSlice Element

   name: "TimeSlice"

   path: "0*(\Segment\Cluster\BlockGroup\Slices\TimeSlice)"

   id: "0xE8"

   maxOccurs: "unbounded"




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   type: "master"

   minver: "1"

   documentation: Contains extra time information about the data
   contained in the Block.  While there are a few files in the wild with
   this Element, it is no longer in use and has been deprecated.  Being
   able to interpret this Element is not REQUIRED for playback.

7.2.46.  LaceNumber Element

   name: "LaceNumber"

   path: "0*1(\Segment\Cluster\BlockGroup\Slices\TimeSlice\LaceNumber)"

   id: "0xCC"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The reverse number of the frame in the lace (0 is the
   last frame, 1 is the next to last, etc).  While there are a few files
   in the wild with this Element, it is no longer in use and has been
   deprecated.  Being able to interpret this Element is not REQUIRED for
   playback.

7.2.47.  FrameNumber Element

   name: "FrameNumber"

   path: "0*1(\Segment\Cluster\BlockGroup\Slices\TimeSlice\FrameNumber)"

   id: "0xCD"

   default: "0"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: The number of the frame to generate from this lace
   with this delay (allow you to generate many frames from the same
   Block/Frame).



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7.2.48.  BlockAdditionID Element

   name: "BlockAdditionID"

   path:
   "0*1(\Segment\Cluster\BlockGroup\Slices\TimeSlice\BlockAdditionID)"

   id: "0xCB"

   default: "0"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: The ID of the BlockAdditional Element (0 is the main
   Block).

7.2.49.  Delay Element

   name: "Delay"

   path: "0*1(\Segment\Cluster\BlockGroup\Slices\TimeSlice\Delay)"

   id: "0xCE"

   default: "0"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: The (scaled) delay to apply to the Element.

7.2.50.  SliceDuration Element

   name: "SliceDuration"

   path:
   "0*1(\Segment\Cluster\BlockGroup\Slices\TimeSlice\SliceDuration)"

   id: "0xCF"

   default: "0"



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   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: The (scaled) duration to apply to the Element.

7.2.51.  ReferenceFrame Element

   name: "ReferenceFrame"

   path: "0*1(\Segment\Cluster\BlockGroup\ReferenceFrame)"

   id: "0xC8"

   type: "master"

   minver: "0"

   maxver: "0"

   documentation: DivX trick track extenstions

7.2.52.  ReferenceOffset Element

   name: "ReferenceOffset"

   path:
   "1*1(\Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceOffset)"

   id: "0xC9"

   minOccurs: "1"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: DivX trick track extenstions

7.2.53.  ReferenceTimeCode Element

   name: "ReferenceTimeCode"





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   path:
   "1*1(\Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceTimeCode)"

   id: "0xCA"

   minOccurs: "1"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: DivX trick track extenstions

7.2.54.  EncryptedBlock Element

   name: "EncryptedBlock"

   path: "0*(\Segment\Cluster\EncryptedBlock)"

   id: "0xAF"

   maxOccurs: "unbounded"

   type: "binary"

   minver: "0"

   maxver: "0"

   documentation: Similar to SimpleBlock but the data inside the Block
   are Transformed (encrypt and/or signed). (see EncryptedBlock
   Structure)

7.2.55.  Tracks Element

   name: "Tracks"

   path: "0*(\Segment\Tracks)"

   id: "0x1654AE6B"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"



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   documentation: A Top-Level Element of information with many tracks
   described.

7.2.56.  TrackEntry Element

   name: "TrackEntry"

   path: "1*(\Segment\Tracks\TrackEntry)"

   id: "0xAE"

   minOccurs: "1"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   documentation: Describes a track with all Elements.

7.2.57.  TrackNumber Element

   name: "TrackNumber"

   path: "1*1(\Segment\Tracks\TrackEntry\TrackNumber)"

   id: "0xD7"

   minOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: The track number as used in the Block Header (using
   more than 127 tracks is not encouraged, though the design allows an
   unlimited number).

7.2.58.  TrackUID Element

   name: "TrackUID"

   path: "1*1(\Segment\Tracks\TrackEntry\TrackUID)"

   id: "0x73C5"



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   minOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: A unique ID to identify the Track.  This SHOULD be
   kept the same when making a direct stream copy of the Track to
   another file.

7.2.59.  TrackType Element

   name: "TrackType"

   path: "1*1(\Segment\Tracks\TrackEntry\TrackType)"

   id: "0x83"

   minOccurs: "1"

   range: "1-254"

   type: "uinteger"

   minver: "1"

   documentation: A set of track types coded on 8 bits (1: video, 2:
   audio, 3: complex, 0x10: logo, 0x11: subtitle, 0x12: buttons, 0x20:
   control).

7.2.60.  FlagEnabled Element

   name: "FlagEnabled"

   path: "1*1(\Segment\Tracks\TrackEntry\FlagEnabled)"

   id: "0xB9"

   minOccurs: "1"

   range: "0-1"

   default: "1"

   type: "uinteger"




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   minver: "2"

   documentation: Set if the track is usable. (1 bit)

7.2.61.  FlagDefault Element

   name: "FlagDefault"

   path: "1*1(\Segment\Tracks\TrackEntry\FlagDefault)"

   id: "0x88"

   minOccurs: "1"

   range: "0-1"

   default: "1"

   type: "uinteger"

   minver: "1"

   documentation: Set if that track (audio, video or subs) SHOULD be
   active if no language found matches the user preference. (1 bit)

7.2.62.  FlagForced Element

   name: "FlagForced"

   path: "1*1(\Segment\Tracks\TrackEntry\FlagForced)"

   id: "0x55AA"

   minOccurs: "1"

   range: "0-1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: Set if that track MUST be active during playback.
   There can be many forced track for a kind (audio, video or subs), the
   player SHOULD select the one which language matches the user
   preference or the default + forced track.  Overlay MAY happen between
   a forced and non-forced track of the same kind. (1 bit)



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7.2.63.  FlagLacing Element

   name: "FlagLacing"

   path: "1*1(\Segment\Tracks\TrackEntry\FlagLacing)"

   id: "0x9C"

   minOccurs: "1"

   range: "0-1"

   default: "1"

   type: "uinteger"

   minver: "1"

   documentation: Set if the track MAY contain blocks using lacing. (1
   bit)

7.2.64.  MinCache Element

   name: "MinCache"

   path: "1*1(\Segment\Tracks\TrackEntry\MinCache)"

   id: "0x6DE7"

   minOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The minimum number of frames a player SHOULD be able
   to cache during playback.  If set to 0, the reference pseudo-cache
   system is not used.

7.2.65.  MaxCache Element

   name: "MaxCache"

   path: "0*1(\Segment\Tracks\TrackEntry\MaxCache)"

   id: "0x6DF8"



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   type: "uinteger"

   minver: "1"

   documentation: The maximum cache size necessary to store referenced
   frames in and the current frame. 0 means no cache is needed.

7.2.66.  DefaultDuration Element

   name: "DefaultDuration"

   path: "0*1(\Segment\Tracks\TrackEntry\DefaultDuration)"

   id: "0x23E383"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: Number of nanoseconds (not scaled via TimecodeScale)
   per frame ('frame' in the Matroska sense -- one Element put into a
   (Simple)Block).

7.2.67.  DefaultDecodedFieldDuration Element

   name: "DefaultDecodedFieldDuration"

   path: "0*1(\Segment\Tracks\TrackEntry\DefaultDecodedFieldDuration)"

   id: "0x234E7A"

   range: "not 0"

   type: "uinteger"

   minver: "4"

   documentation: The period in nanoseconds (not scaled by TimcodeScale)
   between two successive fields at the output of the decoding process
   (see the notes)

7.2.68.  TrackTimecodeScale Element

   name: "TrackTimecodeScale"

   path: "1*1(\Segment\Tracks\TrackEntry\TrackTimecodeScale)"



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   id: "0x23314F"

   minOccurs: "1"

   range: "> 0x0p+0"

   default: "0x1p+0"

   type: "float"

   minver: "0"

   maxver: "0"

   documentation: DEPRECATED, DO NOT USE.  The scale to apply on this
   track to work at normal speed in relation with other tracks (mostly
   used to adjust video speed when the audio length differs).

7.2.69.  TrackOffset Element

   name: "TrackOffset"

   path: "0*1(\Segment\Tracks\TrackEntry\TrackOffset)"

   id: "0x537F"

   default: "0"

   type: "integer"

   minver: "0"

   maxver: "0"

   documentation: A value to add to the Block's Timestamp.  This can be
   used to adjust the playback offset of a track.

7.2.70.  MaxBlockAdditionID Element

   name: "MaxBlockAdditionID"

   path: "1*1(\Segment\Tracks\TrackEntry\MaxBlockAdditionID)"

   id: "0x55EE"

   minOccurs: "1"

   default: "0"



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   type: "uinteger"

   minver: "1"

   documentation: The maximum value of BlockAddID.  A value 0 means
   there is no BlockAdditions for this track.

7.2.71.  Name Element

   name: "Name"

   path: "0*1(\Segment\Tracks\TrackEntry\Name)"

   id: "0x536E"

   type: "utf-8"

   minver: "1"

   documentation: A human-readable track name.

7.2.72.  Language Element

   name: "Language"

   path: "0*1(\Segment\Tracks\TrackEntry\Language)"

   id: "0x22B59C"

   default: "eng"

   type: "string"

   minver: "1"

   documentation: Specifies the language of the track in the Matroska
   languages form.

7.2.73.  CodecID Element

   name: "CodecID"

   path: "1*1(\Segment\Tracks\TrackEntry\CodecID)"

   id: "0x86"

   minOccurs: "1"




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   type: "string"

   minver: "1"

   documentation: An ID corresponding to the codec, see the codec page
   for more info.

7.2.74.  CodecPrivate Element

   name: "CodecPrivate"

   path: "0*1(\Segment\Tracks\TrackEntry\CodecPrivate)"

   id: "0x63A2"

   type: "binary"

   minver: "1"

   documentation: Private data only known to the codec.

7.2.75.  CodecName Element

   name: "CodecName"

   path: "0*1(\Segment\Tracks\TrackEntry\CodecName)"

   id: "0x258688"

   type: "utf-8"

   minver: "1"

   documentation: A human-readable string specifying the codec.

7.2.76.  AttachmentLink Element

   name: "AttachmentLink"

   path: "0*1(\Segment\Tracks\TrackEntry\AttachmentLink)"

   id: "0x7446"

   range: "not 0"

   type: "uinteger"

   minver: "1"



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   documentation: The UID of an attachment that is used by this codec.

7.2.77.  CodecSettings Element

   name: "CodecSettings"

   path: "0*1(\Segment\Tracks\TrackEntry\CodecSettings)"

   id: "0x3A9697"

   type: "utf-8"

   minver: "0"

   maxver: "0"

   documentation: A string describing the encoding setting used.

7.2.78.  CodecInfoURL Element

   name: "CodecInfoURL"

   path: "0*(\Segment\Tracks\TrackEntry\CodecInfoURL)"

   id: "0x3B4040"

   maxOccurs: "unbounded"

   type: "string"

   minver: "0"

   maxver: "0"

   documentation: A URL to find information about the codec used.

7.2.79.  CodecDownloadURL Element

   name: "CodecDownloadURL"

   path: "0*(\Segment\Tracks\TrackEntry\CodecDownloadURL)"

   id: "0x26B240"

   maxOccurs: "unbounded"

   type: "string"




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   minver: "0"

   maxver: "0"

   documentation: A URL to download about the codec used.

7.2.80.  CodecDecodeAll Element

   name: "CodecDecodeAll"

   path: "1*1(\Segment\Tracks\TrackEntry\CodecDecodeAll)"

   id: "0xAA"

   minOccurs: "1"

   range: "0-1"

   default: "1"

   type: "uinteger"

   minver: "2"

   documentation: The codec can decode potentially damaged data (1 bit).

7.2.81.  TrackOverlay Element

   name: "TrackOverlay"

   path: "0*(\Segment\Tracks\TrackEntry\TrackOverlay)"

   id: "0x6FAB"

   maxOccurs: "unbounded"

   type: "uinteger"

   minver: "1"

   documentation: Specify that this track is an overlay track for the
   Track specified (in the u-integer).  That means when this track has a
   gap (see SilentTracks) the overlay track SHOULD be used instead.  The
   order of multiple TrackOverlay matters, the first one is the one that
   SHOULD be used.  If not found it SHOULD be the second, etc.






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7.2.82.  CodecDelay Element

   name: "CodecDelay"

   path: "0*1(\Segment\Tracks\TrackEntry\CodecDelay)"

   id: "0x56AA"

   default: "0"

   type: "uinteger"

   minver: "4"

   documentation: CodecDelay is The codec-built-in delay in nanoseconds.
   This value MUST be subtracted from each block timestamp in order to
   get the actual timestamp.  The value SHOULD be small so the muxing of
   tracks with the same actual timestamp are in the same Cluster.

7.2.83.  SeekPreRoll Element

   name: "SeekPreRoll"

   path: "1*1(\Segment\Tracks\TrackEntry\SeekPreRoll)"

   id: "0x56BB"

   minOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "4"

   documentation: After a discontinuity, SeekPreRoll is the duration in
   nanoseconds of the data the decoder MUST decode before the decoded
   data is valid.

7.2.84.  TrackTranslate Element

   name: "TrackTranslate"

   path: "0*(\Segment\Tracks\TrackEntry\TrackTranslate)"

   id: "0x6624"

   maxOccurs: "unbounded"



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   type: "master"

   minver: "1"

   documentation: The track identification for the given Chapter Codec.

7.2.85.  TrackTranslateEditionUID Element

   name: "TrackTranslateEditionUID"

   path: "0*(\Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateEdi
   tionUID)"

   id: "0x66FC"

   maxOccurs: "unbounded"

   type: "uinteger"

   minver: "1"

   documentation: Specify an edition UID on which this translation
   applies.  When not specified, it means for all editions found in the
   Segment.

7.2.86.  TrackTranslateCodec Element

   name: "TrackTranslateCodec"

   path:
   "1*1(\Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateCodec)"

   id: "0x66BF"

   minOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: The chapter codec using this ID (0: Matroska Script,
   1: DVD-menu).

7.2.87.  TrackTranslateTrackID Element

   name: "TrackTranslateTrackID"





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   path: "1*1(\Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateTr
   ackID)"

   id: "0x66A5"

   minOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: The binary value used to represent this track in the
   chapter codec data.  The format depends on the ChapProcessCodecID
   used.

7.2.88.  Video Element

   name: "Video"

   path: "0*1(\Segment\Tracks\TrackEntry\Video)"

   id: "0xE0"

   type: "master"

   minver: "1"

   documentation: Video settings.

7.2.89.  FlagInterlaced Element

   name: "FlagInterlaced"

   path: "1*1(\Segment\Tracks\TrackEntry\Video\FlagInterlaced)"

   id: "0x9A"

   minOccurs: "1"

   range: "0-2"

   default: "0"

   type: "uinteger"

   minver: "2"





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   documentation: A flag to declare is the video is known to be
   progressive or interlaced and if applicable to declare details about
   the interlacement. (0: undetermined, 1: interlaced, 2: progressive)

7.2.90.  FieldOrder Element

   name: "FieldOrder"

   path: "1*1(\Segment\Tracks\TrackEntry\Video\FieldOrder)"

   id: "0x9D"

   minOccurs: "1"

   range: "0-14"

   default: "2"

   type: "uinteger"

   minver: "4"

   documentation: Declare the field ordering of the video.  If
   FlagInterlaced is not set to 1, this Element MUST be ignored. (0:
   Progressive, 1: Interlaced with top field display first and top field
   stored first, 2: Undetermined field order, 6: Interlaced with bottom
   field displayed first and bottom field stored first, 9: Interlaced
   with bottom field displayed first and top field stored first, 14:
   Interlaced with top field displayed first and bottom field stored
   first)

7.2.91.  StereoMode Element

   name: "StereoMode"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\StereoMode)"

   id: "0x53B8"

   default: "0"

   type: "uinteger"

   minver: "3"

   documentation: Stereo-3D video mode (0: mono, 1: side by side (left
   eye is first), 2: top-bottom (right eye is first), 3: top-bottom
   (left eye is first), 4: checkboard (right is first), 5: checkboard



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   (left is first), 6: row interleaved (right is first), 7: row
   interleaved (left is first), 8: column interleaved (right is first),
   9: column interleaved (left is first), 10: anaglyph (cyan/red), 11:
   side by side (right eye is first), 12: anaglyph (green/magenta), 13
   both eyes laced in one Block (left eye is first), 14 both eyes laced
   in one Block (right eye is first)) . There are some more details on
   3D support in the Specification Notes.

7.2.92.  AlphaMode Element

   name: "AlphaMode"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\AlphaMode)"

   id: "0x53C0"

   default: "0"

   type: "uinteger"

   minver: "3"

   documentation: Alpha Video Mode.  Presence of this Element indicates
   that the BlockAdditional Element could contain Alpha data.

7.2.93.  OldStereoMode Element

   name: "OldStereoMode"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\OldStereoMode)"

   id: "0x53B9"

   type: "uinteger"

   maxver: "0"

   documentation: DEPRECATED, DO NOT USE.  Bogus StereoMode value used
   in old versions of libmatroska. (0: mono, 1: right eye, 2: left eye,
   3: both eyes).

7.2.94.  PixelWidth Element

   name: "PixelWidth"

   path: "1*1(\Segment\Tracks\TrackEntry\Video\PixelWidth)"

   id: "0xB0"



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   minOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: Width of the encoded video frames in pixels.

7.2.95.  PixelHeight Element

   name: "PixelHeight"

   path: "1*1(\Segment\Tracks\TrackEntry\Video\PixelHeight)"

   id: "0xBA"

   minOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: Height of the encoded video frames in pixels.

7.2.96.  PixelCropBottom Element

   name: "PixelCropBottom"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\PixelCropBottom)"

   id: "0x54AA"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The number of video pixels to remove at the bottom of
   the image (for HDTV content).







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7.2.97.  PixelCropTop Element

   name: "PixelCropTop"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\PixelCropTop)"

   id: "0x54BB"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The number of video pixels to remove at the top of the
   image.

7.2.98.  PixelCropLeft Element

   name: "PixelCropLeft"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\PixelCropLeft)"

   id: "0x54CC"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The number of video pixels to remove on the left of
   the image.

7.2.99.  PixelCropRight Element

   name: "PixelCropRight"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\PixelCropRight)"

   id: "0x54DD"

   default: "0"

   type: "uinteger"

   minver: "1"




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   documentation: The number of video pixels to remove on the right of
   the image.

7.2.100.  DisplayWidth Element

   name: "DisplayWidth"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\DisplayWidth)"

   id: "0x54B0"

   range: "not 0"

   default: "PixelWidth - PixelCropLeft - PixelCropRight"

   type: "uinteger"

   minver: "1"

   documentation: Width of the video frames to display.  Applies to the
   video frame after cropping (PixelCrop* Elements).  The default value
   is only valid when DisplayUnit is 0.

7.2.101.  DisplayHeight Element

   name: "DisplayHeight"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\DisplayHeight)"

   id: "0x54BA"

   range: "not 0"

   default: "PixelHeight - PixelCropTop - PixelCropBottom"

   type: "uinteger"

   minver: "1"

   documentation: Height of the video frames to display.  Applies to the
   video frame after cropping (PixelCrop* Elements).  The default value
   is only valid when DisplayUnit is 0.

7.2.102.  DisplayUnit Element

   name: "DisplayUnit"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\DisplayUnit)"



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   id: "0x54B2"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: How DisplayWidth & DisplayHeight are interpreted (0:
   pixels, 1: centimeters, 2: inches, 3: Display Aspect Ratio, 4:
   Unknown).

7.2.103.  AspectRatioType Element

   name: "AspectRatioType"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\AspectRatioType)"

   id: "0x54B3"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: Specify the possible modifications to the aspect ratio
   (0: free resizing, 1: keep aspect ratio, 2: fixed).

7.2.104.  ColourSpace Element

   name: "ColourSpace"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\ColourSpace)"

   id: "0x2EB524"

   size: "4"

   type: "binary"

   minver: "1"

   documentation: Same value as in AVI (32 bits).







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7.2.105.  GammaValue Element

   name: "GammaValue"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\GammaValue)"

   id: "0x2FB523"

   range: "> 0x0p+0"

   type: "float"

   minver: "0"

   maxver: "0"

   documentation: Gamma Value.

7.2.106.  FrameRate Element

   name: "FrameRate"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\FrameRate)"

   id: "0x2383E3"

   range: "> 0x0p+0"

   type: "float"

   minver: "0"

   maxver: "0"

   documentation: Number of frames per second.  Informational only.

7.2.107.  Colour Element

   name: "Colour"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour)"

   id: "0x55B0"

   type: "master"

   minver: "4"




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   documentation: Settings describing the colour format.

7.2.108.  MatrixCoefficients Element

   name: "MatrixCoefficients"

   path:
   "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MatrixCoefficients)"

   id: "0x55B1"

   default: "2"

   type: "uinteger"

   minver: "4"

   documentation: The Matrix Coefficients of the video used to derive
   luma and chroma values from reg, green, and blue color primaries.
   For clarity, the value and meanings for MatrixCoefficients are
   adopted from Table 4 of ISO/IEC 23001-8:2013/DCOR1. (0:GBR, 1: BT709,
   2: Unspecified, 3: Reserved, 4: FCC, 5: BT470BG, 6: SMPTE 170M, 7:
   SMPTE 240M, 8: YCOCG, 9: BT2020 Non-constant Luminance, 10: BT2020
   Constant Luminance)

7.2.109.  BitsPerChannel Element

   name: "BitsPerChannel"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\BitsPerChannel)"

   id: "0x55B2"

   default: "0"

   type: "uinteger"

   minver: "4"

   documentation: Number of decoded bits per channel.  A value of 0
   indicates that the BitsPerChannel is unspecified.

7.2.110.  ChromaSubsamplingHorz Element

   name: "ChromaSubsamplingHorz"

   path:
   "0*1(\Segment\Tracks\TrackEntry\Video\Colour\ChromaSubsamplingHorz)"



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   id: "0x55B3"

   type: "uinteger"

   minver: "4"

   documentation: The amount of pixels to remove in the Cr and Cb
   channels for every pixel not removed horizontally.  Example: For
   video with 4:2:0 chroma subsampling, the ChromaSubsamplingHorz SHOULD
   be set to 1.

7.2.111.  ChromaSubsamplingVert Element

   name: "ChromaSubsamplingVert"

   path:
   "0*1(\Segment\Tracks\TrackEntry\Video\Colour\ChromaSubsamplingVert)"

   id: "0x55B4"

   type: "uinteger"

   minver: "4"

   documentation: The amount of pixels to remove in the Cr and Cb
   channels for every pixel not removed vertically.  Example: For video
   with 4:2:0 chroma subsampling, the ChromaSubsamplingVert SHOULD be
   set to 1.

7.2.112.  CbSubsamplingHorz Element

   name: "CbSubsamplingHorz"

   path:
   "0*1(\Segment\Tracks\TrackEntry\Video\Colour\CbSubsamplingHorz)"

   id: "0x55B5"

   type: "uinteger"

   minver: "4"

   documentation: The amount of pixels to remove in the Cb channel for
   every pixel not removed horizontally.  This is additive with
   ChromaSubsamplingHorz.  Example: For video with 4:2:1 chroma
   subsampling, the ChromaSubsamplingHorz SHOULD be set to 1 and
   CbSubsamplingHorz SHOULD be set to 1.




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7.2.113.  CbSubsamplingVert Element

   name: "CbSubsamplingVert"

   path:
   "0*1(\Segment\Tracks\TrackEntry\Video\Colour\CbSubsamplingVert)"

   id: "0x55B6"

   type: "uinteger"

   minver: "4"

   documentation: The amount of pixels to remove in the Cb channel for
   every pixel not removed vertically.  This is additive with
   ChromaSubsamplingVert.

7.2.114.  ChromaSitingHorz Element

   name: "ChromaSitingHorz"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\ChromaSitingHorz)"

   id: "0x55B7"

   default: "0"

   type: "uinteger"

   minver: "4"

   documentation: How chroma is subsampled horizontally. (0:
   Unspecified, 1: Left Collocated, 2: Half)

7.2.115.  ChromaSitingVert Element

   name: "ChromaSitingVert"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\ChromaSitingVert)"

   id: "0x55B8"

   default: "0"

   type: "uinteger"

   minver: "4"




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   documentation: How chroma is subsampled vertically. (0: Unspecified,
   1: Top Collocated, 2: Half)

7.2.116.  Range Element

   name: "Range"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\Range)"

   id: "0x55B9"

   default: "0"

   type: "uinteger"

   minver: "4"

   documentation: Clipping of the color ranges. (0: Unspecified, 1:
   Broadcast Range, 2: Full range (no clipping), 3: Defined by
   MatrixCoefficients/TransferCharacteristics)

7.2.117.  TransferCharacteristics Element

   name: "TransferCharacteristics"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\TransferCharacteri
   stics)"

   id: "0x55BA"

   default: "2"

   type: "uinteger"

   minver: "4"

   documentation: The transfer characteristics of the video.  For
   clarity, the value and meanings for TransferCharacteristics 1-15 are
   adopted from Table 3 of ISO/IEC 23001-8:2013/DCOR1.
   TransferCharacteristics 16-18 are proposed values. (0: Reserved, 1:
   ITU-R BT.709, 2: Unspecified, 3: Reserved, 4: Gamma 2.2 curve, 5:
   Gamma 2.8 curve, 6: SMPTE 170M, 7: SMPTE 240M, 8: Linear, 9: Log, 10:
   Log Sqrt, 11: IEC 61966-2-4, 12: ITU-R BT.1361 Extended Colour Gamut,
   13: IEC 61966-2-1, 14: ITU-R BT.2020 10 bit, 15: ITU-R BT.2020 12
   bit, 16: SMPTE ST 2084, 17: SMPTE ST 428-1 18: ARIB STD-B67 (HLG))






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7.2.118.  Primaries Element

   name: "Primaries"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\Primaries)"

   id: "0x55BB"

   default: "2"

   type: "uinteger"

   minver: "4"

   documentation: The colour primaries of the video.  For clarity, the
   value and meanings for Primaries are adopted from Table 2 of ISO/IEC
   23001-8:2013/DCOR1. (0: Reserved, 1: ITU-R BT.709, 2: Unspecified, 3:
   Reserved, 4: ITU-R BT.470M, 5: ITU-R BT.470BG, 6: SMPTE 170M, 7:
   SMPTE 240M, 8: FILM, 9: ITU-R BT.2020, 10: SMPTE ST 428-1, 22: JEDEC
   P22 phosphors)

7.2.119.  MaxCLL Element

   name: "MaxCLL"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MaxCLL)"

   id: "0x55BC"

   type: "uinteger"

   minver: "4"

   documentation: Maximum brightness of a single pixel (Maximum Content
   Light Level) in candelas per square meter (cd/m^2).

7.2.120.  MaxFALL Element

   name: "MaxFALL"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MaxFALL)"

   id: "0x55BD"

   type: "uinteger"

   minver: "4"




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   documentation: Maximum brightness of a single full frame (Maximum
   Frame-Average Light Level) in candelas per square meter (cd/m^2).

7.2.121.  MasteringMetadata Element

   name: "MasteringMetadata"

   path:
   "0*1(\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata)"

   id: "0x55D0"

   type: "master"

   minver: "4"

   documentation: SMPTE 2086 mastering data.

7.2.122.  PrimaryRChromaticityX Element

   name: "PrimaryRChromaticityX"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\PrimaryRChromatici
   tyX\PrimaryRChromaticityX)"

   id: "0x55D1"

   range: "0-1"

   type: "float"

   minver: "4"

   documentation: Red X chromaticity coordinate as defined by CIE 1931.

7.2.123.  PrimaryRChromaticityY Element

   name: "PrimaryRChromaticityY"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\PrimaryRChromatici
   tyX\PrimaryRChromaticityY)"

   id: "0x55D2"

   range: "0-1"

   type: "float"




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   minver: "4"

   documentation: Red Y chromaticity coordinate as defined by CIE 1931.

7.2.124.  PrimaryGChromaticityX Element

   name: "PrimaryGChromaticityX"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\PrimaryRChromatici
   tyX\PrimaryGChromaticityX)"

   id: "0x55D3"

   range: "0-1"

   type: "float"

   minver: "4"

   documentation: Green X chromaticity coordinate as defined by CIE
   1931.

7.2.125.  PrimaryGChromaticityY Element

   name: "PrimaryGChromaticityY"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\PrimaryRChromatici
   tyX\PrimaryGChromaticityY)"

   id: "0x55D4"

   range: "0-1"

   type: "float"

   minver: "4"

   documentation: Green Y chromaticity coordinate as defined by CIE
   1931.

7.2.126.  PrimaryBChromaticityX Element

   name: "PrimaryBChromaticityX"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\PrimaryRChromatici
   tyX\PrimaryBChromaticityX)"

   id: "0x55D5"



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   range: "0-1"

   type: "float"

   minver: "4"

   documentation: Blue X chromaticity coordinate as defined by CIE 1931.

7.2.127.  PrimaryBChromaticityY Element

   name: "PrimaryBChromaticityY"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\PrimaryRChromatici
   tyX\PrimaryBChromaticityY)"

   id: "0x55D6"

   range: "0-1"

   type: "float"

   minver: "4"

   documentation: Blue Y chromaticity coordinate as defined by CIE 1931.

7.2.128.  WhitePointChromaticityX Element

   name: "WhitePointChromaticityX"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\PrimaryRChromatici
   tyX\WhitePointChromaticityX)"

   id: "0x55D7"

   range: "0-1"

   type: "float"

   minver: "4"

   documentation: White X chromaticity coordinate as defined by CIE
   1931.

7.2.129.  WhitePointChromaticityY Element

   name: "WhitePointChromaticityY"





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   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\PrimaryRChromatici
   tyX\WhitePointChromaticityY)"

   id: "0x55D8"

   range: "0-1"

   type: "float"

   minver: "4"

   documentation: White Y chromaticity coordinate as defined by CIE
   1931.

7.2.130.  LuminanceMax Element

   name: "LuminanceMax"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\PrimaryRChromatici
   tyX\LuminanceMax)"

   id: "0x55D9"

   range: "0-9999.99"

   type: "float"

   minver: "4"

   documentation: Maximum luminance.  Represented in candelas per square
   meter (cd/m^2).

7.2.131.  LuminanceMin Element

   name: "LuminanceMin"

   path: "0*1(\Segment\Tracks\TrackEntry\Video\Colour\PrimaryRChromatici
   tyX\LuminanceMin)"

   id: "0x55DA"

   range: "0-999.9999"

   type: "float"

   minver: "4"





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   documentation: Mininum luminance.  Represented in candelas per square
   meter (cd/m^2).

7.2.132.  Audio Element

   name: "Audio"

   path: "0*1(\Segment\Tracks\TrackEntry\Audio)"

   id: "0xE1"

   type: "master"

   minver: "1"

   documentation: Audio settings.

7.2.133.  SamplingFrequency Element

   name: "SamplingFrequency"

   path: "1*1(\Segment\Tracks\TrackEntry\Audio\SamplingFrequency)"

   id: "0xB5"

   minOccurs: "1"

   range: "> 0x0p+0"

   default: "0x1.f4p+12"

   type: "float"

   minver: "1"

   documentation: Sampling frequency in Hz.

7.2.134.  OutputSamplingFrequency Element

   name: "OutputSamplingFrequency"

   path: "0*1(\Segment\Tracks\TrackEntry\Audio\OutputSamplingFrequency)"

   id: "0x78B5"

   range: "> 0x0p+0"

   default: "SamplingFrequency"



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   type: "float"

   minver: "1"

   documentation: Real output sampling frequency in Hz (used for SBR
   techniques).

7.2.135.  Channels Element

   name: "Channels"

   path: "1*1(\Segment\Tracks\TrackEntry\Audio\Channels)"

   id: "0x9F"

   minOccurs: "1"

   range: "not 0"

   default: "1"

   type: "uinteger"

   minver: "1"

   documentation: Numbers of channels in the track.

7.2.136.  ChannelPositions Element

   name: "ChannelPositions"

   path: "0*1(\Segment\Tracks\TrackEntry\Audio\ChannelPositions)"

   id: "0x7D7B"

   type: "binary"

   minver: "0"

   maxver: "0"

   documentation: Table of horizontal angles for each successive
   channel, see appendix.








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7.2.137.  BitDepth Element

   name: "BitDepth"

   path: "0*1(\Segment\Tracks\TrackEntry\Audio\BitDepth)"

   id: "0x6264"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: Bits per sample, mostly used for PCM.

7.2.138.  TrackOperation Element

   name: "TrackOperation"

   path: "0*1(\Segment\Tracks\TrackEntry\TrackOperation)"

   id: "0xE2"

   type: "master"

   minver: "3"

   documentation: Operation that needs to be applied on tracks to create
   this virtual track.  For more details look at the Specification Notes
   on the subject.

7.2.139.  TrackCombinePlanes Element

   name: "TrackCombinePlanes"

   path:
   "0*1(\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes)"

   id: "0xE3"

   type: "master"

   minver: "3"

   documentation: Contains the list of all video plane tracks that need
   to be combined to create this 3D track




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7.2.140.  TrackPlane Element

   name: "TrackPlane"

   path: "1*(\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlane
   s\TrackPlane)"

   id: "0xE4"

   minOccurs: "1"

   maxOccurs: "unbounded"

   type: "master"

   minver: "3"

   documentation: Contains a video plane track that need to be combined
   to create this 3D track

7.2.141.  TrackPlaneUID Element

   name: "TrackPlaneUID"

   path: "1*1(\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlan
   es\TrackPlane\TrackPlaneUID)"

   id: "0xE5"

   minOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "3"

   documentation: The trackUID number of the track representing the
   plane.

7.2.142.  TrackPlaneType Element

   name: "TrackPlaneType"

   path: "1*1(\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlan
   es\TrackPlane\TrackPlaneType)"

   id: "0xE6"



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   minOccurs: "1"

   type: "uinteger"

   minver: "3"

   documentation: The kind of plane this track corresponds to (0: left
   eye, 1: right eye, 2: background).

7.2.143.  TrackJoinBlocks Element

   name: "TrackJoinBlocks"

   path:
   "0*1(\Segment\Tracks\TrackEntry\TrackOperation\TrackJoinBlocks)"

   id: "0xE9"

   type: "master"

   minver: "3"

   documentation: Contains the list of all tracks whose Blocks need to
   be combined to create this virtual track

7.2.144.  TrackJoinUID Element

   name: "TrackJoinUID"

   path: "1*(\Segment\Tracks\TrackEntry\TrackOperation\TrackJoinBlocks\T
   rackJoinUID)"

   id: "0xED"

   minOccurs: "1"

   maxOccurs: "unbounded"

   range: "not 0"

   type: "uinteger"

   minver: "3"

   documentation: The trackUID number of a track whose blocks are used
   to create this virtual track.





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7.2.145.  TrickTrackUID Element

   name: "TrickTrackUID"

   path: "0*1(\Segment\Tracks\TrackEntry\TrickTrackUID)"

   id: "0xC0"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: DivX trick track extenstions

7.2.146.  TrickTrackSegmentUID Element

   name: "TrickTrackSegmentUID"

   path: "0*1(\Segment\Tracks\TrackEntry\TrickTrackSegmentUID)"

   id: "0xC1"

   size: "16"

   type: "binary"

   minver: "0"

   maxver: "0"

   documentation: DivX trick track extenstions

7.2.147.  TrickTrackFlag Element

   name: "TrickTrackFlag"

   path: "0*1(\Segment\Tracks\TrackEntry\TrickTrackFlag)"

   id: "0xC6"

   default: "0"

   type: "uinteger"

   minver: "0"




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   maxver: "0"

   documentation: DivX trick track extenstions

7.2.148.  TrickMasterTrackUID Element

   name: "TrickMasterTrackUID"

   path: "0*1(\Segment\Tracks\TrackEntry\TrickMasterTrackUID)"

   id: "0xC7"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: DivX trick track extenstions

7.2.149.  TrickMasterTrackSegmentUID Element

   name: "TrickMasterTrackSegmentUID"

   path: "0*1(\Segment\Tracks\TrackEntry\TrickMasterTrackSegmentUID)"

   id: "0xC4"

   size: "16"

   type: "binary"

   minver: "0"

   maxver: "0"

   documentation: DivX trick track extenstions

7.2.150.  ContentEncodings Element

   name: "ContentEncodings"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings)"

   id: "0x6D80"

   type: "master"




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   minver: "1"

   documentation: Settings for several content encoding mechanisms like
   compression or encryption.

7.2.151.  ContentEncoding Element

   name: "ContentEncoding"

   path:
   "1*(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding)"

   id: "0x6240"

   minOccurs: "1"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   documentation: Settings for one content encoding like compression or
   encryption.

7.2.152.  ContentEncodingOrder Element

   name: "ContentEncodingOrder"

   path: "1*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncodingOrder)"

   id: "0x5031"

   minOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: Tells when this modification was used during encoding/
   muxing starting with 0 and counting upwards.  The decoder/demuxer has
   to start with the highest order number it finds and work its way
   down.  This value has to be unique over all ContentEncodingOrder
   Elements in the Segment.




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7.2.153.  ContentEncodingScope Element

   name: "ContentEncodingScope"

   path: "1*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncodingScope)"

   id: "0x5032"

   minOccurs: "1"

   range: "not 0"

   default: "1"

   type: "uinteger"

   minver: "1"

   documentation: A bit field that describes which Elements have been
   modified in this way.  Values (big endian) can be OR'ed.  Possible
   values: 1 - all frame contents, 2 - the track's private data, 4 - the
   next ContentEncoding (next ContentEncodingOrder.  Either the data
   inside ContentCompression and/or ContentEncryption)

7.2.154.  ContentEncodingType Element

   name: "ContentEncodingType"

   path: "1*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncodingType)"

   id: "0x5033"

   minOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: A value describing what kind of transformation has
   been done.  Possible values: 0 - compression, 1 - encryption







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7.2.155.  ContentCompression Element

   name: "ContentCompression"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentCompression)"

   id: "0x5034"

   type: "master"

   minver: "1"

   documentation: Settings describing the compression used.  This
   Element MUST be present if the value of ContentEncodingType is 0 and
   absent otherwise.  Each block MUST be decompressable even if no
   previous block is available in order not to prevent seeking.

7.2.156.  ContentCompAlgo Element

   name: "ContentCompAlgo"

   path: "1*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentCompression\ContentCompAlgo)"

   id: "0x4254"

   minOccurs: "1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The compression algorithm used.  Algorithms that have
   been specified so far are: 0 - zlib, 1 - bzlib, 2 - lzo1x 3 - Header
   Stripping

7.2.157.  ContentCompSettings Element

   name: "ContentCompSettings"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentCompression\ContentCompSettings)"

   id: "0x4255"




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   type: "binary"

   minver: "1"

   documentation: Settings that might be needed by the decompressor.
   For Header Stripping (ContentCompAlgo=3), the bytes that were removed
   from the beggining of each frames of the track.

7.2.158.  ContentEncryption Element

   name: "ContentEncryption"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncryption)"

   id: "0x5035"

   type: "master"

   minver: "1"

   documentation: Settings describing the encryption used.  This Element
   MUST be present if the value of ContentEncodingType is 1 and absent
   otherwise.

7.2.159.  ContentEncAlgo Element

   name: "ContentEncAlgo"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncryption\ContentEncAlgo)"

   id: "0x47E1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The encryption algorithm used.  The value '0' means
   that the contents have not been encrypted but only signed.
   Predefined values: 1 - DES, 2 - 3DES, 3 - Twofish, 4 - Blowfish, 5 -
   AES







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7.2.160.  ContentEncKeyID Element

   name: "ContentEncKeyID"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncryption\ContentEncKeyID)"

   id: "0x47E2"

   type: "binary"

   minver: "1"

   documentation: For public key algorithms this is the ID of the public
   key the the data was encrypted with.

7.2.161.  ContentSignature Element

   name: "ContentSignature"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncryption\ContentSignature)"

   id: "0x47E3"

   type: "binary"

   minver: "1"

   documentation: A cryptographic signature of the contents.

7.2.162.  ContentSigKeyID Element

   name: "ContentSigKeyID"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncryption\ContentSigKeyID)"

   id: "0x47E4"

   type: "binary"

   minver: "1"

   documentation: This is the ID of the private key the data was signed
   with.





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7.2.163.  ContentSigAlgo Element

   name: "ContentSigAlgo"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncryption\ContentSigAlgo)"

   id: "0x47E5"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The algorithm used for the signature.  A value of '0'
   means that the contents have not been signed but only encrypted.
   Predefined values: 1 - RSA

7.2.164.  ContentSigHashAlgo Element

   name: "ContentSigHashAlgo"

   path: "0*1(\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncodin
   g\ContentEncryption\ContentSigHashAlgo)"

   id: "0x47E6"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: The hash algorithm used for the signature.  A value of
   '0' means that the contents have not been signed but only encrypted.
   Predefined values: 1 - SHA1-160 2 - MD5

7.2.165.  Cues Element

   name: "Cues"

   path: "0*1(\Segment\Cues)"

   id: "0x1C53BB6B"

   type: "master"




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   minver: "1"

   documentation: A Top-Level Element to speed seeking access.  All
   entries are local to the Segment.  This Element SHOULD be mandatory
   for non "live" streams.

7.2.166.  CuePoint Element

   name: "CuePoint"

   path: "1*(\Segment\Cues\CuePoint)"

   id: "0xBB"

   minOccurs: "1"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   documentation: Contains all information relative to a seek point in
   the Segment.

7.2.167.  CueTime Element

   name: "CueTime"

   path: "1*1(\Segment\Cues\CuePoint\CueTime)"

   id: "0xB3"

   minOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: Absolute timestamp according to the Segment time base.

7.2.168.  CueTrackPositions Element

   name: "CueTrackPositions"

   path: "1*(\Segment\Cues\CuePoint\CueTrackPositions)"

   id: "0xB7"



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   minOccurs: "1"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   documentation: Contain positions for different tracks corresponding
   to the timestamp.

7.2.169.  CueTrack Element

   name: "CueTrack"

   path: "1*1(\Segment\Cues\CuePoint\CueTrackPositions\CueTrack)"

   id: "0xF7"

   minOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: The track for which a position is given.

7.2.170.  CueClusterPosition Element

   name: "CueClusterPosition"

   path:
   "1*1(\Segment\Cues\CuePoint\CueTrackPositions\CueClusterPosition)"

   id: "0xF1"

   minOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: The position of the Cluster containing the associated
   Block.





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7.2.171.  CueRelativePosition Element

   name: "CueRelativePosition"

   path:
   "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueRelativePosition)"

   id: "0xF0"

   type: "uinteger"

   minver: "4"

   documentation: The relative position of the referenced block inside
   the cluster with 0 being the first possible position for an Element
   inside that cluster.

7.2.172.  CueDuration Element

   name: "CueDuration"

   path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueDuration)"

   id: "0xB2"

   type: "uinteger"

   minver: "4"

   documentation: The duration of the block according to the Segment
   time base.  If missing the track's DefaultDuration does not apply and
   no duration information is available in terms of the cues.

7.2.173.  CueBlockNumber Element

   name: "CueBlockNumber"

   path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueBlockNumber)"

   id: "0x5378"

   range: "not 0"

   default: "1"

   type: "uinteger"

   minver: "1"



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   documentation: Number of the Block in the specified Cluster.

7.2.174.  CueCodecState Element

   name: "CueCodecState"

   path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueCodecState)"

   id: "0xEA"

   default: "0"

   type: "uinteger"

   minver: "2"

   documentation: The position of the Codec State corresponding to this
   Cue Element. 0 means that the data is taken from the initial Track
   Entry.

7.2.175.  CueReference Element

   name: "CueReference"

   path: "0*(\Segment\Cues\CuePoint\CueTrackPositions\CueReference)"

   id: "0xDB"

   maxOccurs: "unbounded"

   type: "master"

   minver: "2"

   documentation: The Clusters containing the referenced Blocks.

7.2.176.  CueRefTime Element

   name: "CueRefTime"

   path: "1*1(\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueR
   efTime)"

   id: "0x96"

   minOccurs: "1"

   type: "uinteger"



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   minver: "2"

   documentation: Timestamp of the referenced Block.

7.2.177.  CueRefCluster Element

   name: "CueRefCluster"

   path: "1*1(\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueR
   efCluster)"

   id: "0x97"

   minOccurs: "1"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: The Position of the Cluster containing the referenced
   Block.

7.2.178.  CueRefNumber Element

   name: "CueRefNumber"

   path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueR
   efNumber)"

   id: "0x535F"

   range: "not 0"

   default: "1"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: Number of the referenced Block of Track X in the
   specified Cluster.






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7.2.179.  CueRefCodecState Element

   name: "CueRefCodecState"

   path: "0*1(\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueR
   efCodecState)"

   id: "0xEB"

   default: "0"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: The position of the Codec State corresponding to this
   referenced Element. 0 means that the data is taken from the initial
   Track Entry.

7.2.180.  Attachments Element

   name: "Attachments"

   path: "0*1(\Segment\Attachments)"

   id: "0x1941A469"

   type: "master"

   minver: "1"

   documentation: Contain attached files.

7.2.181.  AttachedFile Element

   name: "AttachedFile"

   path: "1*(\Segment\Attachments\AttachedFile)"

   id: "0x61A7"

   minOccurs: "1"

   maxOccurs: "unbounded"

   type: "master"



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   minver: "1"

   documentation: An attached file.

7.2.182.  FileDescription Element

   name: "FileDescription"

   path: "0*1(\Segment\Attachments\AttachedFile\FileDescription)"

   id: "0x467E"

   type: "utf-8"

   minver: "1"

   documentation: A human-friendly name for the attached file.

7.2.183.  FileName Element

   name: "FileName"

   path: "1*1(\Segment\Attachments\AttachedFile\FileName)"

   id: "0x466E"

   minOccurs: "1"

   type: "utf-8"

   minver: "1"

   documentation: Filename of the attached file.

7.2.184.  FileMimeType Element

   name: "FileMimeType"

   path: "1*1(\Segment\Attachments\AttachedFile\FileMimeType)"

   id: "0x4660"

   minOccurs: "1"

   type: "string"

   minver: "1"




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   documentation: MIME type of the file.

7.2.185.  FileData Element

   name: "FileData"

   path: "1*1(\Segment\Attachments\AttachedFile\FileData)"

   id: "0x465C"

   minOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: The data of the file.

7.2.186.  FileUID Element

   name: "FileUID"

   path: "1*1(\Segment\Attachments\AttachedFile\FileUID)"

   id: "0x46AE"

   minOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: Unique ID representing the file, as random as
   possible.

7.2.187.  FileReferral Element

   name: "FileReferral"

   path: "0*1(\Segment\Attachments\AttachedFile\FileReferral)"

   id: "0x4675"

   type: "binary"

   minver: "0"



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   maxver: "0"

   documentation: A binary value that a track/codec can refer to when
   the attachment is needed.

7.2.188.  FileUsedStartTime Element

   name: "FileUsedStartTime"

   path: "0*1(\Segment\Attachments\AttachedFile\FileUsedStartTime)"

   id: "0x4661"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: DivX font extension

7.2.189.  FileUsedEndTime Element

   name: "FileUsedEndTime"

   path: "0*1(\Segment\Attachments\AttachedFile\FileUsedEndTime)"

   id: "0x4662"

   type: "uinteger"

   minver: "0"

   maxver: "0"

   documentation: DivX font extension

7.2.190.  Chapters Element

   name: "Chapters"

   path: "0*1(\Segment\Chapters)"

   id: "0x1043A770"

   type: "master"

   minver: "1"



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   documentation: A system to define basic menus and partition data.
   For more detailed information, look at the Chapters Explanation.

7.2.191.  EditionEntry Element

   name: "EditionEntry"

   path: "1*(\Segment\Chapters\EditionEntry)"

   id: "0x45B9"

   minOccurs: "1"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   documentation: Contains all information about a Segment edition.

7.2.192.  EditionUID Element

   name: "EditionUID"

   path: "0*1(\Segment\Chapters\EditionEntry\EditionUID)"

   id: "0x45BC"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: A unique ID to identify the edition.  It's useful for
   tagging an edition.

7.2.193.  EditionFlagHidden Element

   name: "EditionFlagHidden"

   path: "1*1(\Segment\Chapters\EditionEntry\EditionFlagHidden)"

   id: "0x45BD"

   minOccurs: "1"




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   range: "0-1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: If an edition is hidden (1), it SHOULD NOT be
   available to the user interface (but still to Control Tracks; see
   flag notes). (1 bit)

7.2.194.  EditionFlagDefault Element

   name: "EditionFlagDefault"

   path: "1*1(\Segment\Chapters\EditionEntry\EditionFlagDefault)"

   id: "0x45DB"

   minOccurs: "1"

   range: "0-1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: If a flag is set (1) the edition SHOULD be used as the
   default one. (1 bit)

7.2.195.  EditionFlagOrdered Element

   name: "EditionFlagOrdered"

   path: "0*1(\Segment\Chapters\EditionEntry\EditionFlagOrdered)"

   id: "0x45DD"

   range: "0-1"

   default: "0"

   type: "uinteger"

   minver: "1"



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   documentation: Specify if the chapters can be defined multiple times
   and the order to play them is enforced. (1 bit)

7.2.196.  ChapterAtom Element

   name: "ChapterAtom"

   path: "1*(\Segment\Chapters\EditionEntry(1*(\ChapterAtom)))"

   id: "0xB6"

   minOccurs: "1"

   maxOccurs: "unbounded"

   type: "master"

   recursive: "1"

   minver: "1"

   documentation: Contains the atom information to use as the chapter
   atom (apply to all tracks).

7.2.197.  ChapterUID Element

   name: "ChapterUID"

   path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterUID)"

   id: "0x73C4"

   minOccurs: "1"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: A unique ID to identify the Chapter.

7.2.198.  ChapterStringUID Element

   name: "ChapterStringUID"

   path:
   "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterStringUID)"



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   id: "0x5654"

   type: "utf-8"

   minver: "3"

   documentation: A unique string ID to identify the Chapter.  Use for
   WebVTT cue identifier storage.

7.2.199.  ChapterTimeStart Element

   name: "ChapterTimeStart"

   path:
   "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterTimeStart)"

   id: "0x91"

   minOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: Timestamp of the start of Chapter (not scaled).

7.2.200.  ChapterTimeEnd Element

   name: "ChapterTimeEnd"

   path:
   "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterTimeEnd)"

   id: "0x92"

   type: "uinteger"

   minver: "1"

   documentation: Timestamp of the end of Chapter (timestamp excluded,
   not scaled).

7.2.201.  ChapterFlagHidden Element

   name: "ChapterFlagHidden"

   path:
   "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterFlagHidden)"



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   id: "0x98"

   minOccurs: "1"

   range: "0-1"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: If a chapter is hidden (1), it SHOULD NOT be available
   to the user interface (but still to Control Tracks; see flag notes).
   (1 bit)

7.2.202.  ChapterFlagEnabled Element

   name: "ChapterFlagEnabled"

   path:
   "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterFlagEnabled)"

   id: "0x4598"

   minOccurs: "1"

   range: "0-1"

   default: "1"

   type: "uinteger"

   minver: "1"

   documentation: Specify wether the chapter is enabled.  It can be
   enabled/disabled by a Control Track.  When disabled, the movie SHOULD
   skip all the content between the TimeStart and TimeEnd of this
   chapter (see flag notes). (1 bit)

7.2.203.  ChapterSegmentUID Element

   name: "ChapterSegmentUID"

   path:
   "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterSegmentUID)"

   id: "0x6E67"



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   range: ">0"

   size: "16"

   type: "binary"

   minver: "1"

   documentation: The SegmentUID of another Segment to play during this
   chapter.

   usage notes: ChapterSegmentUID is mandatory if
   ChapterSegmentEditionUID is used.

7.2.204.  ChapterSegmentEditionUID Element

   name: "ChapterSegmentEditionUID"

   path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterSegmentE
   ditionUID)"

   id: "0x6EBC"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: The EditionUID to play from the Segment linked in
   ChapterSegmentUID.  If ChapterSegmentEditionUID is undeclared then no
   Edition of the linked Segment is used.

7.2.205.  ChapterPhysicalEquiv Element

   name: "ChapterPhysicalEquiv"

   path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterPhysical
   Equiv)"

   id: "0x63C3"

   type: "uinteger"

   minver: "1"

   documentation: Specify the physical equivalent of this ChapterAtom
   like "DVD" (60) or "SIDE" (50), see complete list of values.



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7.2.206.  ChapterTrack Element

   name: "ChapterTrack"

   path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterTrack)"

   id: "0x8F"

   type: "master"

   minver: "1"

   documentation: List of tracks on which the chapter applies.  If this
   Element is not present, all tracks apply

7.2.207.  ChapterTrackNumber Element

   name: "ChapterTrackNumber"

   path: "1*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterTrack\Cha
   pterTrackNumber)"

   id: "0x89"

   minOccurs: "1"

   maxOccurs: "unbounded"

   range: "not 0"

   type: "uinteger"

   minver: "1"

   documentation: UID of the Track to apply this chapter too.  In the
   absence of a control track, choosing this chapter will select the
   listed Tracks and deselect unlisted tracks.  Absence of this Element
   indicates that the Chapter SHOULD be applied to any currently used
   Tracks.

7.2.208.  ChapterDisplay Element

   name: "ChapterDisplay"

   path: "0*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterDisplay)"

   id: "0x80"




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   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   documentation: Contains all possible strings to use for the chapter
   display.

7.2.209.  ChapString Element

   name: "ChapString"

   path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterDisplay\
   ChapString)"

   id: "0x85"

   minOccurs: "1"

   type: "utf-8"

   minver: "1"

   documentation: Contains the string to use as the chapter atom.

7.2.210.  ChapLanguage Element

   name: "ChapLanguage"

   path: "1*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterDisplay\C
   hapLanguage)"

   id: "0x437C"

   minOccurs: "1"

   maxOccurs: "unbounded"

   default: "eng"

   type: "string"

   minver: "1"

   documentation: The languages corresponding to the string, in the
   bibliographic ISO-639-2 form.




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7.2.211.  ChapCountry Element

   name: "ChapCountry"

   path: "0*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapterDisplay\C
   hapCountry)"

   id: "0x437E"

   maxOccurs: "unbounded"

   type: "string"

   minver: "1"

   documentation: The countries corresponding to the string, same 2
   octets as in Internet domains.

7.2.212.  ChapProcess Element

   name: "ChapProcess"

   path: "0*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess)"

   id: "0x6944"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   documentation: Contains all the commands associated to the Atom.

7.2.213.  ChapProcessCodecID Element

   name: "ChapProcessCodecID"

   path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess\Cha
   pProcessCodecID)"

   id: "0x6955"

   minOccurs: "1"

   default: "0"

   type: "uinteger"



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   minver: "1"

   documentation: Contains the type of the codec used for the
   processing.  A value of 0 means native Matroska processing (to be
   defined), a value of 1 means the DVD command set is used.  More codec
   IDs can be added later.

7.2.214.  ChapProcessPrivate Element

   name: "ChapProcessPrivate"

   path: "0*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess\Cha
   pProcessPrivate)"

   id: "0x450D"

   type: "binary"

   minver: "1"

   documentation: Some optional data attached to the ChapProcessCodecID
   information.  For ChapProcessCodecID = 1, it is the "DVD level"
   equivalent.

7.2.215.  ChapProcessCommand Element

   name: "ChapProcessCommand"

   path: "0*(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess\Chap
   ProcessCommand)"

   id: "0x6911"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   documentation: Contains all the commands associated to the Atom.

7.2.216.  ChapProcessTime Element

   name: "ChapProcessTime"

   path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess\Cha
   pProcessCommand\ChapProcessTime)"




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   id: "0x6922"

   minOccurs: "1"

   type: "uinteger"

   minver: "1"

   documentation: Defines when the process command SHOULD be handled (0:
   during the whole chapter, 1: before starting playback, 2: after
   playback of the chapter).

7.2.217.  ChapProcessData Element

   name: "ChapProcessData"

   path: "1*1(\Segment\Chapters\EditionEntry\ChapterAtom\ChapProcess\Cha
   pProcessCommand\ChapProcessData)"

   id: "0x6933"

   minOccurs: "1"

   type: "binary"

   minver: "1"

   documentation: Contains the command information.  The data SHOULD be
   interpreted depending on the ChapProcessCodecID value.  For
   ChapProcessCodecID = 1, the data correspond to the binary DVD cell
   pre/post commands.

7.2.218.  Tags Element

   name: "Tags"

   path: "0*(\Segment\Tags)"

   id: "0x1254C367"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   documentation: Element containing Elements specific to Tracks/
   Chapters.  A list of valid tags can be found here.



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7.2.219.  Tag Element

   name: "Tag"

   path: "1*(\Segment\Tags\Tag)"

   id: "0x7373"

   minOccurs: "1"

   maxOccurs: "unbounded"

   type: "master"

   minver: "1"

   documentation: Element containing Elements specific to Tracks/
   Chapters.

7.2.220.  Targets Element

   name: "Targets"

   path: "1*1(\Segment\Tags\Tag\Targets)"

   id: "0x63C0"

   minOccurs: "1"

   type: "master"

   minver: "1"

   documentation: Contain all UIDs where the specified meta data apply.
   It is empty to describe everything in the Segment.

7.2.221.  TargetTypeValue Element

   name: "TargetTypeValue"

   path: "0*1(\Segment\Tags\Tag\Targets\TargetTypeValue)"

   id: "0x68CA"

   default: "50"

   type: "uinteger"




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   minver: "1"

   documentation: A number to indicate the logical level of the target
   (see TargetType).

7.2.222.  TargetType Element

   name: "TargetType"

   path: "0*1(\Segment\Tags\Tag\Targets\TargetType)"

   id: "0x63CA"

   type: "string"

   minver: "1"

   documentation: An informational string that can be used to display
   the logical level of the target like "ALBUM", "TRACK", "MOVIE",
   "CHAPTER", etc (see TargetType).

7.2.223.  TagTrackUID Element

   name: "TagTrackUID"

   path: "0*(\Segment\Tags\Tag\Targets\TagTrackUID)"

   id: "0x63C5"

   maxOccurs: "unbounded"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: A unique ID to identify the Track(s) the tags belong
   to.  If the value is 0 at this level, the tags apply to all tracks in
   the Segment.

7.2.224.  TagEditionUID Element

   name: "TagEditionUID"

   path: "0*(\Segment\Tags\Tag\Targets\TagEditionUID)"

   id: "0x63C9"



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   maxOccurs: "unbounded"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: A unique ID to identify the EditionEntry(s) the tags
   belong to.  If the value is 0 at this level, the tags apply to all
   editions in the Segment.

7.2.225.  TagChapterUID Element

   name: "TagChapterUID"

   path: "0*(\Segment\Tags\Tag\Targets\TagChapterUID)"

   id: "0x63C4"

   maxOccurs: "unbounded"

   default: "0"

   type: "uinteger"

   minver: "1"

   documentation: A unique ID to identify the Chapter(s) the tags belong
   to.  If the value is 0 at this level, the tags apply to all chapters
   in the Segment.

7.2.226.  TagAttachmentUID Element

   name: "TagAttachmentUID"

   path: "0*(\Segment\Tags\Tag\Targets\TagAttachmentUID)"

   id: "0x63C6"

   maxOccurs: "unbounded"

   default: "0"

   type: "uinteger"

   minver: "1"




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   documentation: A unique ID to identify the Attachment(s) the tags
   belong to.  If the value is 0 at this level, the tags apply to all
   the attachments in the Segment.

7.2.227.  SimpleTag Element

   name: "SimpleTag"

   path: "1*(\Segment\Tags\Tag(1*(\SimpleTag)))"

   id: "0x67C8"

   minOccurs: "1"

   maxOccurs: "unbounded"

   type: "master"

   recursive: "1"

   minver: "1"

   documentation: Contains general information about the target.

7.2.228.  TagName Element

   name: "TagName"

   path: "1*1(\Segment\Tags\Tag\SimpleTag\TagName)"

   id: "0x45A3"

   minOccurs: "1"

   type: "utf-8"

   minver: "1"

   documentation: The name of the Tag that is going to be stored.

7.2.229.  TagLanguage Element

   name: "TagLanguage"

   path: "1*1(\Segment\Tags\Tag\SimpleTag\TagLanguage)"

   id: "0x447A"




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   minOccurs: "1"

   default: "und"

   type: "string"

   minver: "1"

   documentation: Specifies the language of the tag specified, in the
   Matroska languages form.

7.2.230.  TagDefault Element

   name: "TagDefault"

   path: "1*1(\Segment\Tags\Tag\SimpleTag\TagDefault)"

   id: "0x4484"

   minOccurs: "1"

   range: "0-1"

   default: "1"

   type: "uinteger"

   minver: "1"

   documentation: Indication to know if this is the default/original
   language to use for the given tag. (1 bit)

7.2.231.  TagString Element

   name: "TagString"

   path: "0*1(\Segment\Tags\Tag\SimpleTag\TagString)"

   id: "0x4487"

   type: "utf-8"

   minver: "1"

   documentation: The value of the Tag.






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7.2.232.  TagBinary Element

   name: "TagBinary"

   path: "0*1(\Segment\Tags\Tag\SimpleTag\TagBinary)"

   id: "0x4485"

   type: "binary"

   minver: "1"

   documentation: The values of the Tag if it is binary.  Note that this
   cannot be used in the same SimpleTag as TagString.

   If you intend to implement a Matroska player, make sure you can
   handle all the files in our test suite [17], or at least the features
   presented there, not necessarily the same codecs.

8.  Beginning of File

   An EBML file always starts with 0x1A.  The 0x1A makes the DOS command
   "type" ends display.  That way you can include ASCII text before the
   EBML data and it can be displayed.  The EBML parser is safe from
   false-alarm with these ASCII only codes.

   Next the EBML header is stored.  This allows the the parser to know
   what type of EBML file it is parsing.

9.  Block Timecodes

   The Block's timecode is signed integer that represents the Raw
   Timecode relative to the Cluster's [18] Timecode [19], multiplied by
   the TimecodeScale (see the TimecodeScale notes [20]).

   The Block's timecode is represented by a 16bit signed integer
   (sint16).  This means that the Block's timecode has a range of -32768
   to +32767 units.  When using the default value of TimecodeScale, each
   integer represents 1ms.  So, the maximum time span of Blocks in a
   Cluster using the default TimecodeScale of 1ms is 65536ms.

   If a Cluster's [21] Timecode [22] is set to zero, it is possible to
   have Blocks with a negative Raw Timecode.  Blocks with a negative Raw
   Timecode are not valid.







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10.  Default decoded field duration

   The "DefaultDecodedFieldDuration" Element can signal to the
   displaying application how often fields of a video sequence will be
   available for displaying.  It can be used for both interlaced and
   progressive content.

   If the video sequence is signaled as interlaced, then the period
   between two successive fields at the output of the decoding process
   equals DefaultDecodedFieldDuration.

   For video sequences signaled as progressive it is twice the value of
   DefaultDecodedFieldDuration.

   These values are valid at the end of the decoding process before
   post-processing like deinterlacing or inverse telecine is applied.

   Examples:

   o  Blu-ray movie: 1000000000ns/(48/1.001) = 20854167ns

   o  PAL broadcast/DVD: 1000000000ns/(50/1.000) = 20000000ns

   o  N/ATSC broadcast: 1000000000ns/(60/1.001) = 16683333ns

   o  hard-telecined DVD: 1000000000ns/(60/1.001) = 16683333ns (60
      encoded interlaced fields per second)

   o  soft-telecined DVD: 1000000000ns/(60/1.001) = 16683333ns (48
      encoded interlaced fields per second, with "repeat_first_field =
      1")

11.  Default Values

   The default value of an Element is assumed when not present in the
   data stream.  It is assumed only in the scope of its Parent Element
   (for example "Language" in the scope of the "Track" element).  If the
   "Parent Element" is not present or assumed, then the Element cannot
   be assumed.

12.  DRM

   Digital Rights Management.  See Encryption [23].








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13.  Encryption

   Encryption in Matroska is designed in a very generic style that
   allows people to implement whatever form of encryption is best for
   them.  It is easily possible to use the encryption framework in
   Matroska as a type of DRM.

   Because the encryption occurs within the Block, it is possible to
   manipulate encrypted streams without decrypting them.  The streams
   could potentially be copied, deleted, cut, appended, or any number of
   other possible editing techniques without ever decrypting them.  This
   means that the data is more useful, without having to expose it, or
   go through the intensive process of decrypting.

   Encryption can also be layered within Matroska.  This means that two
   completely different types of encryption can be used, requiring two
   seperate keys to be able to decrypt a stream.

   Encryption information is stored in the "ContentEncodings" Master-
   element under the "ContentEncryption" Element.

14.  Image cropping

   Thanks to the PixelCropXXX elements, it's possible to crop the image
   before being resized.  That means the image size follows this path:

   PixelXXX (size of the coded image) -> PixelCropXXX (size of the image
   to keep) -> DisplayXXX (resized cropped image)

15.  Matroska version indicators

   The EBML Header each Matroska file starts with contains two version
   number fields that inform a reading application about what to expect.
   These are "DocTypeVersion" and "DocTypeReadVersion".

   "DocTypeVersion" MUST contain the highest Matroska version number of
   any Element present in the Matroska file.  For example, a file using
   the SimpleBlock Element MUST have a "DocTypeVersion" of at least 2
   while a file containing "CueRelativePosition" Elements MUST have a
   "DocTypeVersion" of at least 4.

   The "DocTypeReadVersion" MUST contain the minimum version number a
   reading application MUST at least suppost properly in order to play
   the file back (optionally with a reduced feature set).  For example,
   if a file contains only Elements of version 2 or lower except for
   "CueRelativePosition" (which is a version 4 Matroska Element) then
   "DocTypeReadVersion" SHOULD still be set to 2 and not 4 because




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   evaluating "CueRelativePosition" is not REQUIRED for standard
   playback -- it only makes seeking more precise if used.

   "DocTypeVersion" MUST always be equal to or greater than
   "DocTypeReadVersion".

   A reading application supporting Matroska version "V" MUST NOT refuse
   to read an application with "DocReadTypeVersion" equal to or lower
   than "V" even if "DocTypeVersion" is greater than "V".  See also the
   note about Unknown Elements [24].

16.  Mime Types

   There is no IETF endorsed MIME type for Matroska files.  But you can
   use the ones we have defined on our web server:

   o  .mka : Matroska audio "audio/x-matroska"

   o  .mkv : Matroska video "video/x-matroska"

   o  .mk3d : Matroska 3D video "video/x-matroska-3d"

17.  Octet

   An Octet refers to a byte made of 8 bits.

18.  Overlay Track

   Overlay tracks SHOULD be rendered in the same 'channel' as the track
   it's linked to.  When content is found in such a track it is played
   on the rendering channel instead of the original track.

19.  Position References

   The position in some Elements refers to the position, in octets, from
   the beginning of an Element.  The reference is the beginning of the
   first Segment (= its position + the size of its ID and size fields).
   0 = first possible position of a level 1 Element in the Segment.
   When data is spanned over mutiple Segments within a Section 21 (in
   the same file or in different files), the position represents the
   accumulated offset of each Segment.  For example to reference a
   position in the third Segment, the position will be: the first
   segment total size + second segment total size + offset of the
   Element in the third segment.







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20.  Raw Timecode

   The exact time of an object represented in nanoseconds.  To find out
   a Block's Raw Timecode, you need the Block's timecode, the Cluster's
   [25] Timecode [26], and the TimecodeScale.  For calculation, please
   see the see the TimecodeScale notes.

21.  Linked Segments

   Matroska provides several methods to link two or many Segments
   together to create a Linked Segment.  A Linked Segment is a set of
   multiple Segments related together into a single presentation by
   using Hard Linking, Soft Linking, or Medium Linking.  All Segments
   within a Linked Segment MUST utilize the same track numbers and
   timescale.  All Segments within a Linked Segment MUST be stored
   within the same directory.  All Segments within a Linked Segment MUST
   store a "SegmentUID".

21.1.  Hard Linking

   Hard Linking (also called splitting) is the process of creating a
   Linked Segment by relating multiple Segments using the "PrevUID" and
   "NextUID" Elements.  Within a Linked Segment the timestamps of each
   Segment MUST follow consecutively in linking order.  With Hard
   Linking, the chapters of any Segment within the Linked Segment MUST
   only reference the current Segment.  With Hard Linking, the "NextUID"
   and "PrevUID" MUST reference the respective "SegmentUID" values of
   the next and previous Segments.  The first Segment of a Linked
   Segment MUST have a "NextUID" Element and MUST NOT have a "PrevUID"
   Element.  The last Segment of a Linked Segment MUST have a "PrevUID"
   Element and MUST NOT have a "NextUID" Element.  The middle Segments
   of a Linked Segment MUST have both a "NextUID" Element and a
   "PrevUID" Element.

   As an example four Segments MAY be Hard Linked as a Linked Segment
   through cross-referencing each other with "SegmentUID", "PrevUID",
   and "NextUID" as in this table.














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   +--------+------------------+-------------------+-------------------+
   | file   | SegmentUID       | PrevUID           | NextUID           |
   | name   |                  |                   |                   |
   +--------+------------------+-------------------+-------------------+
   | "start | "71000c23cd31099 | n/a               | "a77b3598941cb803 |
   | .mkv"  | 853fbc94dd984a5d |                   | eac0fcdafe44fac9" |
   |        | d"               |                   |                   |
   | "middl | "a77b3598941cb80 | "71000c23cd310998 | "6c92285fa6d3e827 |
   | e.mkv" | 3eac0fcdafe44fac | 53fbc94dd984a5dd" | b198d120ea3ac674" |
   |        | 9"               |                   |                   |
   | "end.m | "6c92285fa6d3e82 | "a77b3598941cb803 | n/a               |
   | kv"    | 7b198d120ea3ac67 | eac0fcdafe44fac9" |                   |
   |        | 4"               |                   |                   |
   +--------+------------------+-------------------+-------------------+

21.2.  Soft Linking

   Soft Linking is used by codec chapters.  They can reference another
   Segment and jump to that Segment.  The way the Segments are described
   are internal to the chapter codec and unknown to the Matroska level.
   But there are Elements within the "Info" Element (such as
   "ChapterTranslate") that can translate a value representing a Segment
   in the chapter codec and to the current "SegmentUID".  All Segments
   that could be used in a Linked Segment in this way SHOULD be marked
   as members of the same family via the SegmentFamily Element, so that
   the player can quickly switch from one to the other.

21.3.  Medium Linking

   Medium Linking creates relationships between Segments using Ordered
   Chapters and the "ChapterSegmentUID" Element.  A Segment Edition with
   Ordered Chapters MAY contain Chapters that reference timestamp ranges
   from other Segments.  The Segment referenced by the Ordered Chapter
   via the "ChapterSegmentUID" Element SHOULD be played as part of a
   Linked Segment.  The timestamps of Segment content referenced by
   Ordered Chapters MUST be adjusted according to the cumulative
   duration of the the previous Ordered Chapters.

   As an example a file named "intro.mkv" could have a "SegmentUID" of
   "0xb16a58609fc7e60653a60c984fc11ead".  Another file called
   "program.mkv" could use a Chapter Edition that contains two Ordered
   Chapters.  The first chapter references the Segment of "intro.mkv"
   with the use of a "ChapterSegmentUID", "ChapterSegmentEditionUID",
   "ChapterTimeStart" and optionally a "ChapterTimeEnd" element.  The
   second chapter references content within the Segment of
   "program.mkv".  A player SHOULD recognize the Linked Segment created
   by the use of "ChapterSegmentUID" in an enabled Edition and present
   the reference content of the two Segments together.



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22.  Timecode Types

   o  Absolute Timecode = Block+Cluster

   o  Relative Timecode = Block

   o  Scaled Timecode = Block+Cluster

   o  Raw Timecode = (Block+Cluster)_TimecodeScale_TrackTimecodeScale

23.  TimecodeScale

   The TimecodeScale [27] is used to calculate the Raw Timecode of a
   Block.  The timecode is obtained by adding the Block's timecode to
   the Cluster's [28] Timecode [29], and then multiplying that result by
   the TimecodeScale.  The result will be the Block's Raw Timecode in
   nanoseconds.  The formula for this would look like:

     (a + b) * c

     a = [Block's Timecode]({{site.baseurl}}/index.html#block-header)
     b = [Cluster's](#cluster) [Timecode](#timecode)
     c = [TimeCodeScale]({{site.baseurl}}/index.html#TimeCodeScale)

   An example of this is, assume a Cluster's [30] Timecode [31] has a
   value of 564264, the Block has a Timecode of 1233, and the
   timecodescale is the default of 1000000.

                 (1233 + 564264) * 1000000 = 565497000000

   So, the Block in this example has a specific time of 565497000000 in
   nanoseconds.  In milliseconds this would be 565497ms.

24.  TimecodeScale Rounding

   Because the default value of TimecodeScale is 1000000, which makes
   each integer in the Cluster and Block timecodes equal 1ms, this is
   the most commonly used.  When dealing with audio, this causes
   innaccuracy with where you are seeking to.  When the audio is
   combined with video, this is not an issue.  For most cases the the
   synch of audio to video does not need to be more than 1ms accurate.
   This becomes obvious when one considers that sound will take 2-3ms to
   travel a single meter, so distance from your speakers will have a
   greater effect on audio/visual synch than this.

   However, when dealing with audio only files, seeking accuracy can
   become critical.  For instance, when storing a whole CD in a single
   track, you want to be able to seek to the exact sample that a song



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   begins at.  If you seek a few sample ahead or behind then a 'crack'
   or 'pop' may result as a few odd samples are rendered.  Also, when
   performing precise editing, it may be very useful to have the audio
   accuracy down to a single sample.

   It is usually true that when storing timecodes for an audio stream,
   the TimecodeScale MUST have an accuracy of at least that of the audio
   samplerate, otherwise there are rounding errors that prevent you from
   knowing the precise location of a sample.  Here's how a program has
   to round each timecode in order to be able to recreate the sample
   number accurately.

   Let's assume that the application has an audio track with a sample
   rate of 44100.  As written above the TimecodeScale MUST have at least
   the accuracy of the sample rate itself: 1000000000 / 44100 =
   22675.7369614512.  This value MUST always be truncated.  Otherwise
   the accuracy will not suffice.  So in this example the application
   wil use 22675 for the TimecodeScale.  The application could even use
   some lower value like 22674 which would allow it to be a little bit
   imprecise about the original timecodes.  But more about that in a
   minute.

   Next the application wants to write sample number 52340 and
   calculates the timecode.  This is easy.  In order to calculate the
   Raw Timecode in ns all it has to do is calculate "RawTimecode =
   round(1000000000 * sample_number / sample_rate)".  Rounding at this
   stage is very important!  The application might skip it if it choses
   a slightly smaller value for the TimecodeScale factor instead of the
   truncated one like shown above.  Otherwise it has to round or the
   results won't be reversible.  For our example we get "RawTimecode =
   round(1000000000 * 52340 / 44100) = round(1186848072.56236) =
   1186848073".

   The next step is to calculate the Absolute Timecode - that is the
   timecode that will be stored in the Matroska file.  Here the
   application has to divide the Raw Timecode from the previous
   paragraph by the TimecodeScale factor and round the result:
   "AbsoluteTimecode = round(RawTimecode / TimecodeScale_facotr)" which
   will result in the following for our example: "AbsoluteTimecode =
   round(1186848073 / 22675) = round(52341.7011245866) = 52342".  This
   number is the one the application has to write to the file.

   Now our file is complete, and we want to play it back with another
   application.  Its task is to find out which sample the first
   application wrote into the file.  So it starts reading the Matroska
   file and finds the TimecodeScale factor 22675 and the audio sample
   rate 44100.  Later it finds a data block with the Absolute Timecode
   of 52342.  But how does it get the sample number from these numbers?



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   First it has to calculate the Raw Timecode of the block it has just
   read.  Here's no rounding involved, just an integer multiplication:
   "RawTimecode = AbsoluteTimecode * TimecodeScale_factor".  In our
   example: "RawTimecode = 52342 * 22675 = 1186854850".

   The conversion from the RawTimecode to the sample number again
   requires rounding: "sample_number = round(RawTimecode * sample_rate /
   1000000000)".  In our example: "sample_number = round(1186854850 *
   44100 / 1000000000) = round(52340.298885) = 52340".  This is exactly
   the sample number that the previous program started with.

   Some general notes for a program:

   1.  Always calculate the timestamps / sample numbers with floating
       point numbers of at least 64bit precision (called 'double' in
       most modern programming languages).  If you're calculating with
       integers then make sure they're 64bit long, too.

   2.  Always round if you divide.  Always!  If you don't you'll end up
       with situations in which you have a timecode in the Matroska file
       that does not correspond to the sample number that it started
       with.  Using a slightly lower timecode scale factor can help here
       in that it removes the need for proper rounding in the conversion
       from sample number to Raw Timecode.

25.  Track Flags

25.1.  Default flag

   The "default track" flag is a hint for the playback application and
   SHOULD always be changeable by the user.  If the user wants to see or
   hear a track of a certain kind (audio, video, subtitles) and she
   hasn't chosen a specific track then the player SHOULD use the first
   track of that kind whose "default track" flag is set to "1".  If no
   such track is found then the first track of this kind SHOULD be
   chosen.

   Only one track of a kind MAY have its "default track" flag set in a
   segment.  If a track entry does not contain the "default track" flag
   element then its default value "1" is to be used.

25.2.  Forced flag

   The "forced" flag tells the playback application that it MUST
   display/play this track or another track of the same kind that also
   has its "forced" flag set.  When there are multiple "forced" tracks,
   the player SHOULD determined based upon the language of the forced
   flag or use the default flag if no track matches the use languages.



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   Another track of the same kind without the "forced" flag may be use
   simultaneously with the "forced" track (like DVD subtitles for
   example).

26.  TrackTimecodeScale

   The TrackTimecodeScale [32] is used align tracks that would otherwise
   be played at different speeds.  An example of this would be if you
   have a film that was originally recorded at 24fps video.  When
   playing this back through a PAL broadcasting system, it is standard
   to speed up the film to 25fps to match the 25fps display speed of the
   PAL broadcasting standard.  However, when broadcasting the video
   through NTSC, it is typical to leave the film at its original speed.
   If you wanted to make a single file where there was one video stream,
   and an audio stream used from the PAL broadcast, as well as an audio
   stream used from the NTSC broadcast, you would have the problem that
   the PAL audio stream would be 1/24th faster than the NTSC audio
   stream, quickly leading to problems.  It is possible to stretch out
   the PAL audio track and reencode it at a slower speed, however when
   dealing with lossy audio codecs, this often results in a loss of
   audio quality and/or larger file sizes.

   This is the type of problem that TrackTimecodeScale was designed to
   fix.  Using it, the video can be played back at a speed that will
   synch with either the NTSC or the PAL audio stream, depending on
   which is being used for playback.  To continue the above example:

                            Track 1: Video
                            Track 2: NTSC Audio
                            Track 3: PAL Audio

   Because the NTSC track is at the original speed, it will used as the
   default value of 1.0 for its TrackTimecodeScale.  The video will also
   be aligned to the NTSC track with the default value of 1.0.

   The TrackTimecodeScale value to use for the PAL track would be
   calculated by determining how much faster the PAL track is than the
   NTSC track.  In this case, because we know the video for the NTSC
   audio is being played back at 24fps and the video for the PAL audio
   is being played back at 25fps, the calculation would be:

                   (25 / 24) = ~ 1.04166666666666666667

   When writing a file that uses a non-default TrackTimecodeScale, the
   values of the Block's timecode are whatever they would be when
   normally storing the track with a default value for the
   TrackTimecodeScale.  However, the data is interleaved a little
   differently.  Data SHOULD be interleaved by its Raw Timecode [33] in



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   the order handed back from the encoder.  The Raw Timecode of a Block
   from a track using TrackTimecodeScale is calculated using:

   "(Block's Timecode + Cluster's Timecode) * TimecodeScale *
   TrackTimecodeScale"

   So, a Block from the PAL track above that had a Scaled Timecode [34]
   of 100 seconds would have a Raw Timecode of 104.66666667 seconds, and
   so would be stored in that part of the file.

   When playing back a track using the TrackTimecodeScale, if the track
   is being played by itself, there is no need to scale it.  From the
   above example, when playing the Video with the NTSC Audio, neither
   are scaled.  However, when playing back the Video with the PAL Audio,
   the timecodes from the PAL Audio track are scaled using the
   TrackTimecodeScale, resulting in the video playing back in synch with
   the audio.

   It would be possible for a player to also adjust the audio's
   samplerate at the same time as adjusting the timecodes if you wanted
   to play the two audio streams synchronously.  It would also be
   possible to adjust the video to match the audio's speed.  However,
   for playback, the selected track(s) timecodes SHOULD be adjusted if
   they need to be scaled.

   While the above example deals specifically with audio tracks, this
   element can be used to align video, audio, subtitles, or any other
   type of track contained in a Matroska file.

27.  Unknown elements

   Matroska is based upon the principal that a reading application does
   not have to support 100% of the specifications in order to be able to
   play the file.  A Matroska file therefore contains version indicators
   [35] that tell a reading application what to expect.

   It is possible and valid to have the version fields indicate that the
   file contains Matroska Elements from a higher specification version
   number while signalling that a reading application MUST only support
   a lower version number properly in order to play it back (possibly
   with a reduced feature set).  This implies that a reading application
   supporting at least Matroska version V reading a file whose
   DocTypeReadVersion field is equal to or lower than V MUST skip
   Matroska/EBML Elements it encounters but which it does not know about
   if that unknown element fits into the size constraints set by the
   current parent element.





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28.  Multi-planar and 3D videos

   There are 2 different ways to compress 3D videos: have each 'eye'
   track in a separate track and have one track have both 'eyes'
   combined inside (which is more efficient, compression-wise).
   Matroska supports both ways.

   For the single track variant, there is the StereoMode [36] Element
   which defines how planes are assembled in the track (mono or left-
   right combined).  Odd values of StereoMode means the left plane comes
   first for more convenient reading.  The pixel count of the track
   (PixelWidth/PixelHeight) is the raw amount of pixels (for example
   3840x1080 for full HD side by side) and the DisplayWidth/Height in
   pixels is the amount of pixels for one plane (1920x1080 for that full
   HD stream).  Old stereo 3D were displayed using anaglyph (cyan and
   red colours separated).  For compatibility with such movies, there is
   a value of the StereoMode that corresponds to AnaGlyph.

   There is also a "packed" mode (values 13 and 14) which consists of
   packing 2 frames together in a Block using lacing.  The first frame
   is the left eye and the other frame is the right eye (or vice versa).
   The frames SHOULD be decoded in that order and are possibly dependent
   on each other (P and B frames).

   For separate tracks, Matroska needs to define exactly which track
   does what.  TrackOperation [37] with TrackCombinePlanes [38] do that.
   For more details look at how TrackOperation works [39].

   The 3D support is still in infancy and may evolve to support more
   features.



   /index.html#StereoMode) used to be part of Matroska v2 but it didn't
   meet the requirement for multiple tracks.  There was also a bug in
   libmatroska prior to 0.9.0 that would save/read it as 0x53B9 instead
   of 0x53B8.  Readers may support these legacy files by checking
   Matroska v2 or 0x53B9.  The olders values were 0: mono, 1: right eye,
   2: left eye, 3: both eyes

29.  Track Operation

   TrackOperation [40] allows combining multiple tracks to make a
   virtual one.  It uses 2 separate system to combine tracks.  One to
   create a 3D "composition" (left/right/background planes) and one to
   simplify join 2 tracks together to make a single track.





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   A track created with TrackOperation is a proper track with a UID and
   all its flags.  However the codec ID is meaningless because each
   "sub" track needs to be decoded by its own decoder before the
   "operation" is applied.  The Cues corresponding to such a virtual
   track SHOULD be the sum of the Cues elements for each of the tracks
   it's composed of (when the Cues are defined per track).

   In the case of TrackJoinBlocks, the Blocks (from BlockGroup and
   SimpleBlock) of all the tracks SHOULD be used as if they were defined
   for this new virtual Track.  When 2 Blocks have overlapping start or
   end timecodes, it's up to the underlying system to either drop some
   of these frames or render them the way they overlap.  In the end this
   situation SHOULD be avoided when creating such tracks as you can
   never be sure of the end result on different platforms.

30.  Matroska Element Ordering Guidelines

   Except for the EBML Header and the CRC-32 Element, the EBML
   specification does not require any particular storage order for
   Elements.  The Matroska specification however defines mandates and
   recommendations for ordering certain Elements in order to facilitate
   better playback, seeking, and editing efficiency.  This section
   describes and offers rationale for ordering requirements and
   recommendations for Matroska.

30.1.  Top-Level Elements

   A valid Matroska file requires only one Top-Level Element, the "Info"
   Element; however, to be playable Matroska MUST also contain at least
   one "Tracks" and "Cluster" Element.  The first "Info" Element and the
   first "Tracks" Element MUST either be stored before the first
   "Cluster" Element or both be referenced by a "SeekHead" Element which
   occurs before the first "Cluster" Element.

   After a Matroska file has been created it could still be edited.  For
   example chapters, tags or attachments can be added.  When new Top-
   Level Elements are added to a Matroska file the "SeekHead" Element(s)
   MUST be updated so that the "SeekHead" Element(s) itemize the
   identity and position of all Top-Level Elements.  Editing, removing,
   or adding Elements to a Matroska file often requires that some
   existing Elements be voided or extended; therefore, it is RECOMMENDED
   to use Void Elements as padding in between Top-Level Elements.

30.2.  CRC-32

   As noted by the EBML specification, if a "CRC-32" Element is used
   then the "CRC-32" Element MUST be the first ordered Element within
   its Parent Element.  The Matroska specification recommends that "CRC-



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   32" Elements SHOULD NOT be used as an immediate Child Element of the
   "Segment" Element; however all Top-Level Elements of an EBML Document
   SHOULD include a CRC-32 Element as a Child Element.

30.3.  SeekHead

   If used, the first "SeekHead" Element SHOULD be the first non-"CRC-
   32" Child Element of the "Segment" Element.  If a second "SeekHead"
   Element is used then the first "SeekHead" MUST reference the identity
   and position of the second "SeekHead", the second "SeekHead" MUST
   only reference "Cluster" Elements and not any other Top-Level Element
   already contained within the first "SeekHead", and the second
   "SeekHead" MAY be stored in any order relative to the other Top-Level
   Elements.  Whether one or two "SeekHead" Element(s) are used, the
   "SeekHead" Element(s) MUST collectively reference the identity and
   position of all Top-Level Elements except for the first "SeekHead"
   itself.

   It is RECOMMENDED that the first "SeekHead" Element be followed by
   some padding (a "Void" Element) to allow for the "SeekHead" Element
   to be expanded to cover new Top-Level Elements that could be added to
   the Matroska file, such as "Tags", "Chapters" and "Attachments"
   Elements.

30.4.  Cues (index)

   The "Cues" Element is RECOMMENDED to optimize seeking access in
   Matroska.  It is programmatically simpler to add the "Cues" Element
   after all of the "Cluster" Elements are written because this does not
   require a prediction of how much space to reserve before writing the
   "Cluster" Elements.  On the other hand, storing the "Cues" Element
   before the "Clusters" can provide some seeking advantages.

30.5.  Info

   The first "Info" Element SHOULD occur before the first "Tracks" and
   first "Cluster" Element.

30.6.  Chapters

   The "Chapters" Element SHOULD be placed before the "Cluster"
   Element(s).  The "Chapters" Element can be used during playback even
   if the user doesn't need to seek.  It immediately gives the user
   information of what section is being read and what other sections are
   available.  In the case of Ordered Chapters it RECOMMENDED to
   evaluate the logical linking even before starting playing anything.
   The "Chapters" Element SHOULD be placed before the first "Tracks"
   Element and after the first "Info" Element.



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30.7.  Attachments

   The "Attachments" Element is not meant to use by default when playing
   the file, but could contain the cover art and/or fonts.  Cover art is
   useful even before the file is played and fonts could be needed
   before playback starts for initialization of subtitles that could use
   them.  The "Attachments" Element MAY be placed before the first
   "Cluster" Element; however if the "Attachments" Element is likely to
   be edited, then it SHOULD be placed after the last "Cluster" Element.

30.8.  Tags

   The "Tags" Element is the one that is most subject to changes after
   the file was originally created.  So for easier editing the "Tags"
   Element SHOULD be placed at the end of the "Segment" Element, even
   after the "Attachments" Element.  On the other hand, it is
   inconvenient to have to seek in the "Segment" for tags especially for
   network streams.  So it's better if the "Tags" Element(s) are found
   early in the stream.  When editing the "Tags" Element(s), the
   original "Tags" Element at the beginning can be voided [41] and a new
   one written right at the end [42] of the "Segment" Element.  The file
   size will only marginally change.

30.9.  Optimum layout from a muxer

   o  SeekHead

   o  Info

   o  Tracks

   o  Chapters

   o  Attachments

   o  Tags

   o  Clusters

   o  Cues

30.10.  Optimum layout after editing tags

   o  SeekHead

   o  Info

   o  Tracks



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   o  Chapters

   o  Attachments

   o  Void

   o  Clusters

   o  Cues

   o  Tags

30.11.  Optimum layout with Cues at the front

   o  SeekHead

   o  Info

   o  Tracks

   o  Chapters

   o  Attachments

   o  Tags

   o  Cues

   o  Clusters

30.12.  Cluster Timecode

   As each "BlockGroup" and "SimpleBlock" of a "Cluster" Element needs
   the Cluster "Timecode", the "Timecode" Element MUST occur as the
   first Child Element within the "Cluster" Element.

31.  CodecID

   As an additional resource to this page Haali has created a list of
   codec IDs in a PDF [43].

   For each TrackEntry inside matroska [44], there has to be a CodecID
   [45] defined.  This ID is represent the codec used to encode data in
   the Track.  The codec works with the coded data in the stream, but
   also with some codec initialisation.  There are 2 different kind of
   codec "initialisation":

   o  CodecPrivate in the TrackEntry



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   o  CodecState in the BlockGroup

   Each of these elements contain the same kind of data.  And these data
   depend on the codec used.

   Important Note:

   The intention behind this list is "NOT" to list all existing audio
   and video codecs, but rather to list those codecs that are "currently
   supported" in Matroska and therefore need a well defined codec ID so
   that all developers supporting Matroska will use the same ID.  If you
   feel we missed support for a very important codec, please tell us on
   our development mailing list (matroska-devel at lists.matroska.org).

31.1.  Video Codecs

   *Codec ID:* "V_MS/VFW/FOURCC"
   *Codec Name:* Microsoft (TM) Video Codec Manager (VCM)
   *Description:* The private data contains the VCM structure
   BITMAPINFOHEADER including the extra private bytes, as defined by
   Microsoft [46].  The data are stored in little endian format (like on
   IA32 machines).  Where is the Huffman table stored in HuffYUV, not
   AVISTREAMINFO ??? And the FourCC, not in AVISTREAMINFO.fccHandler ???

   *Codec ID:* V_UNCOMPRESSED
   *Codec Name:* Video, raw uncompressed video frames
   *Description:* The private data is void, all details about the used
   colour specs and bit depth are to be put/read from the
   KaxCodecColourSpace elements.

   *Codec ID:* V_MPEG4/ISO/???
   *Codec Name:* MPEG4 ISO Profile Video
   *Description:* The stream complies with, and uses the CodecID for,
   one of the MPEG-4 profiles listed below.

   *Codec ID:* V_MPEG4/ISO/SP
   *Codec Name:* MPEG4 ISO simple profile (DivX4)
   *Description:* Stream was created via improved codec API (UCI) or
   even transmuxed from AVI (no b-frames in Simple Profile), frame order
   is coding order

   *Codec ID:* V_MPEG4/ISO/ASP
   *Codec Name:* MPEG4 ISO advanced simple profile (DivX5, XviD, FFMPEG)
   *Description:* Stream was created via improved codec API (UCI) or
   transmuxed from MP4, not simply transmuxed from AVI!  Note there are
   differences how b-frames are handled in these native streams, when
   being compared to a VfW created stream, as here there are "no" dummy




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   frames inserted, the frame order is exactly the same as the coding
   order, same as in MP4 streams!

   *Codec ID:* V_MPEG4/ISO/AP
   *Codec Name:* MPEG4 ISO advanced profile
   *Description:* (Same as above)

   *Codec ID:* V_MPEG4/MS/V3
   *Codec Name:* Microsoft (TM) MPEG4 V3
   *Description:* and derivates, means DivX3, Angelpotion, SMR, etc.;
   stream was created using VfW codec or transmuxed from AVI; note that
   V1/V2 are covered in VfW compatibility mode

   *Codec ID:* V_MPEG1
   *Codec Name:* MPEG 1
   *Description:* The matroska video stream will contain a demuxed
   Elementary Stream (ES ), where block boundaries are still to be
   defined.  Its RECOMMENDED to use MPEG2MKV.exe for creating those
   files, and to compare the results with selfmade implementations

   *Codec ID:* V_MPEG2
   *Codec Name:* MPEG 2
   *Description:* The matroska video stream will contain a demuxed
   Elementary Stream (ES ), where block boundaries are still to be
   defined.  Its RECOMMENDED to use MPEG2MKV.exe for creating those
   files, and to compare the results with selfmade implementations

   *Codec ID:* V_REAL/????
   *Codec Name:* Real Video(TM)
   *Description:* The stream is one of the Real Video(TM) video streams
   listed below.  Source for the codec names are from Karl Lillevold on
   Doom9 [47].  The CodecPrivate element contains a "real_video_props_t"
   structure in Big Endian byte order as found in librmff [48].

   *Codec ID:* V_REAL/RV10
   *Codec Name:* RealVideo 1.0 aka RealVideo 5
   *Description:* Individual slices from the Real container are combined
   into a single frame.

   *Codec ID:* V_REAL/RV20
   *Codec Name:* RealVideo G2 and RealVideo G2+SVT
   *Description:* Individual slices from the Real container are combined
   into a single frame.

   *Codec ID:* V_REAL/RV30
   *Codec Name:* RealVideo 8
   *Description:* Individual slices from the Real container are combined
   into a single frame.



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   *Codec ID:* V_REAL/RV40
   *Codec Name:* rv40 : RealVideo 9
   *Description:* Individual slices from the Real container are combined
   into a single frame.

   *Codec ID:* V_QUICKTIME
   *Codec Name:* Video taken from QuickTime(TM) files
   *Description:* Several codecs as stored in QuickTime, e.g.  Sorenson
   or Cinepak.  The CodecPrivate contains all additional data that is
   stored in the 'stsd' (sample description) atom in the QuickTime file
   *after* the mandatory video descriptor structure (starting with the
   size and FourCC fields).  For an explanation of the QuickTime file
   format read QuickTime File Format Specification [49].

   *Codec ID:* V_THEORA
   *Codec Name:* Theora
   *Description:* The private data contains the first three Theora
   packets in order.  The lengths of the packets precedes them.  The
   actual layout is:

   o  Byte 1: number of distinct packets '"#p"' minus one inside the
      CodecPrivate block.  This MUST be '2' for current (as of
      2016-07-08) Theora headers.

   o  Bytes 2..n: lengths of the first '"#p"' packets, coded in Xiph-
      style lacing [50].  The length of the last packet is the length of
      the CodecPrivate block minus the lengths coded in these bytes
      minus one.

   o  Bytes n+1..: The Theora identification header, followed by the
      commend header followed by the codec setup header.  Those are
      described in the Theora specs [51].

   *Codec ID:* V_PRORES
   *Codec Name:* Apple ProRes
   *Description:* The private data contains the fourcc as found in MP4
   movies:

   o  apch: ProRes 422 High Quality

   o  apcn: ProRes 422 Standard Definition

   o  apcs: ProRes 422 LT

   o  apco: ProRes 422 Proxy

   o  ap4h: ProRes 4444




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   this page for more technical details on ProRes [52]

31.2.  Audio

   *Codec ID:* A_MPEG/L3
   *Codec Name:* MPEG Audio 1, 2, 2.5 Layer III
   *Description:* The private data is void.  The data contain everything
   needed for playback in the MPEG Audio header of each frame.
   Corresponding ACM wFormatTag : 0x0055

   *Codec ID:* A_MPEG/L2
   *Codec Name:* MPEG Audio 1, 2 Layer II
   *Description:* The private data is void.  The data contain everything
   needed for playback in the MPEG Audio header of each frame.
   Corresponding ACM wFormatTag : 0x0050

   *Codec ID:* A_MPEG/L1
   *Codec Name:* MPEG Audio 1, 2 Layer I
   *Description:* The private data is void.  The data contain everything
   needed for playback in the MPEG Audio header of each frame.
   Corresponding ACM wFormatTag : 0x0050

   *Codec ID:* A_PCM/INT/BIG
   *Codec Name:* PCM Integer Big Endian
   *Description:* The private data is void.  The bitdepth has to be read
   and set from KaxAudioBitDepth element.  Corresponding ACM wFormatTag
   : ???

   *Codec ID:* A_PCM/INT/LIT
   *Codec Name:* PCM Integer Little Endian
   *Description:* The private data is void.  The bitdepth has to be read
   and set from KaxAudioBitDepth element.  Corresponding ACM wFormatTag
   : 0x0001

   *Codec ID:* A_PCM/FLOAT/IEEE
   *Codec Name:* Floating Point, IEEE compatible
   *Description:* The private data is void.  The bitdepth has to be read
   and set from KaxAudioBitDepth element (32 bit in most cases).  The
   float are stored in little endian order (most common float format).
   Corresponding ACM wFormatTag : 0x0003

   *Codec ID:* A_MPC
   *Codec Name:* MPC (musepack) SV8
   *Description:* The main developer for musepack has requested that we
   wait until the SV8 framing has been fully defined for musepack before
   defining how to store it in Matroska.

   *Codec ID:* A_AC3



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   *Codec Name:* (Dolby[TM]) AC3
   *Description:* BSID <= 8 !! The private data is void ???
   Corresponding ACM wFormatTag : 0x2000 ; channel number have to be
   read from the corresponding audio element

   *Codec ID:* A_AC3/BSID9
   *Codec Name:* (Dolby[TM]) AC3
   *Description:* The ac3 frame header has, similar to the mpeg-audio
   header a version field.  Normal ac3 is defiened as bitstream id 8 (5
   Bits, numbers are 0-15).  Everything below 8 is still compatible with
   all decoders that handle 8 correctly.  Everything higher are
   additions that break decoder compatibility.  For the samplerates
   24kHz (00); 22,05kHz (01) and 16kHz (10) the BSID is 9 For the
   samplerates 12kHz (00); 11,025kHz (01) and 8kHz (10) the BSID is 10

   *Codec ID:* A_AC3/BSID10
   *Codec Name:* (Dolby[TM]) AC3
   *Description:* (Same as above)

   *Codec ID:* A_ALAC
   *Codec Name:* ALAC (Apple Lossless Audio Codec)
   *Description:* The private data contains ALAC's magic cookie (both
   the codec specific configuration as well as the optional channel
   layout information).  Its format is described in ALAC's official
   source code [53].

   *Codec ID:* A_DTS
   *Codec Name:* Digital Theatre System
   *Description:* Supports DTS, DTS-ES, DTS-96/26, DTS-HD High
   Resolution Audio and DTS-HD Master Audio.  The private data is void.
   Corresponding ACM wFormatTag : 0x2001

   *Codec ID:* A_DTS/EXPRESS
   *Codec Name:* Digital Theatre System Express
   *Description:* DTS Express (a.k.a.  LBR) audio streams.  The private
   data is void.  Corresponding ACM wFormatTag : 0x2001

   *Codec ID:* A_DTS/LOSSLESS
   *Codec Name:* Digital Theatre System Lossless
   *Description:* DTS Lossless audio that does not have a core
   substream.  The private data is void.  Corresponding ACM wFormatTag :
   0x2001

   *Codec ID:* A_VORBIS
   *Codec Name:* Vorbis
   *Description:* The private data contains the first three Vorbis
   packet in order.  The lengths of the packets precedes them.  The
   actual layout is: Byte 1: number of distinct packets '"#p"' minus one



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   inside the CodecPrivate block.  This MUST be '2' for current (as of
   2016-07-08) Vorbis headers.  Bytes 2..n: lengths of the first '"#p"'
   packets, coded in Xiph-style lacing [54].  The length of the last
   packet is the length of the CodecPrivate block minus the lengths
   coded in these bytes minus one.  Bytes n+1..: The Vorbis
   identification header [55], followed by the Vorbis comment header
   [56] followed by the codec setup header [57].

   *Codec ID:* A_FLAC
   *Codec Name:* FLAC (Free Lossless Audio Codec) [58]
   *Description:* The private data contains all the header/metadata
   packets before the first data packet.  These include the first header
   packet containing only the word "fLaC" as well as all metadata
   packets.

   *Codec ID:* A_REAL/????
   *Codec Name:* Realmedia Audio codecs
   *Description:* The stream contains one of the following audio codecs.
   In each case the CodecPrivate element contains either the
   "real_audio_v4_props_t" or the "real_audio_v5_props_t" structure
   (differentiated by their "version" field; Big Endian byte order) as
   found in librmff [59].

   *Codec ID:* A_REAL/14_4
   *Codec Name:* Real Audio 1
   *Description:*

   *Codec ID:* A_REAL/28_8
   *Codec Name:* Real Audio 2
   *Description:*

   *Codec ID:* A_REAL/COOK
   *Codec Name:* Real Audio Cook Codec (codename: Gecko)
   *Description:*

   *Codec ID:* A_REAL/SIPR
   *Codec Name:* Sipro Voice Codec
   *Description:*

   *Codec ID:* A_REAL/RALF
   *Codec Name:* Real Audio Lossless Format
   *Description:*

   *Codec ID:* A_REAL/ATRC
   *Codec Name:* Sony Atrac3 Codec
   *Description:*

   *Codec ID:* A_MS/ACM



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   *Codec Name:* Microsoft(TM) Audio Codec Manager (ACM)
   *Description:* The private data contains the ACM structure
   WAVEFORMATEX including the extra private bytes, as defined by
   Microsoft [60].  The data are stored in little endian format (like on
   IA32 machines).

   *Codec ID:* A_AAC/?????/???
   *Codec Name:* AAC Profile Audio
   *Description:* The stream complies with, and uses the CodecID for,
   one of the AAC profiles listed below.  AAC audio always uses
   wFormatTag 0xFF

   *Codec ID:* A_AAC/MPEG2/MAIN
   *Codec Name:* MPEG2 Main Profile
   *Description:* The private data is void.  Channel number and sample
   rate have to be read from the corresponding audio element.  Audio
   stream is stripped from ADTS headers and normal matroska frame based
   muxing scheme is applied.

   *Codec ID:* A_AAC/MPEG2/LC
   *Codec Name:* Low Complexity
   *Description:* The private data is void.  Channel number and sample
   rate have to be read from the corresponding audio element.  Audio
   stream is stripped from ADTS headers and normal matroska frame based
   muxing scheme is applied.

   *Codec ID:* A_AAC/MPEG2/LC/SBR
   *Codec Name:* Low Complexity with Spectral Band Replication
   *Description:* The private data is void.  Channel number and sample
   rate have to be read from the corresponding audio element.  Audio
   stream is stripped from ADTS headers and normal matroska frame based
   muxing scheme is applied.

   *Codec ID:* A_AAC/MPEG2/SSR
   *Codec Name:* Scalable Sampling Rate
   *Description:* The private data is void.  Channel number and sample
   rate have to be read from the corresponding audio element.  Audio
   stream is stripped from ADTS headers and normal matroska frame based
   muxing scheme is applied.

   *Codec ID:* A_AAC/MPEG4/MAIN
   *Codec Name:* MPEG4 Main Profile
   *Description:* The private data is void.  Channel number and sample
   rate have to be read from the corresponding audio element.  Audio
   stream is stripped from ADTS headers and normal matroska frame based
   muxing scheme is applied.

   *Codec ID:* A_AAC/MPEG4/LC



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   *Codec Name:* Low Complexity
   *Description:* The private data is void.  Channel number and sample
   rate have to be read from the corresponding audio element.  Audio
   stream is stripped from ADTS headers and normal matroska frame based
   muxing scheme is applied.

   *Codec ID:* A_AAC/MPEG4/LC/SBR
   *Codec Name:* Low Complexity with Spectral Band Replication
   *Description:* The private data is void.  Channel number and sample
   rate have to be read from the corresponding audio element.  Audio
   stream is stripped from ADTS headers and normal matroska frame based
   muxing scheme is applied.

   *Codec ID:* A_AAC/MPEG4/SSR
   *Codec Name:* Scalable Sampling Rate
   *Description:* The private data is void.  Channel number and sample
   rate have to be read from the corresponding audio element.  Audio
   stream is stripped from ADTS headers and normal matroska frame based
   muxing scheme is applied.

   *Codec ID:* A_AAC/MPEG4/LTP
   *Codec Name:* Long Term Prediction
   *Description:* The private data is void.  Channel number and sample
   rate have to be read from the corresponding audio element.  Audio
   stream is stripped from ADTS headers and normal matroska frame based
   muxing scheme is applied.

   *Codec ID:* A_QUICKTIME
   *Codec Name:* Audio taken from QuickTime(TM) files
   *Description:* Several codecs as stored in QuickTime, e.g.  QDesign
   Music v1 or v2.  The CodecPrivate contains all additional data that
   is stored in the 'stsd' (sample description) atom in the QuickTime
   file *after* the mandatory sound descriptor structure (starting with
   the size and FourCC fields).  For an explanation of the QuickTime
   file format read QuickTime File Format Specification [61].

   *Codec ID:* A_QUICKTIME/????
   *Codec Name:* QuickTime audio codecs
   *Description:* This CodecID is deprecated in favor of A_QUICKTIME
   (without a trailing codec name).  Otherwise the storage is identical;
   see A_QUICKTIME for details.

   *Codec ID:* A_QUICKTIME/QDMC
   *Codec Name:* QDesign Music
   *Description:*

   *Codec ID:* A_QUICKTIME/QDM2
   *Codec Name:* QDesign Music v2



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   *Description:*

   *Codec ID:* A_TTA1
   *Codec Name:* The True Audio [62] lossles audio compressor
   *Description:* TTA format description [63] Each frame is kept intact,
   including the CRC32.  The header and seektable are dropped.  The
   private data is void.  SamplingFrequency, Channels and BitDepth are
   used in the TrackEntry. wFormatTag = 0x77A1

   *Codec ID:* A_WAVPACK4
   *Codec Name:* WavPack [64] lossles audio compressor
   *Description:* The Wavpack packets consist of a stripped header
   followed by the frame data.  For multi-track (> 2 tracks) a frame
   consists of many packets.  For hybrid files (lossy part + correction
   part), the correction part is stored in an additional block (level
   1).  For more details, check the WavPack muxing description [65].

31.3.  Subtitle

   *Codec ID:* S_TEXT/UTF8
   *Codec Name:* UTF-8 Plain Text
   *Description:* Basic text subtitles.  For more information, please
   look at the Subtitle specifications [66].

   *Codec ID:* S_TEXT/SSA
   *Codec Name:* Subtitles Format
   *Description:* The [Script Info] and [V4 Styles] sections are stored
   in the codecprivate.  Each event is stored in its own Block.  For
   more information, please read the specs for SSA/ASS [67].

   *Codec ID:* S_TEXT/ASS
   *Codec Name:* Advanced Subtitles Format
   *Description:* The [Script Info] and [V4 Styles] sections are stored
   in the codecprivate.  Each event is stored in its own Block.  For
   more information, please read the specs for SSA/ASS [68].

   *Codec ID:* S_TEXT/USF
   *Codec Name:* Universal Subtitle Format
   *Description:* This is mostly defined, but not typed out yet.  It
   will first be available on the USF specs page [69].

   *Codec ID:* S_TEXT/WEBVTT
   *Codec Name:* Web Video Text Tracks Format (WebVTT)
   *Description:* Advanced text subtitles.  For more information about
   the storage please look at the WebVTT in Matroska specifications
   [70].

   *Codec ID:* S_IMAGE/BMP



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   *Codec Name:* Bitmap
   *Description:* Basic image based subtitle format; The subtitles are
   stored as images, like in the DVD.  The timestamp in the block header
   of matroska indicates the start display time, the duration is set
   with the Duration element.  The full data for the subtitle bitmap is
   stored in the Block's data section.

   *Codec ID:* S_VOBSUB
   *Codec Name:* VobSub subtitles
   *Description:* The same subtitle format used on DVDs.  Supoprted is
   only format version 7 and newer.  VobSubs consist of two files, the
   .idx containing information, and the .sub, containing the actual
   data.  The .idx file is stripped of all empty lines, of all comments
   and of lines beginning with "alt:" or "langidx:".  The line beginning
   with "id:" SHOULD be transformed into the appropriate Matroska track
   language element and is discarded.  All remaining lines but the ones
   containing timestamps and file positions are put into the
   "CodecPrivate" element.  For each line containing the timestamp and
   file position data is read from the appropriate position in the .sub
   file.  This data consists of a MPEG program stream which in turn
   contains SPU packets.  The MPEG program stream data is discarded, and
   each SPU packet is put into one Matroska frame.

   *Codec ID:* S_KATE
   *Codec Name:* Karaoke And Text Encapsulation
   *Description:* A subtitle format developped for ogg.  The mapping for
   Matroska is described on the Xiph wiki [71].  As for Theora and
   Vorbis, Kate headers are stored in the private data as xiph-laced
   packets.

31.4.  Buttons

   *Codec ID:* B_VOBBTN
   *Codec Name:* VobBtn Buttons
   *Description:* Based on MPEG/VOB PCI packets [72].  The file contains
   a header consisting of the string "butonDVD" followed by the width
   and height in pixels (16 bits integer each) and 4 reserved bytes.
   The rest is full PCI packets [73].  #Chapters

31.5.  Example 1 : basic chaptering

   In this example a movie is split in different chapters.  It could
   also just be an audio file (album) on which each track corresponds to
   a chapter.

   o  00000ms - 05000ms : Intro

   o  05000ms - 25000ms : Before the crime



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   o  25000ms - 27500ms : The crime

   o  27500ms - 38000ms : The killer arrested

   o  38000ms - 43000ms : Credits

   This would translate in the following matroska form :

   | Chapters | EditionEntry | ChapterAtom | ChapterUID | 0x123456 |
   ChapterTimeStart | 0 ns | ChapterTimeEnd | 5,000,000 ns |
   ChapterDisplay | ChapterString | Intro | ChapterLanguage | eng |
   ChapterAtom | ChapterUID | 0x234567 | ChapterTimeStart | 5,000,000
   ns | ChapterTimeEnd | 25,000,000 ns | ChapterDisplay |
   ChapterString | Before the crime | ChapterLanguage | eng |
   ChapterDisplay | ChapterString | Avant le crime | ChapterLanguage |
   fra | ChapterAtom | ChapterUID | 0x345678 | ChapterTimeStart |
   25,000,000 ns | ChapterTimeEnd | 27,500,000 ns | ChapterDisplay |
   ChapterString | The crime | ChapterLanguage | eng | ChapterDisplay |
   ChapterString | Le crime | ChapterLanguage | fra | ChapterAtom |
   ChapterUID | 0x456789 | ChapterTimeStart | 27,500,000 ns |
   ChapterTimeEnd | 38,000,000 ns | ChapterDisplay | ChapterString |
   After the crime | ChapterLanguage | eng | ChapterDisplay |
   ChapterString | Apres le crime | ChapterLanguage | fra |
   ChapterAtom | ChapterUID | 0x456789 | ChapterTimeStart | 38,000,000
   ns | ChapterTimeEnd | 43,000,000 ns | ChapterDisplay |
   ChapterString | Credits | ChapterLanguage | eng | ChapterDisplay |
   ChapterString | Generique | ChapterLanguage | fra |

31.6.  Example 2 : nested chapters

   In this example an (existing) album is split into different chapters,
   and one of them contain another splitting.

31.6.1.  The Micronauts "Bleep To Bleep"

   o  00:00 - 12:28 : Baby Wants To Bleep/Rock

      *  00:00 - 04:38 : Baby wants to bleep (pt.1)

      *  04:38 - 07:12 : Baby wants to rock

      *  07:12 - 10:33 : Baby wants to bleep (pt.2)

      *  10:33 - 12:28 : Baby wants to bleep (pt.3)

   o  12:30 - 19:38 : Bleeper_O+2

   o  19:40 - 22:20 : Baby wants to bleep (pt.4)



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   o  22:22 - 25:18 : Bleep to bleep

   o  25:20 - 33:35 : Baby wants to bleep (k)

   o  33:37 - 44:28 : Bleeper

   | Chapters | EditionEntry | ChapterAtom | ChapterUID | 0x654321 |
   ChapterTimeStart | 0 ns | ChapterTimeEnd | 748,000,000 ns |
   ChapterDisplay | ChapterString | Baby wants to bleep/rock |
   ChapterAtom | ChapterUID | 0x123456 | ChapterTimeStart | 0 ns |
   ChapterTimeEnd | 278,000,000 ns | ChapterDisplay | ChapterString |
   Baby wants to bleep (pt.1) | ChapterAtom | ChapterUID | 0x234567 |
   ChapterTimeStart | 278,000,000 ns | ChapterTimeEnd | 432,000,000 ns |
   ChapterDisplay | ChapterString | Baby wants to rock | ChapterAtom |
   ChapterUID | 0x345678 | ChapterTimeStart | 432,000,000 ns |
   ChapterTimeEnd | 633,000,000 ns | ChapterDisplay | ChapterString |
   Baby wants to bleep (pt.2) | ChapterAtom | ChapterUID | 0x456789 |
   ChapterTimeStart | 633,000,000 ns | ChapterTimeEnd | 748,000,000 ns |
   ChapterDisplay | ChapterString | Baby wants to bleep (pt.3) |
   ChapterAtom | ChapterUID | 0x567890 | ChapterTimeStart | 750,000,000
   ns | ChapterTimeEnd | 1,178,500,000 ns | ChapterDisplay |
   ChapterString | Bleeper_O+2 | ChapterAtom | ChapterUID | 0x678901 |
   ChapterTimeStart | 1,180,500,000 ns | ChapterTimeEnd | 1,340,000,000
   ns | ChapterDisplay | ChapterString | Baby wants to bleep (pt.4) |
   ChapterAtom | ChapterUID | 0x789012 | ChapterTimeStart |
   1,342,000,000 ns | ChapterTimeEnd | 1,518,000,000 ns |
   ChapterDisplay | ChapterString | Bleep to bleep | ChapterAtom |
   ChapterUID | 0x890123 | ChapterTimeStart | 1,520,000,000 ns |
   ChapterTimeEnd | 2,015,000,000 ns | ChapterDisplay | ChapterString |
   Baby wants to bleep (k) | ChapterAtom | ChapterUID | 0x901234 |
   ChapterTimeStart | 2,017,000,000 ns | ChapterTimeEnd | 2,668,000,000
   ns | ChapterDisplay | ChapterString | Bleeper |

31.7.  Edition and chapter flags

31.7.1.  Chapter flags

   There are two important flags that apply to chapter atoms: _enabled_
   and _hidden_. The effect of those flags always applies to child atoms
   of an atom affected by that flag.

   For example: Let's assume a parent atom with flag _hidden_ set to
   _true_; that parent contains two child atom, the first with _hidden_
   set to _true_ as well and the second child with the flag either set
   to _false_ or not present at all (in which case the default value
   applies, and that again is _false_).





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   As the parent is hidden all of its children are initially hidden as
   well.  However, when a control track toggles the parent's _hidden_
   flag to _false_ then only the the parent and its second child will be
   visible.  The first child's explicitely set flag retains its value
   until its value is toggled to _false_ by a control track.

   Corresponding behavior applies to the _enabled_ flag.

31.7.2.  Edition flags

   The edition's _hidden_ flag behaves much the same as the chapter's
   _hidden_ flag: if an edition is hidden then none of its children
   SHALL be visible, no matter their own _hidden_ flags.  If the edition
   is toggled to being visible then the chapter atom's _hidden_ flags
   decide whether or not the chapter is visible.

31.8.  Menu features

   The menu features are handled like a _chapter codec_. That means each
   codec has a type, some private data and some data in the chapters.

   The type of the menu system is defined by the ChapProcessCodecID
   parameter.  For now only 2 values are supported : 0 matroska script,
   1 menu borrowed from the DVD.  The private data depend on the type of
   menu system (stored in ChapProcessPrivate), idem for the data in the
   chapters (stored in ChapProcessData).

31.8.1.  Matroska Script (0)

   This is the case when ChapProcessCodecID [74] = 0.  This is a script
   language build for Matroska purposes.  The inspiration comes from
   ActionScript, javascript and other similar scripting languages.  The
   commands are stored as text commands, in UTF-8.  The syntax is C
   like, with commands spanned on many lines, each terminating with a
   ";".  You can also include comments at the end of lines with "//" or
   comment many lines using "/* */".  The scripts are stored in
   ChapProcessData.  For the moment ChapProcessPrivate is not used.

   The one and only command existing for the moment is "GotoAndPlay(
   ChapterUID );".  As the same suggests, it means that when this
   command is encountered, the playback SHOULD jump to the Chapter
   specified by the UID and play it.

31.8.2.  DVD menu (1)

   This is the case when ChapProcessCodecID [75] = 1.  Each level of a
   chapter corresponds to a logical level in the DVD system that is




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   stored in the first octet of the ChapProcessPrivate.  This DVD
   hierarchy is as follows:

   | ChapProcessPrivate | DVD Name | Hierarchy | Commands Possible |
   Comment | | 0x30 | SS | DVD domain | - | First Play, Video Manager,
   Video Title | | 0x2A | LU | Language Unit | - | Contains only
   PGCs | | 0x28 | TT | Title | - | Contains only PGCs | | 0x20 | PGC |
   Program Group Chain (PGC) | * | | 0x18 | PG | Program 1 | Program 2 |
   Program 3 | - | | 0x10 | PTT | Part Of Title 1 | Part Of Title 2 |
   - | Equivalent to the chapters on the sleeve. | | 0x08 | CN | Cell
   1 | Cell 2 | Cell 3 | Cell 4 | Cell 5 | Cell 6 | - |

   You can also recover wether a Segment is a Video Manager (VMG), Video
   Title Set (VTS) or Video Title Set Menu (VTSM) from the
   ChapterTranslateID [76] element found in the Segment Info.  This
   field uses 2 octets as follows:

   1.  Domain Type: 0 for VMG, the domain number for VTS and VTSM

   2.  Domain Value: 0 for VMG and VTSM, 1 for the VTS source.

   For instance, the menu part from VTS_01_0.VOB would be coded [1,0]
   and the content part from VTS_02_3.VOB would be [2,1].  The VMG is
   always [0,0]

   The following octets of ChapProcessPrivate are as follows:

   | Octet 1 | DVD Name | Following Octets | | 0x30 | SS | Domain name
   code (1: 0x00= First play, 0xC0= VMG, 0x40= VTSM, 0x80= VTS) + VTS(M)
   number (2) | | 0x2A | LU | Language code (2) + Language extension
   (1) | | 0x28 | TT | global Title number (2) + corresponding TTN of
   the VTS (1) | | 0x20 | PGC | PGC number (2) + Playback Type (1) +
   Disabled User Operations (4) | | 0x18 | PG | Program number (2) | |
   0x10 | PTT | PTT-chapter number (1) | | 0x08 | CN | Cell number [VOB
   ID(2)][Cell ID(1)][Angle Num(1)] |

   If the level specified in ChapProcessPrivate is a PGC (0x20), there
   is an octet called the Playback Type, specifying the kind of PGC
   defined:

   o  0x00: entry only/basic PGC

   o  0x82: Title+Entry Menu (only found in the Video Manager domain)

   o  0x83: Root Menu (only found in the VTSM domain)

   o  0x84: Subpicture Menu (only found in the VTSM domain)




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   o  0x85: Audio Menu (only found in the VTSM domain)

   o  0x86: Angle Menu (only found in the VTSM domain)

   o  0x87: Chapter Menu (only found in the VTSM domain)

   The next 4 following octets correspond to the User Operation flags
   [77] in the standard PGC.  When a bit is set, the command SHOULD be
   disabled.

   ChapProcessData contains the pre/post/cell commands in binary format
   as there are stored on a DVD.  There is just an octet preceeding
   these data to specify the number of commands in the element.  As
   follows: [# of commands(1)][command 1 (8)][command 2 (8)][command 3
   (8)].

   More information on the DVD commands and format on DVD-replica [78],
   where we got most of the info about it.  You can also get information
   on DVD from the DVDinfo project [79].---

32.  Subtitles

   Because Matroska is a general container format, we try to avoid
   specifying the formats to store in it.  This type of work is really
   outside of the scope of a container-only format.  However, because
   the use of subtitles in A/V containers has been so limited (with the
   exception of DVD) we are taking the time to specify how to store some
   of the more common subtitle formats in Matroska.  This is being done
   to help facilitate their growth.  Otherwise, incompatabilities could
   prevent the standardization and use of subtitle storage.

   This page is not meant to be a complete listing of all subtitle
   formats that will be used in Matroska, it is only meant to be a guide
   for the more common, current formats.  It is possible that we will
   add future formats to this page as they are created, but it is not
   likely as any other new subtitle format designer would likely have
   their own specifications.  Any specification listed here SHOULD be
   strictly adhered to or it SHOULD NOT use the corresponding Codec ID.

   Here is a list of pointers for storing subtitles in Matroska:

   o  Any Matroska file containing only subtitles SHOULD use the
      extension ".mks".

   o  As a general rule of thumb for all codecs, information that is
      global to an entire stream SHOULD be stored in the CodecPrivate
      element.




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   o  Start and stop timecodes that are used in a timecodes native
      storage format SHOULD be removed when being placed in Matroska as
      they could interfere if the file is edited afterwards.  Instead,
      the Blocks timecode and Duration SHOULD be used to say when the
      timecode is displayed.

   o  Because a "subtitle" stream is actually just an overlay stream,
      anything with a transparency layer could be use, including video.

33.  Images Subtitles

   The first image format that is a goal to import into Matroska is the
   VobSub subtitle format.  This subtitle type is generated by exporting
   the subtitles from a DVD.

   The requirement for muxing VobSub into Matroska is v7 subtitles (see
   first line of the .IDX file).  If the version is smaller, you must
   remux them using the SubResync utility from VobSub 2.23 (or MPC) into
   v7 format.  Generally any newly created subs will be in v7 format.

   The .IFO file will not be used at all.

   If there is more than one subtitle stream in the VobSub set, each
   stream will need to be seperated into seperate tracks for storage in
   Matroska.  E.g. the VobSub file contains streams for both English and
   German subtitles.  Then the resulting Matroska file SHOULD contain
   two tracks.  That way the language information can be 'dropped' and
   mapped to Matroska's language tags.

   The .IDX file is reformatted (see below) and placed in the
   CodecPrivate.

   Each .BMP will be stored in its own Block.  The Timestamp with be
   stored in the Blocks Timecode and the duration will be stored in the
   Default Duration.

   Here is an example .IDX file:

  # VobSub index file, v7 (do not modify this line!)
  #
  # To repair desyncronization, you can insert gaps this way:
  # (it usually happens after vob id changes)
  #
  # delay: [sign]hh:mm:ss:ms
  #
  # Where:
  # [sign]: +, - (optional)
  # hh: hours (0 <= hh)



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  # mm/ss: minutes/seconds (0 <= mm/ss <= 59)
  # ms: milliseconds (0 <= ms <= 999)
  #
  # Note: You can't position a sub before the previous with a negative
  # value.
  #
  # You can also modify timestamps or delete a few subs you don't like.
  # Just make sure they stay in increasing order.

  # Settings

  # Original frame size
  size: 720x480

  # Origin, relative to the upper-left corner, can be overloaded by
  # aligment
  org: 0, 0

  # Image scaling (hor,ver), origin is at the upper-left corner or at
  # the alignment coord (x, y)
  scale: 100%, 100%

  # Alpha blending
  alpha: 100%

  # Smoothing for very blocky images (use OLD for no filtering)
  smooth: OFF

  # In millisecs
  fadein/out: 50, 50

  # Force subtitle placement relative to (org.x, org.y)
  align: OFF at LEFT TOP

  # For correcting non-progressive desync. (in millisecs or hh:mm:ss:ms)
  # Note: Not effective in DirectVobSub, use "delay: ... " instead.
  time offset: 0

  # ON: displays only forced subtitles, OFF: shows everything
  forced subs: OFF

  # The original palette of the DVD
  palette: 000000, 7e7e7e, fbff8b, cb86f1, 7f74b8, e23f06, 0a48ea, \
  b3d65a, 6b92f1, 87f087, c02081, f8d0f4, e3c411, 382201, e8840b, fdfdfd

  # Custom colors (transp idxs and the four colors)
  custom colors: OFF, tridx: 0000, colors: 000000, 000000, 000000, \
  000000



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  # Language index in use
  langidx: 0

  # English
  id: en, index: 0
  # Decomment next line to activate alternative name in DirectVobSub /
  # Windows Media Player 6.x
  # alt: English
  # Vob/Cell ID: 1, 1 (PTS: 0)
  timestamp: 00:00:01:101, filepos: 000000000
  timestamp: 00:00:08:708, filepos: 000001000

   First, lines beginning with "#" are removed.  These are comments to
   make text file editing easier, and as this is not a text file, they
   aren't needed.

   Next remove the "langidx" and "id" lines.  These are used to
   differenciate the subtitle streams and define the language.  As the
   streams will be stored seperately anyway, there is no need to
   differenciate them here.  Also, the language setting will be stored
   in the Matroska tags, so there is no need to store it here.

   Finally, the "timestamp" will be used to set the Block's timecode.
   Once it is set there, there is no need for it to be stored here.
   Also, as it may interfere if the file is edited, it SHOULD NOT be
   stored here.

   Once all of these items are removed, the data to store in the
   CodecPrivate SHOULD look like this:

  size: 720x480
  org: 0, 0
  scale: 100%, 100%
  alpha: 100%
  smooth: OFF
  fadein/out: 50, 50
  align: OFF at LEFT TOP
  time offset: 0
  forced subs: OFF
  palette: 000000, 7e7e7e, fbff8b, cb86f1, 7f74b8, e23f06, 0a48ea, \
  b3d65a, 6b92f1, 87f087, c02081, f8d0f4, e3c411, 382201, e8840b, fdfdfd
  custom colors: OFF, tridx: 0000, colors: 000000, 000000, 000000, \
  000000

   There SHOULD also be two Blocks containing one image each with the
   timecodes "00:00:01:101" and "00:00:08:708".





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34.  SRT Subtitles

   SRT is perhaps the most basic of all subtitle formats.

   It consists of four parts, all in text..

   1.  A number indicating which subtitle it is in the sequence.  2.
   The time that the subtitle appears on the screen, and then
   disappears.  3.  The subtitle itself.  4.  A blank line indicating
   the start of a new subtitle.

   When placing SRT in Matroska, part 3 is converted to UTF-8 (S_TEXT/
   UTF8) and placed in the data portion of the Block.  Part 2 is used to
   set the timecode of the Block, and BlockDuration element.  Nothing
   else is used.

   Here is an example SRT file:

   |

   1 00:02:17,440 --> 00:02:20,375 Senator, we're making our final
   approach into Coruscant.

   2 00:02:20,476 --> 00:02:22,501 Very good, Lieutenant.

   |

   In this example, the text "Senator, we're making our final approach
   into Coruscant." would be converted into UTF-8 and placed in the
   Block.  The timecode of the block would be set to "00:02:17,440".
   And the BlockDuration element would be set to "00:00:02,935".

   The same is repeated for the next subtitle.

   Because there are no general settings for SRT, the CodecPrivate is
   left blank.

35.  SSA/ASS Subtitles

   SSA stands for Sub Station Alpha.  It's the file format used by the
   popular subtitle editor, SubStation Alpha [80].  This format is
   widely used by fansubbers.

   It allows you to do some advanced display features, like positioning,
   karaoke, style managements...

   For detailed information on SSA/ASS, see the SSA specs [81].  It
   includes an SSA specs description and the avanced features added by



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   ASS format (standing for Advanced SSA).  Because SSA and ASS are so
   similar, they are treated the same here.

   Like SRT, this format is text based with a particular syntax.

   A file consists of 4 or 5 parts, declared ala INI file (but it's not
   an INI !)

   The first, "[Script Info]" contains some information about the
   subtitle file, such as it's title, who created it, type of script and
   a very important one : "PlayResY".  Be carefull of this value,
   everything in your script (font size, positioning) is scaled by it.
   Sub Station Alpha uses your desktops Y resolution to write this
   value, so if a friend with a large monitor and a high screen
   resolution gives you an edited script, you can mess everything up by
   saving the script in SSA with your low-cost monitor.

   The second, "[V4 Styles]", is a list of style definitions.  A style
   describe how will look a text on the screen.  It defines font, font
   size, primary/.../outile colour, position, aligment etc ...

   For example this :

   |

   Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour,
   TertiaryColour, BackColour, Bold, Italic, BorderStyle, Outline,
   Shadow, Alignment, MarginL, MarginR, MarginV, AlphaLevel, Encoding
   Style: Wolf main,Wolf_Rain,56,15724527,15724527,15724527,4144959,0,0,
   1,1,2,2,5,5,30,0,0

   |

   The third, "[Events]", is the list of text you want to display at the
   right timing.  You can specify some attribute here.  Like the style
   to use for this event (MUST be defined in the list), the position of
   the text (Left, Right, Vertical Margin), an effect.  Name is mostly
   used by translator to know who said this sentence.  Timing is in
   h:mm:ss.cc (centisec).

   |

   Format: Marked, Start, End, Style, Name, MarginL, MarginR, MarginV,
   Effect, Text Dialogue: Marked=0,0:02:40.65,0:02:41.79,Wolf
   main,Cher,0000,0000,0000,,Et les enregistrements de ses ondes delta ?
   Dialogue: Marked=0,0:02:42.42,0:02:44.15,Wolf
   main,autre,0000,0000,0000,,Toujours rien.




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   |

   "[Pictures]" or "[Fonts]" part can be found in some SSA file, they
   contains UUE-encoded pictures/font but those features are only used
   by Sub Station Alpha, i.e. no filter (Vobsub/Avery Lee Subtiler
   filter) use them.

   Now, how are they stored in Matroska ?

   o  All text is converted to UTF-8* All the headers are stored in
      CodecPrivate ( Script Info and the Styles list)* Start & End field
      are used to set TimeStamp and the BlockDuration element. the data
      stored is :* Events are stored in the Block in this order:
      ReadOrder, Layer, Style, Name, MarginL, MarginR, MarginV, Effect,
      Text (Layer comes from ASS specs ... it's empty for SSA.)
      "ReadOrder field is needed for the decoder to be able to reorder
      the streamed samples as they were placed originally in the file."

   Here is an example of an SSA file.

   | [Script Info] ; This is a Sub Station Alpha v4 script.  ; For Sub
   Station Alpha info and downloads, ; go to
   http://www.eswat.demon.co.uk/ ; or email kotus@eswat.demon.co.uk [83]
   Title: Wolf's rain 2 Original Script: Anime-spirit Ishin-francais
   Original Translation: Coolman Original Editing: Spikewolfwood
   Original Timing: Lord_alucard Original Script Checking: Spikewolfwood
   ScriptType: v4.00 Collisions: Normal PlayResY: 1024 PlayDepth: 0 Wav:
   0, 128697,D:\Alex\Anime- Fansub -- TAFF -\Wolf's Rain\WR_-_02_Wav.wav
   Wav: 0, 120692,H:\team truc\WR_-_02.wav Wav: 0,
   116504,E:\sub\wolf's_rain\WOLF'S RAIN 02.wav LastWav: 3 Timer:
   100,0000

   [V4 Styles] Format: Name, Fontname, Fontsize, PrimaryColour,
   SecondaryColour, TertiaryColour, BackColour, Bold, Italic,
   BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV,
   AlphaLevel, Encoding Style: Default,Arial,20,65535,65535,65535,-
   2147483640,-1,0,1,3,0,2,30,30,30,0,0 Style:
   Titre_episode,Akbar,140,15724527,65535,65535,986895,-
   1,0,1,1,0,3,30,30,30,0,0 Style: Wolf main,Wolf_Rain,56,15724527,15724
   527,15724527,4144959,0,0,1,1,2,2,5,5,30,0,0

   [Events] Format: Marked, Start, End, Style, Name, MarginL, MarginR,
   MarginV, Effect, Text Dialogue: Marked=0,0:02:40.65,0:02:41.79,Wolf
   main,Cher,0000,0000,0000,,Et les enregistrements de ses ondes delta ?
   Dialogue: Marked=0,0:02:42.42,0:02:44.15,Wolf
   main,autre,0000,0000,0000,,Toujours rien. |

   Here is what would be placed into the CodecPrivate element.



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   | [Script Info] ; This is a Sub Station Alpha v4 script.  ; For Sub
   Station Alpha info and downloads, ; go to
   http://www.eswat.demon.co.uk/ ; or email kotus@eswat.demon.co.uk [85]
   Title: Wolf's rain 2 Original Script: Anime-spirit Ishin-francais
   Original Translation: Coolman Original Editing: Spikewolfwood
   Original Timing: Lord_alucard Original Script Checking: Spikewolfwood
   ScriptType: v4.00 Collisions: Normal PlayResY: 1024 PlayDepth: 0 Wav:
   0, 128697,D:\Alex\Anime- Fansub -- TAFF -\Wolf's Rain\WR_-_02_Wav.wav
   Wav: 0, 120692,H:\team truc\WR_-_02.wav Wav: 0,
   116504,E:\sub\wolf's_rain\WOLF'S RAIN 02.wav LastWav: 3 Timer:
   100,0000

   [V4 Styles] Format: Name, Fontname, Fontsize, PrimaryColour,
   SecondaryColour, TertiaryColour, BackColour, Bold, Italic,
   BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV,
   AlphaLevel, Encoding Style: Default,Arial,20,65535,65535,65535,-
   2147483640,-1,0,1,3,0,2,30,30,30,0,0 Style:
   Titre_episode,Akbar,140,15724527,65535,65535,986895,-
   1,0,1,1,0,3,30,30,30,0,0 Style: Wolf main,Wolf_Rain,56,15724527,15724
   527,15724527,4144959,0,0,1,1,2,2,5,5,30,0,0 |

   And here are the two blocks that would be generated.

   Block's timecode: 00:02:40.650 BlockDuration: 00:00:01.140

   | 1,,Wolf main,Cher,0000,0000,0000,,Et les enregistrements de ses
   ondes delta ? |

   Block's timecode: 00:02:42.420 BlockDuration: 00:00:01.730

   | 2,,Wolf main,autre,0000,0000,0000,,Toujours rien. |

36.  USF Subtitles

   Under construction

37.  WebVTT

   The "Web Video Text Tracks Format" (short: WebVTT) is developed by
   the World Wide Web Consortium (W3C) [86].  Its specifications are
   freely available [87].

   The guiding principles for the storage of WebVTT in Matroska are:

   o  Consistency: store data in a similar way to other subtitle codecs

   o  Simplicity: making decoding and remuxing as easy as possible for
      existing infrastructures



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   o  Completeness: keeping as much data as possible from the original
      WebVTT file

37.1.  Storage of WebVTT in Matroska

37.1.1.  CodecID: codec identification

   The CodecID to use is S_TEXT/WEBVTT.

37.1.2.  CodecPrivate: storage of gloal WebVTT blocks

   This element contains all global blocks before the first subtitle
   entry.  This starts at the "WEBVTT" file identification marker but
   excludes the optional byte order mark.

37.1.3.  Storage of non-global WebVTT blocks

   Non-global WebVTT blocks (e.g.  "NOTE") before a WebVTT Cue Text are
   stored in Matroska's BlockAddition element together with the Matroska
   Block containing the WebVTT Cue Text these blocks precede (see below
   for the actual format).

37.1.4.  Storage of Cues in Matroska blocks

   Each WebVTT Cue Text is stored directly in the Matroska Block.

   A muxer MUST change all WebVTT Cue Timestamps present within the Cue
   Text to be relative to the Matroska Block's timestamp.

   The Cue's start timestamp is used as the Matroska Block's timestamp.

   The difference between the Cue's end timestamp and its start
   timestamp is used as the Matroska Block's duration.

37.1.5.  BlockAdditions: storing non-global WebVTT blocks, Cue Settings
         Lists and Cue identifiers

   Each Matroska Block may be accompanied by one BlockAdditions element.
   Its format is as follows:

   1.  The first line contains the WebVTT Cue Text's optional Cue
       Settings List followed by one line feed character (U+0x000a).
       The Cue Settings List may be empty in which case the line
       consists of the line feed character only.

   2.  The second line contains the WebVTT Cue Text's optional Cue
       Identifier followed by one line feed character (U+0x000a).  The
       line may be empty indicating that there was no Cue Identifier in



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       the source file in which case the line consists of the line feed
       character only.

   3.  The third and all following lines contain all WebVTT Comment
       Blocks that precede the current WebVTT Cue Block.  These may be
       absent.

   If there is no Matroska BlockAddition element stored together with
   the Matroska Block then all three components (Cue Settings List, Cue
   Identifier, Cue Comments) MUST be assumed to be absent.

37.2.  Examples of transformation

   Here's an example how a WebVTT is transformed.

37.2.1.  Example WebVTT file

   Let's take the following example file:

37.2.2.  CodecPrivate

   The resulting CodecPrivate element will look like this:

37.2.3.  Storage of Cue 1

   Example Cue 1: timestamp 00:00:00.000, duration 00:00:10.000, Block's
   content:

   BlockAddition's content starts with one empty line as there's no Cue
   Settings List:

37.2.4.  Storage of Cue 2

   Example Cue 2: timestamp 00:00:25.000, duration 00:00:10.000, Block's
   content:

   BlockAddition's content starts with two empty lines as there's
   neither a Cue Settings List nor a Cue Identifier:

37.2.5.  Storage of Cue 3

   Example Cue 3: timestamp 00:01:03.000, duration 00:00:03.500, Block's
   content:

   BlockAddition's content ends with an empty line as there's no Cue
   Identifier and there were no WebVTT Comment blocks:





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37.2.6.  Storage of Cue 4

   Example Cue 4: timestamp 00:03:10.000, duration 00:00:10.000, Block's
   content:

   Example entry 4: Entries can even include timestamps.  For
   example:<00:00:05.000>This becomes visible five seconds after the
   first part.

   This Block does not need a BlockAddition as the Cue did not contain
   an Identifier, nor a Settings List, and it wasn't preceded by Comment
   blocks.

37.3.  Storage of WebVTT in Matroska vs. WebM

   Note: the storage of WebVTT in Matroska is not the same as the design
   document for storage of WebVTT in WebM.  There are several reasons
   for this including but not limited to: the WebM document is old (from
   February 2012) and was based on an earlier draft of WebVTT and
   ignores several parts that were added to WebVTT later; WebM does
   still not support subtitles at all [88]; the proposal suggests
   splitting the information across multiple tracks making demuxer's and
   remuxer's life very difficult.---

38.  Tagging

   When a Tag is nested within another Tag, the nested Tag becomes an
   attribute of the base tag.  For instance, if you wanted to store the
   dates that a singer used certain addresses for, that singer being the
   lead singer for a track that included multiple bands simultaneously,
   then your tag tree would look something like this: Targets - TrackUID
   BAND - LEADPERFORMER -- ADDRESS --- DATE --- DATEEND -- ADDRESS ---
   DATE In this way, it becomes possible to store any Tag as attributes
   of another tag.  Multiple items SHOULD never be stored as a list in a
   single TagString.  If there is more than one tag of a certain type to
   be stored, then more than one SimpleTag SHOULD be used.  For
   authoring Tags outside of EBML, the following XML syntax is proposed
   [89] used in mkvmerge [90].  Binary data SHOULD be stored using
   BASE64 encoding if it is being stored at authoring time.

38.1.  Why official tags matter

   There is a debate between people who think all tags SHOULD be free
   and those who think all tags SHOULD be strict.  If you look at this
   page you will realise we are in between.

   Advanced-users application might let you put any tag in your file.
   But for the rest of the applications, they usually give you a basic



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   list of tags you can use.  Both have their needs.  But it's usually a
   bad idea to use custom/exotic tags because you will probably be the
   only person to use this information even though everyone else could
   benefit from it.  So hopefully when someone wants to put information
   in one's file, they will find an official one that fit them and
   hopefully use it ! If it's not in the list, this person can contact
   us any time for addition of such a missing tag.  But it doesn't mean
   it will be accepted... Matroska files are not meant the become a
   whole database of people who made costumes for a film.  A website
   would be better for that... It's hard to define what SHOULD be in and
   what doesn't make sense in a file.  So we'll treat each request
   carefully.

   We also need an official list simply for developpers to be able to
   display relevant information in their own design (if they choose to
   support a list of meta-information they SHOULD know which tag has the
   wanted meaning so that other apps could understand the same meaning).

38.2.  Tag translations

   To be able to save tags from other systems to Matroska we need to
   translate them to our system.  There is a translation table on our
   site [91].

38.3.  Tag Formatting

   o  The TagName SHOULD always be written in all capital letters and
      contain no space.

   o  The fields with dates SHOULD have the following format: YYYY-MM-DD
      HH:MM:SS.MSS YYYY = Year, -MM = Month, -DD = Days, HH = Hours, :MM
      = Minutes, :SS = Seconds, :MSS = Milliseconds.  To store less
      accuracy, you remove items starting from the right.  To store only
      the year, you would use, "2004".  To store a specific day such as
      May 1st, 2003, you would use "2003-05-01".

   o  Fields that require a Float SHOULD use the "." mark instead of the
      "," mark.  To display it differently for another local,
      applications SHOULD support auto replacement on display.  Also, a
      thousandths separator SHOULD NOT be used.

   o  For currency amounts, there SHOULD only be a numeric value in the
      Tag. Only numbers, no letters or symbols other than ".".  For
      instance, you would store "15.59" instead of "$15.59USD".







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38.4.  Target types

   The TargetType element allows tagging of different parts that are
   inside or outside a given file.  For example in an audio file with
   one song you could have information about the album it comes from and
   even the CD set even if it's not found in the file.

   For application to know what kind of information (like TITLE) relates
   to a certain level (CD title or track title), we also need a set of
   official TargetType names.  For now audio and video will have
   different values & names.  That also means the same tag name can have
   different meanings depending on where it is (otherwise we would end
   up with 15 TITLE_ tags).

   An upper level value tag applies to the lower level.  That means if a
   CD has the same artist for all tracks, you just need to set the
   ARTIST tag at level 50 (ALBUM) and not to each TRACK (but you can).
   That also means that if some parts of the CD have no known ARTIST the
   value MUST be set to nothing (a void string "").

   When a level doesn't exist it MUST NOT be specified in the files, so
   that the TOTAL_PARTS and PART_NUMBER elements match the same levels.

   Here is an example of how these "organizational" tags work: If you
   set 10 TOTAL_PARTS to the ALBUM level (40) it means the album
   contains 10 lower parts.  The lower part in question is the first
   lower level that is specified in the file.  So if it's TRACK (30)
   then that means it contains 10 tracks.  If it's MOVEMENT (20) that
   means it's 10 movements, etc.

38.5.  Official tags

   The following is a complete list of the supported Matroska Tags.
   While it is possible to use Tag names that are not listed below, this
   is not reccommended as compatability will be compromised.  If you
   find that there is a Tag missing that you would like to use, then
   please contact the Matroska team for its inclusion in the
   specifications before the format reaches 1.0.

38.6.  Notes

   o  In the Target list, a logicial OR is applied on all tracks, a
      logicial OR is applied on all chapters.  Then a logical AND is
      applied between the Tracks list and the Chapters list to know if
      an element belongs to this Target.






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39.  Attachments

39.1.  Introduction

   Matroska supports storage of related files and data in the
   Attachments Top-Level Element.  Attachments can be used to store
   related cover art, font files, transcripts, reports, or other
   ancilliary files related to the Segment.

39.2.  Cover Art

   Matroska supports attachments and they can be used for cover arts.
   This document defines a set of guidelines to add cover arts correctly
   in Matroska files.

   The pictures SHOULD only use the JPEG and PNG picture formats.

   There can be 2 different cover for a movie/album.  A portrait one
   (like a DVD case) and a landscape one (like a banner ad for example,
   looking better on a wide screen).

   There can be 2 versions of the same cover, the normal one and the
   small one.  The dimension of the normal one SHOULD be 600 on the
   smallest side (eg 960x600 for landscape and 600x800 for portrait,
   600x600 for square).  The dimension of the small one SHOULD be 120
   (192x120 or 120x160).

   The way to differentiate between all these versions is by the
   filename.  The default filename is cover.(png/jpg) for backward
   compatibility reasons.  That is the "big" version of the file (600)
   in square or portrait mode.  It SHOULD also be the first file in the
   attachments.  The smaller resolution SHOULD be prefixed with
   "small_", ie small_cover.(jpg/png).  The landscape variant SHOULD be
   suffixed with "_land", ie cover_land.jpg.  The filenames are case
   sensitive and SHOULD all be lower case.

   o  cover.jpg (portrait/square 600)

   o  small_cover.png (portrait/square 120)

   o  cover_land.png (landscape 600)

   o  small_cover_land.jpg (landscape 120)

   There is a sample file [92] available to test player compatibility or
   to demonstrate the use of cover art in Matroska files.





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39.3.  Font files

40.  Matroska Streaming

   There exist multiple ways to stream content.  The term streaming
   itself is very vague.  It means reading a file stored on a server.
   But the server could be very distant or very close.  The transport
   system and the protocol used for streaming makes the whole
   difference.

   In the case of Matroska, there are mostly 2 different kinds of
   stream: file access and live streaming.

41.  File Access

   File access can simply be reading a file located on your computer,
   but also accessing it from an HTTP (web) server or CIFS (windows
   share) server.  All these protocols are usually safe from reading
   errors and seeking in the stream is possible.  On other hand when the
   file is stored far away or on a slow server, seeking can be an
   expensive operation and SHOULD be avoided.  That's why we set a few
   guidelines [93] that, when followed, help reduce the number of
   seeking for regular playback and also have the playback start quickly
   without a lot of data needed to read first (like the Cues (index),
   Attachments or Meta Seek of all the Clusters).

   Matroska having a small overhead, it is well suited for storing
   music/videos on file servers without having a big impact on the
   bandwidth used.  It doesn't require to load the index before playing
   (the index can be loaded only when seeking is requested the first
   time), so playback can start very quickly too.

42.  Live Streaming

   Live streaming is the equivalent of TV broadcasting on the internet.
   There are 2 families of servers for that.  The RTP/RTSP ones and the
   HTTP servers.  Matroska is not meant to be used over RTP.  RTP
   already has timing and channel mechanisms that would wasted if
   doubled in Matroska.  On the other hand live streaming of Matroska
   over HTTP (or any other plain protocol based on TCP) is very
   possible.

   A live Matroska stream is different than a file, because it may have
   no known end (only when the client disconnects).  For that the
   Segment MUST use the "unknown" size (all 1s in the size).  The other
   option would be to concatenate Segments with known sizes one after
   the other.  This solution allows a change of codec/resolution between




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   each segment which can be useful in some cases (switch between 4:3
   and 16:9 in some TV programs for example).

   The Segment(s) being continuous, certain elements like Meta Seek,
   Cues, Chapters, Attachments MUST NOT be used in this context.

   On the player side, it is possible to detect that a stream is not
   seekable.  If the stream does not have a Meta Seek list or a Cues
   list at the beginning of the stream, it SHOULD be considered as non
   seekable.  Even though it's still theoretically possible to seek
   blindly forward in the stream, if the server supports it.

   In the context of a live radio or even web TV it is possible to "Tag"
   the content that is currently playing.  The Tags level 1 element can
   be placed between Clusters each time necessary.  In that case, the
   new Tags found MUST reset the previously encountered tags and use the
   new values instead (be they empty).

43.  Menu Specifications

44.  Introduction

   This document is a _draft of the Menu system_ that will be the
   default one in Matroska.  As it will just be composed of a Control
   Track, it will be seen as a "codec" and could be replaced later by
   something else if needed.

   A menu is like what you see on DVDs, when you have some screens to
   select the audio format, subtitles or scene selection.

45.  Requirements

   What we'll try to have is a system that can do almost everything done
   on a DVD, or more, or better, or drop the unused features if
   necessary.

   As the name suggests, a Control Track is a track that can control the
   playback of the file and/or all the playback features.  To make it as
   simple as possible for players, the Control Track will just give
   orders to the player and get the actions associated with the
   highlights/hotspots.

45.1.  Highlights/Hotspots

   A hightlight is basically a rectangle/key associated with an action
   UID.  When that rectangle/key is activated, the player send the UID
   of the action to the Control Track handler (codec).  The fact that it
   can also be a key means that even for audio only files, a keyboard



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   shortcut or button panel could be used for menues.  But in that case,
   the hotspot will have to be associated with a name to display.

   So this hightlight is sent from the Control Track to the Player.
   Then the player has to handle that highlight until it's disactivated
   (see Playback features [94])

   The hightlight contains a UID of the action, a displayable name (UTF-
   8), an associated key (list of keys to be defined, probably
   up/down/left/right/select), a screen position/range and an image to
   display.  The image will be displayed either when the user place the
   mouse over the rectangle (or any other shape), or when an option of
   the screen is selected (not activated).  There could be a second
   image used when the option is activated.  And there could be a third
   image that can serve as background.  This way you could have a still
   image (like in some DVDs) for the menu and behind that image blank
   video (small bitrate).

   When a highlight is activated by the user, the player has to send the
   UID of the action to the Control Track.  Then the Control Track codec
   will handle the action and possibly give new orders to the player.

   The format used for storing images SHOULD be extensible.  For the
   moment we'll use PNG and BMP, both with alpha channel.

45.2.  Playback features

   All the following features will be sent from the Control Track to the
   Player :

   o  Jump to chapter (UID, prev, next, number)

   o  Disable all tracks of a kind (audio, video, subtitle)

   o  Enable track UID (the kind doesn't matter)

   o  Define/Disable a highlight

   o  Enable/Disable jumping

   o  Enable/Disable track selection of a kind

   o  Select Edition ID (see chapters)

   o  Pause playback

   o  Stop playback




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   o  Enable/Disable a Chapter UID

   o  Hide/Unhide a Chapter UID

   All the actions will be writen in a normal Matroska track, with a
   timecode.  A "Menu Frame" SHOULD be able to contain more that one
   action/highlight for a given timecode. (to be determined, EBML format
   structure)

45.3.  Player requirements

   Some players might not support the control track.  That mean they
   will play the active/looped parts as part of the data.  So I suggest
   putting the active/looped parts of a movie at the end of a movie.
   When a Menu-aware player encouter the default Control Track of a
   Matroska file, the first order SHOULD be to jump at the start of the
   active/looped part of the movie.

46.  Working Graph

47.  Ideas

48.  Data Structure

   As a Matroska side project, the obvious choice for storing binary
   data is EBML.

49.  References

49.1.  URIs

   [1] http://mukoli.free.fr/mcf/mcf.html

   [2] https://github.com/Matroska-Org/ebml-specification/blob/master/
       specification.markdown

   [3] https://datatracker.ietf.org/wg/cellar/charter/

   [4] https://matroska.org/files/matroska.pdf

   [5] {{site.baseurl}}/diagram.html

   [6] https://github.com/Matroska-Org/ebml-specification/blob/master/
       specification.markdown

   [7] https://github.com/Matroska-Org/foundation-
       source/blob/master/spectool/specdata.xml




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   [8] https://tools.ietf.org/html/rfc2119

   [9] https://github.com/Matroska-Org/ebml-specification/blob/master/
       specification.markdown

   [10] https://github.com/Matroska-Org/ebml-specification/blob/master/
        specification.markdown#ebml-element-types

   [11] https://github.com/Matroska-Org/ebml-specification/blob/master/
        specification.markdown#ebml-schema

   [12] https://github.com/Matroska-Org/ebml-specification/blob/master/
        specification.markdown#structure

   [13] http://www.loc.gov/standards/iso639-2/php/English_list.php

   [14] http://www.iana.org/cctld/cctld-whois.htm

   [15] {{site.baseurl}}/index.html#block

   [16] http://www.webmproject.org/docs/container/

   [17] http://www.matroska.org/downloads/test_w1.html

   [18] {{site.baseurl}}/index.html#Cluster

   [19] {{site.baseurl}}/index.html#Timecode

   [20] {{site.baseurl}}/notes.html#TimecodeScale

   [21] {{site.baseurl}}/index.html#Cluster

   [22] {{site.baseurl}}/index.html#Timecode

   [23] {{site.baseurl}}/notes.html#Encryption

   [24] {{site.baseurl}}/notes.html#unknown-elements

   [25] {{site.baseurl}}/index.html#Cluster

   [26] {{site.baseurl}}/index.html#Timecode

   [27] {{site.baseurl}}/index.html#TimecodeScale

   [28] {{site.baseurl}}/index.html#Cluster

   [29] {{site.baseurl}}/index.html#Timecode




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   [30] {{site.baseurl}}/index.html#Cluster

   [31] {{site.baseurl}}/index.html#Timecode

   [32] {{site.baseurl}}/index.html#TrackTimeCodeScale

   [33] {{site.baseurl}}/notes.html#raw-timecode

   [34] {{site.baseurl}}/notes.html#timecode-types

   [35] {{site.baseurl}}/notes.html#matroska-version-indicators-
        doctypeversion-and-doctypereadversion

   [36] {{site.baseurl}}/index.html#StereoMode

   [37] {{site.baseurl}}/index.html#TrackOperation

   [38] {{site.baseurl}}/index.html#TrackCombinePlanes

   [39] {{site.baseurl}}/notes.html#track-operation

   [40] {{site.baseurl}}/index.html#TrackOperation

   [41] {{site.baseurl}}/index.html#Void

   [42] {{site.baseurl}}/order_guidelines.html#tags-end

   [43] http://haali.su/mkv/codecs.pdf

   [44] {{site.baseurl}}/index.html

   [45] {{site.baseurl}}/index.html#CodecID

   [46] http://msdn.microsoft.com/library/default.asp?url=/library/en-
        us/gdi/bitmaps_1rw2.asp

   [47] http://forum.doom9.org/showthread.php?s=&threadid=55773&perpage=
        20&pagenumber=2#post331855

   [48] https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/
        librmff.h

   [49] https://developer.apple.com/library/mac/documentation/QuickTime/
        QTFF/QTFFPreface/qtffPreface.html

   [50] {{site.baseurl}}/index.html#lacing

   [51] http://www.theora.org/doc/Theora_I_spec.pdf



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   [52] http://wiki.multimedia.cx/
        index.php?title=Apple_ProRes#Frame_layout

   [53] http://alac.macosforge.org/trac/browser/trunk/
        ALACMagicCookieDescription.txt

   [54] {{site.baseurl}}/index.html#lacing

   [55] http://www.xiph.org/ogg/vorbis/doc/vorbis-spec-ref.html

   [56] http://www.xiph.org/ogg/vorbis/doc/v-comment.html

   [57] http://www.xiph.org/ogg/vorbis/doc/vorbis-spec-ref.html

   [58] http://flac.sourceforge.net/

   [59] https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/
        librmff.h

   [60] http://msdn.microsoft.com/library/default.asp?url=/library/en-
        us/multimed/mmstr_625u.asp

   [61] https://developer.apple.com/library/mac/documentation/QuickTime/
        QTFF/QTFFPreface/qtffPreface.html

   [62] http://tausoft.org/

   [63] http://tausoft.org/wiki/True_Audio_Codec_Format

   [64] http://www.wavpack.com/

   [65] wavpack.html

   [66] {{site.baseurl}}/subtitles.html

   [67] {{site.baseurl}}/subtitles.html

   [68] {{site.baseurl}}/subtitles.html

   [69] {{site.baseurl}}/subtitles.html

   [70] {{site.baseurl}}/subtitles.html

   [71] http://wiki.xiph.org/index.php/OggKate#Matroska_mapping

   [72] http://dvd.sourceforge.net/dvdinfo/pci_pkt.html

   [73] http://dvd.sourceforge.net/dvdinfo/pci_pkt.html



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   [74] {{site.baseurl}}/index.html#ChapProcessCodecID

   [75] {{site.baseurl}}/index.html#ChapProcessCodecID

   [76] {{site.baseurl}}/index.html#ChapterTranslateID

   [77] http://dvd.sourceforge.net/dvdinfo/uops.html

   [78] http://www.dvd-replica.com/DVD/

   [79] http://dvd.sourceforge.net/dvdinfo/

   [80] http://wiki.multimedia.cx/index.php?title=SubStation_Alpha

   [81] http://moodub.free.fr/video/ass-specs.doc

   [83] mailto:kotus@eswat.demon.co.uk

   [85] mailto:kotus@eswat.demon.co.uk

   [86] https://www.w3.org/

   [87] https://w3c.github.io/webvtt/

   [88] http://www.webmproject.org/docs/container/

   [89] http://www.matroska.org/files/tags/matroskatags.dtd

   [90] http://www.bunkus.org/videotools/mkvtoolnix/doc/
        mkvmerge.html#mkvmerge.tags

   [91] othertagsystems/comparetable.html

   [92] https://sourceforge.net/projects/matroska/files/test_files/
        cover_art.mkv/download

   [93] {{site.baseurl}}/index.html

   [94] {{site.baseurl}}/chapters/menu.html#playback-features

Authors' Addresses

   Steve Lhomme


   Moritz Bunkus





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   Dave Rice


















































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