Quicktime File Format (2012-08-14).pdf

Movie AtomsMedia AtomsFigure 2-22 (page 83) shows the layout of this atom.Figure 2-22The layout of an extended language tag atomBytesExtended Language Tag atomAtom sizeType = 'elng'VersionFlagsLanguage tag string4413variableExtended language tag atoms contain the following data elements.SizeA 32-bit integer that specifies the number of bytes in this media header atom.TypeA 32-bit integer that identifies the atom type; this field must be set to 'elng'.VersionOne byte that specifies the version of this header atom.FlagsThree bytes of space for media header flags. Set this field to 0.Language tag stringA NULL-terminated C string containing an RFC 4646 (BCP 47) compliant language tag string in ASCIIencoding, such as "en-US", "fr-FR", or "zh-CN".Additional notes:●●●●The extended language tag overrides the media language if they are not consistent.The extended language tag atom is optional, and if it is absent the media language should be used.No validation of the language tag string is performed. Applications parsing QuickTime movies need to beprepared for an invalid language tag, and are expected to behave as if no information is found.For best compatibility with earlier players, if an extended language tag is specified, the most compatiblelanguage code should be specified in the language field of the 'mdhd' atom (for example, "eng" if theextended language tag is "en-UK"). If there is no reasonably compatible tag, the packed form of 'und' canbe specified in the language code of the 'mdhd' atom.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.83