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

MetadataMetadata StructureData LocationMetadata is stored immediately in the corresponding atom structures, by value.LocalizationA metadata item can be identified as specific to a country or set of countries, to a language or set of languages,or to some combination of languages and countries. This identification allows for a default value (suitable forany language or country not explicitly called out), a single value, or a list of values.Storage Location in a QuickTime FileWithin a QuickTime file, metadata can be stored within a movie atom (‘moov’), a track atom (‘trak’) or amedia atom (‘mdia’). Only one metadata atom is allowed for each location. If there is user data and metadatastored in the same location, and both declare the same information, for example, declare a copyright notice,the metadata takes precedence.Metadata StructureThe container for metadata is an atom of type ‘meta’. The metadata atom must contain the following subatoms:metadata handler atom (‘hdlr’), metadata item keys atom (‘keys’), and metadata item list atom (‘ilst’).Other optional atoms that may be contained in a metadata atom include the country list atom (‘ctry’),language list atom (‘lang’) and free space atom (‘free’). The country list and language list atoms can beused to store localized data in an efficient manner. The free space atom may be used to reserve space in ametadata atom for later additions to it, or to zero out bytes within a metadata atom after editing and removingelements from it. The free space atom may not occur within any other subatom contained in the metadataatom.Metadata AtomThe metadata atom is the container for carrying metadata.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.129