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

Movie AtomsMedia AtomsMedia atoms contain the following data elements.SizeA 32-bit integer that specifies the number of bytes in this media atom.TypeA 32-bit integer that identifies the atom type; this field must be set to 'mdia'.Media header atomThis atom contains the standard media information. See “Media Header Atoms” (page 80).Extended language tag atomThis atom contains the extended language tag describing the media language. See “Extended LanguageTag Atom” (page 82).Handler reference atomThis atom identifies the media handler component that is to be used to interpret the media data. See“Handler Reference Atoms” (page 84) for more information.Note that the handler reference atom tells you the kind of media this media atom contains—for example,video or sound. The layout of the media information atom is specific to the media handler that is tointerpret the media. “Media Information Atoms” (page 85) discusses how data may be stored in a media,using the video media format defined by Apple as an example.Media information atomThis atom contains data specific to the media type for use by the media handler component. See “MediaInformation Atoms” (page 85).User data atomSee “User Data Atoms” (page 47).Media Header AtomsThe media header atom specifies the characteristics of a media, including time scale and duration. The mediaheader atom has an atom type of 'mdhd'.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.80