Inside Macintosh: QuickTime /

Chapter 4 - Movie Resource Formats / Overview of the Movie Resource Atom

User-Defined Data Atoms

Many movie, track, and media atoms contain atoms that store user-defined data. Your application may store data in these user-defined data atoms.

Figure 4-12 shows the layout of a user-defined data atom.

Figure 4-12 The layout of a user-defined data atom

You define a user-defined data atom by specifying these elements:

• Size. The number of bytes in the data element.
• Type. The type of the data in the data element (defined by the 'udta' atom type).
• User data list. The movie user data atom contains a user data list that is itself formatted like a series of atoms. Each data element in the private data portion of the user-defined data atom contains size and type information along with the data. Furthermore, the list of atoms is optionally terminated by a 0.

The following user data types are currently defined:

'©cpy'	Copyright statement
'©day'	Date the movie content was created
'©dir'	Name of movie's director
'©ed1' to '©ed9'	Edit dates and descriptions
'©fmt'	Indication of movie format (computer-generated, digitized, and so on)
'©inf'	Information about the movie
'©prd'	Name of movie's producer
'©prf'	Names of performers
'©req'	Special hardware and software requirements
'©src'	Credits for those who provided movie source content
'©wrt'	Name of movie's writer

User data items of these types must contain text data only.