mvGetTrackUserDataListHandle(3dm)

NAME
     mvGetTrackUserDataListHandle, mvGetMovieUserDataListHandle - get user
     data dmParams of the track/movie


SYNOPSIS
     #include <dmedia/moviefile.h>

     DMstatus mvGetTrackUserDataListHandle( MVid track, DMparams ** userData );
     DMstatus mvGetMovieUserDataListHandle( MVid movie, DMparams ** userData );


DESCRIPTION
     These functions return a pointer to the user data dmParams, which you can
     then examine and modify using dmParamsGet* and dmParamsSet*. You should
     not free this pointer, as it is owned by the movie library. The params
     set in this fashion will be stored in the file when it is written, if the
     file format supports user data. Note that currently, the QuickTime file
     format is the only file format that supports user data.


QUICKTIME INTEROPERABILITY
     The names of QuickTime user data atoms are required to be four characters
     by the file format, and that Apple has reserved all lowercase user data
     type values. (Please see Inside Macintosh:  QuickTime, published by
     Addisson Wesley.)

     If the paramName used is a 4 character string, this is what will be
     written in the QuickTime file, and it will be natively accessible via the
     QuickTime API. However, if you choose to use a paramName that is not four
     characters long, these will be written in a Silicon Grahics extended user
     data atom, and will not be easy to access on other platforms (although it
     will be readable, and will be a fully compatible QuickTime file).

     For this reason, Silicon Graphics suggests the use of four capital letter
     character paramNames when interoperability with other QuickTime platforms
     is desired.


KNOWN BUGS & WORKAROUNDS
     If you have called mvWrite after getting a user data list dmParams, and
     wish to change a user data entry later, you need to call
     mvGet*UserDataListHandle again, in order for the next change to be
     written to the file the next time mvWrite or mvClose is called.


SEE ALSO
     dmParamsGetInt(3dm), dmParamsSetInt(3dm), mvGetTitle(3dm), mvIntro(3dm),
     mvWrite(3dm), Inside Macintosh: QuickTime.