mvGetTrackUserDataListHandle(3dm)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 ALSOdmParamsGetInt(3dm), dmParamsSetInt(3dm), mvGetTitle(3dm), mvIntro(3dm),
mvWrite(3dm), Inside Macintosh: QuickTime.
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