Since QuickTime 7, a new architecture has been introduced in order to read and write metainformation in a QuickTime movie. This
architecture defines a new metainformation storage format called the QuickTime metadata format. In this type of storage, metadata is accessed via
a metadata reference. There is one metadata reference per
,
, or
. A single metadata reference can pick out one or more
metadata containers, which are distinguished from one another by their
.
A metadata container holds one or more metadata items. Each metadata item is accessed by a
.
A given metadata item has a number of attributes,
including its
and its .
The key is analogous to the
,
insofar as it is a label for the sort of data contained in the metadata item.
The of the key for
a specific metadata item
depends on the
of that item.
The QTPlgMetaData class lets you manage metadata references
This class requires QuickTime 7 or later.
The
QTPlgMetaData class constructors are called when you create a new instance of the class, while
the
˜QTPlgMetaData class destructor, is called automatically when the
class is no more in use. Also, you can invoke the class destructor by setting the instance of the class to
nil.
Once a new class instance is returned, it is good practice to check the
class property to
be sure that the new object can be used.
The class provides you with the following initializer methods:
This is the default constructor. The object will be initialized with the metadata reference associated to the specified
source
Note: a more convenient way to access the container’s metadata is to use the
object returned from the
class instance in use
[Deprecated]: since version 6.1 of the plugin this redundant constructor is deprecated
and will be removed from a future plugin version
This is the copy constructor. The properties of the object to be copied will be used to initialize the
new class instance properties
indicates the four–char code that identifies the owner of this metaadata object
(i.e. "moov" for movie)
a collection of objects that list
all of the metadata containers associated to this metadata object
use this method to find about how many are
associated to the metadata container specified by the optional
storageFormat parameter; if you omit this
parameter the result is set to the total number of
contained by the metadata reference regardless of the type of metadata container
use this method to remove every from the
metadata container specified by the optional
storageFormat parameter; to remove all of the items
contained by the metadata reference in use, simply omit to indicate a specific metadata container
use this method to obtain a collection of
associated to the metadata container specified by the optional
storageFormat parameter; do not specify any
storage format if you want to obtain the list of
all of the owned by the metadata reference in use
use this method to obtain a collection of that are
labeled with the specified
key. The metadata container to look for is implicitly specified by the
; if the
value is
, then this method
will scan any metadata container associated to the metadata container in use
use this method to set the value of an existing
by this method you can add a new to a
metadata container; the metadata container target is implictly deduced by the
of the
. You can not use the
constant value to
specify the format of the key; this being the case, the method will fail to add the metadata item to the metadata container
use this method to remove from the metadata container in use just the first
labeled with the specified
key if it exists
use this method to remove from the metadata container in use all of the
labeled with the specified
key
identifies the new QuickTime metadata format
identifies the iTunes metadata format
identifies the user data format