User data functions

These functions allow you to access and manipulate track and movie user data. More...

Functions
MP4Err	MP4GetMovieUserData (MP4Movie theMovie, MP4UserData *outUserData)
	Get the movie level user data 'udta'.
MP4Err	MP4GetTrackUserData (MP4Track theTrack, MP4UserData *outUserData)
	Get the track level user data 'udta'.
MP4Err	MP4AddUserData (MP4UserData theUserData, MP4Handle dataH, u32 userDataType, u32 *outIndex)
	Adds an entry to the user data list.
MP4Err	MP4GetIndUserDataType (MP4UserData theUserData, u32 typeIndex, u32 *outType)
	Queries an indexed type of user data in the user data list.
MP4Err	MP4GetUserDataEntryCount (MP4UserData theUserData, u32 userDataType, u32 *outCount)
	Returns the count of user data atoms of the specified type.
MP4Err	MP4GetUserDataItem (MP4UserData theUserData, MP4Handle dataH, u32 userDataType, u32 itemIndex)
	Returns the contents of the requested user data item.
MP4Err	MP4GetAtomFromUserData (MP4UserData theUserData, MP4GenericAtom *outAtom, u32 userDataType, u32 itemIndex)
	Returns the contents of the requested user data item.
MP4Err	MP4GetUserDataTypeCount (MP4UserData theUserData, u32 *outCount)
	Returns the count of user data types.
MP4Err	MP4DeleteUserDataItem (MP4UserData theUserData, u32 userDataType, u32 itemIndex)
	Deletes a user-data item, by index.
MP4Err	MP4NewUserData (MP4UserData *outUserData)
	Creates a new user data list.
MP4Err	MP4NewForeignAtom (MP4GenericAtom *outAtom, u32 atomType, MP4Handle atomPayload)
	Construct a new custom atom object.
MP4Err	MP4NewUUIDAtom (MP4GenericAtom *outAtom, u8 the_uuid[16], MP4Handle atomPayload)
	Construct a new custom atom object with UUID type.
MP4Err	MP4GetForeignAtom (MP4GenericAtom atom, u32 *atomType, u8 the_uuid[16], MP4Handle atomPayload)
	Returns the type and contents of the given foreign atom, and, if it is a UUID atom, its UUID also.

Detailed Description

These functions allow you to access and manipulate track and movie user data.

Function Documentation

MP4AddUserData()

MP4Err MP4AddUserData	(	MP4UserData	theUserData,
		MP4Handle	dataH,
		u32	userDataType,
		u32 *	outIndex
	)

Adds an entry to the user data list.

Parameters

theUserData	The user data list you are modifying
dataH	An ISOHandle containing the data you are adding
userDataType	The atom type that will identify this data
outIndex	Returns the index (of entries of userDataType) that corresponds to this entry. You will need this to retrieve this particular entry.

MP4GetAtomFromUserData()

MP4Err MP4GetAtomFromUserData	(	MP4UserData	theUserData,
		MP4GenericAtom *	outAtom,
		u32	userDataType,
		u32	itemIndex
	)

Returns the contents of the requested user data item.

Parameters

theUserData	The user data list you are querying
outAtom	A generic atom, which will contain the requested atom
userDataType	The type of user data
itemIndex	The index for the atom type you are querying. This should be one based

MP4GetIndUserDataType()

MP4Err MP4GetIndUserDataType	(	MP4UserData	theUserData,
		u32	typeIndex,
		u32 *	outType
	)

Queries an indexed type of user data in the user data list.

Parameters

theUserData	The user data list you are querying
typeIndex	The index for the atom type you are querying. This should be one based.
outType	Returns the atom type corresponding to the given index.

MP4GetMovieUserData()

MP4Err MP4GetMovieUserData	(	MP4Movie	theMovie,
		MP4UserData *	outUserData
	)

Get the movie level user data 'udta'.

Note

If no 'udta' is found, the default one is created in theMovie and returned.

Parameters

theMovie	input movie object
outUserData	output pointer to user data

Returns

MP4Err error code

MP4GetTrackUserData()

MP4Err MP4GetTrackUserData	(	MP4Track	theTrack,
		MP4UserData *	outUserData
	)

Get the track level user data 'udta'.

Note

If no 'udta' is found, the default one is created in theTrack and returned.

Parameters

theTrack	input track object
outUserData	output pointer to user data

Returns

MP4Err error code

MP4GetUserDataItem()

MP4Err MP4GetUserDataItem	(	MP4UserData	theUserData,
		MP4Handle	dataH,
		u32	userDataType,
		u32	itemIndex
	)

Returns the contents of the requested user data item.

Parameters

theUserData	The user data list you are querying
dataH	A handle to contain the returned data
userDataType	The type of user data
itemIndex	The index for the atom type you are querying. This should be one based

MP4NewForeignAtom()

MP4Err MP4NewForeignAtom	(	MP4GenericAtom *	outAtom,
		u32	atomType,
		MP4Handle	atomPayload
	)

Construct a new custom atom object.

Parameters

outAtom	output new atom object
atomType	atom type fourcc
atomPayload	atom payload data handle

Returns

MP4Err error code

MP4NewUUIDAtom()

MP4Err MP4NewUUIDAtom	(	MP4GenericAtom *	outAtom,
		u8	the_uuid[16],
		MP4Handle	atomPayload
	)

Construct a new custom atom object with UUID type.

Parameters

outAtom	output new atom object
the_uuid	atom UUID
atomPayload	atom payload data handle

Returns

MP4Err error code