List of pre-defined metadata types

Classes
struct	MMAL_METATDATA_T
struct	MMAL_METATDATA_HELLO_WORLD_T

Typedefs
typedef struct MMAL_METATDATA_T	MMAL_METADATA_T
typedef struct MMAL_METATDATA_HELLO_WORLD_T	MMAL_METADATA_HELLO_WORLD_T

Functions
MMAL_METADATA_T *	mmal_metadata_get (MMAL_BUFFER_HEADER_T *header, uint32_t id)
MMAL_STATUS_T	mmal_metadata_set (MMAL_BUFFER_HEADER_T *header, MMAL_METADATA_T *metadata)

Pre-defined metadata FourCCs
#define	MMAL_METADATA_HELLO_WORLD   MMAL_FOURCC('H','E','L','O')

Detailed Description

This defines a list of standard metadata types. Components can still define proprietary metadata types by using their own FourCC and defining their own metadata structures.

Typedef Documentation

typedef struct MMAL_METATDATA_HELLO_WORLD_T MMAL_METADATA_HELLO_WORLD_T

Hello World metadata.

typedef struct MMAL_METATDATA_T MMAL_METADATA_T

Generic metadata type. All metadata structures need to begin with these fields.

Function Documentation

MMAL_METADATA_T* mmal_metadata_get	(	MMAL_BUFFER_HEADER_T *	header,
		uint32_t	id
	)

Get metadata item from buffer header. This will search through all the metadata in the buffer header and return a pointer to the first instance of the requested metadata id.

Parameters

header	buffer header containing the metadata
id	requested metadata id

Returns

Pointer to metadata requested or NULL if not found.

MMAL_STATUS_T mmal_metadata_set	(	MMAL_BUFFER_HEADER_T *	header,
		MMAL_METADATA_T *	metadata
	)

Set metadata item in buffer header. This will store the metadata item into the buffer header. This operation can fail if not enough memory is available in the data section of the buffer header.

Parameters

header	buffer header to store the metadata into
metadata	metadata item to store in buffer header

Returns

MMAL_SUCCESS on success or MMAL_ENOMEM if not enough memory is available for storing the metadata