Gst.Meta¶

Fields¶

Name	Type	Access	Description
flags	`Gst.MetaFlags`	r/w	extra flags for the metadata
info	`Gst.MetaInfo`	r/w	pointer to the `Gst.MetaInfo`

Methods¶

class	`api_type_get_tags` (api)
class	`api_type_has_tag` (api, tag)
class	`api_type_register` (api, tags)
class	`get_info` (impl)
class	`register` (api, impl, size, init_func, free_func, transform_func)
	`compare_seqnum` (meta2)
	`get_seqnum` ()

Details¶

class Gst.Meta¶

The Gst.Meta structure should be included as the first member of a Gst.Buffer metadata structure. The structure defines the API of the metadata and should be accessible to all elements using the metadata.

A metadata API is registered with Gst.Meta.api_type_register() which takes a name for the metadata API and some tags associated with the metadata. With Gst.Meta.api_type_has_tag() one can check if a certain metadata API contains a given tag.

Multiple implementations of a metadata API can be registered. To implement a metadata API, Gst.Meta.register() should be used. This function takes all parameters needed to create, free and transform metadata along with the size of the metadata. The function returns a Gst.MetaInfo structure that contains the information for the implementation of the API.

A specific implementation can be retrieved by name with Gst.Meta.get_info().

See Gst.Buffer for how the metadata can be added, retrieved and removed from buffers.

classmethod api_type_get_tags(api)[source]¶

Parameters:	api (`GObject.GType`) – an API
Returns:	an array of tags as strings.
Return type:	[`str`]

New in version 1.2.

classmethod api_type_has_tag(api, tag)[source]¶

Parameters:	api (`GObject.GType`) – an API tag (`int`) – the tag to check
Returns:	`True` if api was registered with tag.
Return type:	`bool`

Check if api was registered with tag.

classmethod api_type_register(api, tags)[source]¶

Parameters:	api (`str`) – an API to register tags ([`str`]) – tags for api
Returns:	a unique `GObject.GType` for api.
Return type:	`GObject.GType`

Register and return a GObject.GType for the api and associate it with tags.

classmethod get_info(impl)[source]¶

Parameters:	impl (`str`) – the name
Returns:	a `Gst.MetaInfo` with impl, or `None` when no such metainfo exists.
Return type:	`Gst.MetaInfo` or `None`

Lookup a previously registered meta info structure by its implementation name impl.

classmethod register(api, impl, size, init_func, free_func, transform_func)[source]¶

Parameters:	api (`GObject.GType`) – the type of the `Gst.Meta` API impl (`str`) – the name of the `Gst.Meta` implementation size (`int`) – the size of the `Gst.Meta` structure init_func (`Gst.MetaInitFunction`) – a `Gst.MetaInitFunction` free_func (`Gst.MetaFreeFunction`) – a `Gst.MetaFreeFunction` transform_func (`Gst.MetaTransformFunction`) – a `Gst.MetaTransformFunction`
Returns:	a `Gst.MetaInfo` that can be used to access metadata.
Return type:	`Gst.MetaInfo` or `None`

Register a new Gst.Meta implementation.

The same info can be retrieved later with Gst.Meta.get_info() by using impl as the key.

compare_seqnum(meta2)[source]¶

Parameters:	meta2 (`Gst.Meta`) – a `Gst.Meta`
Returns:	a negative number if self comes before meta2, 0 if both metas have an equal sequence number, or a positive integer if self comes after meta2.
Return type:	`int`

Meta sequence number compare function. Can be used as GLib.CompareFunc or a GLib.CompareDataFunc.

New in version 1.16.

get_seqnum()[source]¶

Return type:	`int`

Gets seqnum for this meta.

New in version 1.16.