Package org.freedesktop.gstreamer.gst

Class Meta

java.lang.Object

org.javagi.base.ProxyInstance

org.freedesktop.gstreamer.gst.Meta

All Implemented Interfaces:

Proxy

@Generated("io.github.jwharm.JavaGI")
public class Meta
extends ProxyInstance

The GstMeta structure should be included as the first member of a GstBuffer 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 GstMetaInfo 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 GstBuffer for how the metadata can be added, retrieved and removed from buffers.

Constructor Summary

Constructors

Constructor	Description
Meta()	Allocate a new Meta.
Meta(Arena arena)	Allocate a new Meta.
Meta(MemorySegment address)	Create a Meta proxy instance for the provided memory address.
Meta(Set<MetaFlags> flags, MetaInfo info)	Allocate a new Meta with the fields set to the provided values.
Meta(Set<MetaFlags> flags, MetaInfo info, Arena arena)	Allocate a new Meta with the fields set to the provided values.

Method Summary

Modifier and Type	Method	Description
static boolean	apiTypeAggregateParams(Type api, Structure[] aggregatedParams, Structure params0, Structure params1)	When a element like tee decides the allocation, each downstream element may fill different parameters and pass them to gst_query_add_allocation_meta().
static String[]	apiTypeGetTags(Type api)
static boolean	apiTypeHasTag(Type api, Quark tag)	Check if api was registered with tag.
static Type	apiTypeRegister(String api, @Nullable String @Nullable [] tags)	Register and return a GType for the api and associate it with tags.
static void	apiTypeSetParamsAggregator(Type api, @Nullable AllocationMetaParamsAggregator aggregator)	This function sets the aggregator function for a specific API type.
int	compareSeqnum(Meta meta2)	Meta sequence number compare function.
static @Nullable Meta	deserialize(Buffer buffer, MemorySegment data, long size, Out<Integer> consumed)	Recreate a GstMeta from serialized data returned by gst_meta_serialize() and add it to buffer.
static @Nullable MetaInfo	getInfo(String impl)	Lookup a previously registered meta info structure by its implementation name impl.
static MemoryLayout	getMemoryLayout()	The memory layout of the native struct.
long	getSeqnum()	Gets seqnum for this meta.
Set<MetaFlags>	readFlags()	Read the value of the field flags.
MetaInfo	readInfo()	Read the value of the field info.
static MetaInfo	register(Type api, String impl, long size, @Nullable MetaInitFunction initFunc, @Nullable MetaFreeFunction freeFunc, @Nullable MetaTransformFunction transformFunc)	Register a new GstMeta implementation.
static MetaInfo	registerCustom(String name, @Nullable String @Nullable [] tags, @Nullable CustomMetaTransformFunction transformFunc)	Register a new custom GstMeta implementation, backed by an opaque structure holding a GstStructure.
static MetaInfo	registerCustomSimple(String name)	Simplified version of gst_meta_register_custom(), with no tags and no transform function.
boolean	serialize(ByteArrayInterface data)	Serialize this Meta into a format that can be stored or transmitted and later deserialized by gst_meta_deserialize().
boolean	serializeSimple(@org.jspecify.annotations.Nullable byte @Nullable [] data)	Same as gst_meta_serialize() but with a GByteArray instead of GstByteArrayInterface.
void	writeFlags(Set<MetaFlags> flags)	Write a value in the field flags.
void	writeInfo(MetaInfo info)	Write a value in the field info.

Methods inherited from class org.javagi.base.ProxyInstance

equals, handle, hashCode

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Meta

public Meta(MemorySegment address)

Create a Meta proxy instance for the provided memory address.

Parameters:

address - the memory address of the native object

Meta

public Meta(Arena arena)

Allocate a new Meta.

Parameters:

arena - to control the memory allocation scope

Meta

public Meta()

Allocate a new Meta. The memory is allocated with Arena.ofAuto().

Meta

public Meta(Set<MetaFlags> flags,
 MetaInfo info,
 Arena arena)

Allocate a new Meta with the fields set to the provided values.

Parameters:

flags - value for the field flags

info - value for the field info

arena - to control the memory allocation scope

Meta

public Meta(Set<MetaFlags> flags,
 MetaInfo info)

Allocate a new Meta with the fields set to the provided values. The memory is allocated with Arena.ofAuto().

Parameters:

flags - value for the field flags

info - value for the field info

Method Details

getMemoryLayout

public static MemoryLayout getMemoryLayout()

The memory layout of the native struct.

Returns:

the memory layout

readFlags

public Set<MetaFlags> readFlags()

Read the value of the field flags.

Returns:

The value of the field flags

writeFlags

public void writeFlags(Set<MetaFlags> flags)

Write a value in the field flags.

Parameters:

flags - The new value for the field flags

readInfo

public MetaInfo readInfo()

Read the value of the field info.

Returns:

The value of the field info

writeInfo

public void writeInfo(MetaInfo info)

Write a value in the field info.

Parameters:

info - The new value for the field info

apiTypeAggregateParams

public static boolean apiTypeAggregateParams(Type api,
 Structure[] aggregatedParams,
 Structure params0,
 Structure params1)

When a element like tee decides the allocation, each downstream element may fill different parameters and pass them to gst_query_add_allocation_meta(). In order to keep these parameters, a merge operation is needed. This aggregate function can combine the parameters from params0 and param1, and write the result back into aggregatedParams.

Parameters:

api - the GType of the API for which the parameters are being aggregated.

aggregatedParams - This structure will be updated with the combined parameters from both params0 and params1.

params0 - a GstStructure containing the new parameters to be aggregated.

params1 - a GstStructure containing the new parameters to be aggregated.

Returns:

true if the parameters were successfully aggregated, false otherwise.

Since:

1.26

apiTypeGetTags

public static String[] apiTypeGetTags(Type api)

apiTypeHasTag

public static boolean apiTypeHasTag(Type api,
 Quark tag)

Check if api was registered with tag.

Parameters:

api - an API

tag - the tag to check

Returns:

true if api was registered with tag.

apiTypeRegister

public static Type apiTypeRegister(String api,
 @Nullable String @Nullable [] tags)

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

Parameters:

api - an API to register

tags - tags for api

Returns:

a unique GType for api.

apiTypeSetParamsAggregator

public static void apiTypeSetParamsAggregator(Type api,
 @Nullable AllocationMetaParamsAggregator aggregator)

This function sets the aggregator function for a specific API type.

Parameters:

api - the GType of the API for which the aggregator function is being set.

aggregator - the aggregator function to be associated with the given API type.

Since:

1.26

deserialize

public static @Nullable Meta deserialize(Buffer buffer,
 MemorySegment data,
 long size,
 Out<Integer> consumed)

Recreate a GstMeta from serialized data returned by gst_meta_serialize() and add it to buffer.

Note that the meta must have been previously registered by calling one of gst_*_meta_get_info () functions.

consumed is set to the number of bytes that can be skipped from data to find the next meta serialization, if any. In case of parsing error that does not allow to determine that size, consumed is set to 0.

Parameters:

buffer - a GstBuffer

data - serialization data obtained from gst_meta_serialize()

size - size of data

consumed - total size used by this meta, could be less than size

Returns:

the metadata owned by buffer, or null.

Since:

1.24

getInfo

public static @Nullable MetaInfo getInfo(String impl)

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

Parameters:

impl - the name

Returns:

a GstMetaInfo with impl, or null when no such metainfo exists.

register

public static MetaInfo register(Type api,
 String impl,
 long size,
 @Nullable MetaInitFunction initFunc,
 @Nullable MetaFreeFunction freeFunc,
 @Nullable MetaTransformFunction transformFunc)

Register a new GstMeta implementation.

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

Parameters:

api - the type of the GstMeta API

impl - the name of the GstMeta implementation

size - the size of the GstMeta structure

initFunc - a GstMetaInitFunction

freeFunc - a GstMetaFreeFunction

transformFunc - a GstMetaTransformFunction

Returns:

a GstMetaInfo that can be used to access metadata.

registerCustom

public static MetaInfo registerCustom(String name,
 @Nullable String @Nullable [] tags,
 @Nullable CustomMetaTransformFunction transformFunc)

Register a new custom GstMeta implementation, backed by an opaque structure holding a GstStructure.

The registered info can be retrieved later with gst_meta_get_info() by using name as the key.

The backing GstStructure can be retrieved with gst_custom_meta_get_structure(), its mutability is conditioned by the writability of the buffer the meta is attached to.

When transformFunc is null, the meta and its backing GstStructure will always be copied when the transform operation is copy, other operations are discarded, copy regions are ignored.

Parameters:

name - the name of the GstMeta implementation

tags - tags for api

transformFunc - a GstMetaTransformFunction

Returns:

a GstMetaInfo that can be used to access metadata.

Since:

1.20

registerCustomSimple

public static MetaInfo registerCustomSimple(String name)

Simplified version of gst_meta_register_custom(), with no tags and no transform function.

Parameters:

name - the name of the GstMeta implementation

Returns:

a GstMetaInfo that can be used to access metadata.

Since:

1.24

compareSeqnum

public int compareSeqnum(Meta meta2)

Meta sequence number compare function. Can be used as GCompareFunc or a GCompareDataFunc.

Parameters:

meta2 - a GstMeta

Returns:

a negative number if this Meta comes before meta2, 0 if both metas have an equal sequence number, or a positive integer if this Meta comes after meta2.

Since:

1.16

getSeqnum

public long getSeqnum()

Gets seqnum for this meta.

Since:

1.16

serialize

public boolean serialize(ByteArrayInterface data)

Serialize this Meta into a format that can be stored or transmitted and later deserialized by gst_meta_deserialize().

This is only supported for meta that implements GstMetaInfo.serialize_func, false is returned otherwise.

Upon failure, data>data pointer could have been reallocated, but data>len won't be modified. This is intended to be able to append multiple metas into the same GByteArray.

Since serialization size is often the same for every buffer, caller may want to remember the size of previous data to preallocate the next.

Parameters:

data - GstByteArrayInterface to append serialization data

Returns:

true on success, false otherwise.

Since:

1.24

serializeSimple

public boolean serializeSimple(@org.jspecify.annotations.Nullable byte @Nullable [] data)

Same as gst_meta_serialize() but with a GByteArray instead of GstByteArrayInterface.

Parameters:

data - GByteArray to append serialization data

Returns:

true on success, false otherwise.

Since:

1.24