Service abstract base class. More...

#include <mlt_service.h>

Inheritance diagram for mlt_service_s:

Public Member Functions
void	mlt_service_apply_filters (mlt_service self, mlt_frame frame, int index)
	Recursively apply attached filters.
int	mlt_service_attach (mlt_service self, mlt_filter filter)
	Attach a filter.
mlt_cache_item	mlt_service_cache_get (mlt_service self, const char *name)
	Get an object from a service's cache.
int	mlt_service_cache_get_size (mlt_service self, const char *name)
	Get the current maximum size of the named cache.
void	mlt_service_cache_put (mlt_service self, const char name, void data, int size, mlt_destructor destructor)
	Put an object into a service's cache.
void	mlt_service_cache_set_size (mlt_service self, const char *name, int size)
	Set the number of items to cache for the named cache.
void	mlt_service_close (mlt_service self)
	Destroy a service.
int	mlt_service_connect_producer (mlt_service self, mlt_service producer, int index)
	Connect a producer to the service.
mlt_service	mlt_service_consumer (mlt_service self)
	Obtain the consumer a service is connected to.
int	mlt_service_detach (mlt_service self, mlt_filter filter)
	Detach a filter.
static void	mlt_service_disconnect (mlt_service self)
	Disconnect a service from its consumer.
mlt_filter	mlt_service_filter (mlt_service self, int index)
	Retrieve a filter.
int	mlt_service_get_frame (mlt_service self, mlt_frame_ptr frame, int index)
	Obtain a frame.
mlt_service	mlt_service_get_producer (mlt_service self)
	Get the first connected producer.
mlt_service_type	mlt_service_identify (mlt_service self)
	Identify the subclass of the service.
int	mlt_service_init (mlt_service self, void *child)
	Initialize a service.
void	mlt_service_lock (mlt_service self)
	Acquire a mutual exclusion lock on this service.
mlt_service	mlt_service_producer (mlt_service self)
	Obtain the producer a service is connected to.
mlt_profile	mlt_service_profile (mlt_service self)
	Retrieve the profile.
mlt_properties	mlt_service_properties (mlt_service self)
	Return the properties object.
void	mlt_service_unlock (mlt_service self)
	Release a mutual exclusion lock on this service.
Data Fields
mlt_destructor	close
	the destructor virtual function
void *	close_object
	the object supplied to the close virtual function
int(*	get_frame )(mlt_service self, mlt_frame_ptr frame, int index)
	Get a frame of data (virtual function).
Private Member Functions
static mlt_cache	get_cache (mlt_service self, const char *name)
	Lookup the cache object for a service.
void	mlt_service_cache_purge (mlt_service self)
	Release a service's cache items.
static void	mlt_service_connect (mlt_service self, mlt_service that)
	Associate a service to a consumer.
static void	mlt_service_filter_changed (mlt_service owner, mlt_service self)
	The service-changed event handler.
static void	mlt_service_property_changed (mlt_listener listener, mlt_properties owner, mlt_service self, void **args)
	The transmitter for property changes.
static int	service_get_frame (mlt_service self, mlt_frame_ptr frame, int index)
	Default implementation of the get_frame virtual function.
Private Attributes
void *	child
	the object of a subclass
void *	local
	instance object
struct mlt_properties_s	parent
	A service extends properties.

Detailed Description

Service abstract base class.

The service is the base class for all of the interesting classes and plugins for MLT. A service can have multiple inputs connections to other services called its "producers" but only a single output to another service called its "consumer." A service that has both producer and consumer connections is called a filter. Any service can have zero or more filters "attached" to it. We call any collection of services and their connections a "service network," which is similar to what DirectShow calls a filter graph or what gstreamer calls an element pipeline.

Event:: service-changed

Event:: property-changed

Property:: mlt_type identifies the subclass

Property:: _mlt_service_hidden a flag that indicates whether to hide the mlt_service

Property:: mlt_service is the name of the implementation of the service

Property:: resource is either the stream identifier or grandchild-class

Property:: in when to start, what is started is service-specific

Property:: out when to stop

Property:: _filter_private Set this on a service to ensure that attached filters are handled privately. See modules/core/filter_region.c and modules/core/filter_watermark.c for examples.

Property:: disable Set this on a filter to disable it while keeping it in the object model.

Property:: _profile stores the mlt_profile for a service

Property:: _unique_id is a unique identifier

Property:: _need_previous_next boolean that instructs producers to get preceding and following frames inside of mlt_service_get_frame

Member Function Documentation

static mlt_cache get_cache	(	mlt_service	self,
		const char *	name
	)		`[private]`

Lookup the cache object for a service.

Parameters:

self	a service
name	a name for the object

Returns:: a cache

void mlt_service_apply_filters	(	mlt_service	self,
		mlt_frame	frame,
		int	index
	)

Recursively apply attached filters.

Parameters:

self	a service
frame	a frame
index	used to track depth of recursion, top caller should supply 0

int mlt_service_attach	(	mlt_service	self,
		mlt_filter	filter
	)

Attach a filter.

Parameters:

self	a service
filter	the filter to attach

Returns:: true if there was an error

mlt_cache_item mlt_service_cache_get	(	mlt_service	self,
		const char *	name
	)

Get an object from a service's cache.

Parameters:

self	a service
name	a name for the object that is unique to the service class, but not to the instance

Returns:: a cache item or NULL if an object is not found

See also:: mlt_cache_item_data

int mlt_service_cache_get_size	(	mlt_service	self,
		const char *	name
	)

Get the current maximum size of the named cache.

Parameters:

self	a service
name	a name for the object that is unique to the service class, but not to the instance

Returns:: the current maximum number of items to cache or zero if there is an error

void mlt_service_cache_purge ( mlt_service self ) [private]

Release a service's cache items.

Parameters:

self a service

void mlt_service_cache_put	(	mlt_service	self,
		const char *	name,
		void *	data,
		int	size,
		mlt_destructor	destructor
	)

Put an object into a service's cache.

Parameters:

self	a service
name	a name for the object that is unique to the service class, but not to the instance
data	an opaque pointer to the object to put into the cache
size	the number of bytes pointed to by data
destructor	a function that releases the data

void mlt_service_cache_set_size	(	mlt_service	self,
		const char *	name,
		int	size
	)

Set the number of items to cache for the named cache.

Parameters:

self	a service
name	a name for the object that is unique to the service class, but not to the instance
size	the number of items to cache

void mlt_service_close ( mlt_service self )

Destroy a service.

Parameters:

self	the service to destroy

static void mlt_service_connect	(	mlt_service	self,
		mlt_service	that
	)		`[private]`

Associate a service to a consumer.

Overwrites connection to any existing consumer.

Parameters:

self	a service
that	a consumer

int mlt_service_connect_producer	(	mlt_service	self,
		mlt_service	producer,
		int	index
	)

Connect a producer to the service.

Parameters:

self	a service
producer	a producer
index	which of potentially multiple producers to this service (0 based)

Returns:: > 0 warning, == 0 success, < 0 serious error, 1 = this service does not accept input, 2 = the producer is invalid, 3 = the producer is already registered with self consumer

mlt_service mlt_service_consumer ( mlt_service self )

Obtain the consumer a service is connected to.

Parameters:

self a service

Returns:: the consumer

int mlt_service_detach	(	mlt_service	self,
		mlt_filter	filter
	)

Detach a filter.

Parameters:

self	a service
filter	the filter to detach

Returns:: true if there was an error

static void mlt_service_disconnect ( mlt_service self )

Disconnect a service from its consumer.

Parameters:

self a service

mlt_filter mlt_service_filter	(	mlt_service	self,
		int	index
	)

Retrieve a filter.

Parameters:

self	a service
index	which one of potentially multiple filters

Returns:: the filter or null if there was an error

static void mlt_service_filter_changed	(	mlt_service	owner,
		mlt_service	self
	)		`[private]`

The service-changed event handler.

Parameters:

owner	ignored
self	the service on which the "service-changed" event is fired

int mlt_service_get_frame	(	mlt_service	self,
		mlt_frame_ptr	frame,
		int	index
	)

Obtain a frame.

Parameters:

	self	a service
[out]	frame	a frame by reference
	index	as determined by the producer

Returns:: true if there was an error

mlt_service mlt_service_get_producer ( mlt_service self )

Get the first connected producer.

Parameters:

self a service

Returns:: the first producer

mlt_service_type mlt_service_identify ( mlt_service self )

Identify the subclass of the service.

Parameters:

self a service

Returns:: the subclass

int mlt_service_init	(	mlt_service	self,
		void *	child
	)

Initialize a service.

Parameters:

self	the service structure to initialize
child	pointer to the child object for the subclass

Returns:: true if there was an error

void mlt_service_lock ( mlt_service self )

Acquire a mutual exclusion lock on this service.

Parameters:

self	the service to lock

mlt_service mlt_service_producer ( mlt_service self )

Obtain the producer a service is connected to.

Parameters:

self a service

Returns:: the last-most producer

mlt_profile mlt_service_profile ( mlt_service self )

Retrieve the profile.

Parameters:

self a service

Returns:: the profile

mlt_properties mlt_service_properties ( mlt_service self )

Return the properties object.

Parameters:

self a service

Returns:: the properties

static void mlt_service_property_changed	(	mlt_listener	listener,
		mlt_properties	owner,
		mlt_service	self,
		void **	args
	)		`[private]`

The transmitter for property changes.

Invokes the listener.

Parameters:

listener	a function pointer that will be invoked
owner	a properties list that will be passed to `listener`
self	a service that will be passed to `listener`
args	an array of pointers - the first entry is passed as a string to `listener`