Filter

Files
file	filter.h
	pipewire/filter.h

Data Structures
struct	pw_filter_events
	Events for a filter. More...
struct	pw_filter

Enumerations
enum	pw_filter_state {   PW_FILTER_STATE_ERROR = -1 , PW_FILTER_STATE_UNCONNECTED = 0 , PW_FILTER_STATE_CONNECTING = 1 , PW_FILTER_STATE_PAUSED = 2 ,   PW_FILTER_STATE_STREAMING = 3 }
	The state of a filter More...
enum	pw_filter_flags {   PW_FILTER_FLAG_NONE = 0 , PW_FILTER_FLAG_INACTIVE = (1 << 0) , PW_FILTER_FLAG_DRIVER = (1 << 1) , PW_FILTER_FLAG_RT_PROCESS = (1 << 2) ,   PW_FILTER_FLAG_CUSTOM_LATENCY = (1 << 3) , PW_FILTER_FLAG_TRIGGER = (1 << 4) , PW_FILTER_FLAG_ASYNC = (1 << 5) }
	Extra flags that can be used in pw_filter_connect() More...
enum	pw_filter_port_flags { PW_FILTER_PORT_FLAG_NONE = 0 , PW_FILTER_PORT_FLAG_MAP_BUFFERS = (1 << 0) , PW_FILTER_PORT_FLAG_ALLOC_BUFFERS = (1 << 1) }

Macros
#define	PW_VERSION_FILTER_EVENTS   1

Functions
const char *	pw_filter_state_as_string (enum pw_filter_state state)
	Convert a filter state to a readable string
struct pw_filter *	pw_filter_new (struct pw_core *core, const char *name, struct pw_properties *props)
	Create a new unconnected Filter.
struct pw_filter *	pw_filter_new_simple (struct pw_loop *loop, const char *name, struct pw_properties *props, const struct pw_filter_events *events, void *data)
void	pw_filter_destroy (struct pw_filter *filter)
	Destroy a filter
void	pw_filter_add_listener (struct pw_filter *filter, struct spa_hook *listener, const struct pw_filter_events *events, void *data)
enum pw_filter_state	pw_filter_get_state (struct pw_filter *filter, const char **error)
const char *	pw_filter_get_name (struct pw_filter *filter)
struct pw_core *	pw_filter_get_core (struct pw_filter *filter)
int	pw_filter_connect (struct pw_filter *filter, enum pw_filter_flags flags, const struct spa_pod **params, uint32_t n_params)
	Connect a filter for processing.
uint32_t	pw_filter_get_node_id (struct pw_filter *filter)
	Get the node ID of the filter.
int	pw_filter_disconnect (struct pw_filter *filter)
	Disconnect filter
void *	pw_filter_add_port (struct pw_filter *filter, enum pw_direction direction, enum pw_filter_port_flags flags, size_t port_data_size, struct pw_properties *props, const struct spa_pod **params, uint32_t n_params)
	add a port to the filter, returns user data of port_data_size.
int	pw_filter_remove_port (void *port_data)
	remove a port from the filter
const struct pw_properties *	pw_filter_get_properties (struct pw_filter *filter, void *port_data)
	get properties, port_data of NULL will give global properties
int	pw_filter_update_properties (struct pw_filter *filter, void *port_data, const struct spa_dict *dict)
	Update properties, use NULL port_data for global filter properties.
int	pw_filter_set_error (struct pw_filter *filter, int res, const char *error,...)
	Set the filter in error state.
int	pw_filter_update_params (struct pw_filter *filter, void *port_data, const struct spa_pod **params, uint32_t n_params)
	Update params, use NULL port_data for global filter params.
int	pw_filter_get_time (struct pw_filter *filter, struct pw_time *time)
	Query the time on the filter, deprecated, use the spa_io_position in the process() method for timing information.
uint64_t	pw_filter_get_nsec (struct pw_filter *filter)
	Get the current time in nanoseconds.
struct pw_loop *	pw_filter_get_data_loop (struct pw_filter *filter)
	Get the data loop that is doing the processing of this filter.
struct pw_buffer *	pw_filter_dequeue_buffer (void *port_data)
	Get a buffer that can be filled for output ports or consumed for input ports.
int	pw_filter_queue_buffer (void *port_data, struct pw_buffer *buffer)
	Submit a buffer for playback or recycle a buffer for capture.
void *	pw_filter_get_dsp_buffer (void *port_data, uint32_t n_samples)
	Get a data pointer to the buffer data.
int	pw_filter_set_active (struct pw_filter *filter, bool active)
	Activate or deactivate the filter
int	pw_filter_flush (struct pw_filter *filter, bool drain)
	Flush a filter.
bool	pw_filter_is_driving (struct pw_filter *filter)
	Check if the filter is driving.
int	pw_filter_trigger_process (struct pw_filter *filter)
	Trigger a push/pull on the filter.

Detailed Description

PipeWire filter object class

The filter object provides a convenient way to implement processing filters.

See also Core API

Enumeration Type Documentation

pw_filter_state

enum pw_filter_state

The state of a filter

Enumerator
PW_FILTER_STATE_ERROR	the stream is in error
PW_FILTER_STATE_UNCONNECTED	unconnected
PW_FILTER_STATE_CONNECTING	connection is in progress
PW_FILTER_STATE_PAUSED	filter is connected and paused
PW_FILTER_STATE_STREAMING	filter is streaming

pw_filter_flags

enum pw_filter_flags

Extra flags that can be used in pw_filter_connect()

Enumerator
PW_FILTER_FLAG_NONE	no flags
PW_FILTER_FLAG_INACTIVE	start the filter inactive, pw_filter_set_active() needs to be called explicitly
PW_FILTER_FLAG_DRIVER	be a driver
PW_FILTER_FLAG_RT_PROCESS	call process from the realtime thread
PW_FILTER_FLAG_CUSTOM_LATENCY	don't call the default latency algorithm but emit the param_changed event for the ports when Latency params are received.
PW_FILTER_FLAG_TRIGGER	the filter will not be scheduled automatically but _trigger_process() needs to be called. This can be used when the filter depends on processing of other filters.
PW_FILTER_FLAG_ASYNC	Buffers will not be dequeued/queued from the realtime process() function. This is assumed when RT_PROCESS is unset but can also be the case when the process() function does a trigger_process() that will then dequeue/queue a buffer from another process() function. since 0.3.73

pw_filter_port_flags

enum pw_filter_port_flags

Enumerator
PW_FILTER_PORT_FLAG_NONE	no flags
PW_FILTER_PORT_FLAG_MAP_BUFFERS	mmap the buffers except DmaBuf that is not explicitly marked as mappable.
PW_FILTER_PORT_FLAG_ALLOC_BUFFERS	the application will allocate buffer memory. In the add_buffer event, the data of the buffer should be set

Macro Definition Documentation

PW_VERSION_FILTER_EVENTS

#define PW_VERSION_FILTER_EVENTS   1

Examples

audio-dsp-filter.c, audio-dsp-src.c, midi-src.c, and video-dsp-play.c.

Function Documentation

pw_filter_state_as_string()

const char * pw_filter_state_as_string

(

enum pw_filter_state

state

)

Convert a filter state to a readable string

Examples

video-dsp-play.c.

pw_filter_new()

struct pw_filter * pw_filter_new	(	struct pw_core *	core,
		const char *	name,
		struct pw_properties *	props )

Create a new unconnected Filter.

Returns

a newly allocated Filter

Parameters

core	a Core
name	a filter media name
props	filter properties, ownership is taken

pw_filter_new_simple()

struct pw_filter * pw_filter_new_simple	(	struct pw_loop *	loop,
		const char *	name,
		struct pw_properties *	props,
		const struct pw_filter_events *	events,
		void *	data )

Parameters

loop	a Loop to use
name	a filter media name
props	filter properties, ownership is taken
events	filter events
data	data passed to events

Examples

audio-dsp-filter.c, audio-dsp-src.c, midi-src.c, and video-dsp-play.c.

pw_filter_destroy()

void pw_filter_destroy

(

struct pw_filter *

filter

)

Destroy a filter

Examples

audio-dsp-filter.c, audio-dsp-src.c, midi-src.c, and video-dsp-play.c.

pw_filter_add_listener()

void pw_filter_add_listener	(	struct pw_filter *	filter,
		struct spa_hook *	listener,
		const struct pw_filter_events *	events,
		void *	data )

pw_filter_get_state()

enum pw_filter_state pw_filter_get_state	(	struct pw_filter *	filter,
		const char **	error )

pw_filter_get_name()

const char * pw_filter_get_name

(

struct pw_filter *

filter

)

pw_filter_get_core()

struct pw_core * pw_filter_get_core

(

struct pw_filter *

filter

)

pw_filter_connect()

int pw_filter_connect	(	struct pw_filter *	filter,
		enum pw_filter_flags	flags,
		const struct spa_pod **	params,
		uint32_t	n_params )

Connect a filter for processing.

Returns

0 on success < 0 on error.

You should connect to the process event and use pw_filter_dequeue_buffer() to get the latest metadata and data.

Parameters

filter	a Filter
flags	filter flags
params	an array with params.
n_params	number of items in params

Examples

audio-dsp-filter.c, audio-dsp-src.c, midi-src.c, and video-dsp-play.c.

pw_filter_get_node_id()

uint32_t pw_filter_get_node_id

(

struct pw_filter *

filter

)

Get the node ID of the filter.

Returns

node ID.

pw_filter_disconnect()

int pw_filter_disconnect

(

struct pw_filter *

filter

)

Disconnect filter

pw_filter_add_port()

void * pw_filter_add_port	(	struct pw_filter *	filter,
		enum pw_direction	direction,
		enum pw_filter_port_flags	flags,
		size_t	port_data_size,
		struct pw_properties *	props,
		const struct spa_pod **	params,
		uint32_t	n_params )

add a port to the filter, returns user data of port_data_size.

Parameters

filter	a Filter
direction	port direction
flags	port flags
port_data_size	allocated and given to the user as port_data
props	port properties, ownership is taken
params	an array of params. The params should ideally contain the supported formats
n_params	number of elements in params

Examples

audio-dsp-filter.c, audio-dsp-src.c, midi-src.c, and video-dsp-play.c.

pw_filter_remove_port()

int pw_filter_remove_port

(

void *

port_data

)

remove a port from the filter

Parameters

port_data

data associated with port

pw_filter_get_properties()

const struct pw_properties * pw_filter_get_properties	(	struct pw_filter *	filter,
		void *	port_data )

get properties, port_data of NULL will give global properties

pw_filter_update_properties()

int pw_filter_update_properties	(	struct pw_filter *	filter,
		void *	port_data,
		const struct spa_dict *	dict )

Update properties, use NULL port_data for global filter properties.

pw_filter_set_error()

int pw_filter_set_error	(	struct pw_filter *	filter,
		int	res,
		const char *	error,
			... )

Set the filter in error state.

Parameters

filter	a Filter
res	a result code
error	an error message

Examples

video-dsp-play.c.

pw_filter_update_params()

int pw_filter_update_params	(	struct pw_filter *	filter,
		void *	port_data,
		const struct spa_pod **	params,
		uint32_t	n_params )

Update params, use NULL port_data for global filter params.

Parameters

filter	a Filter
port_data	data associated with port
params	an array of params.
n_params	number of elements in params

Examples

midi-src.c.

pw_filter_get_time()

int pw_filter_get_time	(	struct pw_filter *	filter,
		struct pw_time *	time )

Query the time on the filter, deprecated, use the spa_io_position in the process() method for timing information.

pw_filter_get_nsec()

uint64_t pw_filter_get_nsec

(

struct pw_filter *

filter

)

Get the current time in nanoseconds.

This value can be compared with the nsec value in the spa_io_position. Since 1.1.0

pw_filter_get_data_loop()

struct pw_loop * pw_filter_get_data_loop

(

struct pw_filter *

filter

)

Get the data loop that is doing the processing of this filter.

This loop is assigned after pw_filter_connect(). * Since 1.1.0

pw_filter_dequeue_buffer()

struct pw_buffer * pw_filter_dequeue_buffer

(

void *

port_data

)

Get a buffer that can be filled for output ports or consumed for input ports.

Examples

midi-src.c, and video-dsp-play.c.

pw_filter_queue_buffer()

int pw_filter_queue_buffer	(	void *	port_data,
		struct pw_buffer *	buffer )

Submit a buffer for playback or recycle a buffer for capture.

Examples

midi-src.c, and video-dsp-play.c.

pw_filter_get_dsp_buffer()

void * pw_filter_get_dsp_buffer	(	void *	port_data,
		uint32_t	n_samples )

Get a data pointer to the buffer data.

Examples

audio-dsp-filter.c, and audio-dsp-src.c.

pw_filter_set_active()

int pw_filter_set_active	(	struct pw_filter *	filter,
		bool	active )

Activate or deactivate the filter

pw_filter_flush()

int pw_filter_flush	(	struct pw_filter *	filter,
		bool	drain )

Flush a filter.

When drain is true, the drained callback will be called when all data is played or recorded

pw_filter_is_driving()

bool pw_filter_is_driving

(

struct pw_filter *

filter

)

Check if the filter is driving.

The filter needs to have the PW_FILTER_FLAG_DRIVER set. When the filter is driving, pw_filter_trigger_process() needs to be called when data is available (output) or needed (input). Since 0.3.66

pw_filter_trigger_process()

int pw_filter_trigger_process

(

struct pw_filter *

filter

)

Trigger a push/pull on the filter.

One iteration of the graph will be scheduled and process() will be called. Since 0.3.66