Mixer Interface. More...

Functions
int	snd_mixer_open (snd_mixer_t **mixerp, int mode)
	Opens an empty mixer.

int	snd_mixer_elem_attach (snd_mixer_elem_t melem, snd_hctl_elem_t helem)
	Attach an HCTL element to a mixer element.

int	snd_mixer_elem_detach (snd_mixer_elem_t melem, snd_hctl_elem_t helem)
	Detach an HCTL element from a mixer element.

int	snd_mixer_elem_empty (snd_mixer_elem_t *melem)
	Return true if a mixer element does not contain any HCTL elements.

int	snd_mixer_attach (snd_mixer_t mixer, const char name)
	Attach an HCTL specified with the CTL device name to an opened mixer.

int	snd_mixer_attach_hctl (snd_mixer_t mixer, snd_hctl_t hctl)
	Attach an HCTL to an opened mixer.

int	snd_mixer_detach (snd_mixer_t mixer, const char name)
	Detach a previously attached HCTL to an opened mixer freeing all related resources.

int	snd_mixer_detach_hctl (snd_mixer_t mixer, snd_hctl_t hctl)
	Detach a previously attached HCTL to an opened mixer freeing all related resources.

int	snd_mixer_get_hctl (snd_mixer_t mixer, const char name, snd_hctl_t **hctl)
	Obtain a HCTL pointer associated to given name.

void *	snd_mixer_elem_get_private (const snd_mixer_elem_t *elem)
	Get private data associated to give mixer element.

int	snd_mixer_elem_new (snd_mixer_elem_t *elem, snd_mixer_elem_type_t type, int compare_weight, void private_data, void(private_free)(snd_mixer_elem_t elem))
	Allocate a new mixer element.

int	snd_mixer_elem_add (snd_mixer_elem_t elem, snd_mixer_class_t class)
	Add an element for a registered mixer element class.

int	snd_mixer_elem_remove (snd_mixer_elem_t *elem)
	Remove a mixer element.

void	snd_mixer_elem_free (snd_mixer_elem_t *elem)
	Free a mixer element.

int	snd_mixer_elem_info (snd_mixer_elem_t *elem)
	Mixer element informations are changed.

int	snd_mixer_elem_value (snd_mixer_elem_t *elem)
	Mixer element values is changed.

int	snd_mixer_class_register (snd_mixer_class_t class, snd_mixer_t mixer)
	Register mixer element class.

int	snd_mixer_class_unregister (snd_mixer_class_t *class)
	Unregister mixer element class and remove all its elements.

int	snd_mixer_load (snd_mixer_t *mixer)
	Load a mixer elements.

void	snd_mixer_free (snd_mixer_t *mixer)
	Unload all mixer elements and free all related resources.

int	snd_mixer_close (snd_mixer_t *mixer)
	Close a mixer and free all related resources.

int	snd_mixer_set_compare (snd_mixer_t *mixer, snd_mixer_compare_t compare)
	Change mixer compare function and reorder elements.

int	snd_mixer_poll_descriptors_count (snd_mixer_t *mixer)
	get count of poll descriptors for mixer handle

int	snd_mixer_poll_descriptors (snd_mixer_t mixer, struct pollfd pfds, unsigned int space)
	get poll descriptors

int	snd_mixer_poll_descriptors_revents (snd_mixer_t mixer, struct pollfd pfds, unsigned int nfds, unsigned short *revents)
	get returned events from poll descriptors

int	snd_mixer_wait (snd_mixer_t *mixer, int timeout)
	Wait for a mixer to become ready (i.e. at least one event pending)

snd_mixer_elem_t *	snd_mixer_first_elem (snd_mixer_t *mixer)
	get first element for a mixer

snd_mixer_elem_t *	snd_mixer_last_elem (snd_mixer_t *mixer)
	get last element for a mixer

snd_mixer_elem_t *	snd_mixer_elem_next (snd_mixer_elem_t *elem)
	get next mixer element

snd_mixer_elem_t *	snd_mixer_elem_prev (snd_mixer_elem_t *elem)
	get previous mixer element

int	snd_mixer_handle_events (snd_mixer_t *mixer)
	Handle pending mixer events invoking callbacks.

void	snd_mixer_set_callback (snd_mixer_t *obj, snd_mixer_callback_t val)
	Set callback function for a mixer.

void	snd_mixer_set_callback_private (snd_mixer_t mixer, void val)
	Set callback private value for a mixer.

void *	snd_mixer_get_callback_private (const snd_mixer_t *mixer)
	Get callback private value for a mixer.

unsigned int	snd_mixer_get_count (const snd_mixer_t *mixer)
	Get elements count for a mixer.

void	snd_mixer_elem_set_callback (snd_mixer_elem_t *mixer, snd_mixer_elem_callback_t val)
	Set callback function for a mixer element.

void	snd_mixer_elem_set_callback_private (snd_mixer_elem_t mixer, void val)
	Set callback private value for a mixer element.

void *	snd_mixer_elem_get_callback_private (const snd_mixer_elem_t *mixer)
	Get callback private value for a mixer element.

snd_mixer_elem_type_t	snd_mixer_elem_get_type (const snd_mixer_elem_t *mixer)
	Get type for a mixer element.

size_t	snd_mixer_class_sizeof ()
	get size of #snd_mixer_class_t

int	snd_mixer_class_malloc (snd_mixer_class_t **ptr)
	allocate an invalid #snd_mixer_class_t using standard malloc

void	snd_mixer_class_free (snd_mixer_class_t *obj)
	frees a previously allocated #snd_mixer_class_t

void	snd_mixer_class_copy (snd_mixer_class_t dst, const snd_mixer_class_t src)
	copy one #snd_mixer_class_t to another

snd_mixer_t *	snd_mixer_class_get_mixer (const snd_mixer_class_t *obj)
	Get a mixer associated to given mixer class.

snd_mixer_event_t	snd_mixer_class_get_event (const snd_mixer_class_t *obj)
	Get mixer event callback associated to given mixer class.

void *	snd_mixer_class_get_private (const snd_mixer_class_t *obj)
	Get mixer private data associated to given mixer class.

snd_mixer_compare_t	snd_mixer_class_get_compare (const snd_mixer_class_t *obj)
	Get mixer compare callback associated to given mixer class.

int	snd_mixer_class_set_event (snd_mixer_class_t *obj, snd_mixer_event_t event)
	Set mixer event callback to given mixer class.

int	snd_mixer_class_set_private (snd_mixer_class_t obj, void private_data)
	Set mixer private data to given mixer class.

int	snd_mixer_class_set_private_free (snd_mixer_class_t obj, void(private_free)(snd_mixer_class_t *))
	Set mixer private data free callback to given mixer class.

int	snd_mixer_class_set_compare (snd_mixer_class_t *obj, snd_mixer_compare_t compare)
	Set mixer compare callback to given mixer class.

Detailed Description

Mixer Interface.

Author: Jaroslav Kysela perex.nosp@m.@per.nosp@m.ex.cz; Abramo Bagnara abram.nosp@m.o@al.nosp@m.sa-pr.nosp@m.ojec.nosp@m.t.org

Date: 2001

Mixer interface is designed to access mixer elements. Callbacks may be used for event handling.

Function Documentation

◆ snd_mixer_attach()

int snd_mixer_attach	(	snd_mixer_t *	mixer,
		const char *	name )

Attach an HCTL specified with the CTL device name to an opened mixer.

Parameters

mixer	Mixer handle
name	HCTL name (see snd_hctl_open)

Returns: 0 on success otherwise a negative error code

◆ snd_mixer_attach_hctl()

int snd_mixer_attach_hctl	(	snd_mixer_t *	mixer,
		snd_hctl_t *	hctl )

Attach an HCTL to an opened mixer.

Parameters

mixer	Mixer handle
hctl	the HCTL to be attached

Returns: 0 on success otherwise a negative error code

Upon error, this function closes the given hctl handle automatically.

◆ snd_mixer_class_copy()

void snd_mixer_class_copy	(	snd_mixer_class_t *	dst,
		const snd_mixer_class_t *	src )

copy one #snd_mixer_class_t to another

Parameters

dst	pointer to destination
src	pointer to source

◆ snd_mixer_class_free()

void snd_mixer_class_free ( snd_mixer_class_t * obj )

frees a previously allocated #snd_mixer_class_t

Parameters

obj	pointer to object to free

◆ snd_mixer_class_get_compare()

snd_mixer_compare_t snd_mixer_class_get_compare ( const snd_mixer_class_t * obj )

Get mixer compare callback associated to given mixer class.

Parameters

obj	Mixer simple class identifier

Returns: event callback pointer

◆ snd_mixer_class_get_event()

snd_mixer_event_t snd_mixer_class_get_event ( const snd_mixer_class_t * obj )

Get mixer event callback associated to given mixer class.

Parameters

obj	Mixer simple class identifier

Returns: event callback pointer

◆ snd_mixer_class_get_mixer()

snd_mixer_t * snd_mixer_class_get_mixer ( const snd_mixer_class_t * obj )

Get a mixer associated to given mixer class.

Parameters

obj	Mixer simple class identifier

Returns: mixer pointer

◆ snd_mixer_class_get_private()

void * snd_mixer_class_get_private ( const snd_mixer_class_t * obj )

Get mixer private data associated to given mixer class.

Parameters

obj	Mixer simple class identifier

Returns: event callback pointer

◆ snd_mixer_class_malloc()

int snd_mixer_class_malloc ( snd_mixer_class_t ** ptr )

allocate an invalid #snd_mixer_class_t using standard malloc

Parameters

ptr	returned pointer

Returns: 0 on success otherwise negative error code

◆ snd_mixer_class_register()

int snd_mixer_class_register	(	snd_mixer_class_t *	class,
		snd_mixer_t *	mixer )

Register mixer element class.

Parameters

class	Mixer element class
mixer	Mixer handle

Returns: 0 on success otherwise a negative error code

For use by mixer element class specific code.

◆ snd_mixer_class_set_compare()

int snd_mixer_class_set_compare	(	snd_mixer_class_t *	obj,
		snd_mixer_compare_t	compare )

Set mixer compare callback to given mixer class.

Parameters

obj	Mixer simple class identifier
compare	the compare callback to be used

Returns: zero if success, otherwise a negative error code

◆ snd_mixer_class_set_event()

int snd_mixer_class_set_event	(	snd_mixer_class_t *	obj,
		snd_mixer_event_t	event )

Set mixer event callback to given mixer class.

Parameters

obj	Mixer simple class identifier
event	Event callback

Returns: zero if success, otherwise a negative error code

◆ snd_mixer_class_set_private()

int snd_mixer_class_set_private	(	snd_mixer_class_t *	obj,
		void *	private_data )

Set mixer private data to given mixer class.

Parameters

obj	Mixer simple class identifier
private_data	class private data

Returns: zero if success, otherwise a negative error code

◆ snd_mixer_class_set_private_free()

int snd_mixer_class_set_private_free	(	snd_mixer_class_t *	obj,
		void(*	private_free )(snd_mixer_class_t *) )

Set mixer private data free callback to given mixer class.

Parameters

obj	Mixer simple class identifier
private_free	Mixer class private data free callback

Returns: zero if success, otherwise a negative error code

◆ snd_mixer_class_sizeof()

size_t snd_mixer_class_sizeof ( )

get size of #snd_mixer_class_t

Returns: size in bytes

◆ snd_mixer_class_unregister()

int snd_mixer_class_unregister ( snd_mixer_class_t * class )

Unregister mixer element class and remove all its elements.

Parameters

class Mixer element class

Returns: 0 on success otherwise a negative error code

Note that the class structure is also deallocated!

◆ snd_mixer_close()

int snd_mixer_close ( snd_mixer_t * mixer )

Close a mixer and free all related resources.

Parameters

mixer Mixer handle

Returns: 0 on success otherwise a negative error code

◆ snd_mixer_detach()

int snd_mixer_detach	(	snd_mixer_t *	mixer,
		const char *	name )

Detach a previously attached HCTL to an opened mixer freeing all related resources.

Parameters

mixer	Mixer handle
name	HCTL previously attached

Returns: 0 on success otherwise a negative error code

◆ snd_mixer_detach_hctl()

int snd_mixer_detach_hctl	(	snd_mixer_t *	mixer,
		snd_hctl_t *	hctl )

Detach a previously attached HCTL to an opened mixer freeing all related resources.

Parameters

mixer	Mixer handle
hctl	HCTL previously attached

Returns: 0 on success otherwise a negative error code

Note: The hctl handle is not closed!

◆ snd_mixer_elem_add()

int snd_mixer_elem_add	(	snd_mixer_elem_t *	elem,
		snd_mixer_class_t *	class )

Add an element for a registered mixer element class.

Parameters

elem	Mixer element
class	Mixer element class

Returns: 0 on success otherwise a negative error code

For use by mixer element class specific code.

◆ snd_mixer_elem_attach()

int snd_mixer_elem_attach	(	snd_mixer_elem_t *	melem,
		snd_hctl_elem_t *	helem )

Attach an HCTL element to a mixer element.

Parameters

melem	Mixer element
helem	HCTL element

Returns: 0 on success otherwise a negative error code

For use by mixer element class specific code.

The implementation of mixer class typically calls it at #SND_CTL_EVENT_MASK_ADD event. Once attaching, the implementation should make sure to detach it by call of snd_mixer_elem_detach() at #SND_CTL_EVENT_MASK_REMOVE event. Unless detaching, mixer API internal hits assertion due to unsatisfied postcondition after the event.

◆ snd_mixer_elem_detach()

int snd_mixer_elem_detach	(	snd_mixer_elem_t *	melem,
		snd_hctl_elem_t *	helem )

Detach an HCTL element from a mixer element.

Parameters

melem	Mixer element
helem	HCTL element

Returns: 0 on success otherwise a negative error code

For use by mixer element class specific code.

The implementation of mixer class typically calls it at #SND_CTL_EVENT_MASK_REMOVE event for attached mixer element at #SND_CTL_EVENT_MASK_ADD. Unless detaching, mixer API internal hits assertion due to unsatisfied postcondition after the event.

◆ snd_mixer_elem_empty()

int snd_mixer_elem_empty ( snd_mixer_elem_t * melem )

Return true if a mixer element does not contain any HCTL elements.

Parameters

melem Mixer element

Returns: 0 if not empty, 1 if empty

For use by mixer element class specific code.

◆ snd_mixer_elem_free()

void snd_mixer_elem_free ( snd_mixer_elem_t * elem )

Free a mixer element.

Parameters

elem	Mixer element

For use by mixer element class specific code.

◆ snd_mixer_elem_get_callback_private()

void * snd_mixer_elem_get_callback_private ( const snd_mixer_elem_t * mixer )

Get callback private value for a mixer element.

Parameters

mixer mixer element

Returns: callback private value

◆ snd_mixer_elem_get_private()

void * snd_mixer_elem_get_private ( const snd_mixer_elem_t * elem )

Get private data associated to give mixer element.

Parameters

elem	Mixer element

Returns: private data

For use by mixer element class specific code.

◆ snd_mixer_elem_get_type()

snd_mixer_elem_type_t snd_mixer_elem_get_type ( const snd_mixer_elem_t * mixer )

Get type for a mixer element.

Parameters

mixer mixer element

Returns: mixer element type

◆ snd_mixer_elem_info()

int snd_mixer_elem_info ( snd_mixer_elem_t * elem )

Mixer element informations are changed.

Parameters

elem	Mixer element

Returns: 0 on success otherwise a negative error code

For use by mixer element class specific code.

◆ snd_mixer_elem_new()

int snd_mixer_elem_new	(	snd_mixer_elem_t **	elem,
		snd_mixer_elem_type_t	type,
		int	compare_weight,
		void *	private_data,
		void(*	private_free )(snd_mixer_elem_t *elem) )

Allocate a new mixer element.

Parameters

elem	Returned mixer element
type	Mixer element type
compare_weight	Mixer element compare weight
private_data	Private data
private_free	Private data free callback

Returns: 0 on success otherwise a negative error code

For use by mixer element class specific code.

◆ snd_mixer_elem_next()

snd_mixer_elem_t * snd_mixer_elem_next ( snd_mixer_elem_t * elem )

get next mixer element

Parameters

elem	mixer element

Returns: pointer to next element

◆ snd_mixer_elem_prev()

snd_mixer_elem_t * snd_mixer_elem_prev ( snd_mixer_elem_t * elem )

get previous mixer element

Parameters

elem	mixer element

Returns: pointer to previous element

◆ snd_mixer_elem_remove()

int snd_mixer_elem_remove ( snd_mixer_elem_t * elem )

Remove a mixer element.

Parameters

elem	Mixer element

Returns: 0 on success otherwise a negative error code

For use by mixer element class specific code.

◆ snd_mixer_elem_set_callback()

void snd_mixer_elem_set_callback	(	snd_mixer_elem_t *	mixer,
		snd_mixer_elem_callback_t	val )

Set callback function for a mixer element.

Parameters

mixer	mixer element
val	callback function

◆ snd_mixer_elem_set_callback_private()

void snd_mixer_elem_set_callback_private	(	snd_mixer_elem_t *	mixer,
		void *	val )

Set callback private value for a mixer element.

Parameters

mixer	mixer element
val	callback private value

◆ snd_mixer_elem_value()

int snd_mixer_elem_value ( snd_mixer_elem_t * elem )

Mixer element values is changed.

Parameters

elem	Mixer element

Returns: 0 on success otherwise a negative error code

For use by mixer element class specific code.

◆ snd_mixer_first_elem()

snd_mixer_elem_t * snd_mixer_first_elem ( snd_mixer_t * mixer )

get first element for a mixer

Parameters

mixer Mixer handle

Returns: pointer to first element

◆ snd_mixer_free()

void snd_mixer_free ( snd_mixer_t * mixer )

Unload all mixer elements and free all related resources.

Parameters

mixer Mixer handle

◆ snd_mixer_get_callback_private()

void * snd_mixer_get_callback_private ( const snd_mixer_t * mixer )

Get callback private value for a mixer.

Parameters

mixer mixer handle

Returns: callback private value

◆ snd_mixer_get_count()

unsigned int snd_mixer_get_count ( const snd_mixer_t * mixer )

Get elements count for a mixer.

Parameters

mixer mixer handle

Returns: elements count

◆ snd_mixer_get_hctl()

int snd_mixer_get_hctl	(	snd_mixer_t *	mixer,
		const char *	name,
		snd_hctl_t **	hctl )

Obtain a HCTL pointer associated to given name.

Parameters

mixer	Mixer handle
name	HCTL previously attached
hctl	HCTL pointer

Returns: 0 on success otherwise a negative error code

◆ snd_mixer_handle_events()

int snd_mixer_handle_events ( snd_mixer_t * mixer )

Handle pending mixer events invoking callbacks.

Parameters

mixer Mixer handle

Returns: Number of events that occured on success, otherwise a negative error code on failure

◆ snd_mixer_last_elem()

snd_mixer_elem_t * snd_mixer_last_elem ( snd_mixer_t * mixer )

get last element for a mixer

Parameters

mixer Mixer handle

Returns: pointer to last element

◆ snd_mixer_load()

int snd_mixer_load ( snd_mixer_t * mixer )

Load a mixer elements.

Parameters

mixer Mixer handle

Returns: 0 on success otherwise a negative error code

◆ snd_mixer_open()

int snd_mixer_open	(	snd_mixer_t **	mixerp,
		int	mode )

Opens an empty mixer.

Parameters

mixerp	Returned mixer handle
mode	Open mode

Returns: 0 on success otherwise a negative error code

◆ snd_mixer_poll_descriptors()

int snd_mixer_poll_descriptors	(	snd_mixer_t *	mixer,
		struct pollfd *	pfds,
		unsigned int	space )

get poll descriptors

Parameters

mixer	Mixer handle
pfds	array of poll descriptors
space	space in the poll descriptor array

Returns: count of filled descriptors

◆ snd_mixer_poll_descriptors_count()

int snd_mixer_poll_descriptors_count ( snd_mixer_t * mixer )

get count of poll descriptors for mixer handle

Parameters

mixer Mixer handle

Returns: count of poll descriptors

◆ snd_mixer_poll_descriptors_revents()

int snd_mixer_poll_descriptors_revents	(	snd_mixer_t *	mixer,
		struct pollfd *	pfds,
		unsigned int	nfds,
		unsigned short *	revents )

get returned events from poll descriptors

Parameters

mixer	Mixer handle
pfds	array of poll descriptors
nfds	count of poll descriptors
revents	returned events

Returns: zero if success, otherwise a negative error code

◆ snd_mixer_set_callback()

void snd_mixer_set_callback	(	snd_mixer_t *	obj,
		snd_mixer_callback_t	val )

Set callback function for a mixer.

Parameters

obj	mixer handle
val	callback function

◆ snd_mixer_set_callback_private()

void snd_mixer_set_callback_private	(	snd_mixer_t *	mixer,
		void *	val )

Set callback private value for a mixer.

Parameters

mixer	mixer handle
val	callback private value

◆ snd_mixer_set_compare()

int snd_mixer_set_compare	(	snd_mixer_t *	mixer,
		snd_mixer_compare_t	compare )

Change mixer compare function and reorder elements.

Parameters

mixer	Mixer handle
compare	Element compare function

Returns: 0 on success otherwise a negative error code

◆ snd_mixer_wait()

int snd_mixer_wait	(	snd_mixer_t *	mixer,
		int	timeout )

Wait for a mixer to become ready (i.e. at least one event pending)

Parameters

mixer	Mixer handle
timeout	maximum time in milliseconds to wait

Returns: 0 otherwise a negative error code on failure

Functions

Detailed Description

Function Documentation

◆ snd_mixer_attach()

◆ snd_mixer_attach_hctl()

◆ snd_mixer_class_copy()

◆ snd_mixer_class_free()

◆ snd_mixer_class_get_compare()

◆ snd_mixer_class_get_event()

◆ snd_mixer_class_get_mixer()

◆ snd_mixer_class_get_private()

◆ snd_mixer_class_malloc()

◆ snd_mixer_class_register()

◆ snd_mixer_class_set_compare()

◆ snd_mixer_class_set_event()

◆ snd_mixer_class_set_private()

◆ snd_mixer_class_set_private_free()

◆ snd_mixer_class_sizeof()

◆ snd_mixer_class_unregister()

◆ snd_mixer_close()

◆ snd_mixer_detach()

◆ snd_mixer_detach_hctl()

◆ snd_mixer_elem_add()

◆ snd_mixer_elem_attach()

◆ snd_mixer_elem_detach()

◆ snd_mixer_elem_empty()

◆ snd_mixer_elem_free()

◆ snd_mixer_elem_get_callback_private()

◆ snd_mixer_elem_get_private()

◆ snd_mixer_elem_get_type()

◆ snd_mixer_elem_info()

◆ snd_mixer_elem_new()

◆ snd_mixer_elem_next()

◆ snd_mixer_elem_prev()

◆ snd_mixer_elem_remove()

◆ snd_mixer_elem_set_callback()

◆ snd_mixer_elem_set_callback_private()

◆ snd_mixer_elem_value()

◆ snd_mixer_first_elem()

◆ snd_mixer_free()

◆ snd_mixer_get_callback_private()

◆ snd_mixer_get_count()

◆ snd_mixer_get_hctl()

◆ snd_mixer_handle_events()

◆ snd_mixer_last_elem()

◆ snd_mixer_load()

◆ snd_mixer_open()

◆ snd_mixer_poll_descriptors()

◆ snd_mixer_poll_descriptors_count()

◆ snd_mixer_poll_descriptors_revents()

◆ snd_mixer_set_callback()

◆ snd_mixer_set_callback_private()

◆ snd_mixer_set_compare()

◆ snd_mixer_wait()