Control Interface

Collaboration diagram for Control Interface:

Modules
	High level Control Interface
	Setup Control Interface

Files
file	control_plugin.c
	Control Interface.

Data Structures
struct	snd_aes_iec958_t

Macros
#define	SND_CONTROL_DLSYM_VERSION   _dlsym_control_001
#define	SND_CTL_EVENT_MASK_REMOVE
#define	SND_CTL_EVENT_MASK_VALUE
#define	SND_CTL_EVENT_MASK_INFO
#define	SND_CTL_EVENT_MASK_ADD
#define	SND_CTL_EVENT_MASK_TLV
#define	SND_CTL_NAME_NONE   ""
#define	SND_CTL_NAME_PLAYBACK   "Playback "
#define	SND_CTL_NAME_CAPTURE   "Capture "
#define	SND_CTL_NAME_IEC958_NONE   ""
#define	SND_CTL_NAME_IEC958_SWITCH   "Switch"
#define	SND_CTL_NAME_IEC958_VOLUME   "Volume"
#define	SND_CTL_NAME_IEC958_DEFAULT   "Default"
#define	SND_CTL_NAME_IEC958_MASK   "Mask"
#define	SND_CTL_NAME_IEC958_CON_MASK   "Con Mask"
#define	SND_CTL_NAME_IEC958_PRO_MASK   "Pro Mask"
#define	SND_CTL_NAME_IEC958_PCM_STREAM   "PCM Stream"
#define	SND_CTL_NAME_IEC958(expl, direction, what)   "IEC958 " expl SND_CTL_NAME_##direction SND_CTL_NAME_IEC958_##what
#define	SND_CTL_POWER_MASK   0xff00
#define	SND_CTL_POWER_D0   0x0000
#define	SND_CTL_POWER_D1   0x0100
#define	SND_CTL_POWER_D2   0x0200
#define	SND_CTL_POWER_D3   0x0300
#define	SND_CTL_POWER_D3hot   (SND_CTL_POWER_D3|0x0000)
#define	SND_CTL_POWER_D3cold   (SND_CTL_POWER_D3|0x0001)
#define	SND_CTL_TLVT_CONTAINER   0x0000
#define	SND_CTL_TLVT_DB_SCALE   0x0001
#define	SND_CTL_TLVT_DB_LINEAR   0x0002
#define	SND_CTL_TLVT_DB_RANGE   0x0003
#define	SND_CTL_TLVT_DB_MINMAX   0x0004
#define	SND_CTL_TLVT_DB_MINMAX_MUTE   0x0005
#define	SND_CTL_TLV_DB_GAIN_MUTE   -9999999
#define	SND_CTL_TLVT_CHMAP_FIXED   0x00101
#define	SND_CTL_TLVT_CHMAP_VAR   0x00102
#define	SND_CTL_TLVT_CHMAP_PAIRED   0x00103
#define	SND_CTL_NONBLOCK
#define	SND_CTL_ASYNC
#define	SND_CTL_READONLY
#define	SND_SCTL_NOFREE   0x0001
#define	snd_ctl_elem_id_alloca(ptr)
	allocate an invalid snd_ctl_elem_id_t using standard alloca More...
#define	snd_ctl_card_info_alloca(ptr)
	Allocate an invalid snd_ctl_card_info_t on the stack. More...
#define	snd_ctl_event_alloca(ptr)
	allocate an invalid snd_ctl_event_t using standard alloca More...
#define	snd_ctl_elem_list_alloca(ptr)
	Allocate a snd_ctl_elem_list_t using standard alloca. More...
#define	snd_ctl_elem_info_alloca(ptr)
	allocate an invalid snd_ctl_elem_info_t using standard alloca More...
#define	snd_ctl_elem_value_alloca(ptr)
	Allocate an invalid snd_ctl_elem_value_t on the stack. More...

Typedefs
typedef struct _snd_ctl_card_info	snd_ctl_card_info_t
	CTL card info container. More...
typedef struct _snd_ctl_elem_id	snd_ctl_elem_id_t
typedef struct _snd_ctl_elem_list	snd_ctl_elem_list_t
typedef struct _snd_ctl_elem_info	snd_ctl_elem_info_t
typedef struct _snd_ctl_elem_value	snd_ctl_elem_value_t
typedef struct _snd_ctl_event	snd_ctl_event_t
typedef struct _snd_ctl	snd_ctl_t
typedef struct _snd_sctl	snd_sctl_t

Enumerations
enum	snd_ctl_elem_type_t {   SND_CTL_ELEM_TYPE_NONE = 0 , SND_CTL_ELEM_TYPE_BOOLEAN , SND_CTL_ELEM_TYPE_INTEGER , SND_CTL_ELEM_TYPE_ENUMERATED ,   SND_CTL_ELEM_TYPE_BYTES , SND_CTL_ELEM_TYPE_IEC958 , SND_CTL_ELEM_TYPE_INTEGER64 , SND_CTL_ELEM_TYPE_LAST = SND_CTL_ELEM_TYPE_INTEGER64 }
enum	snd_ctl_elem_iface_t {   SND_CTL_ELEM_IFACE_CARD = 0 , SND_CTL_ELEM_IFACE_HWDEP , SND_CTL_ELEM_IFACE_MIXER , SND_CTL_ELEM_IFACE_PCM ,   SND_CTL_ELEM_IFACE_RAWMIDI , SND_CTL_ELEM_IFACE_TIMER , SND_CTL_ELEM_IFACE_SEQUENCER , SND_CTL_ELEM_IFACE_LAST = SND_CTL_ELEM_IFACE_SEQUENCER }
enum	snd_ctl_event_type_t { SND_CTL_EVENT_ELEM = 0 , SND_CTL_EVENT_LAST = SND_CTL_EVENT_ELEM }
enum	snd_ctl_type_t {   SND_CTL_TYPE_HW , SND_CTL_TYPE_SHM , SND_CTL_TYPE_INET , SND_CTL_TYPE_EXT ,   SND_CTL_TYPE_REMAP }

Functions
int	snd_card_load (int card)
	Try to load the driver for a card. More...
int	snd_card_next (int *card)
	Iterate over physical sound cards. More...
int	snd_card_get_index (const char *name)
	Convert a card string to the card index. More...
int	snd_card_get_name (int card, char **name)
	Obtain the card name. More...
int	snd_card_get_longname (int card, char **name)
	Obtain the card long name. More...
int	snd_device_name_hint (int card, const char *iface, void ***hints)
int	snd_device_name_free_hint (void **hints)
char *	snd_device_name_get_hint (const void *hint, const char *id)
int	snd_ctl_open (snd_ctl_t **ctl, const char *name, int mode)
	Opens a sound card. More...
int	snd_ctl_open_lconf (snd_ctl_t **ctl, const char *name, int mode, snd_config_t *lconf)
	Opens a CTL using local configuration. More...
int	snd_ctl_open_fallback (snd_ctl_t **ctl, snd_config_t *root, const char *name, const char *orig_name, int mode)
	Opens a fallback CTL. More...
int	snd_ctl_close (snd_ctl_t *ctl)
	close CTL handle More...
int	snd_ctl_nonblock (snd_ctl_t *ctl, int nonblock)
	set nonblock mode More...
int	snd_async_add_ctl_handler (snd_async_handler_t **handler, snd_ctl_t *ctl, snd_async_callback_t callback, void *private_data)
	Add an async handler for a CTL. More...
snd_ctl_t *	snd_async_handler_get_ctl (snd_async_handler_t *handler)
	Return CTL handle related to an async handler. More...
int	snd_ctl_poll_descriptors_count (snd_ctl_t *ctl)
	get count of poll descriptors for CTL handle More...
int	snd_ctl_poll_descriptors (snd_ctl_t *ctl, struct pollfd *pfds, unsigned int space)
	get poll descriptors More...
int	snd_ctl_poll_descriptors_revents (snd_ctl_t *ctl, struct pollfd *pfds, unsigned int nfds, unsigned short *revents)
	get returned events from poll descriptors More...
int	snd_ctl_subscribe_events (snd_ctl_t *ctl, int subscribe)
	Ask to be informed about events (poll, snd_async_add_ctl_handler, snd_ctl_read) More...
int	snd_ctl_card_info (snd_ctl_t *ctl, snd_ctl_card_info_t *info)
	Get information about the sound card. More...
int	snd_ctl_elem_list (snd_ctl_t *ctl, snd_ctl_elem_list_t *list)
	Get a list of element identifiers. More...
int	snd_ctl_elem_info (snd_ctl_t *ctl, snd_ctl_elem_info_t *info)
	Get CTL element information. More...
int	snd_ctl_elem_read (snd_ctl_t *ctl, snd_ctl_elem_value_t *data)
	Get CTL element value. More...
int	snd_ctl_elem_write (snd_ctl_t *ctl, snd_ctl_elem_value_t *data)
	Set CTL element value. More...
int	snd_ctl_elem_lock (snd_ctl_t *ctl, snd_ctl_elem_id_t *id)
	Lock CTL element. More...
int	snd_ctl_elem_unlock (snd_ctl_t *ctl, snd_ctl_elem_id_t *id)
	Unlock CTL element. More...
int	snd_ctl_elem_tlv_read (snd_ctl_t *ctl, const snd_ctl_elem_id_t *id, unsigned int *tlv, unsigned int tlv_size)
	Read structured data from an element set to given buffer. More...
int	snd_ctl_elem_tlv_write (snd_ctl_t *ctl, const snd_ctl_elem_id_t *id, const unsigned int *tlv)
	Write structured data from given buffer to an element set. More...
int	snd_ctl_elem_tlv_command (snd_ctl_t *ctl, const snd_ctl_elem_id_t *id, const unsigned int *tlv)
	Process structured data from given buffer for an element set. More...
int	snd_ctl_set_power_state (snd_ctl_t *ctl, unsigned int state)
	Set Power State to given SND_CTL_POWER_* value and do the power management. More...
int	snd_ctl_get_power_state (snd_ctl_t *ctl, unsigned int *state)
	Get actual Power State. More...
int	snd_ctl_read (snd_ctl_t *ctl, snd_ctl_event_t *event)
	Read an event. More...
int	snd_ctl_wait (snd_ctl_t *ctl, int timeout)
	Wait for a CTL to become ready (i.e. at least one event pending) More...
const char *	snd_ctl_name (snd_ctl_t *ctl)
	get identifier of CTL handle More...
snd_ctl_type_t	snd_ctl_type (snd_ctl_t *ctl)
	get type of CTL handle More...
const char *	snd_ctl_elem_type_name (snd_ctl_elem_type_t type)
	get name of a CTL element type More...
const char *	snd_ctl_elem_iface_name (snd_ctl_elem_iface_t iface)
	get name of a CTL element related interface More...
const char *	snd_ctl_event_type_name (snd_ctl_event_type_t type)
	get name of a CTL event type More...
unsigned int	snd_ctl_event_elem_get_mask (const snd_ctl_event_t *obj)
	Get event mask for an element related event. More...
unsigned int	snd_ctl_event_elem_get_numid (const snd_ctl_event_t *obj)
	Get element numeric identifier for an element related event. More...
void	snd_ctl_event_elem_get_id (const snd_ctl_event_t *obj, snd_ctl_elem_id_t *ptr)
	Get CTL element identifier for an element related event. More...
snd_ctl_elem_iface_t	snd_ctl_event_elem_get_interface (const snd_ctl_event_t *obj)
	Get interface part of CTL element identifier for an element related event. More...
unsigned int	snd_ctl_event_elem_get_device (const snd_ctl_event_t *obj)
	Get device part of CTL element identifier for an element related event. More...
unsigned int	snd_ctl_event_elem_get_subdevice (const snd_ctl_event_t *obj)
	Get subdevice part of CTL element identifier for an element related event. More...
const char *	snd_ctl_event_elem_get_name (const snd_ctl_event_t *obj)
	Get name part of CTL element identifier for an element related event. More...
unsigned int	snd_ctl_event_elem_get_index (const snd_ctl_event_t *obj)
	Get index part of CTL element identifier for an element related event. More...
int	snd_ctl_elem_list_alloc_space (snd_ctl_elem_list_t *obj, unsigned int entries)
	allocate space for CTL element identifiers list More...
void	snd_ctl_elem_list_free_space (snd_ctl_elem_list_t *obj)
	free previously allocated space for CTL element identifiers list More...
char *	snd_ctl_ascii_elem_id_get (snd_ctl_elem_id_t *id)
	return ASCII CTL element identifier name More...
int	snd_ctl_ascii_elem_id_parse (snd_ctl_elem_id_t *dst, const char *str)
	parse ASCII string as CTL element identifier More...
int	snd_ctl_ascii_value_parse (snd_ctl_t *handle, snd_ctl_elem_value_t *dst, snd_ctl_elem_info_t *info, const char *value)
	parse ASCII string as CTL element value More...
size_t	snd_ctl_elem_id_sizeof (void)
	get size of snd_ctl_elem_id_t More...
int	snd_ctl_elem_id_malloc (snd_ctl_elem_id_t **ptr)
	allocate an invalid snd_ctl_elem_id_t using standard malloc More...
void	snd_ctl_elem_id_free (snd_ctl_elem_id_t *obj)
	frees a previously allocated snd_ctl_elem_id_t More...
void	snd_ctl_elem_id_clear (snd_ctl_elem_id_t *obj)
	clear given snd_ctl_elem_id_t object More...
void	snd_ctl_elem_id_copy (snd_ctl_elem_id_t *dst, const snd_ctl_elem_id_t *src)
	copy one snd_ctl_elem_id_t to another More...
int	snd_ctl_elem_id_compare_numid (const snd_ctl_elem_id_t *id1, const snd_ctl_elem_id_t *id2)
	compare one snd_ctl_elem_id_t to another using numid More...
int	snd_ctl_elem_id_compare_set (const snd_ctl_elem_id_t *id1, const snd_ctl_elem_id_t *id2)
	compare one snd_ctl_elem_id_t to another More...
unsigned int	snd_ctl_elem_id_get_numid (const snd_ctl_elem_id_t *obj)
	Get numeric identifier from a CTL element identifier. More...
snd_ctl_elem_iface_t	snd_ctl_elem_id_get_interface (const snd_ctl_elem_id_t *obj)
	Get interface part of a CTL element identifier. More...
unsigned int	snd_ctl_elem_id_get_device (const snd_ctl_elem_id_t *obj)
	Get device part of a CTL element identifier. More...
unsigned int	snd_ctl_elem_id_get_subdevice (const snd_ctl_elem_id_t *obj)
	Get subdevice part of a CTL element identifier. More...
const char *	snd_ctl_elem_id_get_name (const snd_ctl_elem_id_t *obj)
	Get name part of a CTL element identifier. More...
unsigned int	snd_ctl_elem_id_get_index (const snd_ctl_elem_id_t *obj)
	Get index part of a CTL element identifier. More...
void	snd_ctl_elem_id_set_numid (snd_ctl_elem_id_t *obj, unsigned int val)
	Set numeric identifier for a CTL element identifier. More...
void	snd_ctl_elem_id_set_interface (snd_ctl_elem_id_t *obj, snd_ctl_elem_iface_t val)
	Set interface part for a CTL element identifier. More...
void	snd_ctl_elem_id_set_device (snd_ctl_elem_id_t *obj, unsigned int val)
	Set device part for a CTL element identifier. More...
void	snd_ctl_elem_id_set_subdevice (snd_ctl_elem_id_t *obj, unsigned int val)
	Set subdevice part for a CTL element identifier. More...
void	snd_ctl_elem_id_set_name (snd_ctl_elem_id_t *obj, const char *val)
	Set name part for a CTL element identifier. More...
void	snd_ctl_elem_id_set_index (snd_ctl_elem_id_t *obj, unsigned int val)
	Set index part for a CTL element identifier. More...
size_t	snd_ctl_card_info_sizeof (void)
	get size of snd_ctl_card_info_t. More...
int	snd_ctl_card_info_malloc (snd_ctl_card_info_t **ptr)
	Allocate an invalid snd_ctl_card_info_t on the heap. More...
void	snd_ctl_card_info_free (snd_ctl_card_info_t *obj)
	Free an snd_ctl_card_info_t previously allocated using snd_ctl_card_info_malloc(). More...
void	snd_ctl_card_info_clear (snd_ctl_card_info_t *obj)
	Clear given card info object. More...
void	snd_ctl_card_info_copy (snd_ctl_card_info_t *dst, const snd_ctl_card_info_t *src)
	Bitwise copy of a snd_ctl_card_info_t object. More...
int	snd_ctl_card_info_get_card (const snd_ctl_card_info_t *obj)
	Get the sound card index from the given info object. More...
const char *	snd_ctl_card_info_get_id (const snd_ctl_card_info_t *obj)
	Get the sound card ID from the given info object. More...
const char *	snd_ctl_card_info_get_driver (const snd_ctl_card_info_t *obj)
	Get the sound card driver from the given info object. More...
const char *	snd_ctl_card_info_get_name (const snd_ctl_card_info_t *obj)
	Get the sound card name from the given info object. More...
const char *	snd_ctl_card_info_get_longname (const snd_ctl_card_info_t *obj)
	Get the sound cards long name from the given info object. More...
const char *	snd_ctl_card_info_get_mixername (const snd_ctl_card_info_t *obj)
	Get the sound card mixer name from the given info object. More...
const char *	snd_ctl_card_info_get_components (const snd_ctl_card_info_t *obj)
	Get the sound cards "components" property from the given info object. More...
size_t	snd_ctl_event_sizeof (void)
	get size of snd_ctl_event_t More...
int	snd_ctl_event_malloc (snd_ctl_event_t **ptr)
	allocate an invalid snd_ctl_event_t using standard malloc More...
void	snd_ctl_event_free (snd_ctl_event_t *obj)
	frees a previously allocated snd_ctl_event_t More...
void	snd_ctl_event_clear (snd_ctl_event_t *obj)
	clear given snd_ctl_event_t object More...
void	snd_ctl_event_copy (snd_ctl_event_t *dst, const snd_ctl_event_t *src)
	copy one snd_ctl_event_t to another More...
snd_ctl_event_type_t	snd_ctl_event_get_type (const snd_ctl_event_t *obj)
	Get type of a CTL event. More...
size_t	snd_ctl_elem_list_sizeof (void)
	get size of snd_ctl_elem_list_t. More...
int	snd_ctl_elem_list_malloc (snd_ctl_elem_list_t **ptr)
	allocate a snd_ctl_elem_list_t using standard malloc. More...
void	snd_ctl_elem_list_free (snd_ctl_elem_list_t *obj)
	frees a previously allocated snd_ctl_elem_list_t. More...
void	snd_ctl_elem_list_clear (snd_ctl_elem_list_t *obj)
	Clear given snd_ctl_elem_list_t object. More...
void	snd_ctl_elem_list_copy (snd_ctl_elem_list_t *dst, const snd_ctl_elem_list_t *src)
	copy one snd_ctl_elem_list_t to another. More...
void	snd_ctl_elem_list_set_offset (snd_ctl_elem_list_t *obj, unsigned int val)
	Set index of first wanted CTL element identifier in a CTL element identifiers list. More...
unsigned int	snd_ctl_elem_list_get_used (const snd_ctl_elem_list_t *obj)
	Get number of used entries in CTL element identifiers list. More...
unsigned int	snd_ctl_elem_list_get_count (const snd_ctl_elem_list_t *obj)
	Get total count of elements present in CTL device. More...
void	snd_ctl_elem_list_get_id (const snd_ctl_elem_list_t *obj, unsigned int idx, snd_ctl_elem_id_t *ptr)
	Get CTL element identifier for an entry of a CTL element identifiers list. More...
unsigned int	snd_ctl_elem_list_get_numid (const snd_ctl_elem_list_t *obj, unsigned int idx)
	Get CTL element numeric identifier for an entry of a CTL element identifiers list. More...
snd_ctl_elem_iface_t	snd_ctl_elem_list_get_interface (const snd_ctl_elem_list_t *obj, unsigned int idx)
	Get interface part of CTL element identifier for an entry of a CTL element identifiers list. More...
unsigned int	snd_ctl_elem_list_get_device (const snd_ctl_elem_list_t *obj, unsigned int idx)
	Get the device part of CTL element identifier for an entry of a CTL element identifiers list. More...
unsigned int	snd_ctl_elem_list_get_subdevice (const snd_ctl_elem_list_t *obj, unsigned int idx)
	Get subdevice part of CTL element identifier for an entry of a CTL element identifiers list. More...
const char *	snd_ctl_elem_list_get_name (const snd_ctl_elem_list_t *obj, unsigned int idx)
	Get name part of CTL element identifier for an entry of a CTL element identifiers list. More...
unsigned int	snd_ctl_elem_list_get_index (const snd_ctl_elem_list_t *obj, unsigned int idx)
	Get index part of CTL element identifier for an entry of a CTL element identifiers list. More...
size_t	snd_ctl_elem_info_sizeof (void)
	get size of snd_ctl_elem_info_t More...
int	snd_ctl_elem_info_malloc (snd_ctl_elem_info_t **ptr)
	allocate an invalid snd_ctl_elem_info_t using standard malloc More...
void	snd_ctl_elem_info_free (snd_ctl_elem_info_t *obj)
	frees a previously allocated snd_ctl_elem_info_t More...
void	snd_ctl_elem_info_clear (snd_ctl_elem_info_t *obj)
	clear given snd_ctl_elem_info_t object More...
void	snd_ctl_elem_info_copy (snd_ctl_elem_info_t *dst, const snd_ctl_elem_info_t *src)
	copy one snd_ctl_elem_info_t to another More...
snd_ctl_elem_type_t	snd_ctl_elem_info_get_type (const snd_ctl_elem_info_t *obj)
	Get type from a CTL element id/info. More...
int	snd_ctl_elem_info_is_readable (const snd_ctl_elem_info_t *obj)
	Get info about readability from a CTL element id/info. More...
int	snd_ctl_elem_info_is_writable (const snd_ctl_elem_info_t *obj)
	Get info about writability from a CTL element id/info. More...
int	snd_ctl_elem_info_is_volatile (const snd_ctl_elem_info_t *obj)
	Get info about notification feasibility from a CTL element id/info. More...
int	snd_ctl_elem_info_is_inactive (const snd_ctl_elem_info_t *obj)
	Get info about status from a CTL element id/info. More...
int	snd_ctl_elem_info_is_locked (const snd_ctl_elem_info_t *obj)
	Get info whether an element is locked. More...
int	snd_ctl_elem_info_is_tlv_readable (const snd_ctl_elem_info_t *obj)
	Get info about TLV readability from a CTL element id/info. More...
int	snd_ctl_elem_info_is_tlv_writable (const snd_ctl_elem_info_t *obj)
	Get info about TLV writeability from a CTL element id/info. More...
int	snd_ctl_elem_info_is_tlv_commandable (const snd_ctl_elem_info_t *obj)
	Get info about TLV command possibility from a CTL element id/info. More...
int	snd_ctl_elem_info_is_owner (const snd_ctl_elem_info_t *obj)
	Get info if I own an element. More...
int	snd_ctl_elem_info_is_user (const snd_ctl_elem_info_t *obj)
	Get info if it's a user element. More...
pid_t	snd_ctl_elem_info_get_owner (const snd_ctl_elem_info_t *obj)
	Get owner of a locked element. More...
unsigned int	snd_ctl_elem_info_get_count (const snd_ctl_elem_info_t *obj)
	Get number of value entries from a CTL element id/info. More...
long	snd_ctl_elem_info_get_min (const snd_ctl_elem_info_t *obj)
	Get minimum value from a SND_CTL_ELEM_TYPE_INTEGER CTL element id/info. More...
long	snd_ctl_elem_info_get_max (const snd_ctl_elem_info_t *obj)
	Get maximum value from a SND_CTL_ELEM_TYPE_INTEGER CTL element id/info. More...
long	snd_ctl_elem_info_get_step (const snd_ctl_elem_info_t *obj)
	Get value step from a SND_CTL_ELEM_TYPE_INTEGER CTL element id/info. More...
long long	snd_ctl_elem_info_get_min64 (const snd_ctl_elem_info_t *obj)
	Get minimum value from a SND_CTL_ELEM_TYPE_INTEGER64 CTL element id/info. More...
long long	snd_ctl_elem_info_get_max64 (const snd_ctl_elem_info_t *obj)
	Get maximum value from a SND_CTL_ELEM_TYPE_INTEGER64 CTL element id/info. More...
long long	snd_ctl_elem_info_get_step64 (const snd_ctl_elem_info_t *obj)
	Get value step from a SND_CTL_ELEM_TYPE_INTEGER64 CTL element id/info. More...
unsigned int	snd_ctl_elem_info_get_items (const snd_ctl_elem_info_t *obj)
	Get number of items available from a SND_CTL_ELEM_TYPE_ENUMERATED CTL element id/info. More...
void	snd_ctl_elem_info_set_item (snd_ctl_elem_info_t *obj, unsigned int val)
	Select item in a SND_CTL_ELEM_TYPE_ENUMERATED CTL element id/info. More...
const char *	snd_ctl_elem_info_get_item_name (const snd_ctl_elem_info_t *obj)
	Get name for selected item in a SND_CTL_ELEM_TYPE_ENUMERATED CTL element id/info. More...
int	snd_ctl_elem_info_get_dimensions (const snd_ctl_elem_info_t *obj)
	Get count of dimensions for given element. More...
int	snd_ctl_elem_info_get_dimension (const snd_ctl_elem_info_t *obj, unsigned int idx)
	Get specified of dimension width for given element. More...
int	snd_ctl_elem_info_set_dimension (snd_ctl_elem_info_t *info, const int dimension[4])
	Set width to a specified dimension level of given element information. More...
void	snd_ctl_elem_info_get_id (const snd_ctl_elem_info_t *obj, snd_ctl_elem_id_t *ptr)
	Get CTL element identifier of a CTL element id/info. More...
unsigned int	snd_ctl_elem_info_get_numid (const snd_ctl_elem_info_t *obj)
	Get element numeric identifier of a CTL element id/info. More...
snd_ctl_elem_iface_t	snd_ctl_elem_info_get_interface (const snd_ctl_elem_info_t *obj)
	Get interface part of CTL element identifier of a CTL element id/info. More...
unsigned int	snd_ctl_elem_info_get_device (const snd_ctl_elem_info_t *obj)
	Get device part of CTL element identifier of a CTL element id/info. More...
unsigned int	snd_ctl_elem_info_get_subdevice (const snd_ctl_elem_info_t *obj)
	Get subdevice part of CTL element identifier of a CTL element id/info. More...
const char *	snd_ctl_elem_info_get_name (const snd_ctl_elem_info_t *obj)
	Get name part of CTL element identifier of a CTL element id/info. More...
unsigned int	snd_ctl_elem_info_get_index (const snd_ctl_elem_info_t *obj)
	Get index part of CTL element identifier of a CTL element id/info. More...
void	snd_ctl_elem_info_set_id (snd_ctl_elem_info_t *obj, const snd_ctl_elem_id_t *ptr)
	Set CTL element identifier of a CTL element id/info. More...
void	snd_ctl_elem_info_set_numid (snd_ctl_elem_info_t *obj, unsigned int val)
	Set element numeric identifier of a CTL element id/info. More...
void	snd_ctl_elem_info_set_interface (snd_ctl_elem_info_t *obj, snd_ctl_elem_iface_t val)
	Set interface part of CTL element identifier of a CTL element id/info. More...
void	snd_ctl_elem_info_set_device (snd_ctl_elem_info_t *obj, unsigned int val)
	Set device part of CTL element identifier of a CTL element id/info. More...
void	snd_ctl_elem_info_set_subdevice (snd_ctl_elem_info_t *obj, unsigned int val)
	Set subdevice part of CTL element identifier of a CTL element id/info. More...
void	snd_ctl_elem_info_set_name (snd_ctl_elem_info_t *obj, const char *val)
	Set name part of CTL element identifier of a CTL element id/info. More...
void	snd_ctl_elem_info_set_index (snd_ctl_elem_info_t *obj, unsigned int val)
	Set index part of CTL element identifier of a CTL element id/info. More...
void	snd_ctl_elem_info_set_read_write (snd_ctl_elem_info_t *obj, int rval, int wval)
	Set readability/writeability parameter of a CTL element id/info. More...
void	snd_ctl_elem_info_set_tlv_read_write (snd_ctl_elem_info_t *obj, int rval, int wval)
	Set TLV readability/writeability parameter of a CTL element id/info. More...
void	snd_ctl_elem_info_set_inactive (snd_ctl_elem_info_t *obj, int val)
	Set inactive parameter of a CTL element id/info. More...
int	snd_ctl_add_integer_elem_set (snd_ctl_t *ctl, snd_ctl_elem_info_t *info, unsigned int element_count, unsigned int member_count, long min, long max, long step)
	Create and add some user-defined control elements of integer type. More...
int	snd_ctl_add_integer64_elem_set (snd_ctl_t *ctl, snd_ctl_elem_info_t *info, unsigned int element_count, unsigned int member_count, long long min, long long max, long long step)
	Create and add some user-defined control elements of integer64 type. More...
int	snd_ctl_add_boolean_elem_set (snd_ctl_t *ctl, snd_ctl_elem_info_t *info, unsigned int element_count, unsigned int member_count)
	Create and add some user-defined control elements of boolean type. More...
int	snd_ctl_add_enumerated_elem_set (snd_ctl_t *ctl, snd_ctl_elem_info_t *info, unsigned int element_count, unsigned int member_count, unsigned int items, const char *const labels[])
	Create and add some user-defined control elements of enumerated type. More...
int	snd_ctl_add_bytes_elem_set (snd_ctl_t *ctl, snd_ctl_elem_info_t *info, unsigned int element_count, unsigned int member_count)
	Create and add some user-defined control elements of bytes type. More...
int	snd_ctl_elem_add_integer (snd_ctl_t *ctl, const snd_ctl_elem_id_t *id, unsigned int count, long imin, long imax, long istep)
	Create and add an user-defined control element of integer type. More...
int	snd_ctl_elem_add_integer64 (snd_ctl_t *ctl, const snd_ctl_elem_id_t *id, unsigned int count, long long imin, long long imax, long long istep)
	Create and add an user-defined control element of integer64 type. More...
int	snd_ctl_elem_add_boolean (snd_ctl_t *ctl, const snd_ctl_elem_id_t *id, unsigned int count)
	Create and add an user-defined control element of boolean type. More...
int	snd_ctl_elem_add_enumerated (snd_ctl_t *ctl, const snd_ctl_elem_id_t *id, unsigned int count, unsigned int items, const char *const names[])
	Create and add a user-defined control element of enumerated type. More...
int	snd_ctl_elem_add_iec958 (snd_ctl_t *ctl, const snd_ctl_elem_id_t *id)
	Create and add a user-defined control element of IEC958 type. More...
int	snd_ctl_elem_remove (snd_ctl_t *ctl, snd_ctl_elem_id_t *id)
	Remove an user CTL element. More...
size_t	snd_ctl_elem_value_sizeof (void)
	Get size of data structure for an element. More...
int	snd_ctl_elem_value_malloc (snd_ctl_elem_value_t **ptr)
	Allocate an invalid snd_ctl_elem_value_t on the heap. More...
void	snd_ctl_elem_value_free (snd_ctl_elem_value_t *obj)
	Free an snd_ctl_elem_value_t previously allocated using snd_ctl_elem_value_malloc(). More...
void	snd_ctl_elem_value_clear (snd_ctl_elem_value_t *obj)
	Clear given data of an element. More...
void	snd_ctl_elem_value_copy (snd_ctl_elem_value_t *dst, const snd_ctl_elem_value_t *src)
	Bitwise copy of a snd_ctl_elem_value_t value. More...
int	snd_ctl_elem_value_compare (snd_ctl_elem_value_t *left, const snd_ctl_elem_value_t *right)
	Compare two snd_ctl_elem_value_t values, bytewise. More...
void	snd_ctl_elem_value_get_id (const snd_ctl_elem_value_t *obj, snd_ctl_elem_id_t *ptr)
	Get the element identifier from the given element value. More...
unsigned int	snd_ctl_elem_value_get_numid (const snd_ctl_elem_value_t *obj)
	Get the identifiers 'numid' part from the given element value. More...
snd_ctl_elem_iface_t	snd_ctl_elem_value_get_interface (const snd_ctl_elem_value_t *obj)
	Get the identifiers 'interface' part from the given element value. More...
unsigned int	snd_ctl_elem_value_get_device (const snd_ctl_elem_value_t *obj)
	Get the identifiers 'device' part from the given element value. More...
unsigned int	snd_ctl_elem_value_get_subdevice (const snd_ctl_elem_value_t *obj)
	Get the identifiers 'subdevice' part from the given element value. More...
const char *	snd_ctl_elem_value_get_name (const snd_ctl_elem_value_t *obj)
	Get the identifiers 'name' part from the given element value. More...
unsigned int	snd_ctl_elem_value_get_index (const snd_ctl_elem_value_t *obj)
	Get the identifiers 'index' part from the given element value. More...
void	snd_ctl_elem_value_set_id (snd_ctl_elem_value_t *obj, const snd_ctl_elem_id_t *ptr)
	Set the element identifier within the given element value. More...
void	snd_ctl_elem_value_set_numid (snd_ctl_elem_value_t *obj, unsigned int val)
	Set the identifiers 'numid' part within the given element value. More...
void	snd_ctl_elem_value_set_interface (snd_ctl_elem_value_t *obj, snd_ctl_elem_iface_t val)
	Set the identifiers 'interface' part within the given element value. More...
void	snd_ctl_elem_value_set_device (snd_ctl_elem_value_t *obj, unsigned int val)
	Set the identifiers 'device' part within the given element value. More...
void	snd_ctl_elem_value_set_subdevice (snd_ctl_elem_value_t *obj, unsigned int val)
	Set the identifiers 'subdevice' part within the given element value. More...
void	snd_ctl_elem_value_set_name (snd_ctl_elem_value_t *obj, const char *val)
	Set the identifiers 'name' part within the given element value. More...
void	snd_ctl_elem_value_set_index (snd_ctl_elem_value_t *obj, unsigned int val)
	Set the identifiers 'index' part within the given element value. More...
int	snd_ctl_elem_value_get_boolean (const snd_ctl_elem_value_t *obj, unsigned int idx)
	Get an element members value. More...
long	snd_ctl_elem_value_get_integer (const snd_ctl_elem_value_t *obj, unsigned int idx)
	Get an element members value. More...
long long	snd_ctl_elem_value_get_integer64 (const snd_ctl_elem_value_t *obj, unsigned int idx)
	Get an element members value. More...
unsigned int	snd_ctl_elem_value_get_enumerated (const snd_ctl_elem_value_t *obj, unsigned int idx)
	Get an element members value. More...
unsigned char	snd_ctl_elem_value_get_byte (const snd_ctl_elem_value_t *obj, unsigned int idx)
	Get an element members value. More...
void	snd_ctl_elem_value_set_boolean (snd_ctl_elem_value_t *obj, unsigned int idx, long val)
	Set an element members value. More...
void	snd_ctl_elem_value_set_integer (snd_ctl_elem_value_t *obj, unsigned int idx, long val)
	Set an element members value. More...
void	snd_ctl_elem_value_set_integer64 (snd_ctl_elem_value_t *obj, unsigned int idx, long long val)
	Set an element members value. More...
void	snd_ctl_elem_value_set_enumerated (snd_ctl_elem_value_t *obj, unsigned int idx, unsigned int val)
	Set an element members value. More...
void	snd_ctl_elem_value_set_byte (snd_ctl_elem_value_t *obj, unsigned int idx, unsigned char val)
	Set an element members value. More...
void	snd_ctl_elem_set_bytes (snd_ctl_elem_value_t *obj, void *data, size_t size)
	Replace the data stored within the element. More...
const void *	snd_ctl_elem_value_get_bytes (const snd_ctl_elem_value_t *obj)
	Get the data stored within the element. More...
void	snd_ctl_elem_value_get_iec958 (const snd_ctl_elem_value_t *obj, snd_aes_iec958_t *ptr)
	Get an elements IEC958 data. More...
void	snd_ctl_elem_value_set_iec958 (snd_ctl_elem_value_t *obj, const snd_aes_iec958_t *ptr)
	Set an elements IEC958 data. More...
int	snd_tlv_parse_dB_info (unsigned int *tlv, unsigned int tlv_size, unsigned int **db_tlvp)
	Parse TLV stream and retrieve dB information. More...
int	snd_tlv_get_dB_range (unsigned int *tlv, long rangemin, long rangemax, long *min, long *max)
	Get the dB min/max values. More...
int	snd_tlv_convert_to_dB (unsigned int *tlv, long rangemin, long rangemax, long volume, long *db_gain)
	Convert the given raw volume value to a dB gain. More...
int	snd_tlv_convert_from_dB (unsigned int *tlv, long rangemin, long rangemax, long db_gain, long *value, int xdir)
	Convert from dB gain to the corresponding raw value. More...
int	snd_ctl_get_dB_range (snd_ctl_t *ctl, const snd_ctl_elem_id_t *id, long *min, long *max)
	Get the dB min/max values on the given control element. More...
int	snd_ctl_convert_to_dB (snd_ctl_t *ctl, const snd_ctl_elem_id_t *id, long volume, long *db_gain)
	Convert the volume value to dB on the given control element. More...
int	snd_ctl_convert_from_dB (snd_ctl_t *ctl, const snd_ctl_elem_id_t *id, long db_gain, long *value, int xdir)
	Convert from dB gain to the raw volume value on the given control element. More...

Detailed Description

The control interface. See Control interface page for more details.

Macro Definition Documentation

SND_CONTROL_DLSYM_VERSION

#define SND_CONTROL_DLSYM_VERSION   _dlsym_control_001

dlsym version for interface entry callback

SND_CTL_ASYNC

#define SND_CTL_ASYNC

Async notification (flag for open mode)

snd_ctl_card_info_alloca

#define snd_ctl_card_info_alloca

(

ptr

)

Allocate an invalid snd_ctl_card_info_t on the stack.

Allocate space for a card info object on the stack. The allocated memory need not be freed, because it is on the stack.

See snd_ctl_card_info_t for details.

Parameters

ptr	Pointer to a snd_ctl_elem_value_t pointer. The address of the allocated space will returned here.

snd_ctl_elem_id_alloca

#define snd_ctl_elem_id_alloca

(

ptr

)

allocate an invalid snd_ctl_elem_id_t using standard alloca

Parameters

ptr	returned pointer

snd_ctl_elem_info_alloca

#define snd_ctl_elem_info_alloca

(

ptr

)

allocate an invalid snd_ctl_elem_info_t using standard alloca

Parameters

ptr	returned pointer

snd_ctl_elem_list_alloca

#define snd_ctl_elem_list_alloca

(

ptr

)

Allocate a snd_ctl_elem_list_t using standard alloca.

The memory is allocated on the stack and will automatically be released when the stack unwinds (i.e. no free() is needed).

Parameters

ptr	Pointer to allocated memory.

snd_ctl_elem_value_alloca

#define snd_ctl_elem_value_alloca

(

ptr

)

Allocate an invalid snd_ctl_elem_value_t on the stack.

Allocate space for a value object on the stack. The allocated memory need not be freed, because it is on the stack.

See snd_ctl_elem_value_t for details.

Parameters

ptr	Pointer to a snd_ctl_elem_value_t pointer. The address of the allocated space will returned here.

snd_ctl_event_alloca

#define snd_ctl_event_alloca

(

ptr

)

allocate an invalid snd_ctl_event_t using standard alloca

Parameters

ptr	returned pointer

SND_CTL_EVENT_MASK_ADD

#define SND_CTL_EVENT_MASK_ADD

Element has been added

SND_CTL_EVENT_MASK_INFO

#define SND_CTL_EVENT_MASK_INFO

Element info has been changed

SND_CTL_EVENT_MASK_REMOVE

#define SND_CTL_EVENT_MASK_REMOVE

Element has been removed (Warning: test this first and if set don't test the other masks)

SND_CTL_EVENT_MASK_TLV

#define SND_CTL_EVENT_MASK_TLV

Element's TLV value has been changed

SND_CTL_EVENT_MASK_VALUE

#define SND_CTL_EVENT_MASK_VALUE

Element value has been changed

SND_CTL_NAME_CAPTURE

#define SND_CTL_NAME_CAPTURE   "Capture "

CTL name helper

SND_CTL_NAME_IEC958

#define SND_CTL_NAME_IEC958	(		expl,
			direction,
			what
	)		"IEC958 " expl SND_CTL_NAME_##direction SND_CTL_NAME_IEC958_##what

Element name for IEC958 (S/PDIF)

SND_CTL_NAME_IEC958_CON_MASK

#define SND_CTL_NAME_IEC958_CON_MASK   "Con Mask"

CTL name helper

SND_CTL_NAME_IEC958_DEFAULT

#define SND_CTL_NAME_IEC958_DEFAULT   "Default"

CTL name helper

SND_CTL_NAME_IEC958_MASK

#define SND_CTL_NAME_IEC958_MASK   "Mask"

CTL name helper

SND_CTL_NAME_IEC958_NONE

#define SND_CTL_NAME_IEC958_NONE   ""

CTL name helper

SND_CTL_NAME_IEC958_PCM_STREAM

#define SND_CTL_NAME_IEC958_PCM_STREAM   "PCM Stream"

CTL name helper

SND_CTL_NAME_IEC958_PRO_MASK

#define SND_CTL_NAME_IEC958_PRO_MASK   "Pro Mask"

CTL name helper

SND_CTL_NAME_IEC958_SWITCH

#define SND_CTL_NAME_IEC958_SWITCH   "Switch"

CTL name helper

SND_CTL_NAME_IEC958_VOLUME

#define SND_CTL_NAME_IEC958_VOLUME   "Volume"

CTL name helper

SND_CTL_NAME_NONE

#define SND_CTL_NAME_NONE   ""

CTL name helper

SND_CTL_NAME_PLAYBACK

#define SND_CTL_NAME_PLAYBACK   "Playback "

CTL name helper

SND_CTL_NONBLOCK

#define SND_CTL_NONBLOCK

Non blocking mode (flag for open mode)

SND_CTL_POWER_D0

#define SND_CTL_POWER_D0   0x0000

ACPI/PCI Power State D0

SND_CTL_POWER_D1

#define SND_CTL_POWER_D1   0x0100

ACPI/PCI Power State D1

SND_CTL_POWER_D2

#define SND_CTL_POWER_D2   0x0200

ACPI/PCI Power State D2

SND_CTL_POWER_D3

#define SND_CTL_POWER_D3   0x0300

ACPI/PCI Power State D3

SND_CTL_POWER_D3cold

#define SND_CTL_POWER_D3cold   (SND_CTL_POWER_D3|0x0001)

ACPI/PCI Power State D3cold

SND_CTL_POWER_D3hot

#define SND_CTL_POWER_D3hot   (SND_CTL_POWER_D3|0x0000)

ACPI/PCI Power State D3hot

SND_CTL_POWER_MASK

#define SND_CTL_POWER_MASK   0xff00

Mask for the major Power State identifier

SND_CTL_READONLY

#define SND_CTL_READONLY

Read only (flag for open mode)

SND_CTL_TLV_DB_GAIN_MUTE

#define SND_CTL_TLV_DB_GAIN_MUTE   -9999999

Mute state

SND_CTL_TLVT_CHMAP_FIXED

#define SND_CTL_TLVT_CHMAP_FIXED   0x00101

TLV type - fixed channel map positions

SND_CTL_TLVT_CHMAP_PAIRED

#define SND_CTL_TLVT_CHMAP_PAIRED   0x00103

TLV type - pair-wise swappable channel map positions

SND_CTL_TLVT_CHMAP_VAR

#define SND_CTL_TLVT_CHMAP_VAR   0x00102

TLV type - freely swappable channel map positions

SND_CTL_TLVT_CONTAINER

#define SND_CTL_TLVT_CONTAINER   0x0000

TLV type - Container

SND_CTL_TLVT_DB_LINEAR

#define SND_CTL_TLVT_DB_LINEAR   0x0002

TLV type - linear volume

SND_CTL_TLVT_DB_MINMAX

#define SND_CTL_TLVT_DB_MINMAX   0x0004

TLV type - dB scale specified by min/max values

SND_CTL_TLVT_DB_MINMAX_MUTE

#define SND_CTL_TLVT_DB_MINMAX_MUTE   0x0005

TLV type - dB scale specified by min/max values (with mute)

SND_CTL_TLVT_DB_RANGE

#define SND_CTL_TLVT_DB_RANGE   0x0003

TLV type - dB range container

SND_CTL_TLVT_DB_SCALE

#define SND_CTL_TLVT_DB_SCALE   0x0001

TLV type - basic dB scale

SND_SCTL_NOFREE

#define SND_SCTL_NOFREE   0x0001

Don't destroy the ctl handle when close

Typedef Documentation

snd_ctl_card_info_t

typedef struct _snd_ctl_card_info snd_ctl_card_info_t

CTL card info container.

This type contains meta information about a sound card, such as the index, name, longname, etc.

Memory management

Before using a snd_ctl_card_info_t object, it must be allocated using snd_ctl_card_info_alloca() or snd_ctl_card_info_malloc(). When using the latter, it must be freed again using snd_ctl_card_info_free().

A card info object can be zeroed out using snd_ctl_card_info_clear().

A card info object can be copied to another one using snd_ctl_card_info_copy().

Obtaining the Information

To obtain the card information, it must first be opened using snd_ctl_open(), and a snd_ctl_card_info_t container must be allocated. Then, the information can be read using snd_ctl_card_info_get_card().

Thereafter, the card properties can be read using the snd_ctl_card_info_get_*() functions.

snd_ctl_elem_id_t

typedef struct _snd_ctl_elem_id snd_ctl_elem_id_t

CTL element identifier container

snd_ctl_elem_info_t

typedef struct _snd_ctl_elem_info snd_ctl_elem_info_t

CTL element info container

snd_ctl_elem_list_t

typedef struct _snd_ctl_elem_list snd_ctl_elem_list_t

CTL element list container

This is a list of CTL elements. The list contains management information (e.g. how many elements the sound card has) as well as the element identifiers. All functions which operate on the list are named snd_ctl_elem_list_*().

Memory management

There are two memory areas to deal with: The list container itself and the memory for the element identifiers.

To manage the area for the list container, the following functions are used:

• snd_ctl_elem_list_malloc() / snd_ctl_elem_list_free() to allocate and free memory on the heap, or
• snd_ctl_elem_list_alloca() to allocate the memory on the stack. This memory is auto-released when the stack is unwound.

To manage the space for the element identifiers, the snd_ctl_elem_list_alloc_space() and snd_ctl_elem_list_free_space() are used. Allocating the right amount of space can be achieved by first obtaining the number of elements and then calling snd_ctl_elem_list_alloc_space():

snd_ctl_elem_list_t* list;
int count;
 
// Initialise list
snd_ctl_elem_list_malloc(&list);
 
// Get number of elements
snd_ctl_elem_list(ctl, list);
count = snd_ctl_elem_list_get_count(list);
 
// Allocate space for identifiers
snd_ctl_elem_list_alloc_space(list, count);
 
// Get identifiers
snd_ctl_elem_list(ctl, list); // yes, this is same as above :)
 
// Do something useful with the list...
 
// Cleanup
snd_ctl_elem_list_free_space(list);
snd_ctl_elem_list_free(list);

The Elements

The elements in the list are accessed using an index. This index is the location in the list; Don't confuse it with the 'index' of the element identifier. For example:

snd_ctl_elem_list_t list;
unsigned int element_index;
 
// Allocate space, fill list ...
 
element_index = snd_ctl_elem_list_get_index(&list, 2);

This will access the 3rd element in the list (index=2) and get the elements index from the driver (which might be 13, for example).

snd_ctl_elem_value_t

typedef struct _snd_ctl_elem_value snd_ctl_elem_value_t

CTL element value container.

Contains the value(s) (i.e. members) of a single element. All values of a given element are of the same type.

Memory management

To access a value, a snd_ctl_elem_value_t must be allocated using snd_ctl_elem_value_alloca() or snd_ctl_elem_value_malloc(). When using the latter, it must be freed again using snd_ctl_elem_value_free().

A value object can be zeroed out using snd_ctl_elem_value_clear().

A value object can be copied to another one using snd_ctl_elem_value_copy().

Identifier

Then, the ID must be filled. It is sufficient to fill only the numid, if known. Otherwise, interface type, device, subdevice, name, index must all be given. The following functions can be used to fill the ID:

• snd_ctl_elem_value_set_id(): Set the ID. Requires an snd_ctl_elem_id_t object.
• snd_ctl_elem_value_set_numid(): Set the numid.
• Or use all of the following:
  • snd_ctl_elem_value_set_interface()
  • snd_ctl_elem_value_set_device()
  • snd_ctl_elem_value_set_subdevice()
  • snd_ctl_elem_value_set_name()
  • snd_ctl_elem_value_set_index()

When communicating with the driver (snd_ctl_elem_read(), snd_ctl_elem_write()), and the numid was given, the interface, device, ... are filled (even if you set the before). When the numid is unset (i.e. it is 0), it is filled.

Communicating with the driver

After the value container was created and filled with the ID of the desired element, the value(s) can be fetched from the driver (and thus from the hardware) or written to the driver.

To fetch a value, use snd_ctl_elem_read(). Thereafter, use the snd_ctl_elem_value_get_*() functions to obtain the actual value.

To write a new value, first use a snd_ctl_elem_value_set_*() to set it, then call snd_ctl_elem_write() to write it to the driver.

snd_ctl_event_t

typedef struct _snd_ctl_event snd_ctl_event_t

CTL event container

snd_ctl_t

typedef struct _snd_ctl snd_ctl_t

CTL handle

snd_sctl_t

typedef struct _snd_sctl snd_sctl_t

SCTL type

Enumeration Type Documentation

snd_ctl_elem_iface_t

enum snd_ctl_elem_iface_t

CTL related interface

Enumerator
SND_CTL_ELEM_IFACE_CARD	Card level
SND_CTL_ELEM_IFACE_HWDEP	Hardware dependent device
SND_CTL_ELEM_IFACE_MIXER	Mixer
SND_CTL_ELEM_IFACE_PCM	PCM
SND_CTL_ELEM_IFACE_RAWMIDI	RawMidi
SND_CTL_ELEM_IFACE_TIMER	Timer
SND_CTL_ELEM_IFACE_SEQUENCER	Sequencer

snd_ctl_elem_type_t

enum snd_ctl_elem_type_t

CTL element type

Enumerator
SND_CTL_ELEM_TYPE_NONE	Invalid type
SND_CTL_ELEM_TYPE_BOOLEAN	Boolean contents
SND_CTL_ELEM_TYPE_INTEGER	Integer contents
SND_CTL_ELEM_TYPE_ENUMERATED	Enumerated contents
SND_CTL_ELEM_TYPE_BYTES	Bytes contents
SND_CTL_ELEM_TYPE_IEC958	IEC958 (S/PDIF) setting content
SND_CTL_ELEM_TYPE_INTEGER64	64-bit integer contents

snd_ctl_event_type_t

enum snd_ctl_event_type_t

Event class

Enumerator
SND_CTL_EVENT_ELEM	Elements related event

snd_ctl_type_t

enum snd_ctl_type_t

CTL type

Enumerator
SND_CTL_TYPE_HW	Kernel level CTL
SND_CTL_TYPE_SHM	Shared memory client CTL
SND_CTL_TYPE_INET	INET client CTL (not yet implemented)
SND_CTL_TYPE_EXT	External control plugin
SND_CTL_TYPE_REMAP	Control functionality remapping

Function Documentation

snd_async_add_ctl_handler()

int snd_async_add_ctl_handler	(	snd_async_handler_t **	handler,
		snd_ctl_t *	ctl,
		snd_async_callback_t	callback,
		void *	private_data
	)

Add an async handler for a CTL.

Parameters

handler	Returned handler handle
ctl	CTL handle
callback	Callback function
private_data	Callback private data

Returns

0 otherwise a negative error code on failure

snd_async_handler_get_ctl()

snd_ctl_t * snd_async_handler_get_ctl

(

snd_async_handler_t *

handler

)

Return CTL handle related to an async handler.

Parameters

handler

Async handler handle

Returns

CTL handle

snd_card_get_index()

int snd_card_get_index

(

const char *

string

)

Convert a card string to the card index.

This works only for physical sound cards, not for virtual cards.

Parameters

string

A string identifying the card.

Returns

The index of the card. On error, a a negative error code is returned.

The accepted formats for "string" are:

• The index of the card (as listed in /proc/asound/cards), given as string
• The ID of the card (as listed in /proc/asound/cards)
• The control device name (like /dev/snd/controlC0)

snd_card_get_longname()

int snd_card_get_longname	(	int	card,
		char **	name
	)

Obtain the card long name.

Parameters

card	Index of the card.
name	Result - card long name corresponding to card index.

Returns

Zero if success, otherwise a negative error code.

The value returned in name is allocated with strdup and should be freed when no longer used.

snd_card_get_name()

int snd_card_get_name	(	int	card,
		char **	name
	)

Obtain the card name.

Parameters

card	The index of the card.
name	Result - card name corresponding to card index.

Returns

zero if success, otherwise a negative error code

The value returned in name is allocated with strdup and should be freed when no longer used.

snd_card_load()

int snd_card_load

(

int

card

)

Try to load the driver for a card.

Parameters

card	Card index.

Returns

1 if driver is present, zero if driver is not present.

snd_card_next()

int snd_card_next

(

int *

rcard

)

Iterate over physical sound cards.

This function takes the index of a physical sound card and sets it to the index of the next card. If index is -1, it is set to the index of the first card. After the last card, the index is set to -1.

For example, if you have 2 sound cards (with index 0 and 1), the index will be modified as follows:

• -1 --> 0
• 0 --> 1
• 1 --> -1

This does not work for virtual sound cards.

Parameters

rcard

Index of current card. The index of the next card is stored here.

Returns

zero if success, otherwise a negative error code.

snd_ctl_add_boolean_elem_set()

int snd_ctl_add_boolean_elem_set	(	snd_ctl_t *	ctl,
		snd_ctl_elem_info_t *	info,
		unsigned int	element_count,
		unsigned int	member_count
	)

Create and add some user-defined control elements of boolean type.

Parameters

ctl	A handle of backend module for control interface.
info	Common information for a new element set, with ID of the first new element.
element_count	The number of elements added by this operation.
member_count	The number of members which a element has to represent its states.

This function creates some user elements with boolean type. These elements are not controlled by device drivers in kernel. They can be operated by the same way as usual elements added by the device drivers.

The name field of id must be set with unique value to identify new control elements. After returning, all fields of id are filled. A element can be identified by the combination of name and index, or by numid.

All of members in the new elements are locked. The value of each member is initialized with false.

Errors:

-EBUSY

A element with ID id already exists.

-EINVAL

Some parameters include invalid value; i.e. ID has no name, or the number of members is not between 1 to 127.

-ENOMEM

Out of memory, or there are too many user elements.

-ENXIO

This backend module does not support user elements of boolean type.

-ENODEV

Device unplugged.

Compatibility:

This function is added in version 1.1.2.

snd_ctl_add_bytes_elem_set()

int snd_ctl_add_bytes_elem_set	(	snd_ctl_t *	ctl,
		snd_ctl_elem_info_t *	info,
		unsigned int	element_count,
		unsigned int	member_count
	)

Create and add some user-defined control elements of bytes type.

Parameters

ctl	A handle of backend module for control interface.
info	Common information for a new element set, with ID of the first new element.
element_count	The number of elements added by this operation.
member_count	The number of members which a element has to represent its states.

Returns

Zero on success, otherwise a negative error code.

This function creates some user elements with bytes type. These elements are not controlled by device drivers in kernel. They can be operated by the same way as usual elements added by the device drivers.

The name field of id must be set with unique value to identify new control elements. After returning, all fields of id are filled. A element can be identified by the combination of name and index, or by numid.

All of members in the new elements are locked. The value of each member is initialized with the minimum value.

Errors:

-EBUSY

A element with ID id already exists.

-EINVAL

Some arguments include invalid value; i.e. ID has no name, or the number of members is not between 1 to 511.

-ENOMEM

Out of memory, or there are too many user elements.

-ENXIO

This backend module does not support user elements of bytes type.

-ENODEV

Device unplugged.

Compatibility:

This function is added in version 1.1.2.

snd_ctl_add_enumerated_elem_set()

int snd_ctl_add_enumerated_elem_set	(	snd_ctl_t *	ctl,
		snd_ctl_elem_info_t *	info,
		unsigned int	element_count,
		unsigned int	member_count,
		unsigned int	items,
		const char *const	labels[]
	)

Create and add some user-defined control elements of enumerated type.

Parameters

ctl	A handle of backend module for control interface.
info	Common information for a new element set, with ID of the first new element.
element_count	The number of elements added by this operation.
member_count	The number of members which a element has to represent its states.
items	Range of possible values (0 ... items - 1).
labels	An array containing items strings.

Returns

Zero on success, otherwise a negative error code.

This function creates some user elements with enumerated type. These elements are not controlled by device drivers in kernel. They can be operated by the same way as usual elements added by the device drivers.

The name field of id must be set with unique value to identify new control elements. After returning, all fields of id are filled. A element can be identified by the combination of name and index, or by numid.

All of members in the new elements are locked. The value of each member is initialized with the first entry of labels.

Errors:

-EBUSY

A control element with ID id already exists.

-EINVAL

Some arguments include invalid value; i.e. element_count is not between 1 to 127, or items is not at least one, or a string in labels is empty, or longer than 63 bytes, or total length of the labels requires more than 64 KiB storage.

-ENOMEM

Out of memory, or there are too many user control elements.

-ENXIO

This driver does not support (enumerated) user controls.

-ENODEV

Device unplugged.

Compatibility:

This function is added in version 1.1.2.

snd_ctl_add_integer64_elem_set()

int snd_ctl_add_integer64_elem_set	(	snd_ctl_t *	ctl,
		snd_ctl_elem_info_t *	info,
		unsigned int	element_count,
		unsigned int	member_count,
		long long	min,
		long long	max,
		long long	step
	)

Create and add some user-defined control elements of integer64 type.

Parameters

ctl	A handle of backend module for control interface.
info	Common information for a new element set, with ID of the first new element.
element_count	The number of elements added by this operation.
member_count	The number of members which a element has to represent its states.
min	Minimum value for each member of the elements.
max	Maximum value for each member of the elements.
step	The step of value for each member in the elements.

Returns

Zero on success, otherwise a negative error code.

This function creates some user elements with integer64 type. These elements are not controlled by device drivers in kernel. They can be operated by the same way as usual elements added by the device drivers.

The name field of id must be set with unique value to identify new control elements. After returning, all fields of id are filled. A element can be identified by the combination of name and index, or by numid.

All of members in the new elements are locked. The value of each member is initialized with the minimum value.

Errors:

-EBUSY

A element with ID id already exists.

-EINVAL

Some arguments include invalid value; i.e. ID has no name, or the number of members is not between 1 to 127.

-ENOMEM

Out of memory, or there are too many user elements.

-ENXIO

This backend module does not support user elements of integer64 type.

-ENODEV

Device unplugged.

Compatibility:

This function is added in version 1.1.2.

snd_ctl_add_integer_elem_set()

int snd_ctl_add_integer_elem_set	(	snd_ctl_t *	ctl,
		snd_ctl_elem_info_t *	info,
		unsigned int	element_count,
		unsigned int	member_count,
		long	min,
		long	max,
		long	step
	)

Create and add some user-defined control elements of integer type.

Parameters

ctl	A handle of backend module for control interface.
info	Common information for a new element set, with ID of the first new element.
element_count	The number of elements added by this operation.
member_count	The number of members which a element has to represent its states.
min	Minimum value for each member of the elements.
max	Maximum value for each member of the elements.
step	The step of value for each member in the elements.

Returns

Zero on success, otherwise a negative error code.

This function creates some user elements with integer type. These elements are not controlled by device drivers in kernel. They can be operated by the same way as usual elements added by the device drivers.

The name field of id must be set with unique value to identify new control elements. After returning, all fields of id are filled. A element can be identified by the combination of name and index, or by numid.

All of members in the new elements are locked. The value of each member is initialized with the minimum value.

Errors:

-EBUSY

A element with ID id already exists.

-EINVAL

Some arguments include invalid value; i.e. ID field in info has no name, or the number of members is not between 1 to 127.

-ENOMEM

Out of memory, or there are too many user elements.

-ENXIO

This backend module does not support user elements of integer type.

-ENODEV

Device unplugged.

Compatibility:

This function is added in version 1.1.2.

snd_ctl_ascii_elem_id_get()

char * snd_ctl_ascii_elem_id_get

(

snd_ctl_elem_id_t *

id

)

return ASCII CTL element identifier name

Parameters

id	CTL identifier

Returns

ascii identifier of CTL element

The string is allocated using strdup().

snd_ctl_ascii_elem_id_parse()

int snd_ctl_ascii_elem_id_parse	(	snd_ctl_elem_id_t *	dst,
		const char *	str
	)

parse ASCII string as CTL element identifier

Parameters

dst	destination CTL identifier
str	source ASCII string

Returns

zero on success, otherwise a negative error code

snd_ctl_ascii_value_parse()

int snd_ctl_ascii_value_parse	(	snd_ctl_t *	handle,
		snd_ctl_elem_value_t *	dst,
		snd_ctl_elem_info_t *	info,
		const char *	value
	)

parse ASCII string as CTL element value

Parameters

handle	CTL handle
dst	destination CTL element value
info	CTL element info structure
value	source ASCII string

Returns

zero on success, otherwise a negative error code

Note: For toggle command, the dst must contain previous (current) state (do the snd_ctl_elem_read call to obtain it).

snd_ctl_card_info()

int snd_ctl_card_info	(	snd_ctl_t *	ctl,
		snd_ctl_card_info_t *	info
	)

Get information about the sound card.

Obtain information about the sound card previously opened using snd_ctl_open(). The object "info" must be allocated prior to calling this function. See snd_ctl_card_info_t for details.

Parameters

ctl	The CTL handle.
info	The card information is stored here.

Returns

0 on success, otherwise a negative error code.

snd_ctl_card_info_clear()

void snd_ctl_card_info_clear

(

snd_ctl_card_info_t *

obj

)

Clear given card info object.

See snd_ctl_elem_value_t for details.

Parameters

obj	Card info object.

snd_ctl_card_info_copy()

void snd_ctl_card_info_copy	(	snd_ctl_card_info_t *	dst,
		const snd_ctl_card_info_t *	src
	)

Bitwise copy of a snd_ctl_card_info_t object.

Parameters

dst	Pointer to destination.
src	Pointer to source.

snd_ctl_card_info_free()

void snd_ctl_card_info_free

(

snd_ctl_card_info_t *

obj

)

Free an snd_ctl_card_info_t previously allocated using snd_ctl_card_info_malloc().

Parameters

obj	Pointer to the snd_ctl_card_info_t.

snd_ctl_card_info_get_card()

int snd_ctl_card_info_get_card

(

const snd_ctl_card_info_t *

obj

)

Get the sound card index from the given info object.

See snd_ctl_card_info_t for more details.

Parameters

obj	The card info object.

Returns

Sound card index.

snd_ctl_card_info_get_components()

const char * snd_ctl_card_info_get_components

(

const snd_ctl_card_info_t *

obj

)

Get the sound cards "components" property from the given info object.

See snd_ctl_card_info_t for more details.

Parameters

obj	The card info object.

Returns

Sound cards "components" property.

snd_ctl_card_info_get_driver()

const char * snd_ctl_card_info_get_driver

(

const snd_ctl_card_info_t *

obj

)

Get the sound card driver from the given info object.

See snd_ctl_card_info_t for more details.

Parameters

obj	The card info object.

Returns

The sound card driver.

snd_ctl_card_info_get_id()

const char * snd_ctl_card_info_get_id

(

const snd_ctl_card_info_t *

obj

)

Get the sound card ID from the given info object.

See snd_ctl_card_info_t for more details.

Parameters

obj	The card info object.

Returns

Sound card ID.

snd_ctl_card_info_get_longname()

const char * snd_ctl_card_info_get_longname

(

const snd_ctl_card_info_t *

obj

)

Get the sound cards long name from the given info object.

See snd_ctl_card_info_t for more details.

Parameters

obj	The card info object.

Returns

Sound cards long name.

snd_ctl_card_info_get_mixername()

const char * snd_ctl_card_info_get_mixername

(

const snd_ctl_card_info_t *

obj

)

Get the sound card mixer name from the given info object.

See snd_ctl_card_info_t for more details.

Parameters

obj	The card info object.

Returns

Sound card mixer name.

snd_ctl_card_info_get_name()

const char * snd_ctl_card_info_get_name

(

const snd_ctl_card_info_t *

obj

)

Get the sound card name from the given info object.

See snd_ctl_card_info_t for more details.

Parameters

obj	The card info object.

Returns

Sound card name.

snd_ctl_card_info_malloc()

int snd_ctl_card_info_malloc

(

snd_ctl_card_info_t **

ptr

)

Allocate an invalid snd_ctl_card_info_t on the heap.

Allocate space for a card info object on the heap. The allocated memory must be freed using snd_ctl_card_info_free().

See snd_ctl_card_info_t for details.

Parameters

ptr	Pointer to a snd_ctl_card_info_t pointer. The address of the allocated space will be returned here.

Returns

0 on success, otherwise a negative error code.

snd_ctl_card_info_sizeof()

size_t snd_ctl_card_info_sizeof

(

void

)

get size of snd_ctl_card_info_t.

Returns

Size in bytes.

snd_ctl_close()

int snd_ctl_close

(

snd_ctl_t *

ctl

)

close CTL handle

Parameters

ctl	CTL handle

Returns

0 on success otherwise a negative error code

Closes the specified CTL handle and frees all associated resources.

snd_ctl_convert_from_dB()

int snd_ctl_convert_from_dB	(	snd_ctl_t *	ctl,
		const snd_ctl_elem_id_t *	id,
		long	db_gain,
		long *	value,
		int	xdir
	)

Convert from dB gain to the raw volume value on the given control element.

Parameters

ctl	the control handler
id	the element id
db_gain	the dB gain to convert (in 0.01dB unit)
value	the pointer to store the converted raw volume value
xdir	the direction for round-up. The value is round up when this is positive.

Returns

0 if successful, or a negative error code

snd_ctl_convert_to_dB()

int snd_ctl_convert_to_dB	(	snd_ctl_t *	ctl,
		const snd_ctl_elem_id_t *	id,
		long	volume,
		long *	db_gain
	)

Convert the volume value to dB on the given control element.

Parameters

ctl	the control handler
id	the element id
volume	the raw volume value to convert
db_gain	the dB gain (in 0.01dB unit)

Returns

0 if successful, or a negative error code

snd_ctl_elem_add_boolean()

int snd_ctl_elem_add_boolean	(	snd_ctl_t *	ctl,
		const snd_ctl_elem_id_t *	id,
		unsigned int	member_count
	)

Create and add an user-defined control element of boolean type.

This is a wrapper function to snd_ctl_add_boolean_elem_set() for a single control element. This doesn't fill the id data with full information, thus it's recommended to use snd_ctl_add_boolean_elem_set(), instead.

snd_ctl_elem_add_enumerated()

int snd_ctl_elem_add_enumerated	(	snd_ctl_t *	ctl,
		const snd_ctl_elem_id_t *	id,
		unsigned int	member_count,
		unsigned int	items,
		const char *const	labels[]
	)

Create and add a user-defined control element of enumerated type.

This is a wrapper function to snd_ctl_add_enumerated_elem_set() for a single control element. This doesn't fill the id data with full information, thus it's recommended to use snd_ctl_add_enumerated_elem_set(), instead.

This function is added in version 1.0.25.

snd_ctl_elem_add_iec958()

int snd_ctl_elem_add_iec958	(	snd_ctl_t *	ctl,
		const snd_ctl_elem_id_t *	id
	)

Create and add a user-defined control element of IEC958 type.

Parameters

[in]	ctl	A handle of backend module for control interface.
[in,out]	id	ID of the new control element.

This function creates an user element with IEC958 type. This element is not controlled by device drivers in kernel. It can be operated by the same way as usual elements added by the device drivers.

The name field of id must be set with unique value to identify a new control element. After returning, all fields of id are filled. A element can be identified by the combination of name and index, or by numid.

A member in the new element is locked and filled with zero.

Errors:

-EBUSY

A control element with ID id already exists.

-EINVAL

ID has no name.

-ENOMEM

Out of memory, or there are too many user elements.

-ENXIO

This backend module does not support user elements of IEC958 type.

-ENODEV

Device unplugged.

snd_ctl_elem_add_integer()

int snd_ctl_elem_add_integer	(	snd_ctl_t *	ctl,
		const snd_ctl_elem_id_t *	id,
		unsigned int	member_count,
		long	min,
		long	max,
		long	step
	)

Create and add an user-defined control element of integer type.

This is a wrapper function to snd_ctl_add_integer_elem_set() for a control element. This doesn't fill the id data with full information, thus it's recommended to use snd_ctl_add_integer_elem_set(), instead.

snd_ctl_elem_add_integer64()

int snd_ctl_elem_add_integer64	(	snd_ctl_t *	ctl,
		const snd_ctl_elem_id_t *	id,
		unsigned int	member_count,
		long long	min,
		long long	max,
		long long	step
	)

Create and add an user-defined control element of integer64 type.

This is a wrapper function to snd_ctl_add_integer64_elem_set() for a single control element. This doesn't fill the id data with full information, thus it's recommended to use snd_ctl_add_integer64_elem_set(), instead.

snd_ctl_elem_id_clear()

void snd_ctl_elem_id_clear

(

snd_ctl_elem_id_t *

obj

)

clear given snd_ctl_elem_id_t object

Parameters

obj	pointer to object to clear

snd_ctl_elem_id_compare_numid()

int snd_ctl_elem_id_compare_numid	(	const snd_ctl_elem_id_t *	id1,
		const snd_ctl_elem_id_t *	id2
	)

compare one snd_ctl_elem_id_t to another using numid

Parameters

id1	pointer to first id
id2	pointer to second id

Return values

zero	when values are identical, other value on a difference (like strcmp)

This comparison ignores the set of fields part.

The return value can be used for sorting like qsort(). It gives persistent results.

snd_ctl_elem_id_compare_set()

int snd_ctl_elem_id_compare_set	(	const snd_ctl_elem_id_t *	id1,
		const snd_ctl_elem_id_t *	id2
	)

compare one snd_ctl_elem_id_t to another

Parameters

id1	pointer to first id
id2	pointer to second id

Return values

zero	when values are identical, other value on a difference (like strcmp)

This comparison ignores the numid part. The numid comparison can be easily implemented using snd_ctl_elem_id_get_numid() calls.

The identifier set fields are compared in this order: interface, device, subdevice, name, index.

The return value can be used for sorting like qsort(). It gives persistent results.

snd_ctl_elem_id_copy()

void snd_ctl_elem_id_copy	(	snd_ctl_elem_id_t *	dst,
		const snd_ctl_elem_id_t *	src
	)

copy one snd_ctl_elem_id_t to another

Parameters

dst	pointer to destination
src	pointer to source

snd_ctl_elem_id_free()

void snd_ctl_elem_id_free

(

snd_ctl_elem_id_t *

obj

)

frees a previously allocated snd_ctl_elem_id_t

Parameters

obj	pointer to object to free

snd_ctl_elem_id_get_device()

unsigned int snd_ctl_elem_id_get_device

(

const snd_ctl_elem_id_t *

obj

)

Get device part of a CTL element identifier.

Parameters

obj	CTL element identifier

Returns

CTL element related device

snd_ctl_elem_id_get_index()

unsigned int snd_ctl_elem_id_get_index

(

const snd_ctl_elem_id_t *

obj

)

Get index part of a CTL element identifier.

Parameters

obj	CTL element identifier

Returns

CTL element index

snd_ctl_elem_id_get_interface()

snd_ctl_elem_iface_t snd_ctl_elem_id_get_interface

(

const snd_ctl_elem_id_t *

obj

)

Get interface part of a CTL element identifier.

Parameters

obj	CTL element identifier

Returns

CTL element related interface

snd_ctl_elem_id_get_name()

const char * snd_ctl_elem_id_get_name

(

const snd_ctl_elem_id_t *

obj

)

Get name part of a CTL element identifier.

Parameters

obj	CTL element identifier

Returns

CTL element name

snd_ctl_elem_id_get_numid()

unsigned int snd_ctl_elem_id_get_numid

(

const snd_ctl_elem_id_t *

obj

)

Get numeric identifier from a CTL element identifier.

Parameters

obj	CTL element identifier

Returns

CTL element numeric identifier

snd_ctl_elem_id_get_subdevice()

unsigned int snd_ctl_elem_id_get_subdevice

(

const snd_ctl_elem_id_t *

obj

)

Get subdevice part of a CTL element identifier.

Parameters

obj	CTL element identifier

Returns

CTL element related subdevice

snd_ctl_elem_id_malloc()

int snd_ctl_elem_id_malloc

(

snd_ctl_elem_id_t **

ptr

)

allocate an invalid snd_ctl_elem_id_t using standard malloc

Parameters

ptr	returned pointer

Returns

0 on success otherwise negative error code

snd_ctl_elem_id_set_device()

void snd_ctl_elem_id_set_device	(	snd_ctl_elem_id_t *	obj,
		unsigned int	val
	)

Set device part for a CTL element identifier.

Parameters

obj	CTL element identifier
val	CTL element related device

snd_ctl_elem_id_set_index()

void snd_ctl_elem_id_set_index	(	snd_ctl_elem_id_t *	obj,
		unsigned int	val
	)

Set index part for a CTL element identifier.

Parameters

obj	CTL element identifier
val	CTL element index

snd_ctl_elem_id_set_interface()

void snd_ctl_elem_id_set_interface	(	snd_ctl_elem_id_t *	obj,
		snd_ctl_elem_iface_t	val
	)

Set interface part for a CTL element identifier.

Parameters

obj	CTL element identifier
val	CTL element related interface

snd_ctl_elem_id_set_name()

void snd_ctl_elem_id_set_name	(	snd_ctl_elem_id_t *	obj,
		const char *	val
	)

Set name part for a CTL element identifier.

Parameters

obj	CTL element identifier
val	CTL element name

snd_ctl_elem_id_set_numid()

void snd_ctl_elem_id_set_numid	(	snd_ctl_elem_id_t *	obj,
		unsigned int	val
	)

Set numeric identifier for a CTL element identifier.

Parameters

obj	CTL element identifier
val	CTL element numeric identifier

snd_ctl_elem_id_set_subdevice()

void snd_ctl_elem_id_set_subdevice	(	snd_ctl_elem_id_t *	obj,
		unsigned int	val
	)

Set subdevice part for a CTL element identifier.

Parameters

obj	CTL element identifier
val	CTL element related subdevice

snd_ctl_elem_id_sizeof()

size_t snd_ctl_elem_id_sizeof

(

void

)

get size of snd_ctl_elem_id_t

Returns

size in bytes

snd_ctl_elem_iface_name()

const char * snd_ctl_elem_iface_name

(

snd_ctl_elem_iface_t

iface

)

get name of a CTL element related interface

Parameters

iface

CTL element related interface

Returns

ascii name of CTL element related interface

snd_ctl_elem_info()

int snd_ctl_elem_info	(	snd_ctl_t *	ctl,
		snd_ctl_elem_info_t *	info
	)

Get CTL element information.

Parameters

ctl	CTL handle
info	CTL element id/information pointer

Returns

0 on success otherwise a negative error code

snd_ctl_elem_info_clear()

void snd_ctl_elem_info_clear

(

snd_ctl_elem_info_t *

obj

)

clear given snd_ctl_elem_info_t object

Parameters

obj	pointer to object to clear

snd_ctl_elem_info_copy()

void snd_ctl_elem_info_copy	(	snd_ctl_elem_info_t *	dst,
		const snd_ctl_elem_info_t *	src
	)

copy one snd_ctl_elem_info_t to another

Parameters

dst	pointer to destination
src	pointer to source

snd_ctl_elem_info_free()

void snd_ctl_elem_info_free

(

snd_ctl_elem_info_t *

obj

)

frees a previously allocated snd_ctl_elem_info_t

Parameters

obj	pointer to object to free

snd_ctl_elem_info_get_count()

unsigned int snd_ctl_elem_info_get_count

(

const snd_ctl_elem_info_t *

obj

)

Get number of value entries from a CTL element id/info.

Parameters

obj	CTL element id/info

Returns

value entries count

snd_ctl_elem_info_get_device()

unsigned int snd_ctl_elem_info_get_device

(

const snd_ctl_elem_info_t *

obj

)

Get device part of CTL element identifier of a CTL element id/info.

Parameters

obj	CTL element id/info

Returns

device part of element identifier

snd_ctl_elem_info_get_dimension()

int snd_ctl_elem_info_get_dimension	(	const snd_ctl_elem_info_t *	obj,
		unsigned int	idx
	)

Get specified of dimension width for given element.

Parameters

obj	CTL element id/info
idx	The dimension index

Returns

zero value if no dimension width is defined, otherwise positive value with with of specified dimension

Deprecated:

Since 1.1.5 snd_ctl_elem_info_get_dimension is deprecated without any replacement.

snd_ctl_elem_info_get_dimensions()

int snd_ctl_elem_info_get_dimensions

(

const snd_ctl_elem_info_t *

obj

)

Get count of dimensions for given element.

Parameters

obj	CTL element id/info

Returns

zero value if no dimensions are defined, otherwise positive value with count of dimensions

Deprecated:

Since 1.1.5 snd_ctl_elem_info_get_dimensions is deprecated without any replacement.

snd_ctl_elem_info_get_id()

void snd_ctl_elem_info_get_id	(	const snd_ctl_elem_info_t *	obj,
		snd_ctl_elem_id_t *	ptr
	)

Get CTL element identifier of a CTL element id/info.

Parameters

obj	CTL element id/info
ptr	Pointer to returned CTL element identifier

snd_ctl_elem_info_get_index()

unsigned int snd_ctl_elem_info_get_index

(

const snd_ctl_elem_info_t *

obj

)

Get index part of CTL element identifier of a CTL element id/info.

Parameters

obj	CTL element id/info

Returns

index part of element identifier

snd_ctl_elem_info_get_interface()

snd_ctl_elem_iface_t snd_ctl_elem_info_get_interface

(

const snd_ctl_elem_info_t *

obj

)

Get interface part of CTL element identifier of a CTL element id/info.

Parameters

obj	CTL element id/info

Returns

interface part of element identifier

snd_ctl_elem_info_get_item_name()

const char * snd_ctl_elem_info_get_item_name

(

const snd_ctl_elem_info_t *

obj

)

Get name for selected item in a SND_CTL_ELEM_TYPE_ENUMERATED CTL element id/info.

Parameters

obj	CTL element id/info

Returns

name of chosen item

snd_ctl_elem_info_get_items()

unsigned int snd_ctl_elem_info_get_items

(

const snd_ctl_elem_info_t *

obj

)

Get number of items available from a SND_CTL_ELEM_TYPE_ENUMERATED CTL element id/info.

Parameters

obj	CTL element id/info

Returns

items count

snd_ctl_elem_info_get_max()

long snd_ctl_elem_info_get_max

(

const snd_ctl_elem_info_t *

obj

)

Get maximum value from a SND_CTL_ELEM_TYPE_INTEGER CTL element id/info.

Parameters

obj	CTL element id/info

Returns

Maximum value

snd_ctl_elem_info_get_max64()

long long snd_ctl_elem_info_get_max64

(

const snd_ctl_elem_info_t *

obj

)

Get maximum value from a SND_CTL_ELEM_TYPE_INTEGER64 CTL element id/info.

Parameters

obj	CTL element id/info

Returns

Maximum value

snd_ctl_elem_info_get_min()

long snd_ctl_elem_info_get_min

(

const snd_ctl_elem_info_t *

obj

)

Get minimum value from a SND_CTL_ELEM_TYPE_INTEGER CTL element id/info.

Parameters

obj	CTL element id/info

Returns

Minimum value

snd_ctl_elem_info_get_min64()

long long snd_ctl_elem_info_get_min64

(

const snd_ctl_elem_info_t *

obj

)

Get minimum value from a SND_CTL_ELEM_TYPE_INTEGER64 CTL element id/info.

Parameters

obj	CTL element id/info

Returns

Minimum value

snd_ctl_elem_info_get_name()

const char * snd_ctl_elem_info_get_name

(

const snd_ctl_elem_info_t *

obj

)

Get name part of CTL element identifier of a CTL element id/info.

Parameters

obj	CTL element id/info

Returns

name part of element identifier

snd_ctl_elem_info_get_numid()

unsigned int snd_ctl_elem_info_get_numid

(

const snd_ctl_elem_info_t *

obj

)

Get element numeric identifier of a CTL element id/info.

Parameters

obj	CTL element id/info

Returns

element numeric identifier

snd_ctl_elem_info_get_owner()

pid_t snd_ctl_elem_info_get_owner

(

const snd_ctl_elem_info_t *

obj

)

Get owner of a locked element.

Parameters

obj	CTL element id/info

Returns

value entries count

snd_ctl_elem_info_get_step()

long snd_ctl_elem_info_get_step

(

const snd_ctl_elem_info_t *

obj

)

Get value step from a SND_CTL_ELEM_TYPE_INTEGER CTL element id/info.

Parameters

obj	CTL element id/info

Returns

Step

snd_ctl_elem_info_get_step64()

long long snd_ctl_elem_info_get_step64

(

const snd_ctl_elem_info_t *

obj

)

Get value step from a SND_CTL_ELEM_TYPE_INTEGER64 CTL element id/info.

Parameters

obj	CTL element id/info

Returns

Step

snd_ctl_elem_info_get_subdevice()

unsigned int snd_ctl_elem_info_get_subdevice

(

const snd_ctl_elem_info_t *

obj

)

Get subdevice part of CTL element identifier of a CTL element id/info.

Parameters

obj	CTL element id/info

Returns

subdevice part of element identifier

snd_ctl_elem_info_get_type()

snd_ctl_elem_type_t snd_ctl_elem_info_get_type

(

const snd_ctl_elem_info_t *

obj

)

Get type from a CTL element id/info.

Parameters

obj	CTL element id/info

Returns

CTL element content type

snd_ctl_elem_info_is_inactive()

int snd_ctl_elem_info_is_inactive

(

const snd_ctl_elem_info_t *

obj

)

Get info about status from a CTL element id/info.

Parameters

obj	CTL element id/info

Returns

0 if element value is not active, 1 if is active

snd_ctl_elem_info_is_locked()

int snd_ctl_elem_info_is_locked

(

const snd_ctl_elem_info_t *

obj

)

Get info whether an element is locked.

Parameters

obj	CTL element id/info

Returns

0 if element value is currently changeable, 1 if it's locked by another application

snd_ctl_elem_info_is_owner()

int snd_ctl_elem_info_is_owner

(

const snd_ctl_elem_info_t *

obj

)

Get info if I own an element.

Parameters

obj	CTL element id/info

Returns

0 if element value is currently changeable, 1 if it's locked by another application

snd_ctl_elem_info_is_readable()

int snd_ctl_elem_info_is_readable

(

const snd_ctl_elem_info_t *

obj

)

Get info about readability from a CTL element id/info.

Parameters

obj	CTL element id/info

Returns

0 if element is not readable, 1 if element is readable

snd_ctl_elem_info_is_tlv_commandable()

int snd_ctl_elem_info_is_tlv_commandable

(

const snd_ctl_elem_info_t *

obj

)

Get info about TLV command possibility from a CTL element id/info.

Parameters

obj	CTL element id/info

Returns

0 if element's TLV command is not possible, 1 if element's TLV command is supported

snd_ctl_elem_info_is_tlv_readable()

int snd_ctl_elem_info_is_tlv_readable

(

const snd_ctl_elem_info_t *

obj

)

Get info about TLV readability from a CTL element id/info.

Parameters

obj	CTL element id/info

Returns

0 if element's TLV is not readable, 1 if element's TLV is readable

snd_ctl_elem_info_is_tlv_writable()

int snd_ctl_elem_info_is_tlv_writable

(

const snd_ctl_elem_info_t *

obj

)

Get info about TLV writeability from a CTL element id/info.

Parameters

obj	CTL element id/info

Returns

0 if element's TLV is not writable, 1 if element's TLV is writable

snd_ctl_elem_info_is_user()

int snd_ctl_elem_info_is_user

(

const snd_ctl_elem_info_t *

obj

)

Get info if it's a user element.

Parameters

obj	CTL element id/info

Returns

0 if element value is a system element, 1 if it's a user-created element

snd_ctl_elem_info_is_volatile()

int snd_ctl_elem_info_is_volatile

(

const snd_ctl_elem_info_t *

obj

)

Get info about notification feasibility from a CTL element id/info.

Parameters

obj	CTL element id/info

Returns

0 if all element value changes are notified to subscribed applications, 1 otherwise

snd_ctl_elem_info_is_writable()

int snd_ctl_elem_info_is_writable

(

const snd_ctl_elem_info_t *

obj

)

Get info about writability from a CTL element id/info.

Parameters

obj	CTL element id/info

Returns

0 if element is not writable, 1 if element is not writable

snd_ctl_elem_info_malloc()

int snd_ctl_elem_info_malloc

(

snd_ctl_elem_info_t **

ptr

)

allocate an invalid snd_ctl_elem_info_t using standard malloc

Parameters

ptr	returned pointer

Returns

0 on success otherwise negative error code

snd_ctl_elem_info_set_device()

void snd_ctl_elem_info_set_device	(	snd_ctl_elem_info_t *	obj,
		unsigned int	val
	)

Set device part of CTL element identifier of a CTL element id/info.

Parameters

obj	CTL element id/info
val	device part of element identifier

snd_ctl_elem_info_set_dimension()

int snd_ctl_elem_info_set_dimension	(	snd_ctl_elem_info_t *	info,
		const int	dimension[4]
	)

Set width to a specified dimension level of given element information.

Parameters

info	Information of an element.
dimension	Dimension width for each level by member unit.

Returns

Zero on success, otherwise a negative error code.

Errors:

-EINVAL

Invalid arguments are given as parameters.

Compatibility:

This function is added in version 1.1.2.

Deprecated:

Since 1.1.5 snd_ctl_elem_info_set_dimension is deprecated without any replacement.

snd_ctl_elem_info_set_id()

void snd_ctl_elem_info_set_id	(	snd_ctl_elem_info_t *	obj,
		const snd_ctl_elem_id_t *	ptr
	)

Set CTL element identifier of a CTL element id/info.

Parameters

obj	CTL element id/info
ptr	CTL element identifier

snd_ctl_elem_info_set_inactive()

void snd_ctl_elem_info_set_inactive	(	snd_ctl_elem_info_t *	obj,
		int	val
	)

Set inactive parameter of a CTL element id/info.

Parameters

obj	CTL element id/info
val	inactive part of element identifier

snd_ctl_elem_info_set_index()

void snd_ctl_elem_info_set_index	(	snd_ctl_elem_info_t *	obj,
		unsigned int	val
	)

Set index part of CTL element identifier of a CTL element id/info.

Parameters

obj	CTL element id/info
val	index part of element identifier

snd_ctl_elem_info_set_interface()

void snd_ctl_elem_info_set_interface	(	snd_ctl_elem_info_t *	obj,
		snd_ctl_elem_iface_t	val
	)

Set interface part of CTL element identifier of a CTL element id/info.

Parameters

obj	CTL element id/info
val	interface part of element identifier

snd_ctl_elem_info_set_item()

void snd_ctl_elem_info_set_item	(	snd_ctl_elem_info_t *	obj,
		unsigned int	val
	)

Select item in a SND_CTL_ELEM_TYPE_ENUMERATED CTL element id/info.

Parameters

obj	CTL element id/info
val	item number

snd_ctl_elem_info_set_name()

void snd_ctl_elem_info_set_name	(	snd_ctl_elem_info_t *	obj,
		const char *	val
	)

Set name part of CTL element identifier of a CTL element id/info.

Parameters

obj	CTL element id/info
val	name part of element identifier

snd_ctl_elem_info_set_numid()

void snd_ctl_elem_info_set_numid	(	snd_ctl_elem_info_t *	obj,
		unsigned int	val
	)

Set element numeric identifier of a CTL element id/info.

Parameters

obj	CTL element id/info
val	element numeric identifier

snd_ctl_elem_info_set_read_write()

void snd_ctl_elem_info_set_read_write	(	snd_ctl_elem_info_t *	obj,
		int	rval,
		int	wval
	)

Set readability/writeability parameter of a CTL element id/info.

Parameters

obj	CTL element id/info
rval	readability part of element identifier
wval	writeability part of element identifier

snd_ctl_elem_info_set_subdevice()

void snd_ctl_elem_info_set_subdevice	(	snd_ctl_elem_info_t *	obj,
		unsigned int	val
	)

Set subdevice part of CTL element identifier of a CTL element id/info.

Parameters

obj	CTL element id/info
val	subdevice part of element identifier

snd_ctl_elem_info_set_tlv_read_write()

void snd_ctl_elem_info_set_tlv_read_write	(	snd_ctl_elem_info_t *	obj,
		int	rval,
		int	wval
	)

Set TLV readability/writeability parameter of a CTL element id/info.

Parameters

obj	CTL element id/info
rval	TLV readability part of element identifier
wval	TLV writeability part of element identifier

snd_ctl_elem_info_sizeof()

size_t snd_ctl_elem_info_sizeof

(

void

)

get size of snd_ctl_elem_info_t

Returns

size in bytes

snd_ctl_elem_list()

int snd_ctl_elem_list	(	snd_ctl_t *	ctl,
		snd_ctl_elem_list_t *	list
	)

Get a list of element identifiers.

Before calling this function, memoru must be allocated using snd_ctl_elem_list_malloc().

This function obtains data from the sound card driver and puts it into the list.

If there was space allocated for the element identifiers (using snd_ctl_elem_list_alloc_space()), information will be filled in. If too little space was allocated, only a part of the elements will be queried. If there was too much space allocated, some of it remains unused. Use snd_ctl_elem_list_get_count() and snd_ctl_elem_list_get_used() to obtain information about space usage. See snd_ctl_elem_list_t to learn more.

Parameters

ctl	CTL handle
list	CTL element identifiers list pointer

Returns

0 on success otherwise a negative error code

snd_ctl_elem_list_alloc_space()

int snd_ctl_elem_list_alloc_space	(	snd_ctl_elem_list_t *	obj,
		unsigned int	entries
	)

allocate space for CTL element identifiers list

The space can be released with snd_ctl_elem_list_free_space().

Parameters

obj	CTL element identifiers list.
entries	How many entries to allocate. See snd_ctl_elem_list_t to learn how to obtain this number in advance.

Returns

0 on success otherwise a negative error code.

snd_ctl_elem_list_clear()

void snd_ctl_elem_list_clear

(

snd_ctl_elem_list_t *

obj

)

Clear given snd_ctl_elem_list_t object.

This will make the stored identifiers inaccessible without freeing their space.

Warning

The element identifier space cannot be freed after calling this function. Therefore, snd_ctl_elem_list_free_space() must be called in advance.

Parameters

obj	pointer to object to clear

snd_ctl_elem_list_copy()

void snd_ctl_elem_list_copy	(	snd_ctl_elem_list_t *	dst,
		const snd_ctl_elem_list_t *	src
	)

copy one snd_ctl_elem_list_t to another.

This performs a shallow copy. That means the both lists will share the same space for the elements. The elements will not be copied.

Parameters

dst	pointer to destination
src	pointer to source

snd_ctl_elem_list_free()

void snd_ctl_elem_list_free

(

snd_ctl_elem_list_t *

obj

)

frees a previously allocated snd_ctl_elem_list_t.

Release memory previously allocated using snd_ctl_elem_list_malloc().

If you used snd_ctl_elem_list_alloc_space() on the list, you must use snd_ctl_elem_list_free_space() before calling this function.

Parameters

obj	pointer to object to free

snd_ctl_elem_list_free_space()

void snd_ctl_elem_list_free_space

(

snd_ctl_elem_list_t *

obj

)

free previously allocated space for CTL element identifiers list

Releases space previously allocated using snd_ctl_elem_list_alloc_space().

Parameters

obj	CTL element identifiers list

snd_ctl_elem_list_get_count()

unsigned int snd_ctl_elem_list_get_count

(

const snd_ctl_elem_list_t *

obj

)

Get total count of elements present in CTL device.

This function returns how many entries were allocated using snd_ctl_elem_list_alloc_space(). This information is present after snd_ctl_elem_list() was called.

See also snd_ctl_elem_list_get_used().

Parameters

obj	CTL element identifier list

Returns

total number of elements

snd_ctl_elem_list_get_device()

unsigned int snd_ctl_elem_list_get_device	(	const snd_ctl_elem_list_t *	obj,
		unsigned int	idx
	)

Get the device part of CTL element identifier for an entry of a CTL element identifiers list.

Parameters

obj	CTL element identifier list
idx	Index of entry

Returns

CTL element related device

snd_ctl_elem_list_get_id()

void snd_ctl_elem_list_get_id	(	const snd_ctl_elem_list_t *	obj,
		unsigned int	idx,
		snd_ctl_elem_id_t *	ptr
	)

Get CTL element identifier for an entry of a CTL element identifiers list.

Parameters

obj	CTL element identifier list
idx	Index of entry
ptr	Pointer to returned CTL element identifier

snd_ctl_elem_list_get_index()

unsigned int snd_ctl_elem_list_get_index	(	const snd_ctl_elem_list_t *	obj,
		unsigned int	idx
	)

Get index part of CTL element identifier for an entry of a CTL element identifiers list.

Parameters

obj	CTL element identifier list
idx	Index of entry

Returns

CTL element index

snd_ctl_elem_list_get_interface()

snd_ctl_elem_iface_t snd_ctl_elem_list_get_interface	(	const snd_ctl_elem_list_t *	obj,
		unsigned int	idx
	)

Get interface part of CTL element identifier for an entry of a CTL element identifiers list.

Parameters

obj	CTL element identifier list
idx	Index of entry

Returns

CTL element related interface

snd_ctl_elem_list_get_name()

const char * snd_ctl_elem_list_get_name	(	const snd_ctl_elem_list_t *	obj,
		unsigned int	idx
	)

Get name part of CTL element identifier for an entry of a CTL element identifiers list.

Parameters

obj	CTL element identifier list
idx	Index of entry

Returns

CTL element name

snd_ctl_elem_list_get_numid()

unsigned int snd_ctl_elem_list_get_numid	(	const snd_ctl_elem_list_t *	obj,
		unsigned int	idx
	)

Get CTL element numeric identifier for an entry of a CTL element identifiers list.

Parameters

obj	CTL element identifier list
idx	Index of entry

Returns

CTL element numeric identifier

snd_ctl_elem_list_get_subdevice()

unsigned int snd_ctl_elem_list_get_subdevice	(	const snd_ctl_elem_list_t *	obj,
		unsigned int	idx
	)

Get subdevice part of CTL element identifier for an entry of a CTL element identifiers list.

Parameters

obj	CTL element identifier list
idx	Index of entry

Returns

CTL element related subdevice

snd_ctl_elem_list_get_used()

unsigned int snd_ctl_elem_list_get_used

(

const snd_ctl_elem_list_t *

obj

)

Get number of used entries in CTL element identifiers list.

This function returns how many entries are actually filled with useful information.

See also snd_ctl_elem_list_get_count().

Parameters

obj	CTL element identifier list

Returns

number of used entries

snd_ctl_elem_list_malloc()

int snd_ctl_elem_list_malloc

(

snd_ctl_elem_list_t **

ptr

)

allocate a snd_ctl_elem_list_t using standard malloc.

The memory can be released using snd_ctl_elem_list_free().

Parameters

ptr	returned pointer

Returns

0 on success otherwise negative error code

snd_ctl_elem_list_set_offset()

void snd_ctl_elem_list_set_offset	(	snd_ctl_elem_list_t *	obj,
		unsigned int	val
	)

Set index of first wanted CTL element identifier in a CTL element identifiers list.

Parameters

obj	CTL element identifiers list
val	index of CTL element to put at position 0 of list

snd_ctl_elem_list_sizeof()

size_t snd_ctl_elem_list_sizeof

(

void

)

get size of snd_ctl_elem_list_t.

Returns

size in bytes

snd_ctl_elem_lock()

int snd_ctl_elem_lock	(	snd_ctl_t *	ctl,
		snd_ctl_elem_id_t *	id
	)

Lock CTL element.

Parameters

ctl	CTL handle
id	CTL element id pointer

Returns

0 on success otherwise a negative error code

snd_ctl_elem_read()

int snd_ctl_elem_read	(	snd_ctl_t *	ctl,
		snd_ctl_elem_value_t *	data
	)

Get CTL element value.

Read information from sound card. You must set the ID of the element before calling this function.

See snd_ctl_elem_value_t for details.

Parameters

ctl	CTL handle.
data	The element value. The ID must be set before calling the function, and the actual value will be returned here.

Returns

0 on success otherwise a negative error code.

snd_ctl_elem_remove()

int snd_ctl_elem_remove	(	snd_ctl_t *	ctl,
		snd_ctl_elem_id_t *	id
	)

Remove an user CTL element.

Parameters

ctl	CTL handle
id	CTL element identification

Returns

0 on success otherwise a negative error code

snd_ctl_elem_set_bytes()

void snd_ctl_elem_set_bytes	(	snd_ctl_elem_value_t *	obj,
		void *	data,
		size_t	size
	)

Replace the data stored within the element.

Use this function if the element is of type SNDRV_CTL_ELEM_TYPE_BYTES. It replaces the data stored in the element. Note that "bytes" elements don't have members. They have only one single block of data.

See snd_ctl_elem_value_t and Control interface for more details.

Parameters

obj	The element value object.
data	Pointer to the new data.
size	The size of the new data, in bytes.

snd_ctl_elem_tlv_command()

int snd_ctl_elem_tlv_command	(	snd_ctl_t *	ctl,
		const snd_ctl_elem_id_t *	id,
		const unsigned int *	tlv
	)

Process structured data from given buffer for an element set.

Parameters

ctl	A handle of backend module for control interface.
id	ID of an element.
tlv	An array with members of unsigned int type. The second member must represent total bytes of the rest of array.

Return values

0	on success
>0	on success when value was changed
<0	a negative error code

The format of an array of tlv argument is: tlv[0]: Type. One of SND_CTL_TLVT_XXX. tlv[1]: Length. The length of value in units of byte. tlv[2..]: Value. Depending on the type.

Details are described in <sound/tlv.h>.

snd_ctl_elem_tlv_read()

int snd_ctl_elem_tlv_read	(	snd_ctl_t *	ctl,
		const snd_ctl_elem_id_t *	id,
		unsigned int *	tlv,
		unsigned int	tlv_size
	)

Read structured data from an element set to given buffer.

Parameters

ctl	A handle of backend module for control interface.
id	ID of an element.
tlv	An array with members of unsigned int type.
tlv_size	The length of the array.

Returns

0 on success otherwise a negative error code

The format of an array of tlv argument is: tlv[0]: Type. One of SND_CTL_TLVT_XXX. tlv[1]: Length. The length of value in units of byte. tlv[2..]: Value. Depending on the type.

Details are described in <sound/tlv.h>.

snd_ctl_elem_tlv_write()

int snd_ctl_elem_tlv_write	(	snd_ctl_t *	ctl,
		const snd_ctl_elem_id_t *	id,
		const unsigned int *	tlv
	)

Write structured data from given buffer to an element set.

Parameters

ctl	A handle of backend module for control interface.
id	ID of an element.
tlv	An array with members of unsigned int type. The second member must represent total bytes of the rest of array.

Return values

0	on success
>0	on success when value was changed
<0	a negative error code

The format of an array of tlv argument is: tlv[0]: Type. One of SND_CTL_TLVT_XXX. tlv[1]: Length. The length of value in units of byte. tlv[2..]: Value. Depending on the type.

Details are described in <sound/tlv.h>.

snd_ctl_elem_type_name()

const char * snd_ctl_elem_type_name

(

snd_ctl_elem_type_t

type

)

get name of a CTL element type

Parameters

type	CTL element type

Returns

ascii name of CTL element type

snd_ctl_elem_unlock()

int snd_ctl_elem_unlock	(	snd_ctl_t *	ctl,
		snd_ctl_elem_id_t *	id
	)

Unlock CTL element.

Parameters

ctl	CTL handle
id	CTL element id pointer

Returns

0 on success otherwise a negative error code

snd_ctl_elem_value_clear()

void snd_ctl_elem_value_clear

(

snd_ctl_elem_value_t *

obj

)

Clear given data of an element.

See snd_ctl_elem_value_t for details.

Parameters

obj	Data of an element.

snd_ctl_elem_value_compare()

int snd_ctl_elem_value_compare	(	snd_ctl_elem_value_t *	left,
		const snd_ctl_elem_value_t *	right
	)

Compare two snd_ctl_elem_value_t values, bytewise.

Parameters

left	First value.
right	Second value.

Returns

0 on match, less than or greater than otherwise, see memcmp(3).

snd_ctl_elem_value_copy()

void snd_ctl_elem_value_copy	(	snd_ctl_elem_value_t *	dst,
		const snd_ctl_elem_value_t *	src
	)

Bitwise copy of a snd_ctl_elem_value_t value.

Parameters

dst	Pointer to destination.
src	Pointer to source.

snd_ctl_elem_value_free()

void snd_ctl_elem_value_free

(

snd_ctl_elem_value_t *

obj

)

Free an snd_ctl_elem_value_t previously allocated using snd_ctl_elem_value_malloc().

Parameters

obj	Pointer to the snd_ctl_elem_value_t.

snd_ctl_elem_value_get_boolean()

int snd_ctl_elem_value_get_boolean	(	const snd_ctl_elem_value_t *	obj,
		unsigned int	idx
	)

Get an element members value.

Use this function if the element is of type SNDRV_CTL_ELEM_TYPE_BOOLEAN. It returns the value of one member. See snd_ctl_elem_value_t and Control interface for more details.

Parameters

obj	The element value object
idx	The index of the member.

Returns

The members value.

snd_ctl_elem_value_get_byte()

unsigned char snd_ctl_elem_value_get_byte	(	const snd_ctl_elem_value_t *	obj,
		unsigned int	idx
	)

Get an element members value.

Use this function if the element is of type SNDRV_CTL_ELEM_TYPE_BYTE. It returns the value of one member. See snd_ctl_elem_value_t and Control interface for more details.

Parameters

obj	The element value object.
idx	The index of the member.

Returns

The members value.

snd_ctl_elem_value_get_bytes()

const void * snd_ctl_elem_value_get_bytes

(

const snd_ctl_elem_value_t *

obj

)

Get the data stored within the element.

Use this function if the element is of type SNDRV_CTL_ELEM_TYPE_BYTES. It returns the data stored in the element. Note that "bytes" elements don't have members. They have only one single block of data.

See snd_ctl_elem_value_t and Control interface for more details.

Parameters

obj	The element value object.

Returns

Pointer to the elements data.

snd_ctl_elem_value_get_device()

unsigned int snd_ctl_elem_value_get_device

(

const snd_ctl_elem_value_t *

obj

)

Get the identifiers 'device' part from the given element value.

See snd_ctl_elem_value_t for more details.

Parameters

obj	The element value.

Returns

The device part of element identifier.

snd_ctl_elem_value_get_enumerated()

unsigned int snd_ctl_elem_value_get_enumerated	(	const snd_ctl_elem_value_t *	obj,
		unsigned int	idx
	)

Get an element members value.

Use this function if the element is of type SNDRV_CTL_ELEM_TYPE_ENUMERATED. It returns the index of the active item. See snd_ctl_elem_value_t and Control interface for more details.

Parameters

obj	The element value object.
idx	The index of the requested member.

Returns

The index of the active item.

snd_ctl_elem_value_get_id()

void snd_ctl_elem_value_get_id	(	const snd_ctl_elem_value_t *	obj,
		snd_ctl_elem_id_t *	ptr
	)

Get the element identifier from the given element value.

See snd_ctl_elem_value_t for more details.

Parameters

obj	The element value.
ptr	Pointer to an identifier object. The identifier is stored there.

snd_ctl_elem_value_get_iec958()

void snd_ctl_elem_value_get_iec958	(	const snd_ctl_elem_value_t *	obj,
		snd_aes_iec958_t *	ptr
	)

Get an elements IEC958 data.

Use this function if the element is of type SNDRV_CTL_ELEM_TYPE_IEC958. Note that "IEC958" elements don't have members. They have only one single IEC958 information block.

See snd_ctl_elem_value_t and Control interface for more details.

Parameters

obj	The element value object.
ptr	Pointer to an IEC958 structure. The data is stored there.

snd_ctl_elem_value_get_index()

unsigned int snd_ctl_elem_value_get_index

(

const snd_ctl_elem_value_t *

obj

)

Get the identifiers 'index' part from the given element value.

See snd_ctl_elem_value_t for more details.

Parameters

obj	The element value.

Returns

The index part of element identifier.

snd_ctl_elem_value_get_integer()

long snd_ctl_elem_value_get_integer	(	const snd_ctl_elem_value_t *	obj,
		unsigned int	idx
	)

Get an element members value.

Use this function if the element is of type SNDRV_CTL_ELEM_TYPE_INTEGER. It returns the value of one member. See snd_ctl_elem_value_t and Control interface for more details.

Parameters

obj	The element value object.
idx	The index of the member.

Returns

The members value.

snd_ctl_elem_value_get_integer64()

long long snd_ctl_elem_value_get_integer64	(	const snd_ctl_elem_value_t *	obj,
		unsigned int	idx
	)

Get an element members value.

Use this function if the element is of type SNDRV_CTL_ELEM_TYPE_INTEGER64. It returns the value of one member. See snd_ctl_elem_value_t and Control interface for more details.

Parameters

obj	The element value object.
idx	The index of the member.

Returns

The members value.

snd_ctl_elem_value_get_interface()

snd_ctl_elem_iface_t snd_ctl_elem_value_get_interface

(

const snd_ctl_elem_value_t *

obj

)

Get the identifiers 'interface' part from the given element value.

See snd_ctl_elem_value_t for more details.

Parameters

obj	The element value.

Returns

The interface part of element identifier.

snd_ctl_elem_value_get_name()

const char * snd_ctl_elem_value_get_name

(

const snd_ctl_elem_value_t *

obj

)

Get the identifiers 'name' part from the given element value.

See snd_ctl_elem_value_t for more details.

Parameters

obj	The element value.

Returns

The "name" part of element identifier.

snd_ctl_elem_value_get_numid()

unsigned int snd_ctl_elem_value_get_numid

(

const snd_ctl_elem_value_t *

obj

)

Get the identifiers 'numid' part from the given element value.

See snd_ctl_elem_value_t for more details.

Parameters

obj	The element value.

Returns

The numid.

snd_ctl_elem_value_get_subdevice()

unsigned int snd_ctl_elem_value_get_subdevice

(

const snd_ctl_elem_value_t *

obj

)

Get the identifiers 'subdevice' part from the given element value.

See snd_ctl_elem_value_t for more details.

Parameters

obj	The element value.

Returns

The subdevice part of element identifier.

snd_ctl_elem_value_malloc()

int snd_ctl_elem_value_malloc

(

snd_ctl_elem_value_t **

ptr

)

Allocate an invalid snd_ctl_elem_value_t on the heap.

Allocate space for a value object on the heap. The allocated memory must be freed using snd_ctl_elem_value_free().

See snd_ctl_elem_value_t for details.

Parameters

ptr	Pointer to a snd_ctl_elem_value_t pointer. The address of the allocated space will be returned here.

Returns

0 on success, otherwise a negative error code.

snd_ctl_elem_value_set_boolean()

void snd_ctl_elem_value_set_boolean	(	snd_ctl_elem_value_t *	obj,
		unsigned int	idx,
		long	val
	)

Set an element members value.

Use this function if the element is of type SNDRV_CTL_ELEM_TYPE_BOOLEAN. It sets the value of one member. See snd_ctl_elem_value_t and Control interface for more details.

Parameters

obj	The element value object.
idx	The index of the member.
val	The new value.

snd_ctl_elem_value_set_byte()

void snd_ctl_elem_value_set_byte	(	snd_ctl_elem_value_t *	obj,
		unsigned int	idx,
		unsigned char	val
	)

Set an element members value.

Use this function if the element is of type SNDRV_CTL_ELEM_TYPE_BYTE. It sets the value of one member. See snd_ctl_elem_value_t and Control interface for more details.

Parameters

obj	The element value object.
idx	The index of the member.
val	The new value.

snd_ctl_elem_value_set_device()

void snd_ctl_elem_value_set_device	(	snd_ctl_elem_value_t *	obj,
		unsigned int	val
	)

Set the identifiers 'device' part within the given element value.

See snd_ctl_elem_value_t for more details.

Parameters

obj	The element value.
val	The new device.

snd_ctl_elem_value_set_enumerated()

void snd_ctl_elem_value_set_enumerated	(	snd_ctl_elem_value_t *	obj,
		unsigned int	idx,
		unsigned int	val
	)

Set an element members value.

Use this function if the element is of type SNDRV_CTL_ELEM_TYPE_ENUMERATED. It activates the specified item. See snd_ctl_elem_value_t and Control interface for more details.

Parameters

obj	The element value object.
idx	The index of the requested member.
val	The new index of the item to be activated.

snd_ctl_elem_value_set_id()

void snd_ctl_elem_value_set_id	(	snd_ctl_elem_value_t *	obj,
		const snd_ctl_elem_id_t *	ptr
	)

Set the element identifier within the given element value.

See snd_ctl_elem_value_t for more details.

Parameters

obj	The element value.
ptr	The new identifier.

snd_ctl_elem_value_set_iec958()

void snd_ctl_elem_value_set_iec958	(	snd_ctl_elem_value_t *	obj,
		const snd_aes_iec958_t *	ptr
	)

Set an elements IEC958 data.

Use this function if the element is of type SNDRV_CTL_ELEM_TYPE_IEC958. Note that "IEC958" elements don't have members. They have only one single IEC958 information block.

See snd_ctl_elem_value_t and Control interface for more details.

Parameters

obj	The element value object.
ptr	Pointer to the new IEC958 data.

snd_ctl_elem_value_set_index()

void snd_ctl_elem_value_set_index	(	snd_ctl_elem_value_t *	obj,
		unsigned int	val
	)

Set the identifiers 'index' part within the given element value.

See snd_ctl_elem_value_t for more details.

Parameters

obj	The element value.
val	The new index.

snd_ctl_elem_value_set_integer()

void snd_ctl_elem_value_set_integer	(	snd_ctl_elem_value_t *	obj,
		unsigned int	idx,
		long	val
	)

Set an element members value.

Use this function if the element is of type SNDRV_CTL_ELEM_TYPE_INTEGER. It sets the value of one member. See snd_ctl_elem_value_t and Control interface for more details.

Parameters

obj	The element value object.
idx	The index of the member.
val	The new value.

snd_ctl_elem_value_set_integer64()

void snd_ctl_elem_value_set_integer64	(	snd_ctl_elem_value_t *	obj,
		unsigned int	idx,
		long long	val
	)

Set an element members value.

Use this function if the element is of type SNDRV_CTL_ELEM_TYPE_INTEGER64. It sets the value of one member. See snd_ctl_elem_value_t and Control interface for more details.

Parameters

obj	The element value object.
idx	The index of the member.
val	The new value.

snd_ctl_elem_value_set_interface()

void snd_ctl_elem_value_set_interface	(	snd_ctl_elem_value_t *	obj,
		snd_ctl_elem_iface_t	val
	)

Set the identifiers 'interface' part within the given element value.

See snd_ctl_elem_value_t for more details.

Parameters

obj	The element value.
val	The new interface.

snd_ctl_elem_value_set_name()

void snd_ctl_elem_value_set_name	(	snd_ctl_elem_value_t *	obj,
		const char *	val
	)

Set the identifiers 'name' part within the given element value.

See snd_ctl_elem_value_t for more details.

Parameters

obj	The element value.
val	The new name.

snd_ctl_elem_value_set_numid()

void snd_ctl_elem_value_set_numid	(	snd_ctl_elem_value_t *	obj,
		unsigned int	val
	)

Set the identifiers 'numid' part within the given element value.

See snd_ctl_elem_value_t for more details.

Parameters

obj	The element value.
val	The new numid.

snd_ctl_elem_value_set_subdevice()

void snd_ctl_elem_value_set_subdevice	(	snd_ctl_elem_value_t *	obj,
		unsigned int	val
	)

Set the identifiers 'subdevice' part within the given element value.

See snd_ctl_elem_value_t for more details.

Parameters

obj	The element value.
val	The new subdevice.

snd_ctl_elem_value_sizeof()

size_t snd_ctl_elem_value_sizeof

(

void

)

Get size of data structure for an element.

Returns

Size in bytes.

snd_ctl_elem_write()

int snd_ctl_elem_write	(	snd_ctl_t *	ctl,
		snd_ctl_elem_value_t *	data
	)

Set CTL element value.

Write new value(s) to the sound card. You must set the ID and the value of the element before calling this function.

See snd_ctl_elem_value_t for details.

Parameters

ctl	CTL handle.
data	The new value.

Return values

0	on success
>0	on success when value was changed
<0	a negative error code

snd_ctl_event_clear()

void snd_ctl_event_clear

(

snd_ctl_event_t *

obj

)

clear given snd_ctl_event_t object

Parameters

obj	pointer to object to clear

snd_ctl_event_copy()

void snd_ctl_event_copy	(	snd_ctl_event_t *	dst,
		const snd_ctl_event_t *	src
	)

copy one snd_ctl_event_t to another

Parameters

dst	pointer to destination
src	pointer to source

snd_ctl_event_elem_get_device()

unsigned int snd_ctl_event_elem_get_device

(

const snd_ctl_event_t *

obj

)

Get device part of CTL element identifier for an element related event.

Parameters

obj

CTL event

Returns

device part of element identifier

snd_ctl_event_elem_get_id()

void snd_ctl_event_elem_get_id	(	const snd_ctl_event_t *	obj,
		snd_ctl_elem_id_t *	ptr
	)

Get CTL element identifier for an element related event.

Parameters

obj	CTL event
ptr	Pointer to returned CTL element identifier

snd_ctl_event_elem_get_index()

unsigned int snd_ctl_event_elem_get_index

(

const snd_ctl_event_t *

obj

)

Get index part of CTL element identifier for an element related event.

Parameters

obj

CTL event

Returns

index part of element identifier

snd_ctl_event_elem_get_interface()

snd_ctl_elem_iface_t snd_ctl_event_elem_get_interface

(

const snd_ctl_event_t *

obj

)

Get interface part of CTL element identifier for an element related event.

Parameters

obj

CTL event

Returns

interface part of element identifier

snd_ctl_event_elem_get_mask()

unsigned int snd_ctl_event_elem_get_mask

(

const snd_ctl_event_t *

obj

)

Get event mask for an element related event.

Parameters

obj

CTL event

Returns

event mask for element related event

snd_ctl_event_elem_get_name()

const char * snd_ctl_event_elem_get_name

(

const snd_ctl_event_t *

obj

)

Get name part of CTL element identifier for an element related event.

Parameters

obj

CTL event

Returns

name part of element identifier

snd_ctl_event_elem_get_numid()

unsigned int snd_ctl_event_elem_get_numid

(

const snd_ctl_event_t *

obj

)

Get element numeric identifier for an element related event.

Parameters

obj

CTL event

Returns

element numeric identifier

snd_ctl_event_elem_get_subdevice()

unsigned int snd_ctl_event_elem_get_subdevice

(

const snd_ctl_event_t *

obj

)

Get subdevice part of CTL element identifier for an element related event.

Parameters

obj

CTL event

Returns

subdevice part of element identifier

snd_ctl_event_free()

void snd_ctl_event_free

(

snd_ctl_event_t *

obj

)

frees a previously allocated snd_ctl_event_t

Parameters

obj	pointer to object to free

snd_ctl_event_get_type()

snd_ctl_event_type_t snd_ctl_event_get_type

(

const snd_ctl_event_t *

obj

)

Get type of a CTL event.

Parameters

obj

CTL event

Returns

CTL event type

snd_ctl_event_malloc()

int snd_ctl_event_malloc

(

snd_ctl_event_t **

ptr

)

allocate an invalid snd_ctl_event_t using standard malloc

Parameters

ptr	returned pointer

Returns

0 on success otherwise negative error code

snd_ctl_event_sizeof()

size_t snd_ctl_event_sizeof

(

void

)

get size of snd_ctl_event_t

Returns

size in bytes

snd_ctl_event_type_name()

const char * snd_ctl_event_type_name

(

snd_ctl_event_type_t

type

)

get name of a CTL event type

Parameters

type	CTL event type

Returns

ascii name of CTL event type

snd_ctl_get_dB_range()

int snd_ctl_get_dB_range	(	snd_ctl_t *	ctl,
		const snd_ctl_elem_id_t *	id,
		long *	min,
		long *	max
	)

Get the dB min/max values on the given control element.

Parameters

ctl	the control handler
id	the element id
min	the pointer to store the minimum dB value (in 0.01dB unit)
max	the pointer to store the maximum dB value (in 0.01dB unit)

Returns

0 if successful, or a negative error code

snd_ctl_get_power_state()

int snd_ctl_get_power_state	(	snd_ctl_t *	ctl,
		unsigned int *	state
	)

Get actual Power State.

Parameters

ctl	CTL handle
state	Destination value

Returns

0 on success otherwise a negative error code

snd_ctl_name()

const char * snd_ctl_name

(

snd_ctl_t *

ctl

)

get identifier of CTL handle

Parameters

ctl	CTL handle

Returns

ascii identifier of CTL handle

Returns the ASCII identifier of given CTL handle. It's the same identifier specified in snd_ctl_open().

snd_ctl_nonblock()

int snd_ctl_nonblock	(	snd_ctl_t *	ctl,
		int	nonblock
	)

set nonblock mode

Parameters

ctl	CTL handle
nonblock	0 = block, 1 = nonblock mode, 2 = abort

Returns

0 on success otherwise a negative error code

snd_ctl_open()

int snd_ctl_open	(	snd_ctl_t **	ctlp,
		const char *	name,
		int	mode
	)

Opens a sound card.

Parameters

ctlp	Returned CTL handle.
name	A string identifying the card (See Identifying and Opening Control Interfaces).
mode	Open mode (see SND_CTL_NONBLOCK, SND_CTL_ASYNC).

Returns

0 on success otherwise a negative error code.

snd_ctl_open_fallback()

int snd_ctl_open_fallback	(	snd_ctl_t **	ctlp,
		snd_config_t *	root,
		const char *	name,
		const char *	orig_name,
		int	mode
	)

Opens a fallback CTL.

Parameters

ctlp	Returned CTL handle
root	Configuration root
name	ASCII identifier of the CTL handle used as fallback
orig_name	The original ASCII name
mode	Open mode (see SND_CTL_NONBLOCK, SND_CTL_ASYNC)

Returns

0 on success otherwise a negative error code

snd_ctl_open_lconf()

int snd_ctl_open_lconf	(	snd_ctl_t **	ctlp,
		const char *	name,
		int	mode,
		snd_config_t *	lconf
	)

Opens a CTL using local configuration.

Parameters

ctlp	Returned CTL handle
name	ASCII identifier of the CTL handle
mode	Open mode (see SND_CTL_NONBLOCK, SND_CTL_ASYNC)
lconf	Local configuration

Returns

0 on success otherwise a negative error code

snd_ctl_poll_descriptors()

int snd_ctl_poll_descriptors	(	snd_ctl_t *	ctl,
		struct pollfd *	pfds,
		unsigned int	space
	)

get poll descriptors

Parameters

ctl	CTL handle
pfds	array of poll descriptors
space	space in the poll descriptor array

Returns

count of filled descriptors

snd_ctl_poll_descriptors_count()

int snd_ctl_poll_descriptors_count

(

snd_ctl_t *

ctl

)

get count of poll descriptors for CTL handle

Parameters

ctl	CTL handle

Returns

count of poll descriptors

snd_ctl_poll_descriptors_revents()

int snd_ctl_poll_descriptors_revents	(	snd_ctl_t *	ctl,
		struct pollfd *	pfds,
		unsigned int	nfds,
		unsigned short *	revents
	)

get returned events from poll descriptors

Parameters

ctl	CTL handle
pfds	array of poll descriptors
nfds	count of poll descriptors
revents	returned events

Returns

zero if success, otherwise a negative error code

snd_ctl_read()

int snd_ctl_read	(	snd_ctl_t *	ctl,
		snd_ctl_event_t *	event
	)

Read an event.

Parameters

ctl	CTL handle
event	Event pointer

Returns

number of events read otherwise a negative error code on failure

snd_ctl_set_power_state()

int snd_ctl_set_power_state	(	snd_ctl_t *	ctl,
		unsigned int	state
	)

Set Power State to given SND_CTL_POWER_* value and do the power management.

Parameters

ctl	CTL handle
state	Desired Power State

Returns

0 on success otherwise a negative error code

snd_ctl_subscribe_events()

int snd_ctl_subscribe_events	(	snd_ctl_t *	ctl,
		int	subscribe
	)

Ask to be informed about events (poll, snd_async_add_ctl_handler, snd_ctl_read)

Parameters

ctl	CTL handle
subscribe	0 = unsubscribe, 1 = subscribe, -1 = check subscribe or not

Returns

0 on success otherwise a negative error code

snd_ctl_type()

snd_ctl_type_t snd_ctl_type

(

snd_ctl_t *

ctl

)

get type of CTL handle

Parameters

ctl	CTL handle

Returns

type of CTL handle

Returns the type snd_ctl_type_t of given CTL handle.

snd_ctl_wait()

int snd_ctl_wait	(	snd_ctl_t *	ctl,
		int	timeout
	)

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

Parameters

ctl	CTL handle
timeout	maximum time in milliseconds to wait

Returns

0 otherwise a negative error code on failure

snd_tlv_convert_from_dB()

int snd_tlv_convert_from_dB	(	unsigned int *	tlv,
		long	rangemin,
		long	rangemax,
		long	db_gain,
		long *	value,
		int	xdir
	)

Convert from dB gain to the corresponding raw value.

Parameters

tlv	the TLV source returned by snd_tlv_parse_dB_info()
rangemin	the minimum value of the raw volume
rangemax	the maximum value of the raw volume
db_gain	the dB gain to convert (in 0.01dB unit)
value	the pointer to store the converted raw volume value
xdir	the direction for round-up. The value is round up when this is positive. A negative value means round down. Zero means round-up to nearest.

Returns

0 if successful, or a negative error code

snd_tlv_convert_to_dB()

int snd_tlv_convert_to_dB	(	unsigned int *	tlv,
		long	rangemin,
		long	rangemax,
		long	volume,
		long *	db_gain
	)

Convert the given raw volume value to a dB gain.

Parameters

tlv	the TLV source returned by snd_tlv_parse_dB_info()
rangemin	the minimum value of the raw volume
rangemax	the maximum value of the raw volume
volume	the raw volume value to convert
db_gain	the dB gain (in 0.01dB unit)

Returns

0 if successful, or a negative error code

snd_tlv_get_dB_range()

int snd_tlv_get_dB_range	(	unsigned int *	tlv,
		long	rangemin,
		long	rangemax,
		long *	min,
		long *	max
	)

Get the dB min/max values.

Parameters

tlv	the TLV source returned by snd_tlv_parse_dB_info()
rangemin	the minimum value of the raw volume
rangemax	the maximum value of the raw volume
min	the pointer to store the minimum dB value (in 0.01dB unit)
max	the pointer to store the maximum dB value (in 0.01dB unit)

Returns

0 if successful, or a negative error code

snd_tlv_parse_dB_info()

int snd_tlv_parse_dB_info	(	unsigned int *	tlv,
		unsigned int	tlv_size,
		unsigned int **	db_tlvp
	)

Parse TLV stream and retrieve dB information.

Parameters

tlv	the TLV source
tlv_size	the byte size of TLV source
db_tlvp	the pointer stored the dB TLV information

Returns

the byte size of dB TLV information if found in the given TLV source, or a negative error code.

This function parses the given TLV source and stores the TLV start point if the TLV information regarding dB conversion is found. The stored TLV pointer can be passed to the convesion functions snd_tlv_convert_to_dB(), snd_tlv_convert_from_dB() and snd_tlv_get_dB_range().