ALSA project - the C library reference
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namehint.c File Reference

Give device name hints. More...

Functions

int snd_device_name_hint (int card, const char *iface, void ***hints)
 Get a set of device name hints.
 
int snd_device_name_free_hint (void **hints)
 Free a list of device name hints.
 
char * snd_device_name_get_hint (const void *hint, const char *id)
 Extract a value from a hint.
 

Detailed Description

Give device name hints.

Author
Jaroslav Kysela perex.nosp@m.@per.nosp@m.ex.cz
Date
2006

Function Documentation

◆ snd_device_name_free_hint()

int snd_device_name_free_hint ( void ** hints)

Free a list of device name hints.

Parameters
hintsList to free
Returns
zero if success, otherwise a negative error code

◆ snd_device_name_get_hint()

char * snd_device_name_get_hint ( const void * hint,
const char * id )

Extract a value from a hint.

Parameters
hintA pointer to hint
idHint value to extract ("NAME", "DESC", or "IOID", see below)
Returns
an allocated ASCII string if success, otherwise NULL

List of valid IDs: NAME - name of device DESC - description of device IOID - input / output identification ("Input" or "Output"), NULL means both

The return value should be freed when no longer needed.

◆ snd_device_name_hint()

int snd_device_name_hint ( int card,
const char * iface,
void *** hints )

Get a set of device name hints.

Parameters
cardCard number or -1 (means all cards)
ifaceInterface identification (like "pcm", "rawmidi", "timer", "seq")
hintsResult - array of device name hints
Returns
zero if success, otherwise a negative error code

hints will receive a NULL-terminated array of device name hints, which can be passed to snd_device_name_get_hint to extract usable values. When no longer needed, hints should be passed to snd_device_name_free_hint to release resources.

User-defined hints are gathered from namehint.IFACE tree like:

namehint.pcm [
myfile "file:FILE=/tmp/soundwave.raw|Save sound output to /tmp/soundwave.raw"
myplug "plug:front|Do all conversions for front speakers"
]

Note: The device description is separated with '|' char.

Special variables: defaults.namehint.showall specifies if all device definitions are accepted (boolean type).