snd_mixer_groups()
Get the number of groups in the mixer and their group IDs
Synopsis:
#include <sys/asoundlib.h> int snd_mixer_groups( snd_mixer_t *handle, snd_mixer_groups_t *groups );
Arguments:
- handle
- The handle for the mixer device. This must have been created by snd_mixer_open() .
- groups
- A pointer to a snd_mixer_groups_t structure that snd_mixer_groups() fills in with information about the groups.
Library:
libasound.so
Use the -l asound option to qcc to link against this library.
Description:
The snd_mixer_groups() function fills the given snd_mixer_groups_t structure with the number of groups in the mixer that the handle was opened on. It also fills in the array of group IDs pointed to by pgroups to a limit of groups_size.
Before calling snd_mixer_groups(), set the members of the snd_mixer_groups_t as follows:
- pgroups
- This pointer must be NULL or point to a valid storage location for the groups (i.e. an array of snd_mixer_gid_t structures).
- groups_size
- The size of the pgroups storage location in sizeof( snd_mixer_gid_t ) units (i.e. the number of entries in the array).
On a successful return, snd_mixer_groups() fills in these members:
- groups
- The total groups in the mixer.
- groups_over
- The number of groups that couldn't be copied to the storage location.
Returns:
Zero on success, or a negative value on error.
Errors:
- -EINVAL
- Invalid handle.
Classification:
QNX Neutrino
Safety: | |
---|---|
Cancellation point | No |
Interrupt handler | No |
Signal handler | Yes |
Thread | Yes |