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 with 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 number of groups that are currently valid in pgroups. Read only.
- groups_over
- The number of groups that could not be retrieved due to the size constraints of the pgroups local storage. Read only.
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 |
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