Set the control events filter
Synopsis:
#include <sys/asoundlib.h>
int snd_ctl_set_filter( snd_ctl_t *handle, snd_ctl_filter_t * filter );
Arguments:
- handle
- The handle for the control connection to the card.
This must be a handle created by
snd_ctl_open().
- filter
- A filter that specifies which control events io-audio sends to the client
application.
Library:
libasound.so
Use the -l asound option with
qcc
to link against this library.
Description:
The snd_ctl_set_filter()
function sets the control event filter using a snd_ctl_filter_t structure:
typedef struct snd_ctl_filter {
uint32_t enable;
uint8_t reserved[124];
} snd_ctl_filter_t;
This structure includes the following members:
- enable
- A bitfield that represents a control event type. Use the SND_CTL_EVENT_MASK()
macro to translate one of the following control event types to the filter bitmask:
- SND_CTL_READ_REBUILD
- SND_CTL_READ_SWITCH_VALUE
- SND_CTL_READ_SWITCH_ADD
- SND_CTL_READ_SWITCH_REMOVE
- SND_CTL_READ_AFM_STATE
- SND_CTL_READ_AFM_AUDIO_MODE
- SND_CTL_READ_AFM_DATASET
- SND_CTL_READ_AFM_DETECT
- SND_CTL_READ_AUDIOMGMT_STATUS_CHG
- reserved
- Must be filled with 0 (zero).
Returns:
Zero on success, or a negative value on error.
Errors:
- -EINVAL
- Invalid handle argument or pointer to filter is NULL.
Classification:
QNX Neutrino
| Safety: |
|
|---|
| Cancellation point |
No |
| Interrupt handler |
No |
| Signal handler |
Yes |
| Thread |
Yes |