7.12. ioctl VIDIOC_ENUMAUDOUT¶
7.12.1. Name¶
VIDIOC_ENUMAUDOUT - Enumerate audio outputs
7.12.2. Synopsis¶
-
int
ioctl
(int fd, VIDIOC_ENUMAUDOUT, struct v4l2_audioout *argp)¶
7.12.3. Arguments¶
fd
- File descriptor returned by open().
argp
- Pointer to struct
v4l2_audioout
.
7.12.4. Description¶
To query the attributes of an audio output applications initialize the
index
field and zero out the reserved
array of a struct
v4l2_audioout
and call the VIDIOC_G_AUDOUT
ioctl with a pointer to this structure. Drivers fill the rest of the
structure or return an EINVAL
error code when the index is out of
bounds. To enumerate all audio outputs applications shall begin at index
zero, incrementing by one until the driver returns EINVAL
.
Note
Connectors on a TV card to loop back the received audio signal to a sound card are not audio outputs in this sense.
See VIDIOC_G_AUDIOout for a description of struct
v4l2_audioout
.
7.12.5. Return Value¶
On success 0 is returned, on error -1 and the errno
variable is set
appropriately. The generic error codes are described at the
Generic Error Codes chapter.
- EINVAL
- The number of the audio output is out of bounds.