7.32. ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY¶
7.32.1. Name¶
VIDIOC_G_FREQUENCY - VIDIOC_S_FREQUENCY - Get or set tuner or modulator radio frequency
7.32.2. Synopsis¶
-
VIDIOC_G_FREQUENCY
¶
int ioctl(int fd, VIDIOC_G_FREQUENCY, struct v4l2_frequency *argp)
-
VIDIOC_S_FREQUENCY
¶
int ioctl(int fd, VIDIOC_S_FREQUENCY, const struct v4l2_frequency *argp)
7.32.3. Arguments¶
fd
File descriptor returned by
open()
.argp
Pointer to struct
v4l2_frequency
.
7.32.4. Description¶
To get the current tuner or modulator radio frequency applications set
the tuner
field of a struct
v4l2_frequency
to the respective tuner or
modulator number (only input devices have tuners, only output devices
have modulators), zero out the reserved
array and call the
VIDIOC_G_FREQUENCY ioctl with a pointer to this structure. The
driver stores the current frequency in the frequency
field.
To change the current tuner or modulator radio frequency applications
initialize the tuner
, type
and frequency
fields, and the
reserved
array of a struct v4l2_frequency
and call the VIDIOC_S_FREQUENCY ioctl with a pointer to this
structure. When the requested frequency is not possible the driver
assumes the closest possible value. However VIDIOC_S_FREQUENCY is a
write-only ioctl, it does not return the actual new frequency.
-
v4l2_frequency
¶
__u32 |
|
The tuner or modulator index number. This is the same value as in
the struct |
__u32 |
|
The tuner type. This is the same value as in the struct
|
__u32 |
|
Tuning frequency in units of 62.5 kHz, or if the struct
|
__u32 |
|
Reserved for future extensions. Drivers and applications must set the array to zero. |
7.32.5. 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
tuner
index is out of bounds or the value in thetype
field is wrong.- EBUSY
A hardware seek is in progress.