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¶
fdFile descriptor returned by
open().argpPointer 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.
-
type
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
tunerindex is out of bounds or the value in thetypefield is wrong.- EBUSY
A hardware seek is in progress.