7.17. ioctl VIDIOC_ENUM_FREQ_BANDS¶
VIDIOC_ENUM_FREQ_BANDS - Enumerate supported frequency bands
ioctl(int fd, VIDIOC_ENUM_FREQ_BANDS, struct v4l2_frequency_band *argp)¶
- File descriptor returned by open().
- Pointer to struct
Enumerates the frequency bands that a tuner or modulator supports. To do
this applications initialize the
fields, and zero out the
reserved array of a struct
v4l2_frequency_band and call the
ioctl VIDIOC_ENUM_FREQ_BANDS ioctl with a pointer to this structure.
This ioctl is supported if the
of the corresponding tuner/modulator is set.
||The tuner or modulator index number. This is the same value as in
||The tuner type. This is the same value as in the struct
||Identifies the frequency band, set by the application.|
|| The tuner/modulator capability flags for this
frequency band, see Tuner and Modulator Capability Flags. The
|| The lowest tunable frequency in units of 62.5 kHz, or
|| The highest tunable frequency in units of 62.5 kHz,
or if the
The supported modulation systems of this frequency band. See Band Modulation Systems.
Currently only one modulation system per frequency band is supported. More work will need to be done if multiple modulation systems are possible. Contact the linux-media mailing list (https://linuxtv.org/lists.php) if you need such functionality.
Reserved for future extensions.
Applications and drivers must set the array to zero.
||0x02||Vestigial Sideband modulation, used for analog TV.|
||0x04||Frequency Modulation, commonly used for analog radio.|
||0x08||Amplitude Modulation, commonly used for analog radio.|
7.17.5. 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.
indexis out of bounds or the
typefield is wrong.