Name

VIDIOC_G_FREQUENCY - VIDIOC_S_FREQUENCY - Get or set tuner or modulator radio frequency

Synopsis

.. c:macro:: VIDIOC_G_FREQUENCY

int ioctl(int fd, VIDIOC_G_FREQUENCY, struct v4l2_frequency *argp)

.. c:macro:: VIDIOC_S_FREQUENCY

int ioctl(int fd, VIDIOC_S_FREQUENCY, const struct v4l2_frequency *argp)

Arguments

fd File descriptor returned by :c:func:open().

argp Pointer to struct :c:type:v4l2_frequency.

Description

To get the current tuner or modulator radio frequency applications set the tuner field of a struct :c:type: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 :ref:VIDIOC_G_FREQUENCY <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 :c:type:v4l2_frequency and call the :ref:VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY> ioctl with a pointer to this structure. When the requested frequency is not possible the driver assumes the closest possible value. However :ref:VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY> is a write-only ioctl, it does not return the actual new frequency.

.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|

.. c:type:: v4l2_frequency

.. flat-table:: struct v4l2_frequency :header-rows: 0 :stub-columns: 0 :widths: 1 1 2

* - __u32
  - ``tuner``
  - The tuner or modulator index number. This is the same value as in
the struct :c:type:`v4l2_input` ``tuner`` field and
the struct :c:type:`v4l2_tuner` ``index`` field, or
the struct :c:type:`v4l2_output` ``modulator`` field
and the struct :c:type:`v4l2_modulator` ``index``
field.
* - __u32
  - ``type``
  - The tuner type. This is the same value as in the struct
:c:type:`v4l2_tuner` ``type`` field. The type must be
set to ``V4L2_TUNER_RADIO`` for ``/dev/radioX`` device nodes, and
to ``V4L2_TUNER_ANALOG_TV`` for all others. Set this field to
``V4L2_TUNER_RADIO`` for modulators (currently only radio
modulators are supported). See :c:type:`v4l2_tuner_type`
* - __u32
  - ``frequency``
  - Tuning frequency in units of 62.5 kHz, or if the struct
:c:type:`v4l2_tuner` or struct
:c:type:`v4l2_modulator` ``capability`` flag
``V4L2_TUNER_CAP_LOW`` is set, in units of 62.5 Hz. A 1 Hz unit is
used when the ``capability`` flag ``V4L2_TUNER_CAP_1HZ`` is set.
* - __u32
  - ``reserved``\ [8]
  - Reserved for future extensions. Drivers and applications must set
the array to zero.

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 :ref:Generic Error Codes <gen-errors> chapter.

EINVAL The tuner index is out of bounds or the value in the type field is wrong.

EBUSY A hardware seek is in progress.