1 .. -*- coding: utf-8; mode: rst -*-
3 .. _VIDIOC_G_FREQUENCY:
5 ********************************************
6 ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY
7 ********************************************
12 VIDIOC_G_FREQUENCY - VIDIOC_S_FREQUENCY - Get or set tuner or modulator radio frequency
18 .. c:function:: int ioctl( int fd, VIDIOC_G_FREQUENCY, struct v4l2_frequency *argp )
19 :name: VIDIOC_G_FREQUENCY
21 .. c:function:: int ioctl( int fd, VIDIOC_S_FREQUENCY, const struct v4l2_frequency *argp )
22 :name: VIDIOC_S_FREQUENCY
29 File descriptor returned by :ref:`open() <func-open>`.
37 To get the current tuner or modulator radio frequency applications set
38 the ``tuner`` field of a struct
39 :c:type:`v4l2_frequency` to the respective tuner or
40 modulator number (only input devices have tuners, only output devices
41 have modulators), zero out the ``reserved`` array and call the
42 :ref:`VIDIOC_G_FREQUENCY <VIDIOC_G_FREQUENCY>` ioctl with a pointer to this structure. The
43 driver stores the current frequency in the ``frequency`` field.
45 To change the current tuner or modulator radio frequency applications
46 initialize the ``tuner``, ``type`` and ``frequency`` fields, and the
47 ``reserved`` array of a struct :c:type:`v4l2_frequency`
48 and call the :ref:`VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY>` ioctl with a pointer to this
49 structure. When the requested frequency is not possible the driver
50 assumes the closest possible value. However :ref:`VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY>` is a
51 write-only ioctl, it does not return the actual new frequency.
54 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
56 .. c:type:: v4l2_frequency
58 .. flat-table:: struct v4l2_frequency
70 - The tuner or modulator index number. This is the same value as in
71 the struct :c:type:`v4l2_input` ``tuner`` field and
72 the struct :c:type:`v4l2_tuner` ``index`` field, or
73 the struct :c:type:`v4l2_output` ``modulator`` field
74 and the struct :c:type:`v4l2_modulator` ``index``
83 - The tuner type. This is the same value as in the struct
84 :c:type:`v4l2_tuner` ``type`` field. The type must be
85 set to ``V4L2_TUNER_RADIO`` for ``/dev/radioX`` device nodes, and
86 to ``V4L2_TUNER_ANALOG_TV`` for all others. Set this field to
87 ``V4L2_TUNER_RADIO`` for modulators (currently only radio
88 modulators are supported). See :c:type:`v4l2_tuner_type`
96 - Tuning frequency in units of 62.5 kHz, or if the struct
97 :c:type:`v4l2_tuner` or struct
98 :c:type:`v4l2_modulator` ``capability`` flag
99 ``V4L2_TUNER_CAP_LOW`` is set, in units of 62.5 Hz. A 1 Hz unit is
100 used when the ``capability`` flag ``V4L2_TUNER_CAP_1HZ`` is set.
108 - Reserved for future extensions. Drivers and applications must set
115 On success 0 is returned, on error -1 and the ``errno`` variable is set
116 appropriately. The generic error codes are described at the
117 :ref:`Generic Error Codes <gen-errors>` chapter.
120 The ``tuner`` index is out of bounds or the value in the ``type``
124 A hardware seek is in progress.