1 .. SPDX-License-Identifier: GFDL-1.1-no-invari
2 .. c:namespace:: V4L
3
4 .. _VIDIOC_ENUM_FREQ_BANDS:
5
6 ****************************
7 ioctl VIDIOC_ENUM_FREQ_BANDS
8 ****************************
9
10 Name
11 ====
12
13 VIDIOC_ENUM_FREQ_BANDS - Enumerate supported f
14
15 Synopsis
16 ========
17
18 .. c:macro:: VIDIOC_ENUM_FREQ_BANDS
19
20 ``int ioctl(int fd, VIDIOC_ENUM_FREQ_BANDS, st
21
22 Arguments
23 =========
24
25 ``fd``
26 File descriptor returned by :c:func:`open(
27
28 ``argp``
29 Pointer to struct :c:type:`v4l2_frequency_
30
31 Description
32 ===========
33
34 Enumerates the frequency bands that a tuner or
35 this applications initialize the ``tuner``, ``
36 fields, and zero out the ``reserved`` array of
37 :c:type:`v4l2_frequency_band` and call the
38 :ref:`VIDIOC_ENUM_FREQ_BANDS` ioctl with a poi
39
40 This ioctl is supported if the ``V4L2_TUNER_CA
41 of the corresponding tuner/modulator is set.
42
43 .. tabularcolumns:: |p{2.9cm}|p{2.9cm}|p{5.8cm
44
45 .. c:type:: v4l2_frequency_band
46
47 .. flat-table:: struct v4l2_frequency_band
48 :header-rows: 0
49 :stub-columns: 0
50 :widths: 1 1 2 1 1
51
52 * - __u32
53 - ``tuner``
54 - The tuner or modulator index number. T
55 the struct :c:type:`v4l2_input` ``tune
56 the struct :c:type:`v4l2_tuner` ``inde
57 the struct :c:type:`v4l2_output` ``mod
58 and the struct :c:type:`v4l2_modulator
59 field.
60 * - __u32
61 - ``type``
62 - The tuner type. This is the same value
63 :c:type:`v4l2_tuner` ``type`` field. T
64 set to ``V4L2_TUNER_RADIO`` for ``/dev
65 to ``V4L2_TUNER_ANALOG_TV`` for all ot
66 ``V4L2_TUNER_RADIO`` for modulators (c
67 modulators are supported). See :c:type
68 * - __u32
69 - ``index``
70 - Identifies the frequency band, set by
71 * - __u32
72 - ``capability``
73 - :cspan:`2` The tuner/modulator capabil
74 frequency band, see :ref:`tuner-capabi
75 ``V4L2_TUNER_CAP_LOW`` or ``V4L2_TUNER
76 be the same for all frequency bands of
77 tuner/modulator. So either all bands h
78 none of them have that capability.
79 * - __u32
80 - ``rangelow``
81 - :cspan:`2` The lowest tunable frequenc
82 if the ``capability`` flag ``V4L2_TUNE
83 of 62.5 Hz, for this frequency band. A
84 ``capability`` flag ``V4L2_TUNER_CAP_1
85 * - __u32
86 - ``rangehigh``
87 - :cspan:`2` The highest tunable frequen
88 or if the ``capability`` flag ``V4L2_T
89 units of 62.5 Hz, for this frequency b
90 when the ``capability`` flag ``V4L2_TU
91 * - __u32
92 - ``modulation``
93 - :cspan:`2` The supported modulation sy
94 band. See :ref:`band-modulation`.
95
96 .. note::
97
98 Currently only one modulation syste
99 is supported. More work will need t
100 modulation systems are possible. Co
101 mailing list
102 (`https://linuxtv.org/lists.php <ht
103 if you need such functionality.
104 * - __u32
105 - ``reserved``\ [9]
106 - Reserved for future extensions.
107
108 Applications and drivers must set the
109
110
111 .. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.5cm
112
113 .. _band-modulation:
114
115 .. flat-table:: Band Modulation Systems
116 :header-rows: 0
117 :stub-columns: 0
118 :widths: 3 1 4
119
120 * - ``V4L2_BAND_MODULATION_VSB``
121 - 0x02
122 - Vestigial Sideband modulation, used fo
123 * - ``V4L2_BAND_MODULATION_FM``
124 - 0x04
125 - Frequency Modulation, commonly used fo
126 * - ``V4L2_BAND_MODULATION_AM``
127 - 0x08
128 - Amplitude Modulation, commonly used fo
129
130 Return Value
131 ============
132
133 On success 0 is returned, on error -1 and the
134 appropriately. The generic error codes are des
135 :ref:`Generic Error Codes <gen-errors>` chapte
136
137 EINVAL
138 The ``tuner`` or ``index`` is out of bound
139 wrong.
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