1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2 .. c:namespace:: V4L
3
4 .. _VIDIOC_G_SLICED_VBI_CAP:
5
6 *****************************
7 ioctl VIDIOC_G_SLICED_VBI_CAP
8 *****************************
9
10 Name
11 ====
12
13 VIDIOC_G_SLICED_VBI_CAP - Query sliced VBI capabilities
14
15 Synopsis
16 ========
17
18 .. c:macro:: VIDIOC_G_SLICED_VBI_CAP
19
20 ``int ioctl(int fd, VIDIOC_G_SLICED_VBI_CAP, struct v4l2_sliced_vbi_cap *argp)``
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_sliced_vbi_cap`.
30
31 Description
32 ===========
33
34 To find out which data services are supported by a sliced VBI capture or
35 output device, applications initialize the ``type`` field of a struct
36 :c:type:`v4l2_sliced_vbi_cap`, clear the
37 ``reserved`` array and call the :ref:`VIDIOC_G_SLICED_VBI_CAP <VIDIOC_G_SLICED_VBI_CAP>` ioctl. The
38 driver fills in the remaining fields or returns an ``EINVAL`` error code if
39 the sliced VBI API is unsupported or ``type`` is invalid.
40
41 .. note::
42
43 The ``type`` field was added, and the ioctl changed from read-only
44 to write-read, in Linux 2.6.19.
45
46 .. c:type:: v4l2_sliced_vbi_cap
47
48 .. tabularcolumns:: |p{1.4cm}|p{4.4cm}|p{4.5cm}|p{3.6cm}|p{3.6cm}|
49
50 .. flat-table:: struct v4l2_sliced_vbi_cap
51 :header-rows: 0
52 :stub-columns: 0
53 :widths: 3 3 2 2 2
54
55 * - __u16
56 - ``service_set``
57 - :cspan:`2` A set of all data services supported by the driver.
58
59 Equal to the union of all elements of the ``service_lines`` array.
60 * - __u16
61 - ``service_lines``\ [2][24]
62 - :cspan:`2` Each element of this array contains a set of data
63 services the hardware can look for or insert into a particular
64 scan line. Data services are defined in :ref:`vbi-services`.
65 Array indices map to ITU-R line numbers\ [#f1]_ as follows:
66 * -
67 -
68 - Element
69 - 525 line systems
70 - 625 line systems
71 * -
72 -
73 - ``service_lines``\ [0][1]
74 - 1
75 - 1
76 * -
77 -
78 - ``service_lines``\ [0][23]
79 - 23
80 - 23
81 * -
82 -
83 - ``service_lines``\ [1][1]
84 - 264
85 - 314
86 * -
87 -
88 - ``service_lines``\ [1][23]
89 - 286
90 - 336
91 * -
92 * -
93 -
94 - :cspan:`2` The number of VBI lines the hardware can capture or
95 output per frame, or the number of services it can identify on a
96 given line may be limited. For example on PAL line 16 the hardware
97 may be able to look for a VPS or Teletext signal, but not both at
98 the same time. Applications can learn about these limits using the
99 :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl as described in
100 :ref:`sliced`.
101 * -
102 * -
103 -
104 - :cspan:`2` Drivers must set ``service_lines`` [0][0] and
105 ``service_lines``\ [1][0] to zero.
106 * - __u32
107 - ``type``
108 - Type of the data stream, see :c:type:`v4l2_buf_type`. Should be
109 ``V4L2_BUF_TYPE_SLICED_VBI_CAPTURE`` or
110 ``V4L2_BUF_TYPE_SLICED_VBI_OUTPUT``.
111 * - __u32
112 - ``reserved``\ [3]
113 - :cspan:`2` This array is reserved for future extensions.
114
115 Applications and drivers must set it to zero.
116
117 .. [#f1]
118
119 See also :ref:`vbi-525` and :ref:`vbi-625`.
120
121 .. raw:: latex
122
123 \scriptsize
124
125 .. tabularcolumns:: |p{3.9cm}|p{1.0cm}|p{2.0cm}|p{3.0cm}|p{7.0cm}|
126
127 .. _vbi-services:
128
129 .. flat-table:: Sliced VBI services
130 :header-rows: 1
131 :stub-columns: 0
132 :widths: 2 1 1 2 2
133
134 * - Symbol
135 - Value
136 - Reference
137 - Lines, usually
138 - Payload
139 * - ``V4L2_SLICED_TELETEXT_B`` (Teletext System B)
140 - 0x0001
141 - :ref:`ets300706`,
142
143 :ref:`itu653`
144 - PAL/SECAM line 7-22, 320-335 (second field 7-22)
145 - Last 42 of the 45 byte Teletext packet, that is without clock
146 run-in and framing code, lsb first transmitted.
147 * - ``V4L2_SLICED_VPS``
148 - 0x0400
149 - :ref:`ets300231`
150 - PAL line 16
151 - Byte number 3 to 15 according to Figure 9 of ETS 300 231, lsb
152 first transmitted.
153 * - ``V4L2_SLICED_CAPTION_525``
154 - 0x1000
155 - :ref:`cea608`
156 - NTSC line 21, 284 (second field 21)
157 - Two bytes in transmission order, including parity bit, lsb first
158 transmitted.
159 * - ``V4L2_SLICED_WSS_625``
160 - 0x4000
161 - :ref:`en300294`,
162
163 :ref:`itu1119`
164 - PAL/SECAM line 23
165 - See :ref:`v4l2-sliced-vbi-cap-wss-625-payload` below.
166 * - ``V4L2_SLICED_VBI_525``
167 - 0x1000
168 - :cspan:`2` Set of services applicable to 525 line systems.
169 * - ``V4L2_SLICED_VBI_625``
170 - 0x4401
171 - :cspan:`2` Set of services applicable to 625 line systems.
172
173
174 .. raw:: latex
175
176 \normalsize
177
178 .. _v4l2-sliced-vbi-cap-wss-625-payload:
179
180 V4L2_SLICED_VBI_CAP WSS_625 payload
181 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
182
183 The payload for ``V4L2_SLICED_WSS_625`` is:
184
185 +-----+------------------+-----------------------+
186 |Byte | 0 | 1 |
187 +-----+--------+---------+-----------+-----------+
188 | | msb | lsb | msb | lsb |
189 | +-+-+-+--+--+-+-+--+--+-+--+---+---+--+-+--+
190 | Bit |7|6|5|4 | 3|2|1|0 | x|x|13|12 | 11|10|9|8 |
191 +-----+-+-+-+--+--+-+-+--+--+-+--+---+---+--+-+--+
192
193
194 Return Value
195 ============
196
197 On success 0 is returned, on error -1 and the ``errno`` variable is set
198 appropriately. The generic error codes are described at the
199 :ref:`Generic Error Codes <gen-errors>` chapter.
200
201 EINVAL
202 The value in the ``type`` field is wrong.
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