1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
|
.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
.. c:namespace:: V4L
.. _VIDIOC_G_SLICED_VBI_CAP:
*****************************
ioctl VIDIOC_G_SLICED_VBI_CAP
*****************************
Name
====
VIDIOC_G_SLICED_VBI_CAP - Query sliced VBI capabilities
Synopsis
========
.. c:macro:: VIDIOC_G_SLICED_VBI_CAP
``int ioctl(int fd, VIDIOC_G_SLICED_VBI_CAP, struct v4l2_sliced_vbi_cap *argp)``
Arguments
=========
``fd``
File descriptor returned by :c:func:`open()`.
``argp``
Pointer to struct :c:type:`v4l2_sliced_vbi_cap`.
Description
===========
To find out which data services are supported by a sliced VBI capture or
output device, applications initialize the ``type`` field of a struct
:c:type:`v4l2_sliced_vbi_cap`, clear the
``reserved`` array and call the :ref:`VIDIOC_G_SLICED_VBI_CAP <VIDIOC_G_SLICED_VBI_CAP>` ioctl. The
driver fills in the remaining fields or returns an ``EINVAL`` error code if
the sliced VBI API is unsupported or ``type`` is invalid.
.. note::
The ``type`` field was added, and the ioctl changed from read-only
to write-read, in Linux 2.6.19.
.. c:type:: v4l2_sliced_vbi_cap
.. tabularcolumns:: |p{1.2cm}|p{4.2cm}|p{4.1cm}|p{4.0cm}|p{4.0cm}|
.. flat-table:: struct v4l2_sliced_vbi_cap
:header-rows: 0
:stub-columns: 0
:widths: 3 3 2 2 2
* - __u16
- ``service_set``
- :cspan:`2` A set of all data services supported by the driver.
Equal to the union of all elements of the ``service_lines`` array.
* - __u16
- ``service_lines``\ [2][24]
- :cspan:`2` Each element of this array contains a set of data
services the hardware can look for or insert into a particular
scan line. Data services are defined in :ref:`vbi-services`.
Array indices map to ITU-R line numbers\ [#f1]_ as follows:
* -
-
- Element
- 525 line systems
- 625 line systems
* -
-
- ``service_lines``\ [0][1]
- 1
- 1
* -
-
- ``service_lines``\ [0][23]
- 23
- 23
* -
-
- ``service_lines``\ [1][1]
- 264
- 314
* -
-
- ``service_lines``\ [1][23]
- 286
- 336
* -
* -
-
- :cspan:`2` The number of VBI lines the hardware can capture or
output per frame, or the number of services it can identify on a
given line may be limited. For example on PAL line 16 the hardware
may be able to look for a VPS or Teletext signal, but not both at
the same time. Applications can learn about these limits using the
:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl as described in
:ref:`sliced`.
* -
* -
-
- :cspan:`2` Drivers must set ``service_lines`` [0][0] and
``service_lines``\ [1][0] to zero.
* - __u32
- ``type``
- Type of the data stream, see :c:type:`v4l2_buf_type`. Should be
``V4L2_BUF_TYPE_SLICED_VBI_CAPTURE`` or
``V4L2_BUF_TYPE_SLICED_VBI_OUTPUT``.
* - __u32
- ``reserved``\ [3]
- :cspan:`2` This array is reserved for future extensions.
Applications and drivers must set it to zero.
.. [#f1]
See also :ref:`vbi-525` and :ref:`vbi-625`.
.. raw:: latex
\scriptsize
.. tabularcolumns:: |p{3.5cm}|p{1.0cm}|p{2.0cm}|p{2.0cm}|p{8.0cm}|
.. _vbi-services:
.. flat-table:: Sliced VBI services
:header-rows: 1
:stub-columns: 0
:widths: 2 1 1 2 2
* - Symbol
- Value
- Reference
- Lines, usually
- Payload
* - ``V4L2_SLICED_TELETEXT_B`` (Teletext System B)
- 0x0001
- :ref:`ets300706`,
:ref:`itu653`
- PAL/SECAM line 7-22, 320-335 (second field 7-22)
- Last 42 of the 45 byte Teletext packet, that is without clock
run-in and framing code, lsb first transmitted.
* - ``V4L2_SLICED_VPS``
- 0x0400
- :ref:`ets300231`
- PAL line 16
- Byte number 3 to 15 according to Figure 9 of ETS 300 231, lsb
first transmitted.
* - ``V4L2_SLICED_CAPTION_525``
- 0x1000
- :ref:`cea608`
- NTSC line 21, 284 (second field 21)
- Two bytes in transmission order, including parity bit, lsb first
transmitted.
* - ``V4L2_SLICED_WSS_625``
- 0x4000
- :ref:`en300294`,
:ref:`itu1119`
- PAL/SECAM line 23
-
::
Byte 0 1
msb lsb msb lsb
Bit 7 6 5 4 3 2 1 0 x x 13 12 11 10 9
* - ``V4L2_SLICED_VBI_525``
- 0x1000
- :cspan:`2` Set of services applicable to 525 line systems.
* - ``V4L2_SLICED_VBI_625``
- 0x4401
- :cspan:`2` Set of services applicable to 625 line systems.
.. raw:: latex
\normalsize
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 value in the ``type`` field is wrong.
|
