1 .. -*- coding: utf-8; mode: rst -*-
3 .. _VIDIOC_G_SLICED_VBI_CAP:
5 *****************************
6 ioctl VIDIOC_G_SLICED_VBI_CAP
7 *****************************
12 VIDIOC_G_SLICED_VBI_CAP - Query sliced VBI capabilities
18 .. cpp:function:: int ioctl( int fd, int request, struct v4l2_sliced_vbi_cap *argp )
25 File descriptor returned by :ref:`open() <func-open>`.
28 VIDIOC_G_SLICED_VBI_CAP
36 To find out which data services are supported by a sliced VBI capture or
37 output device, applications initialize the ``type`` field of a struct
38 :ref:`v4l2_sliced_vbi_cap <v4l2-sliced-vbi-cap>`, clear the
39 ``reserved`` array and call the :ref:`VIDIOC_G_SLICED_VBI_CAP <VIDIOC_G_SLICED_VBI_CAP>` ioctl. The
40 driver fills in the remaining fields or returns an ``EINVAL`` error code if
41 the sliced VBI API is unsupported or ``type`` is invalid.
43 .. note:: The ``type`` field was added, and the ioctl changed from read-only
44 to write-read, in Linux 2.6.19.
47 .. _v4l2-sliced-vbi-cap:
49 .. flat-table:: struct v4l2_sliced_vbi_cap
61 - :cspan:`2` A set of all data services supported by the driver.
62 Equal to the union of all elements of the ``service_lines`` array.
68 - ``service_lines``\ [2][24]
70 - :cspan:`2` Each element of this array contains a set of data
71 services the hardware can look for or insert into a particular
72 scan line. Data services are defined in :ref:`vbi-services`.
73 Array indices map to ITU-R line numbers (see also :ref:`vbi-525`
74 and :ref:`vbi-625`) as follows:
90 - ``service_lines``\ [0][1]
100 - ``service_lines``\ [0][23]
110 - ``service_lines``\ [1][1]
120 - ``service_lines``\ [1][23]
134 - :cspan:`2` The number of VBI lines the hardware can capture or
135 output per frame, or the number of services it can identify on a
136 given line may be limited. For example on PAL line 16 the hardware
137 may be able to look for a VPS or Teletext signal, but not both at
138 the same time. Applications can learn about these limits using the
139 :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl as described in
150 - :cspan:`2` Drivers must set ``service_lines`` [0][0] and
151 ``service_lines``\ [1][0] to zero.
159 - Type of the data stream, see :ref:`v4l2-buf-type`. Should be
160 ``V4L2_BUF_TYPE_SLICED_VBI_CAPTURE`` or
161 ``V4L2_BUF_TYPE_SLICED_VBI_OUTPUT``.
169 - :cspan:`2` This array is reserved for future extensions.
170 Applications and drivers must set it to zero.
176 .. flat-table:: Sliced VBI services
196 - ``V4L2_SLICED_TELETEXT_B`` (Teletext System B)
200 - :ref:`ets300706`, :ref:`itu653`
202 - PAL/SECAM line 7-22, 320-335 (second field 7-22)
204 - Last 42 of the 45 byte Teletext packet, that is without clock
205 run-in and framing code, lsb first transmitted.
209 - ``V4L2_SLICED_VPS``
217 - Byte number 3 to 15 according to Figure 9 of ETS 300 231, lsb
222 - ``V4L2_SLICED_CAPTION_525``
228 - NTSC line 21, 284 (second field 21)
230 - Two bytes in transmission order, including parity bit, lsb first
235 - ``V4L2_SLICED_WSS_625``
239 - :ref:`en300294`, :ref:`itu1119`
249 Bit 7 6 5 4 3 2 1 0 x x 13 12 11 10 9
253 - ``V4L2_SLICED_VBI_525``
257 - :cspan:`2` Set of services applicable to 525 line systems.
261 - ``V4L2_SLICED_VBI_625``
265 - :cspan:`2` Set of services applicable to 625 line systems.
271 On success 0 is returned, on error -1 and the ``errno`` variable is set
272 appropriately. The generic error codes are described at the
273 :ref:`Generic Error Codes <gen-errors>` chapter.
276 The value in the ``type`` field is wrong.