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{1.4cm}|p{4.4cm}|p{4.5cm}|p{3.6cm}|p{3.6cm}|

.. 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{3.9cm}|p{1.0cm}|p{2.0cm}|p{3.0cm}|p{7.0cm}|

.. _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
  - See :ref:`v4l2-sliced-vbi-cap-wss-625-payload` below.
* - ``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

.. _v4l2-sliced-vbi-cap-wss-625-payload:

V4L2_SLICED_VBI_CAP WSS_625 payload


The payload for ``V4L2_SLICED_WSS_625`` is:

	    +-----+------------------+-----------------------+
	    |Byte |        0         |           1           |
	    +-----+--------+---------+-----------+-----------+
	    |     | msb    | lsb     | msb       | lsb       |
	    |     +-+-+-+--+--+-+-+--+--+-+--+---+---+--+-+--+
	    | Bit |7|6|5|4 | 3|2|1|0 | x|x|13|12 | 11|10|9|8 |
	    +-----+-+-+-+--+--+-+-+--+--+-+--+---+---+--+-+--+


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.