.. -*- coding: utf-8; mode: rst -*- .. _VIDIOC_G_SLICED_VBI_CAP: ***************************** ioctl VIDIOC_G_SLICED_VBI_CAP ***************************** Name ==== VIDIOC_G_SLICED_VBI_CAP - Query sliced VBI capabilities Synopsis ======== .. cpp:function:: int ioctl( int fd, int request, struct v4l2_sliced_vbi_cap *argp ) Arguments ========= ``fd`` File descriptor returned by :ref:`open() `. ``request`` VIDIOC_G_SLICED_VBI_CAP ``argp`` 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 :ref:`v4l2_sliced_vbi_cap `, clear the ``reserved`` array and call the :ref:`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. .. _v4l2-sliced-vbi-cap: .. flat-table:: struct v4l2_sliced_vbi_cap :header-rows: 0 :stub-columns: 0 :widths: 3 3 2 2 2 - .. row 1 - __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. - .. row 2 - __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 (see also :ref:`vbi-525` and :ref:`vbi-625`) as follows: - .. row 3 - - - Element - 525 line systems - 625 line systems - .. row 4 - - - ``service_lines``\ [0][1] - 1 - 1 - .. row 5 - - - ``service_lines``\ [0][23] - 23 - 23 - .. row 6 - - - ``service_lines``\ [1][1] - 264 - 314 - .. row 7 - - - ``service_lines``\ [1][23] - 286 - 336 - .. row 8 - - .. row 9 - - - :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 ` ioctl as described in :ref:`sliced`. - .. row 10 - - .. row 11 - - - :cspan:`2` Drivers must set ``service_lines`` [0][0] and ``service_lines``\ [1][0] to zero. - .. row 12 - __u32 - ``type`` - Type of the data stream, see :ref:`v4l2-buf-type`. Should be ``V4L2_BUF_TYPE_SLICED_VBI_CAPTURE`` or ``V4L2_BUF_TYPE_SLICED_VBI_OUTPUT``. - .. row 13 - __u32 - ``reserved``\ [3] - :cspan:`2` This array is reserved for future extensions. Applications and drivers must set it to zero. .. _vbi-services: .. flat-table:: Sliced VBI services :header-rows: 1 :stub-columns: 0 :widths: 2 1 1 2 2 - .. row 1 - Symbol - Value - Reference - Lines, usually - Payload - .. row 2 - ``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. - .. row 3 - ``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. - .. row 4 - ``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. - .. row 5 - ``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 - .. row 6 - ``V4L2_SLICED_VBI_525`` - 0x1000 - :cspan:`2` Set of services applicable to 525 line systems. - .. row 7 - ``V4L2_SLICED_VBI_625`` - 0x4401 - :cspan:`2` Set of services applicable to 625 line systems. 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 ` chapter. EINVAL The value in the ``type`` field is wrong.