sphinx.addnodesdocument)}( rawsourcechildren]( translations LanguagesNode)}(hhh](h pending_xref)}(hhh]docutils.nodesTextChinese (Simplified)}parenthsba attributes}(ids]classes]names]dupnames]backrefs] refdomainstdreftypedoc reftarget7/translations/zh_CN/userspace-api/media/v4l/dev-raw-vbimodnameN classnameN refexplicitutagnamehhh ubh)}(hhh]hChinese (Traditional)}hh2sbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget7/translations/zh_TW/userspace-api/media/v4l/dev-raw-vbimodnameN classnameN refexplicituh1hhh ubh)}(hhh]hItalian}hhFsbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget7/translations/it_IT/userspace-api/media/v4l/dev-raw-vbimodnameN classnameN refexplicituh1hhh ubh)}(hhh]hJapanese}hhZsbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget7/translations/ja_JP/userspace-api/media/v4l/dev-raw-vbimodnameN classnameN refexplicituh1hhh ubh)}(hhh]hKorean}hhnsbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget7/translations/ko_KR/userspace-api/media/v4l/dev-raw-vbimodnameN classnameN refexplicituh1hhh ubh)}(hhh]hSpanish}hhsbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget7/translations/sp_SP/userspace-api/media/v4l/dev-raw-vbimodnameN classnameN refexplicituh1hhh ubeh}(h]h ]h"]h$]h&]current_languageEnglishuh1h hh _documenthsourceNlineNubhcomment)}(h8SPDX-License-Identifier: GFDL-1.1-no-invariants-or-laterh]h8SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later}hhsbah}(h]h ]h"]h$]h&] xml:spacepreserveuh1hhhhhhQ/var/lib/git/docbuild/linux/Documentation/userspace-api/media/v4l/dev-raw-vbi.rsthKubhtarget)}(h .. _raw-vbi:h]h}(h]h ]h"]h$]h&]refidraw-vbiuh1hhKhhhhhhubhsection)}(hhh](htitle)}(hRaw VBI Data Interfaceh]hRaw VBI Data Interface}(hhhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhhhhhKubh paragraph)}(hXVBI is an abbreviation of Vertical Blanking Interval, a gap in the sequence of lines of an analog video signal. During VBI no picture information is transmitted, allowing some time while the electron beam of a cathode ray tube TV returns to the top of the screen. Using an oscilloscope you will find here the vertical synchronization pulses and short data packages ASK modulated [#f1]_ onto the video signal. These are transmissions of services such as Teletext or Closed Caption.h](hX{VBI is an abbreviation of Vertical Blanking Interval, a gap in the sequence of lines of an analog video signal. During VBI no picture information is transmitted, allowing some time while the electron beam of a cathode ray tube TV returns to the top of the screen. Using an oscilloscope you will find here the vertical synchronization pulses and short data packages ASK modulated }(hhhhhNhNubhfootnote_reference)}(h[#f1]_h]h1}(hhhhhNhNubah}(h]id1ah ]h"]h$]h&]autoKhf1docname#userspace-api/media/v4l/dev-raw-vbiuh1hhhٌresolvedKubh_ onto the video signal. These are transmissions of services such as Teletext or Closed Caption.}(hhhhhNhNubeh}(h]h ]h"]h$]h&]uh1hhhhK hhhhubh)}(hSubject of this interface type is raw VBI data, as sampled off a video signal, or to be added to a signal for output. The data format is similar to uncompressed video images, a number of lines times a number of samples per line, we call this a VBI image.h]hSubject of this interface type is raw VBI data, as sampled off a video signal, or to be added to a signal for output. The data format is similar to uncompressed video images, a number of lines times a number of samples per line, we call this a VBI image.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhhhhubh)}(hX>Conventionally V4L2 VBI devices are accessed through character device special files named ``/dev/vbi`` and ``/dev/vbi0`` to ``/dev/vbi31`` with major number 81 and minor numbers 224 to 255. ``/dev/vbi`` is typically a symbolic link to the preferred VBI device. This convention applies to both input and output devices.h](hZConventionally V4L2 VBI devices are accessed through character device special files named }(hjhhhNhNubhliteral)}(h ``/dev/vbi``h]h/dev/vbi}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhjubh and }(hjhhhNhNubj)}(h ``/dev/vbi0``h]h /dev/vbi0}(hj+hhhNhNubah}(h]h ]h"]h$]h&]uh1jhjubh to }(hjhhhNhNubj)}(h``/dev/vbi31``h]h /dev/vbi31}(hj=hhhNhNubah}(h]h ]h"]h$]h&]uh1jhjubh4 with major number 81 and minor numbers 224 to 255. }(hjhhhNhNubj)}(h ``/dev/vbi``h]h/dev/vbi}(hjOhhhNhNubah}(h]h ]h"]h$]h&]uh1jhjubht is typically a symbolic link to the preferred VBI device. This convention applies to both input and output devices.}(hjhhhNhNubeh}(h]h ]h"]h$]h&]uh1hhhhKhhhhubh)}(hXdTo address the problems of finding related video and VBI devices VBI capturing and output is also available as device function under ``/dev/video``. To capture or output raw VBI data with these devices applications must call the :ref:`VIDIOC_S_FMT ` ioctl. Accessed as ``/dev/vbi``, raw VBI capturing or output is the default device function.h](hTo address the problems of finding related video and VBI devices VBI capturing and output is also available as device function under }(hjghhhNhNubj)}(h``/dev/video``h]h /dev/video}(hjohhhNhNubah}(h]h ]h"]h$]h&]uh1jhjgubhR. To capture or output raw VBI data with these devices applications must call the }(hjghhhNhNubh)}(h":ref:`VIDIOC_S_FMT `h]hinline)}(hjh]h VIDIOC_S_FMT}(hjhhhNhNubah}(h]h ](xrefstdstd-refeh"]h$]h&]uh1jhjubah}(h]h ]h"]h$]h&]refdoch refdomainjreftyperef refexplicitrefwarn reftarget vidioc_g_fmtuh1hhhhKhjgubh ioctl. Accessed as }(hjghhhNhNubj)}(h ``/dev/vbi``h]h/dev/vbi}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhjgubh=, raw VBI capturing or output is the default device function.}(hjghhhNhNubeh}(h]h ]h"]h$]h&]uh1hhhhKhhhhubh)}(hhh](h)}(hQuerying Capabilitiesh]hQuerying Capabilities}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhK%ubh)}(hXxDevices supporting the raw VBI capturing or output API set the ``V4L2_CAP_VBI_CAPTURE`` or ``V4L2_CAP_VBI_OUTPUT`` flags, respectively, in the ``capabilities`` field of struct :c:type:`v4l2_capability` returned by the :ref:`VIDIOC_QUERYCAP` ioctl. At least one of the read/write or streaming I/O methods must be supported. VBI devices may or may not have a tuner or modulator.h](h?Devices supporting the raw VBI capturing or output API set the }(hjhhhNhNubj)}(h``V4L2_CAP_VBI_CAPTURE``h]hV4L2_CAP_VBI_CAPTURE}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhjubh or }(hjhhhNhNubj)}(h``V4L2_CAP_VBI_OUTPUT``h]hV4L2_CAP_VBI_OUTPUT}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhjubh flags, respectively, in the }(hjhhhNhNubj)}(h``capabilities``h]h capabilities}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jhjubh field of struct }(hjhhhNhNubh)}(h:c:type:`v4l2_capability`h]j)}(hjh]hv4l2_capability}(hjhhhNhNubah}(h]h ](jcc-typeeh"]h$]h&]uh1jhjubah}(h]h ]h"]h$]h&]refdoch refdomainjreftypetype refexplicitrefwarn c:parent_keysphinx.domains.c LookupKey)}data]j0 ASTIdentifier)} identifierV4LsbNasbjv4l2_capabilityuh1hhhhK'hjubh returned by the }(hjhhhNhNubh)}(h:ref:`VIDIOC_QUERYCAP`h]j)}(hjEh]hVIDIOC_QUERYCAP}(hjGhhhNhNubah}(h]h ](jstdstd-refeh"]h$]h&]uh1jhjCubah}(h]h ]h"]h$]h&]refdoch refdomainjQreftyperef refexplicitrefwarnjvidioc_querycapuh1hhhhK'hjubh ioctl. At least one of the read/write or streaming I/O methods must be supported. VBI devices may or may not have a tuner or modulator.}(hjhhhNhNubeh}(h]h ]h"]h$]h&]uh1hhhhK'hjhhubeh}(h]querying-capabilitiesah ]h"]querying capabilitiesah$]h&]uh1hhhhhhhhK%ubh)}(hhh](h)}(hSupplemental Functionsh]hSupplemental Functions}(hjxhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjuhhhhhK0ubh)}(hXVBI devices shall support :ref:`video input or output