diff options
Diffstat (limited to 'Documentation/userspace-api/media/v4l/dev-sliced-vbi.rst')
| -rw-r--r-- | Documentation/userspace-api/media/v4l/dev-sliced-vbi.rst | 31 |
1 files changed, 7 insertions, 24 deletions
diff --git a/Documentation/userspace-api/media/v4l/dev-sliced-vbi.rst b/Documentation/userspace-api/media/v4l/dev-sliced-vbi.rst index 807751f305fb..f0df144c9f63 100644 --- a/Documentation/userspace-api/media/v4l/dev-sliced-vbi.rst +++ b/Documentation/userspace-api/media/v4l/dev-sliced-vbi.rst @@ -1,4 +1,5 @@ .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later +.. c:namespace:: V4L .. _sliced: @@ -27,7 +28,6 @@ however the default function here is video capturing or output. Different file descriptors must be used to pass raw and sliced VBI data simultaneously, if this is supported by the driver. - Querying Capabilities ===================== @@ -39,7 +39,6 @@ respectively, in the ``capabilities`` field of struct read/write, streaming or asynchronous :ref:`I/O methods <io>` must be supported. Sliced VBI devices may have a tuner or modulator. - Supplemental Functions ====================== @@ -49,7 +48,6 @@ capabilities, and they may support :ref:`control` ioctls. The :ref:`video standard <standard>` ioctls provide information vital to program a sliced VBI device, therefore must be supported. - .. _sliced-vbi-format-negotitation: Sliced VBI Format Negotiation @@ -96,9 +94,8 @@ at this point, it may return an ``EBUSY`` error code if the required resources are temporarily unavailable. Other resource allocation points which may return ``EBUSY`` can be the :ref:`VIDIOC_STREAMON` ioctl and the first -:ref:`read() <func-read>`, :ref:`write() <func-write>` and -:ref:`select() <func-select>` call. - +:c:func:`read()`, :c:func:`write()` and +:c:func:`select()` call. .. c:type:: v4l2_sliced_vbi_format @@ -191,7 +188,7 @@ struct v4l2_sliced_vbi_format * - __u32 - ``io_size`` - :cspan:`2` Maximum number of bytes passed by one - :ref:`read() <func-read>` or :ref:`write() <func-write>` call, + :c:func:`read()` or :c:func:`write()` call, and the buffer size in bytes for the :ref:`VIDIOC_QBUF` and :ref:`VIDIOC_DQBUF <VIDIOC_QBUF>` ioctl. Drivers set this field @@ -274,7 +271,6 @@ Sliced VBI services \normalsize - Drivers may return an ``EINVAL`` error code when applications attempt to read or write data without prior format negotiation, after switching the video standard (which may invalidate the negotiated VBI parameters) and @@ -284,13 +280,12 @@ return an ``EBUSY`` error code when applications attempt to change the format while i/o is in progress (between a :ref:`VIDIOC_STREAMON` and :ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` call, and after the first -:ref:`read() <func-read>` or :ref:`write() <func-write>` call). - +:c:func:`read()` or :c:func:`write()` call). Reading and writing sliced VBI data =================================== -A single :ref:`read() <func-read>` or :ref:`write() <func-write>` +A single :c:func:`read()` or :c:func:`write()` call must pass all data belonging to one video frame. That is an array of struct :c:type:`v4l2_sliced_vbi_data` structures with one or more elements and a total size not exceeding ``io_size`` bytes. Likewise @@ -298,7 +293,6 @@ in streaming I/O mode one buffer of ``io_size`` bytes must contain data of one video frame. The ``id`` of unused struct :c:type:`v4l2_sliced_vbi_data` elements must be zero. - .. c:type:: v4l2_sliced_vbi_data struct v4l2_sliced_vbi_data @@ -344,9 +338,8 @@ struct v4l2_sliced_vbi_data bytes at the end of this array are undefined, drivers and applications shall ignore them. - Packets are always passed in ascending line number order, without -duplicate line numbers. The :ref:`write() <func-write>` function and +duplicate line numbers. The :c:func:`write()` function and the :ref:`VIDIOC_QBUF` ioctl must return an ``EINVAL`` error code when applications violate this rule. They must also return an EINVAL error code when applications pass an incorrect field or line @@ -370,7 +363,6 @@ streaming (:ref:`memory mapping <mmap>` and/or :ref:`user pointer <userp>`) I/O. The latter bears the possibility of synchronizing video and VBI data by using buffer timestamps. - Sliced VBI Data in MPEG Streams =============================== @@ -405,7 +397,6 @@ data insertion is not supported by the device. The following subsections specify the format of the embedded sliced VBI data. - MPEG Stream Embedded, Sliced VBI Data Format: NONE -------------------------------------------------- @@ -417,7 +408,6 @@ nor driver shall insert "empty" embedded sliced VBI data packets in the MPEG stream when this format is set. No MPEG stream data structures are specified for this format. - MPEG Stream Embedded, Sliced VBI Data Format: IVTV -------------------------------------------------- @@ -460,7 +450,6 @@ the end with unspecified fill bytes to align the end of the payload to a with 18 lines/field with 43 bytes of data/line and a 4 byte magic number). - .. c:type:: v4l2_mpeg_vbi_fmt_ivtv struct v4l2_mpeg_vbi_fmt_ivtv @@ -523,7 +512,6 @@ Magic Constants for struct v4l2_mpeg_vbi_fmt_ivtv magic field valid and that 36 lines of sliced VBI data are present. - .. c:type:: v4l2_mpeg_vbi_itv0 .. c:type:: v4l2_mpeg_vbi_ITV0 @@ -548,7 +536,6 @@ structs v4l2_mpeg_vbi_itv0 and v4l2_mpeg_vbi_ITV0 value: - :: linemask[0] b0: line 6 first field @@ -574,7 +561,6 @@ structs v4l2_mpeg_vbi_itv0 and v4l2_mpeg_vbi_ITV0 applications. - .. _v4l2-mpeg-vbi-itv0-1: struct v4l2_mpeg_vbi_ITV0 @@ -596,7 +582,6 @@ struct v4l2_mpeg_vbi_ITV0 lines 6 through 23 of the second field. - .. c:type:: v4l2_mpeg_vbi_itv0_line struct v4l2_mpeg_vbi_itv0_line @@ -619,7 +604,6 @@ struct v4l2_mpeg_vbi_itv0_line - The sliced VBI data for the line. - .. _ITV0-Line-Identifier-Constants: Line Identifiers for struct v4l2_mpeg_vbi_itv0_line id field @@ -653,7 +637,6 @@ Line Identifiers for struct v4l2_mpeg_vbi_itv0_line id field description of the line payload. - .. [#f1] According to :ref:`ETS 300 706 <ets300706>` lines 6-22 of the first field and lines 5-22 of the second field may carry Teletext data. |