352 lines
11 KiB
ReStructuredText
352 lines
11 KiB
ReStructuredText
.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
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.. c:namespace:: V4L
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.. _VIDIOC_ENUMSTD:
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*******************************************
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ioctl VIDIOC_ENUMSTD, VIDIOC_SUBDEV_ENUMSTD
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*******************************************
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Name
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====
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VIDIOC_ENUMSTD - VIDIOC_SUBDEV_ENUMSTD - Enumerate supported video standards
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Synopsis
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========
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.. c:macro:: VIDIOC_ENUMSTD
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``int ioctl(int fd, VIDIOC_ENUMSTD, struct v4l2_standard *argp)``
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.. c:macro:: VIDIOC_SUBDEV_ENUMSTD
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``int ioctl(int fd, VIDIOC_SUBDEV_ENUMSTD, struct v4l2_standard *argp)``
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Arguments
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=========
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``fd``
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File descriptor returned by :c:func:`open()`.
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``argp``
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Pointer to struct :c:type:`v4l2_standard`.
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Description
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===========
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To query the attributes of a video standard, especially a custom (driver
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defined) one, applications initialize the ``index`` field of struct
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:c:type:`v4l2_standard` and call the :ref:`VIDIOC_ENUMSTD`
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ioctl with a pointer to this structure. Drivers fill the rest of the
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structure or return an ``EINVAL`` error code when the index is out of
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bounds. To enumerate all standards applications shall begin at index
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zero, incrementing by one until the driver returns ``EINVAL``. Drivers may
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enumerate a different set of standards after switching the video input
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or output. [#f1]_
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.. c:type:: v4l2_standard
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.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
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.. flat-table:: struct v4l2_standard
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 1 2
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* - __u32
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- ``index``
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- Number of the video standard, set by the application.
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* - :ref:`v4l2_std_id <v4l2-std-id>`
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- ``id``
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- The bits in this field identify the standard as one of the common
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standards listed in :ref:`v4l2-std-id`, or if bits 32 to 63 are
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set as custom standards. Multiple bits can be set if the hardware
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does not distinguish between these standards, however separate
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indices do not indicate the opposite. The ``id`` must be unique.
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No other enumerated struct :c:type:`v4l2_standard` structure,
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for this input or output anyway, can contain the same set of bits.
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* - __u8
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- ``name``\ [24]
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- Name of the standard, a NUL-terminated ASCII string, for example:
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"PAL-B/G", "NTSC Japan". This information is intended for the
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user.
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* - struct :c:type:`v4l2_fract`
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- ``frameperiod``
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- The frame period (not field period) is numerator / denominator.
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For example M/NTSC has a frame period of 1001 / 30000 seconds.
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* - __u32
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- ``framelines``
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- Total lines per frame including blanking, e. g. 625 for B/PAL.
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* - __u32
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- ``reserved``\ [4]
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- Reserved for future extensions. Drivers must set the array to
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zero.
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.. c:type:: v4l2_fract
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.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
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.. flat-table:: struct v4l2_fract
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 1 2
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* - __u32
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- ``numerator``
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-
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* - __u32
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- ``denominator``
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-
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.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
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.. _v4l2-std-id:
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.. flat-table:: typedef v4l2_std_id
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 1 2
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* - __u64
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- ``v4l2_std_id``
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- This type is a set, each bit representing another video standard
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as listed below and in :ref:`video-standards`. The 32 most
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significant bits are reserved for custom (driver defined) video
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standards.
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.. code-block:: c
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#define V4L2_STD_PAL_B ((v4l2_std_id)0x00000001)
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#define V4L2_STD_PAL_B1 ((v4l2_std_id)0x00000002)
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#define V4L2_STD_PAL_G ((v4l2_std_id)0x00000004)
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#define V4L2_STD_PAL_H ((v4l2_std_id)0x00000008)
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#define V4L2_STD_PAL_I ((v4l2_std_id)0x00000010)
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#define V4L2_STD_PAL_D ((v4l2_std_id)0x00000020)
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#define V4L2_STD_PAL_D1 ((v4l2_std_id)0x00000040)
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#define V4L2_STD_PAL_K ((v4l2_std_id)0x00000080)
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#define V4L2_STD_PAL_M ((v4l2_std_id)0x00000100)
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#define V4L2_STD_PAL_N ((v4l2_std_id)0x00000200)
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#define V4L2_STD_PAL_Nc ((v4l2_std_id)0x00000400)
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#define V4L2_STD_PAL_60 ((v4l2_std_id)0x00000800)
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``V4L2_STD_PAL_60`` is a hybrid standard with 525 lines, 60 Hz refresh
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rate, and PAL color modulation with a 4.43 MHz color subcarrier. Some
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PAL video recorders can play back NTSC tapes in this mode for display on
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a 50/60 Hz agnostic PAL TV.
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.. code-block:: c
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#define V4L2_STD_NTSC_M ((v4l2_std_id)0x00001000)
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#define V4L2_STD_NTSC_M_JP ((v4l2_std_id)0x00002000)
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#define V4L2_STD_NTSC_443 ((v4l2_std_id)0x00004000)
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``V4L2_STD_NTSC_443`` is a hybrid standard with 525 lines, 60 Hz refresh
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rate, and NTSC color modulation with a 4.43 MHz color subcarrier.
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.. code-block:: c
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#define V4L2_STD_NTSC_M_KR ((v4l2_std_id)0x00008000)
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#define V4L2_STD_SECAM_B ((v4l2_std_id)0x00010000)
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#define V4L2_STD_SECAM_D ((v4l2_std_id)0x00020000)
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#define V4L2_STD_SECAM_G ((v4l2_std_id)0x00040000)
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#define V4L2_STD_SECAM_H ((v4l2_std_id)0x00080000)
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#define V4L2_STD_SECAM_K ((v4l2_std_id)0x00100000)
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#define V4L2_STD_SECAM_K1 ((v4l2_std_id)0x00200000)
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#define V4L2_STD_SECAM_L ((v4l2_std_id)0x00400000)
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#define V4L2_STD_SECAM_LC ((v4l2_std_id)0x00800000)
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/* ATSC/HDTV */
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#define V4L2_STD_ATSC_8_VSB ((v4l2_std_id)0x01000000)
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#define V4L2_STD_ATSC_16_VSB ((v4l2_std_id)0x02000000)
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``V4L2_STD_ATSC_8_VSB`` and ``V4L2_STD_ATSC_16_VSB`` are U.S.
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terrestrial digital TV standards. Presently the V4L2 API does not
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support digital TV. See also the Linux DVB API at
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`https://linuxtv.org <https://linuxtv.org>`__.
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.. code-block:: c
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#define V4L2_STD_PAL_BG (V4L2_STD_PAL_B |
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V4L2_STD_PAL_B1 |
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V4L2_STD_PAL_G)
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#define V4L2_STD_B (V4L2_STD_PAL_B |
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V4L2_STD_PAL_B1 |
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V4L2_STD_SECAM_B)
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#define V4L2_STD_GH (V4L2_STD_PAL_G |
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V4L2_STD_PAL_H |
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V4L2_STD_SECAM_G |
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V4L2_STD_SECAM_H)
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#define V4L2_STD_PAL_DK (V4L2_STD_PAL_D |
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V4L2_STD_PAL_D1 |
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V4L2_STD_PAL_K)
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#define V4L2_STD_PAL (V4L2_STD_PAL_BG |
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V4L2_STD_PAL_DK |
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V4L2_STD_PAL_H |
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V4L2_STD_PAL_I)
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#define V4L2_STD_NTSC (V4L2_STD_NTSC_M |
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V4L2_STD_NTSC_M_JP |
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V4L2_STD_NTSC_M_KR)
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#define V4L2_STD_MN (V4L2_STD_PAL_M |
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V4L2_STD_PAL_N |
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V4L2_STD_PAL_Nc |
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V4L2_STD_NTSC)
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#define V4L2_STD_SECAM_DK (V4L2_STD_SECAM_D |
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V4L2_STD_SECAM_K |
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V4L2_STD_SECAM_K1)
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#define V4L2_STD_DK (V4L2_STD_PAL_DK |
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V4L2_STD_SECAM_DK)
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#define V4L2_STD_SECAM (V4L2_STD_SECAM_B |
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V4L2_STD_SECAM_G |
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V4L2_STD_SECAM_H |
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V4L2_STD_SECAM_DK |
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V4L2_STD_SECAM_L |
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V4L2_STD_SECAM_LC)
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#define V4L2_STD_525_60 (V4L2_STD_PAL_M |
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V4L2_STD_PAL_60 |
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V4L2_STD_NTSC |
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V4L2_STD_NTSC_443)
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#define V4L2_STD_625_50 (V4L2_STD_PAL |
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V4L2_STD_PAL_N |
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V4L2_STD_PAL_Nc |
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V4L2_STD_SECAM)
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#define V4L2_STD_UNKNOWN 0
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#define V4L2_STD_ALL (V4L2_STD_525_60 |
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V4L2_STD_625_50)
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.. raw:: latex
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\begingroup
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\tiny
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\setlength{\tabcolsep}{2pt}
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.. NTSC/M PAL/M /N /B /D /H /I SECAM/B /D /K1 /L
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.. tabularcolumns:: |p{1.43cm}|p{1.38cm}|p{1.59cm}|p{1.7cm}|p{1.7cm}|p{1.17cm}|p{0.64cm}|p{1.71cm}|p{1.6cm}|p{1.07cm}|p{1.07cm}|p{1.07cm}|
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.. _video-standards:
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.. flat-table:: Video Standards (based on :ref:`itu470`)
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:header-rows: 1
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:stub-columns: 0
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* - Characteristics
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- M/NTSC [#f2]_
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- M/PAL
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- N/PAL [#f3]_
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- B, B1, G/PAL
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- D, D1, K/PAL
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- H/PAL
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- I/PAL
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- B, G/SECAM
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- D, K/SECAM
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- K1/SECAM
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- L/SECAM
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* - Frame lines
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- :cspan:`1` 525
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- :cspan:`8` 625
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* - Frame period (s)
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- :cspan:`1` 1001/30000
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- :cspan:`8` 1/25
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* - Chrominance sub-carrier frequency (Hz)
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- 3579545 ± 10
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- 3579611.49 ± 10
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- 4433618.75 ± 5
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(3582056.25 ± 5)
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- :cspan:`3` 4433618.75 ± 5
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- 4433618.75 ± 1
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- :cspan:`2` f\ :sub:`OR` = 4406250 ± 2000,
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f\ :sub:`OB` = 4250000 ± 2000
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* - Nominal radio-frequency channel bandwidth (MHz)
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- 6
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- 6
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- 6
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- B: 7; B1, G: 8
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- 8
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- 8
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- 8
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- 8
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- 8
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- 8
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- 8
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* - Sound carrier relative to vision carrier (MHz)
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- 4.5
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- 4.5
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- 4.5
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- 5.5 ± 0.001 [#f4]_ [#f5]_ [#f6]_ [#f7]_
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- 6.5 ± 0.001
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- 5.5
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- 5.9996 ± 0.0005
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- 5.5 ± 0.001
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- 6.5 ± 0.001
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- 6.5
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- 6.5 [#f8]_
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.. raw:: latex
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\endgroup
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Return Value
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============
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On success 0 is returned, on error -1 and the ``errno`` variable is set
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appropriately. The generic error codes are described at the
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:ref:`Generic Error Codes <gen-errors>` chapter.
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EINVAL
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The struct :c:type:`v4l2_standard` ``index`` is out
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of bounds.
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ENODATA
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Standard video timings are not supported for this input or output.
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.. [#f1]
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The supported standards may overlap and we need an unambiguous set to
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find the current standard returned by :ref:`VIDIOC_G_STD <VIDIOC_G_STD>`.
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.. [#f2]
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Japan uses a standard similar to M/NTSC (V4L2_STD_NTSC_M_JP).
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.. [#f3]
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The values in brackets apply to the combination N/PAL a.k.a.
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N\ :sub:`C` used in Argentina (V4L2_STD_PAL_Nc).
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.. [#f4]
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In the Federal Republic of Germany, Austria, Italy, the Netherlands,
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Slovakia and Switzerland a system of two sound carriers is used, the
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frequency of the second carrier being 242.1875 kHz above the
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frequency of the first sound carrier. For stereophonic sound
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transmissions a similar system is used in Australia.
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.. [#f5]
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New Zealand uses a sound carrier displaced 5.4996 ± 0.0005 MHz from
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the vision carrier.
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.. [#f6]
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In Denmark, Finland, New Zealand, Sweden and Spain a system of two
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sound carriers is used. In Iceland, Norway and Poland the same system
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is being introduced. The second carrier is 5.85 MHz above the vision
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carrier and is DQPSK modulated with 728 kbit/s sound and data
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multiplex. (NICAM system)
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.. [#f7]
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In the United Kingdom, a system of two sound carriers is used. The
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second sound carrier is 6.552 MHz above the vision carrier and is
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DQPSK modulated with a 728 kbit/s sound and data multiplex able to
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carry two sound channels. (NICAM system)
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.. [#f8]
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In France, a digital carrier 5.85 MHz away from the vision carrier
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may be used in addition to the main sound carrier. It is modulated in
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differentially encoded QPSK with a 728 kbit/s sound and data
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multiplexer capable of carrying two sound channels. (NICAM system)
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