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