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351 lines
11 KiB
351 lines
11 KiB
.. 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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