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.. -*- coding: utf-8; mode: rst -*-
.. _VIDIOC_ENUM_DV_TIMINGS:
***********************************************************
ioctl VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS
***********************************************************
Name
====
VIDIOC_ENUM_DV_TIMINGS - VIDIOC_SUBDEV_ENUM_DV_TIMINGS - Enumerate supported Digital Video timings
Synopsis
========
.. c:function:: int ioctl( int fd, VIDIOC_ENUM_DV_TIMINGS, struct v4l2_enum_dv_timings *argp )
:name: VIDIOC_ENUM_DV_TIMINGS
.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_ENUM_DV_TIMINGS, struct v4l2_enum_dv_timings *argp )
:name: VIDIOC_SUBDEV_ENUM_DV_TIMINGS
Arguments
=========
``fd``
File descriptor returned by :ref:`open() <func-open>`.
``argp``
Description
===========
While some DV receivers or transmitters support a wide range of timings,
others support only a limited number of timings. With this ioctl
applications can enumerate a list of known supported timings. Call
:ref:`VIDIOC_DV_TIMINGS_CAP` to check if it
also supports other standards or even custom timings that are not in
this list.
To query the available timings, applications initialize the ``index``
field, set the ``pad`` field to 0, zero the reserved array of struct
:c:type:`v4l2_enum_dv_timings` and call the
``VIDIOC_ENUM_DV_TIMINGS`` ioctl on a video node 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 supported
DV timings, applications shall begin at index zero, incrementing by one
until the driver returns ``EINVAL``.
.. note::
Drivers may enumerate a different set of DV timings after
switching the video input or output.
When implemented by the driver DV timings of subdevices can be queried
by calling the ``VIDIOC_SUBDEV_ENUM_DV_TIMINGS`` ioctl directly on a
subdevice node. The DV timings are specific to inputs (for DV receivers)
or outputs (for DV transmitters), applications must specify the desired
pad number in the struct
:c:type:`v4l2_enum_dv_timings` ``pad`` field.
Attempts to enumerate timings on a pad that doesn't support them will
return an ``EINVAL`` error code.
.. c:type:: v4l2_enum_dv_timings
.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
.. flat-table:: struct v4l2_enum_dv_timings
:header-rows: 0
:stub-columns: 0
:widths: 1 1 2
- .. row 1
- __u32
- ``index``
- Number of the DV timings, set by the application.
- .. row 2
- __u32
- ``pad``
- Pad number as reported by the media controller API. This field is
only used when operating on a subdevice node. When operating on a
video node applications must set this field to zero.
- .. row 3
- __u32
- ``reserved``\ [2]
- Reserved for future extensions. Drivers and applications must set
the array to zero.
- .. row 4
- struct :c:type:`v4l2_dv_timings`
- ``timings``
- The timings.
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_enum_dv_timings`
``index`` is out of bounds or the ``pad`` number is invalid.
ENODATA
Digital video presets are not supported for this input or output.
|
