1.. Permission is granted to copy, distribute and/or modify this
2.. document under the terms of the GNU Free Documentation License,
3.. Version 1.1 or any later version published by the Free Software
4.. Foundation, with no Invariant Sections, no Front-Cover Texts
5.. and no Back-Cover Texts. A copy of the license is included at
6.. Documentation/userspace-api/media/fdl-appendix.rst.
7..
8.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
9
10.. _dv-timings:
11
12**************************
13Digital Video (DV) Timings
14**************************
15
16The video standards discussed so far have been dealing with Analog TV
17and the corresponding video timings. Today there are many more different
18hardware interfaces such as High Definition TV interfaces (HDMI), VGA,
19DVI connectors etc., that carry video signals and there is a need to
20extend the API to select the video timings for these interfaces. Since
21it is not possible to extend the :ref:`v4l2_std_id <v4l2-std-id>`
22due to the limited bits available, a new set of ioctls was added to
23set/get video timings at the input and output.
24
25These ioctls deal with the detailed digital video timings that define
26each video format. This includes parameters such as the active video
27width and height, signal polarities, frontporches, backporches, sync
28widths etc. The ``linux/v4l2-dv-timings.h`` header can be used to get
29the timings of the formats in the :ref:`cea861` and :ref:`vesadmt`
30standards.
31
32To enumerate and query the attributes of the DV timings supported by a
33device applications use the
34:ref:`VIDIOC_ENUM_DV_TIMINGS` and
35:ref:`VIDIOC_DV_TIMINGS_CAP` ioctls. To set
36DV timings for the device applications use the
37:ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl and to get
38current DV timings they use the
39:ref:`VIDIOC_G_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl. To detect
40the DV timings as seen by the video receiver applications use the
41:ref:`VIDIOC_QUERY_DV_TIMINGS` ioctl.
42
43Applications can make use of the :ref:`input-capabilities` and
44:ref:`output-capabilities` flags to determine whether the digital
45video ioctls can be used with the given input or output.
46