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1 | .. -*- coding: utf-8; mode: rst -*- |
2 | ||
3 | .. _dv-timings: | |
4 | ||
5 | ************************** | |
6 | Digital Video (DV) Timings | |
7 | ************************** | |
8 | ||
9 | The video standards discussed so far have been dealing with Analog TV | |
10 | and the corresponding video timings. Today there are many more different | |
11 | hardware interfaces such as High Definition TV interfaces (HDMI), VGA, | |
12 | DVI connectors etc., that carry video signals and there is a need to | |
13 | extend the API to select the video timings for these interfaces. Since | |
14 | it is not possible to extend the :ref:`v4l2_std_id <v4l2-std-id>` | |
15 | due to the limited bits available, a new set of ioctls was added to | |
16 | set/get video timings at the input and output. | |
17 | ||
18 | These ioctls deal with the detailed digital video timings that define | |
19 | each video format. This includes parameters such as the active video | |
20 | width and height, signal polarities, frontporches, backporches, sync | |
21 | widths etc. The ``linux/v4l2-dv-timings.h`` header can be used to get | |
22 | the timings of the formats in the :ref:`cea861` and :ref:`vesadmt` | |
23 | standards. | |
24 | ||
25 | To enumerate and query the attributes of the DV timings supported by a | |
26 | device applications use the | |
7347081e MCC |
27 | :ref:`VIDIOC_ENUM_DV_TIMINGS` and |
28 | :ref:`VIDIOC_DV_TIMINGS_CAP` ioctls. To set | |
5377d91f | 29 | DV timings for the device applications use the |
af4a4d0d | 30 | :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl and to get |
5377d91f | 31 | current DV timings they use the |
4e03cb76 | 32 | :ref:`VIDIOC_G_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl. To detect |
5377d91f | 33 | the DV timings as seen by the video receiver applications use the |
7347081e | 34 | :ref:`VIDIOC_QUERY_DV_TIMINGS` ioctl. |
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35 | |
36 | Applications can make use of the :ref:`input-capabilities` and | |
37 | :ref:`output-capabilities` flags to determine whether the digital | |
38 | video ioctls can be used with the given input or output. |