Markus Heiser | 5377d91 | 2016-06-30 15:18:56 +0200 | [diff] [blame^] | 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 |
| 27 | :ref:`VIDIOC_ENUM_DV_TIMINGS <vidioc-enum-dv-timings>` and |
| 28 | :ref:`VIDIOC_DV_TIMINGS_CAP <vidioc-dv-timings-cap>` ioctls. To set |
| 29 | DV timings for the device applications use the |
| 30 | :ref:`VIDIOC_S_DV_TIMINGS <vidioc-g-dv-timings>` ioctl and to get |
| 31 | current DV timings they use the |
| 32 | :ref:`VIDIOC_G_DV_TIMINGS <vidioc-g-dv-timings>` ioctl. To detect |
| 33 | the DV timings as seen by the video receiver applications use the |
| 34 | :ref:`VIDIOC_QUERY_DV_TIMINGS <vidioc-query-dv-timings>` ioctl. |
| 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. |
| 39 | |
| 40 | |
| 41 | .. ------------------------------------------------------------------------------ |
| 42 | .. This file was automatically converted from DocBook-XML with the dbxml |
| 43 | .. library (https://github.com/return42/sphkerneldoc). The origin XML comes |
| 44 | .. from the linux kernel, refer to: |
| 45 | .. |
| 46 | .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook |
| 47 | .. ------------------------------------------------------------------------------ |