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diff --git a/Documentation/userspace-api/media/v4l/dv-timings.rst b/Documentation/userspace-api/media/v4l/dv-timings.rst new file mode 100644 index 000000000..e17f056b1 --- /dev/null +++ b/Documentation/userspace-api/media/v4l/dv-timings.rst @@ -0,0 +1,38 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later + +.. _dv-timings: + +************************** +Digital Video (DV) Timings +************************** + +The video standards discussed so far have been dealing with Analog TV +and the corresponding video timings. Today there are many more different +hardware interfaces such as High Definition TV interfaces (HDMI), VGA, +DVI connectors etc., that carry video signals and there is a need to +extend the API to select the video timings for these interfaces. Since +it is not possible to extend the :ref:`v4l2_std_id <v4l2-std-id>` +due to the limited bits available, a new set of ioctls was added to +set/get video timings at the input and output. + +These ioctls deal with the detailed digital video timings that define +each video format. This includes parameters such as the active video +width and height, signal polarities, frontporches, backporches, sync +widths etc. The ``linux/v4l2-dv-timings.h`` header can be used to get +the timings of the formats in the :ref:`cea861` and :ref:`vesadmt` +standards. + +To enumerate and query the attributes of the DV timings supported by a +device applications use the +:ref:`VIDIOC_ENUM_DV_TIMINGS` and +:ref:`VIDIOC_DV_TIMINGS_CAP` ioctls. To set +DV timings for the device applications use the +:ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl and to get +current DV timings they use the +:ref:`VIDIOC_G_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl. To detect +the DV timings as seen by the video receiver applications use the +:ref:`VIDIOC_QUERY_DV_TIMINGS` ioctl. + +Applications can make use of the :ref:`input-capabilities` and +:ref:`output-capabilities` flags to determine whether the digital +video ioctls can be used with the given input or output. |