Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 68 insertions, 0 deletions

diff --git a/Documentation/media/uapi/v4l/video.rst b/Documentation/media/uapi/v4l/video.rst
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+.. -*- coding: utf-8; mode: rst -*-
+
+.. _video:
+
+************************
+Video Inputs and Outputs
+************************
+
+Video inputs and outputs are physical connectors of a device. These can
+be for example RF connectors (antenna/cable), CVBS a.k.a. Composite
+Video, S-Video and RGB connectors. Camera sensors are also considered to
+be a video input. Video and VBI capture devices have inputs. Video and
+VBI output devices have outputs, at least one each. Radio devices have
+no video inputs or outputs.
+
+To learn about the number and attributes of the available inputs and
+outputs applications can enumerate them with the
+:ref:`VIDIOC_ENUMINPUT` and
+:ref:`VIDIOC_ENUMOUTPUT` ioctl, respectively. The
+struct :c:type:`v4l2_input` returned by the
+:ref:`VIDIOC_ENUMINPUT` ioctl also contains signal
+:status information applicable when the current video input is queried.
+
+The :ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` and
+:ref:`VIDIOC_G_OUTPUT <VIDIOC_G_OUTPUT>` ioctls return the index of
+the current video input or output. To select a different input or output
+applications call the :ref:`VIDIOC_S_INPUT <VIDIOC_G_INPUT>` and
+:ref:`VIDIOC_S_OUTPUT <VIDIOC_G_OUTPUT>` ioctls. Drivers must
+implement all the input ioctls when the device has one or more inputs,
+all the output ioctls when the device has one or more outputs.
+
+Example: Information about the current video input
+==================================================
+
+.. code-block:: c
+
+    struct v4l2_input input;
+    int index;
+
+    if (-1 == ioctl(fd, VIDIOC_G_INPUT, &index)) {
+	perror("VIDIOC_G_INPUT");
+	exit(EXIT_FAILURE);
+    }
+
+    memset(&input, 0, sizeof(input));
+    input.index = index;
+
+    if (-1 == ioctl(fd, VIDIOC_ENUMINPUT, &input)) {
+	perror("VIDIOC_ENUMINPUT");
+	exit(EXIT_FAILURE);
+    }
+
+    printf("Current input: %s\\n", input.name);
+
+
+Example: Switching to the first video input
+===========================================
+
+.. code-block:: c
+
+    int index;
+
+    index = 0;
+
+    if (-1 == ioctl(fd, VIDIOC_S_INPUT, &index)) {
+	perror("VIDIOC_S_INPUT");
+	exit(EXIT_FAILURE);
+    }