From: Hans Verkuil <hans.verk...@cisco.com>
Updates sections "Querying Capabilities", "Application Priority",
"Video Inputs and Outputs" and "Audio Inputs and Outputs".
Signed-off-by: Hans Verkuil <hans.verk...@cisco.com>
---
Documentation/DocBook/media/v4l/common.xml | 89 ++++++++++++------------------
1 file changed, 35 insertions(+), 54 deletions(-)
diff --git a/Documentation/DocBook/media/v4l/common.xml
b/Documentation/DocBook/media/v4l/common.xml
index da08df9..f1e4307 100644
--- a/Documentation/DocBook/media/v4l/common.xml
+++ b/Documentation/DocBook/media/v4l/common.xml
@@ -186,15 +186,15 @@ methods</link> supported by the device.</para>
<para>Starting with kernel version 3.1, VIDIOC-QUERYCAP will return the
V4L2 API version used by the driver, with generally matches the Kernel version.
-There's no need of using &VIDIOC-QUERYCAP; to check if an specific ioctl is
-supported, the V4L2 core now returns ENOIOCTLCMD if a driver doesn't provide
+There's no need of using &VIDIOC-QUERYCAP; to check if a specific ioctl is
+supported, the V4L2 core now returns ENOTTY if a driver doesn't provide
support for an ioctl.</para>
<para>Other features can be queried
by calling the respective ioctl, for example &VIDIOC-ENUMINPUT;
to learn about the number, types and names of video connectors on the
device. Although abstraction is a major objective of this API, the
-ioctl also allows driver specific applications to reliable identify
+&VIDIOC-QUERYCAP; ioctl also allows driver specific applications to reliably
identify
the driver.</para>
<para>All V4L2 drivers must support
@@ -224,9 +224,7 @@ Applications requiring a different priority will usually
call
the &VIDIOC-QUERYCAP; ioctl.</para>
<para>Ioctls changing driver properties, such as &VIDIOC-S-INPUT;,
-return an &EBUSY; after another application obtained higher priority.
-An event mechanism to notify applications about asynchronous property
-changes has been proposed but not added yet.</para>
+return an &EBUSY; after another application obtained higher priority.</para>
</section>
<section id="video">
@@ -234,9 +232,9 @@ changes has been proposed but not added yet.</para>
<para>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 or RGB connectors. Only video and VBI
-capture devices have inputs, output devices have outputs, at least one
-each. Radio devices have no video inputs or outputs.</para>
+a.k.a. Composite Video, S-Video or RGB connectors. 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.</para>
<para>To learn about the number and attributes of the
available inputs and outputs applications can enumerate them with the
@@ -245,30 +243,13 @@ available inputs and outputs applications can enumerate
them with the
ioctl also contains signal status information applicable when the
current video input is queried.</para>
- <para>The &VIDIOC-G-INPUT; and &VIDIOC-G-OUTPUT; ioctl return the
+ <para>The &VIDIOC-G-INPUT; and &VIDIOC-G-OUTPUT; ioctls return the
index of the current video input or output. To select a different
input or output applications call the &VIDIOC-S-INPUT; and
-&VIDIOC-S-OUTPUT; ioctl. Drivers must implement all the input ioctls
+&VIDIOC-S-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.</para>
- <!--
- <figure id=io-tree>
- <title>Input and output enumeration is the root of most device
properties.</title>
- <mediaobject>
- <imageobject>
- <imagedata fileref="links.pdf" format="ps" />
- </imageobject>
- <imageobject>
- <imagedata fileref="links.gif" format="gif" />
- </imageobject>
- <textobject>
- <phrase>Links between various device property structures.</phrase>
- </textobject>
- </mediaobject>
- </figure>
- -->
-
<example>
<title>Information about the current video input</title>
@@ -276,20 +257,20 @@ device has one or more outputs.</para>
&v4l2-input; input;
int index;
-if (-1 == ioctl (fd, &VIDIOC-G-INPUT;, &index)) {
- perror ("VIDIOC_G_INPUT");
- exit (EXIT_FAILURE);
+if (-1 == ioctl(fd, &VIDIOC-G-INPUT;, &index)) {
+ perror("VIDIOC_G_INPUT");
+ exit(EXIT_FAILURE);
}
-memset (&input, 0, sizeof (input));
+memset(&input, 0, sizeof(input));
input.index = index;
-if (-1 == ioctl (fd, &VIDIOC-ENUMINPUT;, &input)) {
- perror ("VIDIOC_ENUMINPUT");
- exit (EXIT_FAILURE);
+if (-1 == ioctl(fd, &VIDIOC-ENUMINPUT;, &input)) {
+ perror("VIDIOC_ENUMINPUT");
+ exit(EXIT_FAILURE);
}
-printf ("Current input: %s\n", input.name);
+printf("Current input: %s\n", input.name);
</programlisting>
</example>
@@ -301,9 +282,9 @@ int index;
index = 0;
-if (-1 == ioctl (fd, &VIDIOC-S-INPUT;, &index)) {
- perror ("VIDIOC_S_INPUT");
- exit (EXIT_FAILURE);
+if (-1 == ioctl(fd, &VIDIOC-S-INPUT;, &index)) {
+ perror("VIDIOC_S_INPUT");
+ exit(EXIT_FAILURE);
}
</programlisting>
</example>
@@ -343,7 +324,7 @@ available inputs and outputs applications can enumerate
them with the
also contains signal status information applicable when the current
audio input is queried.</para>
- <para>The &VIDIOC-G-AUDIO; and &VIDIOC-G-AUDOUT; ioctl report
+ <para>The &VIDIOC-G-AUDIO; and &VIDIOC-G-AUDOUT; ioctls report
the current audio input and output, respectively. Note that, unlike
&VIDIOC-G-INPUT; and &VIDIOC-G-OUTPUT; these ioctls return a structure
as <constant>VIDIOC_ENUMAUDIO</constant> and
@@ -354,11 +335,11 @@ applications call the &VIDIOC-S-AUDIO; ioctl. To select
an audio
output (which presently has no changeable properties) applications
call the &VIDIOC-S-AUDOUT; ioctl.</para>
- <para>Drivers must implement all input ioctls when the device
-has one or more inputs, all output ioctls when the device has one
-or more outputs. When the device has any audio inputs or outputs the
-driver must set the <constant>V4L2_CAP_AUDIO</constant> flag in the
-&v4l2-capability; returned by the &VIDIOC-QUERYCAP; ioctl.</para>
+ <para>Drivers must implement all audio input ioctls when the device
+has multiple selectable audio inputs, all audio output ioctls when the
+device has multiple selectable audio outputs. When the device has any
+audio inputs or outputs the driver must set the
<constant>V4L2_CAP_AUDIO</constant>
+flag in the &v4l2-capability; returned by the &VIDIOC-QUERYCAP; ioctl.</para>
<example>
<title>Information about the current audio input</title>
@@ -366,14 +347,14 @@ driver must set the <constant>V4L2_CAP_AUDIO</constant>
flag in the
<programlisting>
&v4l2-audio; audio;
-memset (&audio, 0, sizeof (audio));
+memset(&audio, 0, sizeof(audio));
-if (-1 == ioctl (fd, &VIDIOC-G-AUDIO;, &audio)) {
- perror ("VIDIOC_G_AUDIO");
- exit (EXIT_FAILURE);
+if (-1 == ioctl(fd, &VIDIOC-G-AUDIO;, &audio)) {
+ perror("VIDIOC_G_AUDIO");
+ exit(EXIT_FAILURE);
}
-printf ("Current input: %s\n", audio.name);
+printf("Current input: %s\n", audio.name);
</programlisting>
</example>
@@ -383,13 +364,13 @@ printf ("Current input: %s\n", audio.name);
<programlisting>
&v4l2-audio; audio;
-memset (&audio, 0, sizeof (audio)); /* clear audio.mode, audio.reserved */
+memset(&audio, 0, sizeof(audio)); /* clear audio.mode, audio.reserved */
audio.index = 0;
-if (-1 == ioctl (fd, &VIDIOC-S-AUDIO;, &audio)) {
- perror ("VIDIOC_S_AUDIO");
- exit (EXIT_FAILURE);
+if (-1 == ioctl(fd, &VIDIOC-S-AUDIO;, &audio)) {
+ perror("VIDIOC_S_AUDIO");
+ exit(EXIT_FAILURE);
}
</programlisting>
</example>
--
1.8.5.2
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