path: root/Documentation/DocBook/media/v4l
diff options
authorSylwester Nawrocki <s.nawrocki@samsung.com>2011-11-14 08:48:18 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2011-12-30 14:05:08 -0200
commitcc1d327232759647ea56725eab1c6b16c92d52fa (patch)
treec929516390d3aade90f4a87f29ceaa05be47aa6a /Documentation/DocBook/media/v4l
parentb4d48c942c17ce3d3a330ad91e109e522bc97378 (diff)
[media] v4l: Add new alpha component control
The V4L2_CID_ALPHA_COMPONENT control is intended for the video capture or memory-to-memory devices that are capable of setting up the per-pixel alpha component to some arbitrary value. It allows to set the alpha component for all pixels to an arbitrary value. Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation/DocBook/media/v4l')
3 files changed, 35 insertions, 8 deletions
diff --git a/Documentation/DocBook/media/v4l/compat.xml b/Documentation/DocBook/media/v4l/compat.xml
index 8b44a43f454..12ba26262d3 100644
--- a/Documentation/DocBook/media/v4l/compat.xml
+++ b/Documentation/DocBook/media/v4l/compat.xml
@@ -2379,6 +2379,17 @@ that used it. It was originally scheduled for removal in 2.6.35.
+ <section>
+ <title>V4L2 in Linux 3.3</title>
+ <orderedlist>
+ <listitem>
+ <para>Added <constant>V4L2_CID_ALPHA_COMPONENT</constant> control
+ to the <link linkend="control">User controls class</link>.
+ </para>
+ </listitem>
+ </orderedlist>
+ </section>
<section id="other">
<title>Relation of V4L2 to other Linux multimedia APIs</title>
diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
index c0422c62233..a1be37897ad 100644
--- a/Documentation/DocBook/media/v4l/controls.xml
+++ b/Documentation/DocBook/media/v4l/controls.xml
@@ -324,12 +324,6 @@ minimum value disables backlight compensation.</entry>
(usually a microscope).</entry>
- <entry><constant>V4L2_CID_LASTP1</constant></entry>
- <entry></entry>
- <entry>End of the predefined control IDs (currently
-<constant>V4L2_CID_ILLUMINATORS_2</constant> + 1).</entry>
- </row>
- <row>
<entry>This is a read-only control that can be read by the application
@@ -345,6 +339,25 @@ and used as a hint to determine the number of OUTPUT buffers to pass to REQBUFS.
The value is the minimum number of OUTPUT buffers that is necessary for hardware
to work.</entry>
+ <row id="v4l2-alpha-component">
+ <entry><constant>V4L2_CID_ALPHA_COMPONENT</constant></entry>
+ <entry>integer</entry>
+ <entry> Sets the alpha color component on the capture device or on
+ the capture buffer queue of a mem-to-mem device. When a mem-to-mem
+ device produces frame format that includes an alpha component
+ (e.g. <link linkend="rgb-formats">packed RGB image formats</link>)
+ and the alpha value is not defined by the mem-to-mem input data
+ this control lets you select the alpha component value of all
+ pixels. It is applicable to any pixel format that contains an alpha
+ component.
+ </entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_CID_LASTP1</constant></entry>
+ <entry></entry>
+ <entry>End of the predefined control IDs (currently
+ <constant>V4L2_CID_ALPHA_COMPONENT</constant> + 1).</entry>
+ </row>
diff --git a/Documentation/DocBook/media/v4l/pixfmt-packed-rgb.xml b/Documentation/DocBook/media/v4l/pixfmt-packed-rgb.xml
index ba56536622f..166c8d65e4f 100644
--- a/Documentation/DocBook/media/v4l/pixfmt-packed-rgb.xml
+++ b/Documentation/DocBook/media/v4l/pixfmt-packed-rgb.xml
@@ -428,8 +428,11 @@ colorspace <constant>V4L2_COLORSPACE_SRGB</constant>.</para>
<para>Bit 7 is the most significant bit. The value of a = alpha
bits is undefined when reading from the driver, ignored when writing
to the driver, except when alpha blending has been negotiated for a
-<link linkend="overlay">Video Overlay</link> or <link
-linkend="osd">Video Output Overlay</link>.</para>
+<link linkend="overlay">Video Overlay</link> or <link linkend="osd">
+Video Output Overlay</link> or when alpha component has been configured
+for a <link linkend="capture">Video Capture</link> by means of <link
+linkend="v4l2-alpha-component"> <constant>V4L2_CID_ALPHA_COMPONENT
+</constant> </link> control.</para>
<title><constant>V4L2_PIX_FMT_BGR24</constant> 4 &times; 4 pixel