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[media] v4l: Add new alpha component control

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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>
This commit is contained in:
Sylwester Nawrocki 2011-11-14 08:48:18 -03:00 committed by Mauro Carvalho Chehab
parent b4d48c942c
commit cc1d327232
5 changed files with 39 additions and 11 deletions
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11
Documentation/DocBook/media/v4l/compat.xml
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@ -2379,6 +2379,17 @@ that used it. It was originally scheduled for removal in 2.6.35.
</orderedlist>
</section>
<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>

25
Documentation/DocBook/media/v4l/controls.xml
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@ -323,12 +323,6 @@ minimum value disables backlight compensation.</entry>
<entry>Switch on or off the illuminator 1 or 2 of the device
(usually a microscope).</entry>
</row>
<row>
<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><constant>V4L2_CID_MIN_BUFFERS_FOR_CAPTURE</constant></entry>
<entry>integer</entry>
@ -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>
<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>
<row>
<entry><constant>V4L2_CID_PRIVATE_BASE</constant></entry>
<entry></entry>

7
Documentation/DocBook/media/v4l/pixfmt-packed-rgb.xml
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@ -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>
<example>
<title><constant>V4L2_PIX_FMT_BGR24</constant> 4 &times; 4 pixel

1
drivers/media/video/v4l2-ctrls.c
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@ -467,6 +467,7 @@ const char *v4l2_ctrl_get_name(u32 id)
case V4L2_CID_ILLUMINATORS_2: return "Illuminator 2";
case V4L2_CID_MIN_BUFFERS_FOR_CAPTURE: return "Minimum Number of Capture Buffers";
case V4L2_CID_MIN_BUFFERS_FOR_OUTPUT: return "Minimum Number of Output Buffers";
case V4L2_CID_ALPHA_COMPONENT: return "Alpha Component";
/* MPEG controls */
/* Keep the order of the 'case's the same as in videodev2.h! */

6
include/linux/videodev2.h
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@ -1204,10 +1204,10 @@ enum v4l2_colorfx {
#define V4L2_CID_MIN_BUFFERS_FOR_CAPTURE (V4L2_CID_BASE+39)
#define V4L2_CID_MIN_BUFFERS_FOR_OUTPUT (V4L2_CID_BASE+40)
/* last CID + 1 */
#define V4L2_CID_LASTP1 (V4L2_CID_BASE+41)
#define V4L2_CID_ALPHA_COMPONENT (V4L2_CID_BASE+41)
/* Minimum number of buffer neede by the device */
/* last CID + 1 */
#define V4L2_CID_LASTP1 (V4L2_CID_BASE+42)
/* MPEG-class control IDs defined by V4L2 */
#define V4L2_CID_MPEG_BASE (V4L2_CTRL_CLASS_MPEG | 0x900)