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@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
Acked-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
---
The only change since v2 is removed limitation of maximum value to 0xff.
---
Documentation/DocBook/media/v4l/compat.xml | 11 ++++++++
Documentation/DocBook/media/v4l/controls.xml | 25 +++++++++++++++----
.../DocBook/media/v4l/pixfmt-packed-rgb.xml | 7 ++++-
drivers/media/video/v4l2-ctrls.c | 1 +
include/linux/videodev2.h | 6 ++--
5 files changed, 39 insertions(+), 11 deletions(-)
diff --git a/Documentation/DocBook/media/v4l/compat.xml b/Documentation/DocBook/media/v4l/compat.xml
index b68698f..0adda43 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.
</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>
diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
index 3bc5ee8..4fd83c0 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>
</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>
<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>
+ <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>
diff --git a/Documentation/DocBook/media/v4l/pixfmt-packed-rgb.xml b/Documentation/DocBook/media/v4l/pixfmt-packed-rgb.xml
index 4db272b..c13278b 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>
<example>
<title><constant>V4L2_PIX_FMT_BGR24</constant> 4 × 4 pixel
diff --git a/drivers/media/video/v4l2-ctrls.c b/drivers/media/video/v4l2-ctrls.c
index b59b00a..03fcb93 100644
--- a/drivers/media/video/v4l2-ctrls.c
+++ b/drivers/media/video/v4l2-ctrls.c
@@ -466,6 +466,7 @@ 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! */
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index 22e632a..2f6bbba 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -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)
--
1.7.7.2
--
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