[media] DocBook: media: Document ALPHA_COMPONENT control usage on output devices

Extend the V4L2_CID_ALPHA_COMPONENT control for use on output devices,
to set the alpha component value when the output format doesn't have an
alpha channel.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
This commit is contained in:
Laurent Pinchart 2014-05-21 19:16:01 -03:00 committed by Mauro Carvalho Chehab
parent 977ff0e4fb
commit b04ef7c075

View file

@ -408,14 +408,17 @@ 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
<entry>Sets the alpha color component. When a capture device (or
capture queue of a mem-to-mem device) produces a 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.
and the alpha value is not defined by the device or the mem-to-mem
input data this control lets you select the alpha component value of
all pixels. When an output device (or output queue of a mem-to-mem
device) consumes a frame format that doesn't include an alpha
component and the device supports alpha channel processing this
control lets you set the alpha component value of all pixels for
further processing in the device.
</entry>
</row>
<row>