On Thursday, November 24, 2011 12:39:54 Sylwester Nawrocki wrote: > Hi Laurent, > > On 11/24/2011 12:09 PM, Laurent Pinchart wrote: > > Hi Sylwester and Hans, > > > > On Thursday 24 November 2011 12:00:45 Hans Verkuil wrote: > >> On Thursday, November 24, 2011 11:53:16 Sylwester Nawrocki wrote: > >>> This control is intended for video capture or memory-to-memory > >>> devices that are capable of setting up the alpha conponent to > >>> some arbitrary value. > >>> The V4L2_CID_COLOR_ALPHA control allows to set the alpha channel > >>> globally to a value in range from 0 to 255. > >>> > >>> Signed-off-by: Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx> > >>> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> > >>> --- > >>> > >>> Documentation/DocBook/media/v4l/controls.xml | 20 > >>> ++++++++++++++------ .../DocBook/media/v4l/pixfmt-packed-rgb.xml > >>> | 7 +++++-- drivers/media/video/v4l2-ctrls.c | > >>> 7 +++++++ include/linux/videodev2.h | 6 > >>> +++--- 4 files changed, 29 insertions(+), 11 deletions(-) > >>> > >>> diff --git a/Documentation/DocBook/media/v4l/controls.xml > >>> b/Documentation/DocBook/media/v4l/controls.xml index 3bc5ee8..7f99222 > >>> 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 +339,20 @@ 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-color-alpha"> > >>> + <entry><constant>V4L2_CID_COLOR_ALPHA</constant></entry> > >>> + <entry>integer</entry> > >>> + <entry> Sets the color alpha component on the capture device. It is > >>> + applicable to any pixel formats that contain the alpha component, > >>> + e.g. <link linkend="rgb-formats">packed RGB image formats</link>. > >>> + </entry> > > > > As the alpha value is global, isn't it applicable to formats with no alpha > > component as well ? > > Hmm, I can't say no.. The control was intended as a means of setting up > the alpha value for packed RGB formats: > http://linuxtv.org/downloads/v4l-dvb-apis/packed-rgb.html#rgb-formats > > However it could well be used for formats with no alpha. Do you think > the second sentence above should be removed or should something else be > added to indicate it doesn't necessarily have to have a connection > with ARGB color formats ? Huh? How can this be used for formats without an alpha channel? > > > > >>> + </row> > >>> + <row> > >>> + <entry><constant>V4L2_CID_LASTP1</constant></entry> > >>> + <entry></entry> > >>> + <entry>End of the predefined control IDs (currently > >>> + <constant>V4L2_CID_COLOR_ALPHA</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..da4c360 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 global alpha has been configured > >>> +for a <link linkend="capture">Video Capture</link> by means of > >>> +<link linkend="v4l2-color-alpha"> <constant>V4L2_CID_COLOR_ALPHA > >>> +</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 5552f81..bd90955 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_COLOR_ALPHA: return "Color Alpha"; > >> > >> I prefer CID_ALPHA_COLOR and string "Alpha Color". I think it is more > >> natural than the other way around. > > OK, I guess you're right. And Google returns about twice as many hits for > "alpha color" than for "color alpha"... > > > > > I'm not too found of "color" in the name. Is the alpha value considered as a > > color ? > > Certainly it isn't, but Alpha alone looks a bit odd. It's too generic IMHO. How about V4L2_CID_ALPHA_COMPONENT? Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
