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[media] V4L: Add camera exposure bias control 

The camera may in some conditions incorrectly determine the exposure,
and a manual automatic exposure correction may be needed. This patch
adds V4L2_CID_AUTO_EXPOSURE_BIAS control which allows to add some
offset in the automatic exposure control loop, to compensate for
frame under- or over-exposure.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Sylwester Nawrocki 2012-03-06 07:06:55 -03:00 committed by Mauro Carvalho Chehab
parent 515f32879a
commit d58083c949
3 changed files with 22 additions and 0 deletions
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16
Documentation/DocBook/media/v4l/controls.xml
View File

@ -2848,6 +2848,22 @@ remain constant.</entry>
</row>
<row><entry></entry></row>
<row>
<entry spanname="id"><constant>V4L2_CID_EXPOSURE_BIAS</constant>&nbsp;</entry>
<entry>integer menu</entry>
</row><row><entry spanname="descr"> Determines the automatic
exposure compensation, it is effective only when <constant>V4L2_CID_EXPOSURE_AUTO</constant>
control is set to <constant>AUTO</constant>, <constant>SHUTTER_PRIORITY </constant>
or <constant>APERTURE_PRIORITY</constant>.
It is expressed in terms of EV, drivers should interpret the values as 0.001 EV
units, where the value 1000 stands for +1 EV.
<para>Increasing the exposure compensation value is equivalent to decreasing
the exposure value (EV) and will increase the amount of light at the image
sensor. The camera performs the exposure compensation by adjusting absolute
exposure time and/or aperture.</para></entry>
</row>
<row><entry></entry></row>
<row>
<entry spanname="id"><constant>V4L2_CID_PAN_RELATIVE</constant>&nbsp;</entry>
<entry>integer</entry>

4
drivers/media/video/v4l2-ctrls.c
View File

@ -604,6 +604,7 @@ const char *v4l2_ctrl_get_name(u32 id)
case V4L2_CID_PRIVACY: return "Privacy";
case V4L2_CID_IRIS_ABSOLUTE: return "Iris, Absolute";
case V4L2_CID_IRIS_RELATIVE: return "Iris, Relative";
case V4L2_CID_AUTO_EXPOSURE_BIAS: return "Auto Exposure, Bias";
/* FM Radio Modulator control */
/* Keep the order of the 'case's the same as in videodev2.h! */
@ -760,6 +761,9 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
case V4L2_CID_RDS_TX_RADIO_TEXT:
*type = V4L2_CTRL_TYPE_STRING;
break;
case V4L2_CID_AUTO_EXPOSURE_BIAS:
*type = V4L2_CTRL_TYPE_INTEGER_MENU;
break;
case V4L2_CID_USER_CLASS:
case V4L2_CID_CAMERA_CLASS:
case V4L2_CID_MPEG_CLASS:

2
include/linux/videodev2.h
View File

@ -1707,6 +1707,8 @@ enum v4l2_exposure_auto_type {
#define V4L2_CID_IRIS_ABSOLUTE (V4L2_CID_CAMERA_CLASS_BASE+17)
#define V4L2_CID_IRIS_RELATIVE (V4L2_CID_CAMERA_CLASS_BASE+18)
#define V4L2_CID_AUTO_EXPOSURE_BIAS (V4L2_CID_CAMERA_CLASS_BASE+19)
/* FM Modulator class control IDs */
#define V4L2_CID_FM_TX_CLASS_BASE (V4L2_CTRL_CLASS_FM_TX | 0x900)
#define V4L2_CID_FM_TX_CLASS (V4L2_CTRL_CLASS_FM_TX | 1)