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libcamera: controls: Updates to gain and exposure controls

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Rename:
ManualExposure -> ExposureTime
ManualGain -> AnalogueGain

Use micro-seconds units for ExposureTime. This is changed from milli-
seconds. The latter would not allow very low exposure times.
AnalogueGain switch to use a float to allow fractional gain adjustments.

Update the uvcvideo pipeline handler to use the new exposure and gain
units. For ExposureTime, UVC uses units of 100 micro-seconds, so map
the values before setting V4L2_CID_EXPOSURE_ABSOLUTE. For AnalogueGain,
UVC has no explicit gain units, so map the default gain value to 1.0
and linearly scale to the requested value.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
This commit is contained in:
Naushir Patuck
2020-04-24 11:46:57 +01:00
committed by Laurent Pinchart
parent 47d09a13b3
commit fa77a02c0a
2 changed files with 88 additions and 12 deletions
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src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
+74 -4
View File
@@ -7,6 +7,7 @@
#include <algorithm>
#include <iomanip>
#include <math.h>
#include <sys/sysmacros.h>
#include <tuple>
@@ -254,13 +255,19 @@ int PipelineHandlerUVC::processControl(ControlList *controls, unsigned int id,
cid = V4L2_CID_SATURATION;
else if (id == controls::AeEnable)
cid = V4L2_CID_EXPOSURE_AUTO;
else if (id == controls::ManualExposure)
else if (id == controls::ExposureTime)
cid = V4L2_CID_EXPOSURE_ABSOLUTE;
else if (id == controls::ManualGain)
else if (id == controls::AnalogueGain)
cid = V4L2_CID_GAIN;
else
return -EINVAL;
const ControlInfo &v4l2Info = controls->infoMap()->at(cid);
/*
* See UVCCameraData::addControl() for explanations of the different
* value mappings.
*/
switch (cid) {
case V4L2_CID_EXPOSURE_AUTO: {
int32_t ivalue = value.get<bool>()
@@ -270,6 +277,28 @@ int PipelineHandlerUVC::processControl(ControlList *controls, unsigned int id,
break;
}
case V4L2_CID_EXPOSURE_ABSOLUTE:
controls->set(cid, value.get<int32_t>() / 100);
break;
case V4L2_CID_GAIN: {
int32_t min = v4l2Info.min().get<int32_t>();
int32_t max = v4l2Info.max().get<int32_t>();
int32_t def = v4l2Info.def().get<int32_t>();
float m = (4.0f - 1.0f) / (max - def);
float p = 1.0f - m * def;
if (m * min + p < 0.5f) {
m = (1.0f - 0.5f) / (def - min);
p = 1.0f - m * def;
}
float fvalue = (value.get<float>() - p) / m;
controls->set(cid, static_cast<int32_t>(lroundf(fvalue)));
break;
}
default: {
int32_t ivalue = value.get<int32_t>();
controls->set(cid, ivalue);
@@ -413,21 +442,62 @@ void UVCCameraData::addControl(uint32_t cid, const ControlInfo &v4l2Info,
id = &controls::AeEnable;
break;
case V4L2_CID_EXPOSURE_ABSOLUTE:
id = &controls::ManualExposure;
id = &controls::ExposureTime;
break;
case V4L2_CID_GAIN:
id = &controls::ManualGain;
id = &controls::AnalogueGain;
break;
default:
return;
}
/* Map the control info. */
int32_t min = v4l2Info.min().get<int32_t>();
int32_t max = v4l2Info.max().get<int32_t>();
int32_t def = v4l2Info.def().get<int32_t>();
switch (cid) {
case V4L2_CID_EXPOSURE_AUTO:
info = ControlInfo{ false, true, true };
break;
case V4L2_CID_EXPOSURE_ABSOLUTE:
/*
* ExposureTime is in units of 1 µs, and UVC expects
* V4L2_CID_EXPOSURE_ABSOLUTE in units of 100 µs.
*/
info = ControlInfo{
{ min * 100 },
{ max * 100 },
{ def * 100 }
};
break;
case V4L2_CID_GAIN: {
/*
* The AnalogueGain control is a float, with 1.0 mapped to the
* default value. UVC doesn't specify units, and cameras have
* been seen to expose very different ranges for the gain
* control. Arbitrarily assume that the minimum and maximum
* values are respectively no lower than 0.5 and no higher than
* 4.0.
*/
float m = (4.0f - 1.0f) / (max - def);
float p = 1.0f - m * def;
if (m * min + p < 0.5f) {
m = (1.0f - 0.5f) / (def - min);
p = 1.0f - m * def;
}
info = ControlInfo{
{ m * min + p },
{ m * max + p },
{ 1.0f }
};
break;
}
default:
info = v4l2Info;
break;