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authorNaushir Patuck <naush@raspberrypi.com>2020-04-24 11:46:57 +0100
committerLaurent Pinchart <laurent.pinchart@ideasonboard.com>2020-04-27 20:18:08 +0300
commitfa77a02c0a099ad02ed55935bdbe8cd441a8d893 (patch)
tree8290bd44507f8ed45ab9cc465a86941c39b1f68a
parent47d09a13b3acead2cd6007d6b6022931756c9ae7 (diff)
libcamera: controls: Updates to gain and exposure controls
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>
-rw-r--r--src/libcamera/control_ids.yaml22
-rw-r--r--src/libcamera/pipeline/uvcvideo/uvcvideo.cpp78
2 files changed, 88 insertions, 12 deletions
diff --git a/src/libcamera/control_ids.yaml b/src/libcamera/control_ids.yaml
index bcbab195..d8bdb382 100644
--- a/src/libcamera/control_ids.yaml
+++ b/src/libcamera/control_ids.yaml
@@ -12,7 +12,7 @@ controls:
description: |
Enable or disable the AE.
- \sa ManualExposure
+ \sa ExposureTime AnalogueGain
- AeLocked:
type: bool
@@ -30,8 +30,6 @@ controls:
description: |
Enable or disable the AWB.
- \sa ManualGain
-
- Brightness:
type: int32_t
description: Specify a fixed brightness parameter
@@ -44,12 +42,20 @@ controls:
type: int32_t
description: Specify a fixed saturation parameter
- - ManualExposure:
+ - ExposureTime:
type: int32_t
- description: Specify a fixed exposure time in milli-seconds
+ description: |
+ Exposure time (shutter speed) for the frame applied in the sensor
+ device. This value is specified in micro-seconds.
- - ManualGain:
- type: int32_t
- description: Specify a fixed gain parameter
+ \sa AnalogueGain AeEnable
+
+ - AnalogueGain:
+ type: float
+ description: |
+ Analogue gain value applied in the sensor device.
+ The value of the control specifies the gain multiplier applied to all
+ colour channels. This value cannot be lower than 1.0.
+ \sa ExposureTime AeEnable
...
diff --git a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
index b040f246..08462542 100644
--- a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
+++ b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
@@ -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;