From fa77a02c0a099ad02ed55935bdbe8cd441a8d893 Mon Sep 17 00:00:00 2001 From: Naushir Patuck Date: Fri, 24 Apr 2020 11:46:57 +0100 Subject: 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 Reviewed-by: Laurent Pinchart Signed-off-by: Laurent Pinchart Reviewed-by: Jacopo Mondi --- src/libcamera/control_ids.yaml | 22 +++++--- src/libcamera/pipeline/uvcvideo/uvcvideo.cpp | 78 ++++++++++++++++++++++++++-- 2 files changed, 88 insertions(+), 12 deletions(-) (limited to 'src') 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 #include +#include #include #include @@ -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() @@ -270,6 +277,28 @@ int PipelineHandlerUVC::processControl(ControlList *controls, unsigned int id, break; } + case V4L2_CID_EXPOSURE_ABSOLUTE: + controls->set(cid, value.get() / 100); + break; + + case V4L2_CID_GAIN: { + int32_t min = v4l2Info.min().get(); + int32_t max = v4l2Info.max().get(); + int32_t def = v4l2Info.def().get(); + + 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() - p) / m; + controls->set(cid, static_cast(lroundf(fvalue))); + break; + } + default: { int32_t ivalue = value.get(); 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 max = v4l2Info.max().get(); + int32_t def = v4l2Info.def().get(); + 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; -- cgit v1.2.1