libcamera: libcamera::controls Namespace Reference

libcamera v0.0.5 Supporting cameras in Linux since 2019

Loading...
Searching...
No Matches
Namespaces | Enumerations | Variables
libcamera::controls Namespace Reference

Namespace for libcamera controls. More...

## Namespaces
namespace | draft
| Namespace for libcamera draft controls.

## Enumerations
enum | { AE_ENABLE = 1 , AE_LOCKED = 2 , AE_METERING_MODE = 3 , AE_CONSTRAINT_MODE = 4 , AE_EXPOSURE_MODE = 5 , EXPOSURE_VALUE = 6 , EXPOSURE_TIME = 7 , ANALOGUE_GAIN = 8 , BRIGHTNESS = 9 , CONTRAST = 10 , LUX = 11 , AWB_ENABLE = 12 , AWB_MODE = 13 , AWB_LOCKED = 14 , COLOUR_GAINS = 15 , COLOUR_TEMPERATURE = 16 , SATURATION = 17 , SENSOR_BLACK_LEVELS = 18 , SHARPNESS = 19 , FOCUS_FO_M = 20 , COLOUR_CORRECTION_MATRIX = 21 , SCALER_CROP = 22 , DIGITAL_GAIN = 23 , FRAME_DURATION = 24 , FRAME_DURATION_LIMITS = 25 , SENSOR_TEMPERATURE = 26 , SENSOR_TIMESTAMP = 27 , AF_MODE = 28 , AF_RANGE = 29 , AF_SPEED = 30 , AF_METERING = 31 , AF_WINDOWS = 32 , AF_TRIGGER = 33 , AF_PAUSE = 34 , LENS_POSITION = 35 , AF_STATE = 36 , AF_PAUSE_STATE = 37 , AE_PRECAPTURE_TRIGGER = 38 , NOISE_REDUCTION_MODE = 39 , COLOR_CORRECTION_ABERRATION_MODE = 40 , AE_STATE = 41 , AWB_STATE = 42 , SENSOR_ROLLING_SHUTTER_SKEW = 43 , LENS_SHADING_MAP_MODE = 44 , SCENE_FLICKER = 45 , PIPELINE_DEPTH = 46 , MAX_LATENCY = 47 , TEST_PATTERN_MODE = 48 }
enum | AeMeteringModeEnum { MeteringCentreWeighted = 0 , MeteringSpot = 1 , MeteringMatrix = 2 , MeteringCustom = 3 }
| Supported AeMeteringMode values. More...
enum | AeConstraintModeEnum { ConstraintNormal = 0 , ConstraintHighlight = 1 , ConstraintShadows = 2 , ConstraintCustom = 3 }
| Supported AeConstraintMode values. More...
enum | AeExposureModeEnum { ExposureNormal = 0 , ExposureShort = 1 , ExposureLong = 2 , ExposureCustom = 3 }
| Supported AeExposureMode values. More...
enum | AwbModeEnum { AwbAuto = 0 , AwbIncandescent = 1 , AwbTungsten = 2 , AwbFluorescent = 3 , AwbIndoor = 4 , AwbDaylight = 5 , AwbCloudy = 6 , AwbCustom = 7 }
| Supported AwbMode values. More...
enum | AfModeEnum { AfModeManual = 0 , AfModeAuto = 1 , AfModeContinuous = 2 }
| Supported AfMode values. More...
enum | AfRangeEnum { AfRangeNormal = 0 , AfRangeMacro = 1 , AfRangeFull = 2 }
| Supported AfRange values. More...
enum | AfSpeedEnum { AfSpeedNormal = 0 , AfSpeedFast = 1 }
| Supported AfSpeed values. More...
enum | AfMeteringEnum { AfMeteringAuto = 0 , AfMeteringWindows = 1 }
| Supported AfMetering values. More...
enum | AfTriggerEnum { AfTriggerStart = 0 , AfTriggerCancel = 1 }
| Supported AfTrigger values. More...
enum | AfPauseEnum { AfPauseImmediate = 0 , AfPauseDeferred = 1 , AfPauseResume = 2 }
| Supported AfPause values. More...
enum | AfStateEnum { AfStateIdle = 0 , AfStateScanning = 1 , AfStateFocused = 2 , AfStateFailed = 3 }
| Supported AfState values. More...
enum | AfPauseStateEnum { AfPauseStateRunning = 0 , AfPauseStatePausing = 1 , AfPauseStatePaused = 2 }
| Supported AfPauseState values. More...

## Variables
const Control< bool > | AeEnable
| Enable or disable the AE.
const Control< bool > | AeLocked
| Report the lock status of a running AE algorithm.
const std::array< const ControlValue, 4 > | AeMeteringModeValues
| List of all AeMeteringMode supported values.
const Control< int32_t > | AeMeteringMode
| Specify a metering mode for the AE algorithm to use. The metering modes determine which parts of the image are used to determine the scene brightness. Metering modes may be platform specific and not all metering modes may be supported.
const std::array< const ControlValue, 4 > | AeConstraintModeValues
| List of all AeConstraintMode supported values.
const Control< int32_t > | AeConstraintMode
| Specify a constraint mode for the AE algorithm to use. These determine how the measured scene brightness is adjusted to reach the desired target exposure. Constraint modes may be platform specific, and not all constraint modes may be supported.
const std::array< const ControlValue, 4 > | AeExposureModeValues
| List of all AeExposureMode supported values.
const Control< int32_t > | AeExposureMode
| Specify an exposure mode for the AE algorithm to use. These specify how the desired total exposure is divided between the shutter time and the sensor's analogue gain. The exposure modes are platform specific, and not all exposure modes may be supported.
const Control< float > | ExposureValue
| Specify an Exposure Value (EV) parameter. The EV parameter will only be applied if the AE algorithm is currently enabled.
const Control< int32_t > | ExposureTime
| Exposure time (shutter speed) for the frame applied in the sensor device. This value is specified in micro-seconds.
const Control< float > | AnalogueGain
| 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.
const Control< float > | Brightness
| Specify a fixed brightness parameter. Positive values (up to 1.0) produce brighter images; negative values (up to -1.0) produce darker images and 0.0 leaves pixels unchanged.
const Control< float > | Contrast
| Specify a fixed contrast parameter. Normal contrast is given by the value 1.0; larger values produce images with more contrast.
const Control< float > | Lux
| Report an estimate of the current illuminance level in lux. The Lux control can only be returned in metadata.
const Control< bool > | AwbEnable
| Enable or disable the AWB.
const std::array< const ControlValue, 8 > | AwbModeValues
| List of all AwbMode supported values.
const Control< int32_t > | AwbMode
| Specify the range of illuminants to use for the AWB algorithm. The modes supported are platform specific, and not all modes may be supported.
const Control< bool > | AwbLocked
| Report the lock status of a running AWB algorithm.
const Control< Span< const float, 2 > > | ColourGains
| Pair of gain values for the Red and Blue colour channels, in that order. ColourGains can only be applied in a Request when the AWB is disabled.
const Control< int32_t > | ColourTemperature
| Report the current estimate of the colour temperature, in kelvin, for this frame. The ColourTemperature control can only be returned in metadata.
const Control< float > | Saturation
| Specify a fixed saturation parameter. Normal saturation is given by the value 1.0; larger values produce more saturated colours; 0.0 produces a greyscale image.
const Control< Span< const int32_t, 4 > > | SensorBlackLevels
| Reports the sensor black levels used for processing a frame, in the order R, Gr, Gb, B. These values are returned as numbers out of a 16-bit pixel range (as if pixels ranged from 0 to 65535). The SensorBlackLevels control can only be returned in metadata.
const Control< float > | Sharpness
| A value of 0.0 means no sharpening. The minimum value means minimal sharpening, and shall be 0.0 unless the camera can't disable sharpening completely. The default value shall give a "reasonable" level of sharpening, suitable for most use cases. The maximum value may apply extremely high levels of sharpening, higher than anyone could reasonably want. Negative values are not allowed. Note also that sharpening is not applied to raw streams.
const Control< int32_t > | FocusFoM
| Reports a Figure of Merit (FoM) to indicate how in-focus the frame is. A larger FocusFoM value indicates a more in-focus frame. This control depends on the IPA to gather ISP statistics from the defined focus region, and combine them in a suitable way to generate a FocusFoM value. In this respect, it is not necessarily aimed at providing a way to implement a focus algorithm by the application, rather an indication of how in-focus a frame is.
const Control< Span< const float, 9 > > | ColourCorrectionMatrix
| The 3x3 matrix that converts camera RGB to sRGB within the imaging pipeline. This should describe the matrix that is used after pixels have been white-balanced, but before any gamma transformation. The 3x3 matrix is stored in conventional reading order in an array of 9 floating point values.
const Control< Rectangle > | ScalerCrop
| Sets the image portion that will be scaled to form the whole of the final output image. The (x,y) location of this rectangle is relative to the PixelArrayActiveAreas that is being used. The units remain native sensor pixels, even if the sensor is being used in a binning or skipping mode.
const Control< float > | DigitalGain
| Digital gain value applied during the processing steps applied to the image as captured from the sensor.
const Control< int64_t > | FrameDuration
| The instantaneous frame duration from start of frame exposure to start of next exposure, expressed in microseconds. This control is meant to be returned in metadata.
const Control< Span< const int64_t, 2 > > | FrameDurationLimits
| The minimum and maximum (in that order) frame duration, expressed in microseconds.
const Control< float > | SensorTemperature
| Temperature measure from the camera sensor in Celsius. This is typically obtained by a thermal sensor present on-die or in the camera module. The range of reported temperatures is device dependent.
const Control< int64_t > | SensorTimestamp
| The time when the first row of the image sensor active array is exposed.
const std::array< const ControlValue, 3 > | AfModeValues
| List of all AfMode supported values.
const Control< int32_t > | AfMode
| Control to set the mode of the AF (autofocus) algorithm.
const std::array< const ControlValue, 3 > | AfRangeValues
| List of all AfRange supported values.
const Control< int32_t > | AfRange
| Control to set the range of focus distances that is scanned. An implementation may choose not to implement all the options here.
const std::array< const ControlValue, 2 > | AfSpeedValues
| List of all AfSpeed supported values.
const Control< int32_t > | AfSpeed
| Control that determines whether the AF algorithm is to move the lens as quickly as possible or more steadily. For example, during video recording it may be desirable not to move the lens too abruptly, but when in a preview mode (waiting for a still capture) it may be helpful to move the lens as quickly as is reasonably possible.
const std::array< const ControlValue, 2 > | AfMeteringValues
| List of all AfMetering supported values.
const Control< int32_t > | AfMetering
| Instruct the AF algorithm how it should decide which parts of the image should be used to measure focus.
const Control< Span< const Rectangle > > | AfWindows
| Sets the focus windows used by the AF algorithm when AfMetering is set to AfMeteringWindows. The units used are pixels within the rectangle returned by the ScalerCropMaximum property.
const std::array< const ControlValue, 2 > | AfTriggerValues
| List of all AfTrigger supported values.
const Control< int32_t > | AfTrigger
| This control starts an autofocus scan when AfMode is set to AfModeAuto, and can also be used to terminate a scan early.
const std::array< const ControlValue, 3 > | AfPauseValues
| List of all AfPause supported values.
const Control< int32_t > | AfPause
| This control has no effect except when in continuous autofocus mode (AfModeContinuous). It can be used to pause any lens movements while (for example) images are captured. The algorithm remains inactive until it is instructed to resume.
const Control< float > | LensPosition
| Acts as a control to instruct the lens to move to a particular position and also reports back the position of the lens for each frame.
const std::array< const ControlValue, 4 > | AfStateValues
| List of all AfState supported values.
const Control< int32_t > | AfState
| Reports the current state of the AF algorithm in conjunction with the reported AfMode value and (in continuous AF mode) the AfPauseState value. The possible state changes are described below, though we note the following state transitions that occur when the AfMode is changed.
const std::array< const ControlValue, 3 > | AfPauseStateValues
| List of all AfPauseState supported values.
const Control< int32_t > | AfPauseState
| Only applicable in continuous (AfModeContinuous) mode, this reports whether the algorithm is currently running, paused or pausing (that is, will pause as soon as any in-progress scan completes).
const ControlIdMap | controls
| List of all supported libcamera controls.

## Detailed Description

Namespace for libcamera controls.

## Enumeration Type Documentation

## ◆ AeConstraintModeEnum

enum libcamera::controls::AeConstraintModeEnum

Supported AeConstraintMode values.

Enumerator
ConstraintNormal | Default constraint mode. This mode aims to balance the exposure of different parts of the image so as to reach a reasonable average level. However, highlights in the image may appear over-exposed and lowlights may appear under-exposed.
ConstraintHighlight | Highlight constraint mode. This mode adjusts the exposure levels in order to try and avoid over-exposing the brightest parts (highlights) of an image. Other non-highlight parts of the image may appear under-exposed.
ConstraintShadows | Shadows constraint mode. This mode adjusts the exposure levels in order to try and avoid under-exposing the dark parts (shadows) of an image. Other normally exposed parts of the image may appear over-exposed.
ConstraintCustom | Custom constraint mode.

## ◆ AeExposureModeEnum

enum libcamera::controls::AeExposureModeEnum

Supported AeExposureMode values.

Enumerator
ExposureNormal | Default exposure mode.
ExposureShort | Exposure mode allowing only short exposure times.
ExposureLong | Exposure mode allowing long exposure times.
ExposureCustom | Custom exposure mode.

## ◆ AeMeteringModeEnum

enum libcamera::controls::AeMeteringModeEnum

Supported AeMeteringMode values.

Enumerator
MeteringCentreWeighted | Centre-weighted metering mode.
MeteringSpot | Spot metering mode.
MeteringMatrix | Matrix metering mode.
MeteringCustom | Custom metering mode.

## ◆ AfMeteringEnum

enum libcamera::controls::AfMeteringEnum

Supported AfMetering values.

Enumerator
AfMeteringAuto | The AF algorithm should decide for itself where it will measure focus.
AfMeteringWindows | The AF algorithm should use the rectangles defined by the AfWindows control to measure focus. If no windows are specified the behaviour is platform dependent.

## ◆ AfModeEnum

enum libcamera::controls::AfModeEnum

Supported AfMode values.

Enumerator
AfModeManual | The AF algorithm is in manual mode. In this mode it will never perform any action nor move the lens of its own accord, but an application can specify the desired lens position using the LensPosition control. In this mode the AfState will always report AfStateIdle.
AfModeAuto | The AF algorithm is in auto mode. This means that the algorithm will never move the lens or change state unless the AfTrigger control is used. The AfTrigger control can be used to initiate a focus scan, the results of which will be reported by AfState. If the autofocus algorithm is moved from AfModeAuto to another mode while a scan is in progress, the scan is cancelled immediately, without waiting for the scan to finish. When first entering this mode the AfState will report AfStateIdle. When a trigger control is sent, AfState will report AfStateScanning for a period before spontaneously changing to AfStateFocused or AfStateFailed, depending on the outcome of the scan. It will remain in this state until another scan is initiated by the AfTrigger control. If a scan is cancelled (without changing to another mode), AfState will return to AfStateIdle.
AfModeContinuous | The AF algorithm is in continuous mode. This means that the lens can re-start a scan spontaneously at any moment, without any user intervention. The AfState still reports whether the algorithm is currently scanning or not, though the application has no ability to initiate or cancel scans, nor to move the lens for itself. However, applications can pause the AF algorithm from continuously scanning by using the AfPause control. This allows video or still images to be captured whilst guaranteeing that the focus is fixed. When set to AfModeContinuous, the system will immediately initiate a scan so AfState will report AfStateScanning, and will settle on one of AfStateFocused or AfStateFailed, depending on the scan result.

## ◆ AfPauseEnum

enum libcamera::controls::AfPauseEnum

Supported AfPause values.

Enumerator
AfPauseImmediate | Pause the continuous autofocus algorithm immediately, whether or not any kind of scan is underway. AfPauseState will subsequently report AfPauseStatePaused. AfState may report any of AfStateScanning, AfStateFocused or AfStateFailed, depending on the algorithm's state when it received this control.
AfPauseDeferred | This is similar to AfPauseImmediate, and if the AfState is currently reporting AfStateFocused or AfStateFailed it will remain in that state and AfPauseState will report AfPauseStatePaused. However, if the algorithm is scanning (AfStateScanning), AfPauseState will report AfPauseStatePausing until the scan is finished, at which point AfState will report one of AfStateFocused or AfStateFailed, and AfPauseState will change to AfPauseStatePaused.
AfPauseResume | Resume continuous autofocus operation. The algorithm starts again from exactly where it left off, and AfPauseState will report AfPauseStateRunning.

## ◆ AfPauseStateEnum

enum libcamera::controls::AfPauseStateEnum

Supported AfPauseState values.

Enumerator
AfPauseStateRunning | Continuous AF is running and the algorithm may restart a scan spontaneously.
AfPauseStatePausing | Continuous AF has been sent an AfPauseDeferred control, and will pause as soon as any in-progress scan completes (and then report AfPauseStatePaused). No new scans will be start spontaneously until the AfPauseResume control is sent.
AfPauseStatePaused | Continuous AF is paused. No further state changes or lens movements will occur until the AfPauseResume control is sent.

## ◆ AfRangeEnum

enum libcamera::controls::AfRangeEnum

Supported AfRange values.

Enumerator
AfRangeNormal | A wide range of focus distances is scanned, all the way from infinity down to close distances, though depending on the implementation, possibly not including the very closest macro positions.
AfRangeMacro | Only close distances are scanned.
AfRangeFull | The full range of focus distances is scanned just as with AfRangeNormal but this time including the very closest macro positions.

## ◆ AfSpeedEnum

enum libcamera::controls::AfSpeedEnum

Supported AfSpeed values.

Enumerator
AfSpeedNormal | Move the lens at its usual speed.
AfSpeedFast | Move the lens more quickly.

## ◆ AfStateEnum

enum libcamera::controls::AfStateEnum

Supported AfState values.

Enumerator
AfStateIdle | The AF algorithm is in manual mode (AfModeManual) or in auto mode (AfModeAuto) and a scan has not yet been triggered, or an in-progress scan was cancelled.
AfStateScanning | The AF algorithm is in auto mode (AfModeAuto), and a scan has been started using the AfTrigger control. The scan can be cancelled by sending AfTriggerCancel at which point the algorithm will either move back to AfStateIdle or, if the scan actually completes before the cancel request is processed, to one of AfStateFocused or AfStateFailed. Alternatively the AF algorithm could be in continuous mode (AfModeContinuous) at which point it may enter this state spontaneously whenever it determines that a rescan is needed.
AfStateFocused | The AF algorithm is in auto (AfModeAuto) or continuous (AfModeContinuous) mode and a scan has completed with the result that the algorithm believes the image is now in focus.
AfStateFailed | The AF algorithm is in auto (AfModeAuto) or continuous (AfModeContinuous) mode and a scan has completed with the result that the algorithm did not find a good focus position.

## ◆ AfTriggerEnum

enum libcamera::controls::AfTriggerEnum

Supported AfTrigger values.

Enumerator
AfTriggerStart | Start an AF scan. Ignored if a scan is in progress.
AfTriggerCancel | Cancel an AF scan. This does not cause the lens to move anywhere else. Ignored if no scan is in progress.

## ◆ AwbModeEnum

enum libcamera::controls::AwbModeEnum

Supported AwbMode values.

Enumerator
AwbAuto | Search over the whole colour temperature range.
AwbIncandescent | Incandescent AWB lamp mode.
AwbTungsten | Tungsten AWB lamp mode.
AwbFluorescent | Fluorescent AWB lamp mode.
AwbIndoor | Indoor AWB lighting mode.
AwbDaylight | Daylight AWB lighting mode.
AwbCloudy | Cloudy AWB lighting mode.
AwbCustom | Custom AWB mode.

## Variable Documentation

## ◆ AeEnable

libcamera::controls::AeEnable
| extern

Enable or disable the AE.

See also
  ExposureTime AnalogueGain

## ◆ AeLocked

libcamera::controls::AeLocked
| extern

Report the lock status of a running AE algorithm.

If the AE algorithm is locked the value shall be set to true, if it's converging it shall be set to false. If the AE algorithm is not running the control shall not be present in the metadata control list.

See also
  AeEnable

## ◆ AfMode

libcamera::controls::AfMode
| extern

Control to set the mode of the AF (autofocus) algorithm.

An implementation may choose not to implement all the modes.

## ◆ AfPauseState

libcamera::controls::AfPauseState
| extern

Only applicable in continuous (AfModeContinuous) mode, this reports whether the algorithm is currently running, paused or pausing (that is, will pause as soon as any in-progress scan completes).

Any change to AfMode will cause AfPauseStateRunning to be reported.

## ◆ AfState

libcamera::controls::AfState
| extern

Reports the current state of the AF algorithm in conjunction with the reported AfMode value and (in continuous AF mode) the AfPauseState value. The possible state changes are described below, though we note the following state transitions that occur when the AfMode is changed.

If the AfMode is set to AfModeManual, then the AfState will always report AfStateIdle (even if the lens is subsequently moved). Changing to the AfModeManual state does not initiate any lens movement.

If the AfMode is set to AfModeAuto then the AfState will report AfStateIdle. However, if AfModeAuto and AfTriggerStart are sent together then AfState will omit AfStateIdle and move straight to AfStateScanning (and start a scan).

If the AfMode is set to AfModeContinuous then the AfState will initially report AfStateScanning.

## ◆ AfTrigger

libcamera::controls::AfTrigger
| extern

This control starts an autofocus scan when AfMode is set to AfModeAuto, and can also be used to terminate a scan early.

It is ignored if AfMode is set to AfModeManual or AfModeContinuous.

## ◆ AfWindows

libcamera::controls::AfWindows
| extern

Sets the focus windows used by the AF algorithm when AfMetering is set to AfMeteringWindows. The units used are pixels within the rectangle returned by the ScalerCropMaximum property.

In order to be activated, a rectangle must be programmed with non-zero width and height. Internally, these rectangles are intersected with the ScalerCropMaximum rectangle. If the window becomes empty after this operation, then the window is ignored. If all the windows end up being ignored, then the behaviour is platform dependent.

On platforms that support the ScalerCrop control (for implementing digital zoom, for example), no automatic recalculation or adjustment of AF windows is performed internally if the ScalerCrop is changed. If any window lies outside the output image after the scaler crop has been applied, it is up to the application to recalculate them.

The details of how the windows are used are platform dependent. We note that when there is more than one AF window, a typical implementation might find the optimal focus position for each one and finally select the window where the focal distance for the objects shown in that part of the image are closest to the camera.

## ◆ AnalogueGain

libcamera::controls::AnalogueGain
| extern

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.

Setting this value means that it is now fixed and the AE algorithm may not change it. Setting it back to zero returns it to the control of the AE algorithm.

See also
  ExposureTime AeEnable

Todo:
  Document the interactions between AeEnable and setting a fixed value for this control. Consider interactions with other AE features, such as aperture and aperture/shutter priority mode, and decide if control of which features should be automatically adjusted shouldn't better be handled through a separate AE mode control.

## ◆ AwbEnable

libcamera::controls::AwbEnable
| extern

Enable or disable the AWB.

See also
  ColourGains

## ◆ AwbLocked

libcamera::controls::AwbLocked
| extern

Report the lock status of a running AWB algorithm.

If the AWB algorithm is locked the value shall be set to true, if it's converging it shall be set to false. If the AWB algorithm is not running the control shall not be present in the metadata control list.

See also
  AwbEnable

## ◆ ColourGains

libcamera::controls::ColourGains
| extern

Pair of gain values for the Red and Blue colour channels, in that order. ColourGains can only be applied in a Request when the AWB is disabled.

See also
  AwbEnable

## ◆ controls

const ControlIdMap libcamera::controls::controls
| extern

List of all supported libcamera controls.

Unless otherwise stated, all controls are bi-directional, i.e. they can be set through Request::controls() and returned out through Request::metadata().

## ◆ DigitalGain

libcamera::controls::DigitalGain
| extern

Digital gain value applied during the processing steps applied to the image as captured from the sensor.

The global digital gain factor is applied to all the colour channels of the RAW image. Different pipeline models are free to specify how the global gain factor applies to each separate channel.

If an imaging pipeline applies digital gain in distinct processing steps, this value indicates their total sum. Pipelines are free to decide how to adjust each processing step to respect the received gain factor and shall report their total value in the request metadata.

## ◆ ExposureTime

libcamera::controls::ExposureTime
| extern

Exposure time (shutter speed) for the frame applied in the sensor device. This value is specified in micro-seconds.

Setting this value means that it is now fixed and the AE algorithm may not change it. Setting it back to zero returns it to the control of the AE algorithm.

See also
  AnalogueGain AeEnable

Todo:
  Document the interactions between AeEnable and setting a fixed value for this control. Consider interactions with other AE features, such as aperture and aperture/shutter priority mode, and decide if control of which features should be automatically adjusted shouldn't better be handled through a separate AE mode control.

## ◆ ExposureValue

libcamera::controls::ExposureValue
| extern

Specify an Exposure Value (EV) parameter. The EV parameter will only be applied if the AE algorithm is currently enabled.

By convention EV adjusts the exposure as log2. For example EV = [-2, -1, 0.5, 0, 0.5, 1, 2] results in an exposure adjustment of [1/4x, 1/2x, 1/sqrt(2)x, 1x, sqrt(2)x, 2x, 4x].

See also
  AeEnable

## ◆ FrameDurationLimits

libcamera::controls::FrameDurationLimits
| extern

The minimum and maximum (in that order) frame duration, expressed in microseconds.

When provided by applications, the control specifies the sensor frame duration interval the pipeline has to use. This limits the largest exposure time the sensor can use. For example, if a maximum frame duration of 33ms is requested (corresponding to 30 frames per second), the sensor will not be able to raise the exposure time above 33ms. A fixed frame duration is achieved by setting the minimum and maximum values to be the same. Setting both values to 0 reverts to using the IPA provided defaults.

The maximum frame duration provides the absolute limit to the shutter speed computed by the AE algorithm and it overrides any exposure mode setting specified with controls::AeExposureMode. Similarly, when a manual exposure time is set through controls::ExposureTime, it also gets clipped to the limits set by this control. When reported in metadata, the control expresses the minimum and maximum frame durations used after being clipped to the sensor provided frame duration limits.

See also
  AeExposureMode
  ExposureTime

Todo:
  Define how to calculate the capture frame rate by defining controls to report additional delays introduced by the capture pipeline or post-processing stages (ie JPEG conversion, frame scaling).

Todo:
  Provide an explicit definition of default control values, for this and all other controls.

## ◆ LensPosition

libcamera::controls::LensPosition
| extern

Acts as a control to instruct the lens to move to a particular position and also reports back the position of the lens for each frame.

The LensPosition control is ignored unless the AfMode is set to AfModeManual, though the value is reported back unconditionally in all modes.

This value, which is generally a non-integer, is the reciprocal of the focal distance in metres, also known as dioptres. That is, to set a focal distance D, the lens position LP is given by

For example:

0 moves the lens to infinity. 0.5 moves the lens to focus on objects 2m away. 2 moves the lens to focus on objects 50cm away. And larger values will focus the lens closer.

The default value of the control should indicate a good general position for the lens, often corresponding to the hyperfocal distance (the closest position for which objects at infinity are still acceptably sharp). The minimum will often be zero (meaning infinity), and the maximum value defines the closest focus position.

Todo:
  Define a property to report the Hyperfocal distance of calibrated lenses.

## ◆ ScalerCrop

libcamera::controls::ScalerCrop
| extern

Sets the image portion that will be scaled to form the whole of the final output image. The (x,y) location of this rectangle is relative to the PixelArrayActiveAreas that is being used. The units remain native sensor pixels, even if the sensor is being used in a binning or skipping mode.

This control is only present when the pipeline supports scaling. Its maximum valid value is given by the properties::ScalerCropMaximum property, and the two can be used to implement digital zoom.

## ◆ SensorTemperature

libcamera::controls::SensorTemperature
| extern

Temperature measure from the camera sensor in Celsius. This is typically obtained by a thermal sensor present on-die or in the camera module. The range of reported temperatures is device dependent.

The SensorTemperature control will only be returned in metadata if a themal sensor is present.

## ◆ SensorTimestamp

libcamera::controls::SensorTimestamp
| extern

The time when the first row of the image sensor active array is exposed.

The timestamp, expressed in nanoseconds, represents a monotonically increasing counter since the system boot time, as defined by the Linux-specific CLOCK_BOOTTIME clock id.

The SensorTimestamp control can only be returned in metadata.

Todo:
  Define how the sensor timestamp has to be used in the reprocessing use case.