libcamera  v0.2.0+85-1c5830a9
Supporting cameras in Linux since 2019
Namespaces | Enumerations | Variables
libcamera::controls Namespace Reference

Namespace for libcamera controls. More...

Namespaces

 draft
 Namespace for 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,
  AE_FLICKER_MODE = 9, AE_FLICKER_PERIOD = 10, AE_FLICKER_DETECTED = 11, BRIGHTNESS = 12,
  CONTRAST = 13, LUX = 14, AWB_ENABLE = 15, AWB_MODE = 16,
  AWB_LOCKED = 17, COLOUR_GAINS = 18, COLOUR_TEMPERATURE = 19, SATURATION = 20,
  SENSOR_BLACK_LEVELS = 21, SHARPNESS = 22, FOCUS_FO_M = 23, COLOUR_CORRECTION_MATRIX = 24,
  SCALER_CROP = 25, DIGITAL_GAIN = 26, FRAME_DURATION = 27, FRAME_DURATION_LIMITS = 28,
  SENSOR_TEMPERATURE = 29, SENSOR_TIMESTAMP = 30, AF_MODE = 31, AF_RANGE = 32,
  AF_SPEED = 33, AF_METERING = 34, AF_WINDOWS = 35, AF_TRIGGER = 36,
  AF_PAUSE = 37, LENS_POSITION = 38, AF_STATE = 39, AF_PAUSE_STATE = 40,
  HDR_MODE = 41, HDR_CHANNEL = 42
}
 
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  AeFlickerModeEnum { FlickerOff = 0, FlickerManual = 1, FlickerAuto = 2 }
 Supported AeFlickerMode 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...
 
enum  HdrModeEnum {
  HdrModeOff = 0, HdrModeMultiExposureUnmerged = 1, HdrModeMultiExposure = 2, HdrModeSingleExposure = 3,
  HdrModeNight = 4
}
 Supported HdrMode values. More...
 
enum  HdrChannelEnum { HdrChannelNone = 0, HdrChannelShort = 1, HdrChannelMedium = 2, HdrChannelLong = 3 }
 Supported HdrChannel values. More...
 

Variables

const Control< bool > AeEnable
 Enable or disable the AE. More...
 
const Control< bool > AeLocked
 Report the lock status of a running AE algorithm. More...
 
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. More...
 
const Control< int32_t > ExposureTime
 Exposure time (shutter speed) for the frame applied in the sensor device. This value is specified in micro-seconds. More...
 
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. More...
 
const std::array< const ControlValue, 3 > AeFlickerModeValues
 List of all AeFlickerMode supported values.
 
const Control< int32_t > AeFlickerMode
 Set the flicker mode, which determines whether, and how, the AGC/AEC algorithm attempts to hide flicker effects caused by the duty cycle of artificial lighting. More...
 
const Control< int32_t > AeFlickerPeriod
 Manual flicker period in microseconds. This value sets the current flicker period to avoid. It is used when AeFlickerMode is set to FlickerManual. To cancel 50Hz mains flicker, this should be set to 10000 (corresponding to 100Hz), or 8333 (120Hz) for 60Hz mains. Setting the mode to FlickerManual when no AeFlickerPeriod has ever been set means that no flicker cancellation occurs (until the value of this control is updated). Switching to modes other than FlickerManual has no effect on the value of the AeFlickerPeriod control. More...
 
const Control< int32_t > AeFlickerDetected
 Flicker period detected in microseconds. The value reported here indicates the currently detected flicker period, or zero if no flicker at all is detected. When AeFlickerMode is set to FlickerAuto, there may be a period during which the value reported here remains zero. Once a non-zero value is reported, then this is the flicker period that has been detected and is now being cancelled. In the case of 50Hz mains flicker, the value would be 10000 (corresponding to 100Hz), or 8333 (120Hz) for 60Hz mains flicker. It is implementation dependent whether the system can continue to detect flicker of different periods when another frequency is already being cancelled. More...
 
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. More...
 
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. More...
 
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. More...
 
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 singular value may be based on a combination of statistics gathered from multiple focus regions within an image. The number of focus regions and method of combination is platform dependent. 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< RectangleScalerCrop
 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. More...
 
const Control< float > DigitalGain
 Digital gain value applied during the processing steps applied to the image as captured from the sensor. More...
 
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. More...
 
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. More...
 
const Control< int64_t > SensorTimestamp
 The time when the first row of the image sensor active array is exposed. More...
 
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. More...
 
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. More...
 
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. More...
 
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. More...
 
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. More...
 
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). More...
 
const std::array< const ControlValue, 5 > HdrModeValues
 List of all HdrMode supported values.
 
const Control< int32_t > HdrMode
 Control to set the mode to be used for High Dynamic Range (HDR) imaging. HDR techniques typically include multiple exposure, image fusion and tone mapping techniques to improve the dynamic range of the resulting images. More...
 
const std::array< const ControlValue, 4 > HdrChannelValues
 List of all HdrChannel supported values.
 
const Control< int32_t > HdrChannel
 This value is reported back to the application so that it can discover whether this capture corresponds to the short or long exposure image (or any other image used by the HDR procedure). An application can monitor the HDR channel to discover when the differently exposed images have arrived. More...
 
const ControlIdMap controls
 List of all supported libcamera controls. More...
 

Detailed Description

Namespace for libcamera controls.

Enumeration Type Documentation

◆ 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

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.

◆ AeFlickerModeEnum

Supported AeFlickerMode values.

Enumerator
FlickerOff 

No flicker avoidance is performed.

FlickerManual 

Manual flicker avoidance. Suppress flicker effects caused by lighting running with a period specified by the AeFlickerPeriod control.

See also
AeFlickerPeriod
FlickerAuto 

Automatic flicker period detection and avoidance. The system will automatically determine the most likely value of flicker period, and avoid flicker of this frequency. Once flicker is being corrected, it is implementation dependent whether the system is still able to detect a change in the flicker period.

See also
AeFlickerDetected

◆ AeMeteringModeEnum

Supported AeMeteringMode values.

Enumerator
MeteringCentreWeighted 

Centre-weighted metering mode.

MeteringSpot 

Spot metering mode.

MeteringMatrix 

Matrix metering mode.

MeteringCustom 

Custom metering mode.

◆ 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

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.

If the camera is started in AfModeManual, it will move the focus lens to the position specified by the LensPosition control.

This mode is the recommended default value for the AfMode control. External cameras (as reported by the Location property set to CameraLocationExternal) may use a different default value.

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

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

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

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

Supported AfSpeed values.

Enumerator
AfSpeedNormal 

Move the lens at its usual speed.

AfSpeedFast 

Move the lens more quickly.

◆ 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

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

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.

◆ HdrChannelEnum

Supported HdrChannel values.

Enumerator
HdrChannelNone 

This image does not correspond to any of the captures used to create an HDR image.

HdrChannelShort 

This is a short exposure image.

HdrChannelMedium 

This is a medium exposure image.

HdrChannelLong 

This is a long exposure image.

◆ HdrModeEnum

Supported HdrMode values.

Enumerator
HdrModeOff 

HDR is disabled. Metadata for this frame will not include the HdrChannel control.

HdrModeMultiExposureUnmerged 

Multiple exposures will be generated in an alternating fashion. However, they will not be merged together and will be returned to the application as they are. Each image will be tagged with the correct HDR channel, indicating what kind of exposure it is. The tag should be the same as in the HdrModeMultiExposure case.

The expectation is that an application using this mode would merge the frames to create HDR images for itself if it requires them.

HdrModeMultiExposure 

Multiple exposures will be generated and merged to create HDR images. Each image will be tagged with the HDR channel (long, medium or short) that arrived and which caused this image to be output.

Systems that use two channels for HDR will return images tagged alternately as the short and long channel. Systems that use three channels for HDR will cycle through the short, medium and long channel before repeating.

HdrModeSingleExposure 

Multiple frames all at a single exposure will be used to create HDR images. These images should be reported as all corresponding to the HDR short channel.

HdrModeNight 

Multiple frames will be combined to produce "night mode" images. It is up to the implementation exactly which HDR channels it uses, and the images will all be tagged accordingly with the correct HDR channel information.

Variable Documentation

◆ AeEnable

libcamera::controls::AeEnable

Enable or disable the AE.

See also
ExposureTime AnalogueGain

◆ AeFlickerDetected

libcamera::controls::AeFlickerDetected

Flicker period detected in microseconds. The value reported here indicates the currently detected flicker period, or zero if no flicker at all is detected. When AeFlickerMode is set to FlickerAuto, there may be a period during which the value reported here remains zero. Once a non-zero value is reported, then this is the flicker period that has been detected and is now being cancelled. In the case of 50Hz mains flicker, the value would be 10000 (corresponding to 100Hz), or 8333 (120Hz) for 60Hz mains flicker. It is implementation dependent whether the system can continue to detect flicker of different periods when another frequency is already being cancelled.

See also
AeFlickerMode

◆ AeFlickerMode

libcamera::controls::AeFlickerMode

Set the flicker mode, which determines whether, and how, the AGC/AEC algorithm attempts to hide flicker effects caused by the duty cycle of artificial lighting.

Although implementation dependent, many algorithms for "flicker avoidance" work by restricting this exposure time to integer multiples of the cycle period, wherever possible.

Implementations may not support all of the flicker modes listed below.

By default the system will start in FlickerAuto mode if this is supported, otherwise the flicker mode will be set to FlickerOff.

◆ AeFlickerPeriod

libcamera::controls::AeFlickerPeriod

Manual flicker period in microseconds. This value sets the current flicker period to avoid. It is used when AeFlickerMode is set to FlickerManual. To cancel 50Hz mains flicker, this should be set to 10000 (corresponding to 100Hz), or 8333 (120Hz) for 60Hz mains. Setting the mode to FlickerManual when no AeFlickerPeriod has ever been set means that no flicker cancellation occurs (until the value of this control is updated). Switching to modes other than FlickerManual has no effect on the value of the AeFlickerPeriod control.

See also
AeFlickerMode

◆ AeLocked

libcamera::controls::AeLocked

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

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

An implementation may choose not to implement all the modes.

◆ AfPauseState

libcamera::controls::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).

Any change to AfMode will cause AfPauseStateRunning to be reported.

◆ AfState

libcamera::controls::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.

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

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

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

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

Enable or disable the AWB.

See also
ColourGains

◆ AwbLocked

libcamera::controls::AwbLocked

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

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

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

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

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

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

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 camera 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.

◆ HdrChannel

libcamera::controls::HdrChannel

This value is reported back to the application so that it can discover whether this capture corresponds to the short or long exposure image (or any other image used by the HDR procedure). An application can monitor the HDR channel to discover when the differently exposed images have arrived.

This metadata is only available when an HDR mode has been enabled.

See also
HdrMode

◆ HdrMode

libcamera::controls::HdrMode

Control to set the mode to be used for High Dynamic Range (HDR) imaging. HDR techniques typically include multiple exposure, image fusion and tone mapping techniques to improve the dynamic range of the resulting images.

When using an HDR mode, images are captured with different sets of AGC settings called HDR channels. Channels indicate in particular the type of exposure (short, medium or long) used to capture the raw image, before fusion. Each HDR image is tagged with the corresponding channel using the HdrChannel control.

See also
HdrChannel

◆ LensPosition

libcamera::controls::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.

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

$LP = \frac{1\mathrm{m}}{D}$

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

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

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 thermal sensor is present.

◆ SensorTimestamp

libcamera::controls::SensorTimestamp

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.