diff --git a/src/libcamera/control_ids.yaml b/src/libcamera/control_ids.yaml index c93f362463dd..694659af4b7d 100644 --- a/src/libcamera/control_ids.yaml +++ b/src/libcamera/control_ids.yaml @@ -25,6 +25,75 @@ controls: \sa AeEnable + - AeState: + type: int32_t + description: | + Control to report the AEGC algorithm state. + + The AEGC algorithm computes the exposure time and the analogue gain + values to be applied to the image sensor. + + The AEGC algorithm behaviour is controlled by the ExposureTimeMode and + AnalogueGainMode controls, which allow applications to decide how + the exposure time and gain are computed, in Auto or Manual mode, + independently from one another. + + The AeState control reports the AEGC algorithm state through a single + value and describes it as a single computation block which computes + both the exposure time and the analogue gain values. + + When both the exposure time and analogue gain values are configured to + be in Manual mode, the AEGC algorithm is quiescent and does not actively + compute any value and the AeState control will report AeStateIdle. + + When at least the exposure time or analogue gain are configured to be + computed by the AEGC algorithm, the AeState control will report if the + algorithm has converged to stable values for all of the controls set + to be computed in Auto mode. + + \sa AnalogueGainMode + \sa ExposureTimeMode + + enum: + - name: AeStateIdle + value: 0 + description: | + The AEGC algorithm is inactive. + + This state is returned when both AnalogueGainMode and + ExposureTimeMode are set to Manual and the algorithm is not + actively computing any value. + + When ExposureTimeMode or AnalogueGainMode are set to Auto mode, the + AEGC algorithm might spontaneously initiate a new scan, in which + case the AeState control is moved to AeStateSearching. + - name: AeStateSearching + value: 1 + description: | + The AEGC algorithm is actively computing new values, for either the + exposure time or the analogue gain, but has not converged to a + stable result yet. + + This state is returned if at least one of AnalogueGainMode + or ExposureTimeMode is set to auto and the algorithm hasn't + converged yet. + + The AEGC algorithm converges once stable values are computed for + any of the controls set to be computed in Auto mode. + + Once the algorithm converges the state is moved to AeStateConverged. + - name: AeStateConverged + value: 2 + description: | + The AEGC algorithm has converged. + + This state is returned if at least one of AnalogueGainMode + or ExposureTimeMode is set to Auto, and the AEGC algorithm has + converged to stable value. + + The AEGC algorithm might spontaneously re-initiate an AE scan, in + which case the state is moved to AeStateSearching. + # AeMeteringMode needs further attention: # - Auto-generate max enum value. # - Better handling of custom types. @@ -93,6 +162,13 @@ controls: 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. + + When one of AnalogueGainMode or ExposureTimeMode is set to Manual, + the fixed values will override any choices made by AeExposureMode. + + \sa AnalogueGainMode + \sa ExposureTimeMode + enum: - name: ExposureNormal value: 0 @@ -111,13 +187,15 @@ controls: type: float description: | Specify an Exposure Value (EV) parameter. The EV parameter will only be - applied if the AE algorithm is currently enabled. + applied if the AE algorithm is currently enabled, that is, at least one + of AnalogueGainMode and ExposureTimeMode are in Auto mode. 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]. - \sa AeEnable + \sa AnalogueGainMode + \sa ExposureTimeMode - ExposureTime: type: int32_t @@ -125,17 +203,95 @@ controls: 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. + This control will only take effect if ExposureTimeMode is Manual. If + this control is set when ExposureTimeMode is Auto, the value will be + ignored and will not be retained. + + When reported in metadata, this control indicates what exposure time + was used for the current request, regardless of ExposureTimeMode. + ExposureTimeMode will indicate the source of the exposure time value, + whether it came from the AE algorithm or not. + + \sa AnalogueGain + \sa ExposureTimeMode + + - ExposureTimeMode: + type: int32_t + description: | + Controls the source of the exposure time that is applied to the image + sensor. When set to Auto, the AE algorithm computes the exposure time + and configures the image sensor accordingly. When set to Manual, + the value of the ExposureTime control is used. + + When transitioning from Auto to Manual mode and no ExposureTime control + is provided by the application, the last value computed by the AE + algorithm when the mode was Auto will be used. If the ExposureTimeMode + was never set to Auto (either because the camera started in Manual mode, + or Auto is not supported by the camera), the camera should use a + best-effort default value. + + If ExposureTimeModeManual is supported, the ExposureTime control must + also be supported. + + The set of ExposureTimeMode modes that are supported by the camera must + have an intersection with the supported set of AnalogueGainMode modes. + + Flickerless exposure mode transitions + + Applications that transition from ExposureTimeModeAuto to the direct + control of the exposure time should aim to do so by selecting an + ExposureTime value as close as possible to the last value computed by + the auto exposure algorithm in order to avoid any visible flickering. + + To select the correct value to use as ExposureTime value, applications + should accommodate the natural delay in applying controls caused by the + capture pipeline frame depth. - \sa AnalogueGain AeEnable + When switching to manual exposure mode, applications should not + immediately specify an ExposureTime value in the same request where + ExposureTimeMode is set to Manual. They should instead wait for the + first Request where ExposureTimeMode is reported as + ExposureTimeModeManual in the Request metadata, and use the reported + ExposureTime to populate the control value in the next Request to be + queued to the Camera. - \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. + The implementation of the auto-exposure algorithm should equally try to + minimize flickering and when transitioning from manual exposure mode to + auto exposure use the last value provided by the application as starting + point. + + 1. Start with ExposureTimeMode set to Auto + + 2. Set ExposureTimeMode to Manual + + 3. Wait for the first completed request that has ExposureTimeMode + set to Manual + + 4. Copy the value reported in ExposureTime into a new request, and + submit it + + 5. Proceed to run manual exposure time + + \sa ExposureTime + enum: + - name: ExposureTimeModeAuto + value: 0 + description: | + The exposure time will be calculated automatically and set by the + AE algorithm. + + If ExposureTime is set while this mode is active, it will be + ignored, and it will also not be retained. + - name: ExposureTimeModeManual + value: 1 + description: | + The exposure time will not be updated by the AE algorithm. + + When transitioning from Auto to Manual mode, the last computed + exposure value is used until a new value is specified through the + ExposureTime control. If an ExposureTime value is specified in the + same request where the ExposureTimeMode is changed from Auto to + Manual, the provided ExposureTime is applied immediately. - AnalogueGain: type: float @@ -144,17 +300,64 @@ controls: 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. + This control will only take effect if AnalogueGainMode is Manual. If + this control is set when AnalogueGainMode is Auto, the value will be + ignored and will not be retained. - \sa ExposureTime AeEnable + When reported in metadata, this control indicates what analogue gain + was used for the current request, regardless of AnalogueGainMode. + AnalogueGainMode will indicate the source of the analogue gain value, + whether it came from the AEGC algorithm or not. + + \sa ExposureTime + \sa AnalogueGainMode - \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. + - AnalogueGainMode: + type: int32_t + description: | + Controls the source of the analogue gain that is applied to the image + sensor. When set to Auto, the AEGC algorithm computes the analogue gain + and configures the image sensor accordingly. When set to Manual, + the value of the AnalogueGain control is used. + + When transitioning from Auto to Manual mode and no AnalogueGain control + is provided by the application, the last value computed by the AEGC + algorithm when the mode was Auto will be used. If the AnalogueGainMode + was never set to Auto (either because the camera started in Manual mode, + or Auto is not supported by the camera), the camera should use a + best-effort default value. + + If AnalogueGainModeManual is supported, the AnalogueGain control must + also be supported. + + The set of AnalogueGainMode modes that are supported by the camera must + have an intersection with the supported set of ExposureTimeMode modes. + + The same procedure described for performing flickerless transitions in + the ExposureTimeMode control documentation should be applied to + analogue gain. + + \sa ExposureTimeMode + \sa AnalogueGain + enum: + - name: AnalogueGainModeAuto + value: 0 + description: | + The analogue gain will be calculated automatically and set by the + AEGC algorithm. + + If AnalogueGain is set while this mode is active, it will be + ignored, and it will also not be retained. + - name: AnalogueGainModeManual + value: 1 + description: | + The analogue gain will not be updated by the AEGC algorithm. + + When transitioning from Auto to Manual mode, the last computed + gain value is used until a new value is specified through the + AnalogueGain control. If an AnalogueGain value is specified in the + same request where the AnalogueGainMode is changed from Auto to + Manual, the provided AnalogueGain is applied immediately. - Brightness: type: float @@ -767,36 +970,6 @@ controls: High quality aberration correction which might reduce the frame rate. - - AeState: - type: int32_t - draft: true - description: | - Control to report the current AE algorithm state. Currently identical to - ANDROID_CONTROL_AE_STATE. - - Current state of the AE algorithm. - enum: - - name: AeStateInactive - value: 0 - description: The AE algorithm is inactive. - - name: AeStateSearching - value: 1 - description: The AE algorithm has not converged yet. - - name: AeStateConverged - value: 2 - description: The AE algorithm has converged. - - name: AeStateLocked - value: 3 - description: The AE algorithm is locked. - - name: AeStateFlashRequired - value: 4 - description: The AE algorithm would need a flash for good results - - name: AeStatePrecapture - value: 5 - description: | - The AE algorithm has started a pre-capture metering session. - \sa AePrecaptureTrigger - - AwbState: type: int32_t draft: true