From 6fdbf3f38c3148f1ba780286715d9a78ffe1e387 Mon Sep 17 00:00:00 2001 From: David Plowman Date: Tue, 18 Jul 2023 15:43:00 +0100 Subject: libcamera: controls: Add controls for AEC/AGC flicker avoidance Flicker is the term used to describe brightness banding or oscillation of images caused typically by artificial lighting driven by a 50 or 60Hz mains supply. We add three controls intended to be used by AEC/AGC algorithms: AeFlickerMode to enable flicker avoidance. AeFlickerPeriod to set the flicker period "manually". AeFlickerDetected to report any flicker that is currently detected. Signed-off-by: David Plowman Reviewed-by: Jacopo Mondi Reviewed-by: Umang Jain Signed-off-by: Naushir Patuck --- src/libcamera/control_ids.yaml | 90 ++++++++++++++++++++++++++++++++++-------- 1 file changed, 73 insertions(+), 17 deletions(-) diff --git a/src/libcamera/control_ids.yaml b/src/libcamera/control_ids.yaml index 056886e6..f2e542f4 100644 --- a/src/libcamera/control_ids.yaml +++ b/src/libcamera/control_ids.yaml @@ -156,6 +156,79 @@ controls: control of which features should be automatically adjusted shouldn't better be handled through a separate AE mode control. + - AeFlickerMode: + type: int32_t + description: | + 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. + + enum: + - name: FlickerOff + value: 0 + description: No flicker avoidance is performed. + - name: FlickerManual + value: 1 + description: Manual flicker avoidance. + Suppress flicker effects caused by lighting running with a period + specified by the AeFlickerPeriod control. + \sa AeFlickerPeriod + - name: FlickerAuto + value: 2 + description: 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. + \sa AeFlickerDetected + + - AeFlickerPeriod: + type: int32_t + description: 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. + + \sa AeFlickerMode + + - AeFlickerDetected: + type: int32_t + description: 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. + + \sa AeFlickerMode + - Brightness: type: float description: | @@ -850,23 +923,6 @@ controls: value: 1 description: The lens shading map mode is available. - - SceneFlicker: - type: int32_t - draft: true - description: | - Control to report the detected scene light frequency. Currently - identical to ANDROID_STATISTICS_SCENE_FLICKER. - enum: - - name: SceneFickerOff - value: 0 - description: No flickering detected. - - name: SceneFicker50Hz - value: 1 - description: 50Hz flickering detected. - - name: SceneFicker60Hz - value: 2 - description: 60Hz flickering detected. - - PipelineDepth: type: int32_t draft: true -- cgit v1.2.1