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/* SPDX-License-Identifier: BSD-2-Clause */
/*
* Copyright (C) 2022-2023, Raspberry Pi Ltd
*
* af.h - Autofocus control algorithm
*/
#pragma once
#include "../af_algorithm.h"
#include "../af_status.h"
#include "../pdaf_data.h"
#include "../pwl.h"
/*
* This algorithm implements a hybrid of CDAF and PDAF, favouring PDAF.
*
* Whenever PDAF is available, it is used in a continuous feedback loop.
* When triggered in auto mode, we simply enable AF for a limited number
* of frames (it may terminate early if the delta becomes small enough).
*
* When PDAF confidence is low (due e.g. to low contrast or extreme defocus)
* or PDAF data are absent, fall back to CDAF with a programmed scan pattern.
* A coarse and fine scan are performed, using ISP's CDAF focus FoM to
* estimate the lens position with peak contrast. This is slower due to
* extra latency in the ISP, and requires a settling time between steps.
*
* Some hysteresis is applied to the switch between PDAF and CDAF, to avoid
* "nuisance" scans. During each interval where PDAF is not working, only
* ONE scan will be performed; CAF cannot track objects using CDAF alone.
*
* This algorithm is unrelated to "rpi.focus" which merely reports CDAF FoM.
*/
namespace RPiController {
class Af : public AfAlgorithm
{
public:
Af(Controller *controller = NULL);
~Af();
char const *name() const override;
int read(const libcamera::YamlObject ¶ms) override;
void initialise() override;
/* IPA calls */
void switchMode(CameraMode const &cameraMode, Metadata *metadata) override;
void prepare(Metadata *imageMetadata) override;
void process(StatisticsPtr &stats, Metadata *imageMetadata) override;
/* controls */
void setRange(AfRange range) override;
void setSpeed(AfSpeed speed) override;
void setMetering(bool use_windows) override;
void setWindows(libcamera::Span<libcamera::Rectangle const> const &wins) override;
void setMode(AfMode mode) override;
AfMode getMode() const override;
bool setLensPosition(double dioptres, int32_t *hwpos) override;
std::optional<double> getLensPosition() const override;
void triggerScan() override;
void cancelScan() override;
void pause(AfPause pause) override;
private:
enum class ScanState {
Idle = 0,
Trigger,
Pdaf,
Coarse,
Fine,
Settle
};
struct RangeDependentParams {
double focusMin; /* lower (far) limit in dipotres */
double focusMax; /* upper (near) limit in dioptres */
double focusDefault; /* default setting ("hyperfocal") */
RangeDependentParams();
void read(const libcamera::YamlObject ¶ms);
};
struct SpeedDependentParams {
double stepCoarse; /* used for scans */
double stepFine; /* used for scans */
double contrastRatio; /* used for scan termination and reporting */
double pdafGain; /* coefficient for PDAF feedback loop */
double pdafSquelch; /* PDAF stability parameter (device-specific) */
double maxSlew; /* limit for lens movement per frame */
uint32_t pdafFrames; /* number of iterations when triggered */
uint32_t dropoutFrames; /* number of non-PDAF frames to switch to CDAF */
uint32_t stepFrames; /* frames to skip in between steps of a scan */
SpeedDependentParams();
void read(const libcamera::YamlObject ¶ms);
};
struct CfgParams {
RangeDependentParams ranges[AfRangeMax];
SpeedDependentParams speeds[AfSpeedMax];
uint32_t confEpsilon; /* PDAF hysteresis threshold (sensor-specific) */
uint32_t confThresh; /* PDAF confidence cell min (sensor-specific) */
uint32_t confClip; /* PDAF confidence cell max (sensor-specific) */
uint32_t skipFrames; /* frames to skip at start or modeswitch */
Pwl map; /* converts dioptres -> lens driver position */
CfgParams();
int read(const libcamera::YamlObject ¶ms);
void initialise();
};
struct ScanRecord {
double focus;
double contrast;
double phase;
double conf;
};
void computeWeights();
bool getPhase(PdafData const &data, double &phase, double &conf) const;
double getContrast(struct bcm2835_isp_stats_focus const focus_stats[FOCUS_REGIONS]) const;
void doPDAF(double phase, double conf);
bool earlyTerminationByPhase(double phase);
double findPeak(unsigned index) const;
void doScan(double contrast, double phase, double conf);
void doAF(double contrast, double phase, double conf);
void updateLensPosition();
void startAF();
void startProgrammedScan();
void goIdle();
/* Configuration and settings */
CfgParams cfg_;
AfRange range_;
AfSpeed speed_;
AfMode mode_;
bool pauseFlag_;
libcamera::Rectangle statsRegion_;
std::vector<libcamera::Rectangle> windows_;
bool useWindows_;
uint8_t phaseWeights_[PDAF_DATA_ROWS][PDAF_DATA_COLS];
uint16_t contrastWeights_[FOCUS_REGIONS];
uint32_t sumWeights_;
/* Working state. */
ScanState scanState_;
bool initted_;
double ftarget_, fsmooth_;
double prevContrast_;
unsigned skipCount_, stepCount_, dropCount_;
unsigned scanMaxIndex_;
double scanMaxContrast_, scanMinContrast_;
std::vector<ScanRecord> scanData_;
AfState reportState_;
};
} // namespace RPiController
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