/* SPDX-License-Identifier: BSD-2-Clause */ /* * Copyright (C) 2019, Raspberry Pi (Trading) Limited * * cam_helper.hpp - helper class providing camera information */ #pragma once #include <string> #include "camera_mode.h" #include "md_parser.hpp" #include "libcamera/internal/v4l2_videodevice.h" namespace RPi { // The CamHelper class provides a number of facilities that anyone trying // trying to drive a camera will need to know, but which are not provided by // by the standard driver framework. Specifically, it provides: // // A "CameraMode" structure to describe extra information about the chosen // mode of the driver. For example, how it is cropped from the full sensor // area, how it is scaled, whether pixels are averaged compared to the full // resolution. // // The ability to convert between number of lines of exposure and actual // exposure time, and to convert between the sensor's gain codes and actual // gains. // // A method to return the number of frames of delay between updating exposure // and analogue gain and the changes taking effect. For many sensors these // take the values 2 and 1 respectively, but sensors that are different will // need to over-ride the default method provided. // // A method to query if the sensor outputs embedded data that can be parsed. // // A parser to parse the metadata buffers provided by some sensors (for // example, the imx219 does; the ov5647 doesn't). This allows us to know for // sure the exposure and gain of the frame we're looking at. CamHelper // provides methods for converting analogue gains to and from the sensor's // native gain codes. // // Finally, a set of methods that determine how to handle the vagaries of // different camera modules on start-up or when switching modes. Some // modules may produce one or more frames that are not yet correctly exposed, // or where the metadata may be suspect. We have the following methods: // HideFramesStartup(): Tell the pipeline handler not to return this many // frames at start-up. This can also be used to hide initial frames // while the AGC and other algorithms are sorting themselves out. // HideFramesModeSwitch(): Tell the pipeline handler not to return this // many frames after a mode switch (other than start-up). Some sensors // may produce innvalid frames after a mode switch; others may not. // MistrustFramesStartup(): At start-up a sensor may return frames for // which we should not run any control algorithms (for example, metadata // may be invalid). // MistrustFramesModeSwitch(): The number of frames, after a mode switch // (other than start-up), for which control algorithms should not run // (for example, metadata may be unreliable). class CamHelper { public: static CamHelper *Create(std::string const &cam_name); CamHelper(MdParser *parser); virtual ~CamHelper(); void SetCameraMode(const CameraMode &mode); MdParser &Parser() const { return *parser_; } uint32_t ExposureLines(double exposure_us) const; double Exposure(uint32_t exposure_lines) const; // in us virtual uint32_t GainCode(double gain) const = 0; virtual double Gain(uint32_t gain_code) const = 0; virtual void GetDelays(int &exposure_delay, int &gain_delay) const; virtual bool SensorEmbeddedDataPresent() const; virtual unsigned int HideFramesStartup() const; virtual unsigned int HideFramesModeSwitch() const; virtual unsigned int MistrustFramesStartup() const; virtual unsigned int MistrustFramesModeSwitch() const; protected: MdParser *parser_; CameraMode mode_; bool initialized_; }; // This is for registering camera helpers with the system, so that the // CamHelper::Create function picks them up automatically. typedef CamHelper *(*CamHelperCreateFunc)(); struct RegisterCamHelper { RegisterCamHelper(char const *cam_name, CamHelperCreateFunc create_func); }; } // namespace RPi