[libcamera-devel] [PATCH v2 2/4] libcamera: camera: Introduce SensorConfiguration

[Kieran Bingham]

Quoting Jacopo Mondi via libcamera-devel (2023-07-31 12:31:13)
> Introduce SensorConfiguration in the libcamera API.
> 
> The SensorConfiguration is part of the CameraConfiguration class
> and allows applications to control the sensor settings.
> 
> Signed-off-by: Jacopo Mondi <jacopo.mondi at ideasonboard.com>
> Reviewed-by: Naushir Patuck <naush at raspberrypi.com>
> ---
>  include/libcamera/camera.h |  43 +++++++++
>  src/libcamera/camera.cpp   | 180 +++++++++++++++++++++++++++++++++++++
>  2 files changed, 223 insertions(+)
> 
> diff --git a/include/libcamera/camera.h b/include/libcamera/camera.h
> index 004bc89455f5..b2aa8d467feb 100644
> --- a/include/libcamera/camera.h
> +++ b/include/libcamera/camera.h
> @@ -19,6 +19,7 @@
>  #include <libcamera/base/signal.h>
>  
>  #include <libcamera/controls.h>
> +#include <libcamera/geometry.h>
>  #include <libcamera/request.h>
>  #include <libcamera/stream.h>
>  #include <libcamera/transform.h>
> @@ -30,6 +31,47 @@ class FrameBufferAllocator;
>  class PipelineHandler;
>  class Request;
>  
> +class SensorConfiguration
> +{
> +public:
> +       unsigned int bitDepth = 0;
> +
> +       Rectangle analogCrop;
> +
> +       struct {
> +               unsigned int binX = 1;
> +               unsigned int binY = 1;
> +       } binning;
> +
> +       struct {
> +               unsigned int xOddInc = 1;
> +               unsigned int xEvenInc = 1;
> +               unsigned int yOddInc = 1;
> +               unsigned int yEvenInc = 1;
> +       } skipping;
> +
> +       Size outputSize;
> +
> +       bool valid() const
> +       {
> +               return validate() != Invalid;
> +       }
> +
> +       explicit operator bool() const
> +       {
> +               return validate() == Populated;
> +       }
> +
> +private:
> +       enum Status {
> +               Unpopulated,
> +               Populated,
> +               Invalid,
> +       };
> +
> +       Status validate() const;
> +};
> +
>  class CameraConfiguration
>  {
>  public:
> @@ -66,6 +108,7 @@ public:
>         bool empty() const;
>         std::size_t size() const;
>  
> +       SensorConfiguration sensorConfig;
>         Transform transform;
>  
>  protected:
> diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
> index 0eecee766f00..e796a5da28c6 100644
> --- a/src/libcamera/camera.cpp
> +++ b/src/libcamera/camera.cpp
> @@ -97,6 +97,21 @@
>   * implemented in the above order at the hardware level. The libcamera pipeline
>   * handlers translate the pipeline model to the real hardware configuration.
>   *
> + * \subsection camera-sensor-mode Camera Sensor Model
> + *
> + * libcamera allows applications to control the configuration of the camera
> + * sensor, particularly it allows to control the frame geometry and frame
> + * delivery rate of the sensor.
> + *
> + * The camera sensor configuration applies to all streams produced by a camera
> + * from the same image source.
> + *
> + * More details about the libcamera implemented camera sensor model are

More details about the camera sensor model implemented by libcamera are

> + * available in the libcamera camera-sensor-model documentation page.
> + *
> + * The sensor configuration is specified by applications by populating the
> + * CameraConfiguration::sensorConfig class member.
> + *
>   * \subsection digital-zoom Digital Zoom
>   *
>   * Digital zoom is implemented as a combination of the cropping and scaling
> @@ -111,6 +126,161 @@ namespace libcamera {
>  
>  LOG_DECLARE_CATEGORY(Camera)
>  
> +/**
> + * \class SensorConfiguration
> + * \brief Camera sensor configuration
> + *
> + * The SensorConfiguration class collects parameters to control the operations
> + * of the camera sensor, accordingly to the abstract camera sensor model
> + * implemented by libcamera.
> + *
> + * \todo Applications shall fully populate all fields of the
> + * CameraConfiguration::sensorConfig class members before validating the
> + * CameraConfiguration. If the SensorConfiguration is not fully populated, or if
> + * any of its parameters cannot be applied to the sensor in use, the
> + * CameraConfiguration validation process will fail and return
> + * CameraConfiguration::Status::Invalid.
> + *
> + * Applications that populate the SensorConfiguration class members are
> + * expected to be highly-specialized applications that know what sensor
> + * they are operating with and what parameters are valid for the sensor in use.
> + *
> + * A detailed description of the abstract camera sensor model implemented by
> + * libcamera and the description of its configuration parameters is available
> + * in the libcamera documentation camera-sensor-model file.
> + */
> +
> +/**
> + * \enum SensorConfiguration::Status
> + * \brief The sensor configuration validation status
> + */
> +
> +/**
> + * \var SensorConfiguration::bitDepth
> + * \brief The sensor image format bit depth
> + *
> + * The number of bits (resolution) used to represent a pixel sample.
> + */
> +
> +/**
> + * \var SensorConfiguration::analogCrop
> + * \brief The analog crop rectangle
> + *
> + * The selected portion of the active pixel array used to produce the image
> + * frame.
> + */
> +
> +/**
> + * \var SensorConfiguration::binning
> + * \brief Sensor binning configuration
> + *
> + * Refer to the camera-sensor-model documentation for an accurate description
> + * of the binning operations. Disabled by default.
> + */
> +
> +/**
> + * \var SensorConfiguration::binX
> + * \brief Horizontal binning factor
> + *
> + * The horizontal binning factor. Default to 1.
> + */
> +
> +/**
> + * \var SensorConfiguration::binY
> + * \brief Vertical binning factor
> + *
> + * The vertical binning factor. Default to 1.
> + */
> +
> +/**
> + * \var SensorConfiguration::skipping
> + * \brief The sensor skipping configuration
> + *
> + * Refer to the camera-sensor-model documentation for an accurate description
> + * of the skipping operations.
> + *
> + * If no skipping is performed, all the structure fields should be
> + * set to 1. Disabled by default.
> + */
> +
> +/**
> + * \var SensorConfiguration::xOddInc
> + * \brief Horizontal increment for odd rows. Default to 1.
> + */
> +
> +/**
> + * \var SensorConfiguration::xEvenInc
> + * \brief Horizontal increment for even rows. Default to 1.
> + */
> +
> +/**
> + * \var SensorConfiguration::yOddInc
> + * \brief Vertical increment for odd columns. Default to 1.
> + */
> +
> +/**
> + * \var SensorConfiguration::yEvenInc
> + * \brief Vertical increment for even columns. Default to 1.
> + */
> +
> +/**
> + * \var SensorConfiguration::outputSize
> + * \brief The frame output (visible) size
> + *
> + * The size of the data frame as received by the host processor.
> + */
> +
> +/**
> + * \fn SensorConfiguration::valid() const
> + * \brief Validate the SensorConfiguration
> + *
> + * Validate the sensor configuration.
> + *
> + * \todo A sensor configuration is valid (or well-formed) if it's either
> + * completely un-populated or fully populated. For now allow applications to
> + * populate the bitDepth and the outputSize only.
> + *
> + * \return True if the SensorConfiguration is either fully populated or
> + * un-populated, false otherwise
> + */
> +
> +/**
> + * \fn SensorConfiguration::operator bool() const
> + * \brief Test if a SensorConfiguration is fully populated
> + * \return True if the SensorConfiguration is fully populated
> + */
> +
> +/**
> + * \brief Validate the sensor configuration
> + *
> + * \todo A sensor configuration is valid (or well-formed) if it's either
> + * completely un-populated or fully populated. For now allow applications to
> + * populate the bitDepth and the outputSize only.
> + *
> + * \return The sensor configuration status
> + * \retval Unpopulated The sensor configuration is fully unpopulated
> + * \retval Populated The sensor configuration is fully populated
> + * \retval Invalid The sensor configuration is invalid (not fully populated
> + * and not fully unpopulated)
> + */
> +SensorConfiguration::Status SensorConfiguration::validate() const
> +{
> +       if (bitDepth && binning.binX && binning.binY &&
> +           skipping.xOddInc && skipping.yOddInc &&
> +           skipping.xEvenInc && skipping.yEvenInc &&
> +           !outputSize.isNull())
> +               return Populated;
> +
> +       if (!bitDepth &&
> +           binning.binX <= 1 && binning.binY <= 1 &&
> +           skipping.xOddInc <= 1 && skipping.yOddInc <= 1 &&
> +           skipping.xEvenInc <= 1 && skipping.yEvenInc <= 1 &&

This looks like the <= is to support if the struct / class has been
unintialised/memset or somehow allocated with 

	SensorConfiguration = {}; ?

Otherwise - is the <= necessary ?

I don't mind keeping it - but a short comment above could explain why we
might accept skipping.yOddInc == 0 as Unpopulated rather than invalid.


> +           outputSize.isNull())
> +               return Unpopulated;
> +
> +       return Invalid;
> +}
> +
>  /**
>   * \class CameraConfiguration
>   * \brief Hold configuration for streams of the camera
> @@ -391,6 +561,16 @@ CameraConfiguration::Status CameraConfiguration::validateColorSpaces(ColorSpaceF
>         return status;
>  }
>  
> +/**
> + * \var CameraConfiguration::sensorConfig
> + * \brief The camera sensor configuration
> + *
> + * The sensorConfig field allows to control the configuration of the camera

s/ allows to control the / allows control of the /


But again, most of all that is easily fixed up so then:


Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

> + * sensor. Refer to the camera-sensor-model documentation and to the
> + * SensorConfiguration class documentation for details about the sensor
> + * configuration process.
> + */
> +
>  /**
>   * \var CameraConfiguration::transform
>   * \brief User-specified transform to be applied to the image
> -- 
> 2.40.1
>