libcamera: camera: Introduce SensorConfiguration

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@ideasonboard.com>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

include/libcamera/camera.h

@@ -9,6 +9,7 @@
 
 #include <initializer_list>
 #include <memory>
+#include <optional>
 #include <set>
 #include <stdint.h>
 #include <string>
@@ -19,6 +20,7 @@
 #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 +32,30 @@ 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 isValid() const;
+};
+
 class CameraConfiguration
 {
 public:
@@ -66,6 +92,7 @@ public:
 	bool empty() const;
 	std::size_t size() const;
 
+	std::optional<SensorConfiguration> sensorConfig;
 	Transform transform;
 
 protected:

src/libcamera/camera.cpp

@@ -97,6 +97,16 @@
  * 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-model Camera Sensor Model
+ *
+ * By default, libcamera configures the camera sensor automatically based on the
+ * configuration of the streams. Applications may instead specify a manual
+ * configuration for the camera sensor. This allows precise control of the frame
+ * geometry and frame rate delivered by the sensor.
+ *
+ * More details about the camera sensor model implemented by libcamera are
+ * available in the libcamera camera-sensor-model documentation page.
+ *
  * \subsection digital-zoom Digital Zoom
  *
  * Digital zoom is implemented as a combination of the cropping and scaling
@@ -111,6 +121,127 @@ 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, according 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.
+ */
+
+/**
+ * \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.
+ */
+
+/**
+ * \brief Check if the sensor configuration is valid
+ *
+ * A sensor configuration is valid if it's fully populated.
+ *
+ * \todo For now allow applications to populate the bitDepth and the outputSize
+ * only as skipping and binnings factors are initialized to 1 and the analog
+ * crop is ignored.
+ *
+ * \return True if the sensor configuration is valid, false otherwise
+ */
+bool SensorConfiguration::isValid() const
+{
+	if (bitDepth && binning.binX && binning.binY &&
+	    skipping.xOddInc && skipping.yOddInc &&
+	    skipping.xEvenInc && skipping.yEvenInc &&
+	    !outputSize.isNull())
+		return true;
+
+	return false;
+}
+
 /**
  * \class CameraConfiguration
  * \brief Hold configuration for streams of the camera
@@ -391,6 +522,23 @@ CameraConfiguration::Status CameraConfiguration::validateColorSpaces(ColorSpaceF
 	return status;
 }
 
+/**
+ * \var CameraConfiguration::sensorConfig
+ * \brief The camera sensor configuration
+ *
+ * The sensorConfig member allows manual control of the configuration of the
+ * camera sensor. By default, if sensorConfig is not set, the camera will
+ * configure the sensor automatically based on the configuration of the streams.
+ * Applications can override this by manually specifying the full sensor
+ * configuration.
+ *
+ * Refer to the camera-sensor-model documentation and to the SensorConfiguration
+ * class documentation for details about the sensor configuration process.
+ *
+ * The camera sensor configuration applies to all streams produced by a camera
+ * from the same image source.
+ */
+
 /**
  * \var CameraConfiguration::transform
  * \brief User-specified transform to be applied to the image