[libcamera-devel] [PATCH v3 3/6] src: ipa: raspberrypi: awb: Add GetConvergenceFrames method to AWB base class

[David Plowman]

We add a GetConvergenceFrames method to the AwbAlgorithm class which
can be called when the AWB is started from scratch. It suggests how
many frames should be dropped before displaying any (while the AWB
converges).

The Raspberry Pi specific implementation makes this customisable from
the tuning file.

Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
Reviewed-by: Naushir Patuck <naush at raspberrypi.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 src/ipa/raspberrypi/controller/awb_algorithm.hpp |  1 +
 src/ipa/raspberrypi/controller/rpi/awb.cpp       | 11 +++++++++++
 src/ipa/raspberrypi/controller/rpi/awb.hpp       |  2 ++
 3 files changed, 14 insertions(+)

diff --git a/src/ipa/raspberrypi/controller/awb_algorithm.hpp b/src/ipa/raspberrypi/controller/awb_algorithm.hpp
index 5be0c9f4..96f88afc 100644
--- a/src/ipa/raspberrypi/controller/awb_algorithm.hpp
+++ b/src/ipa/raspberrypi/controller/awb_algorithm.hpp
@@ -15,6 +15,7 @@ class AwbAlgorithm : public Algorithm
 public:
 	AwbAlgorithm(Controller *controller) : Algorithm(controller) {}
 	// An AWB algorithm must provide the following:
+	virtual unsigned int GetConvergenceFrames() const = 0;
 	virtual void SetMode(std::string const &mode_name) = 0;
 	virtual void SetManualGains(double manual_r, double manual_b) = 0;
 };
diff --git a/src/ipa/raspberrypi/controller/rpi/awb.cpp b/src/ipa/raspberrypi/controller/rpi/awb.cpp
index 020825e3..10600f75 100644
--- a/src/ipa/raspberrypi/controller/rpi/awb.cpp
+++ b/src/ipa/raspberrypi/controller/rpi/awb.cpp
@@ -59,6 +59,7 @@ void AwbConfig::Read(boost::property_tree::ptree const &params)
 	bayes = params.get<int>("bayes", 1);
 	frame_period = params.get<uint16_t>("frame_period", 10);
 	startup_frames = params.get<uint16_t>("startup_frames", 10);
+	convergence_frames = params.get<unsigned int>("convergence_frames", 3);
 	speed = params.get<double>("speed", 0.05);
 	if (params.get_child_optional("ct_curve"))
 		read_ct_curve(ct_r, ct_b, params.get_child("ct_curve"));
@@ -165,6 +166,16 @@ void Awb::Initialise()
 	prev_sync_results_ = sync_results_;
 }
 
+unsigned int Awb::GetConvergenceFrames() const
+{
+	// If colour gains have been explicitly set, there is no convergence
+	// to happen, so no need to drop any frames - return zero.
+	if (manual_r_ && manual_b_)
+		return 0;
+	else
+		return config_.convergence_frames;
+}
+
 void Awb::SetMode(std::string const &mode_name)
 {
 	std::unique_lock<std::mutex> lock(settings_mutex_);
diff --git a/src/ipa/raspberrypi/controller/rpi/awb.hpp b/src/ipa/raspberrypi/controller/rpi/awb.hpp
index 545d85a8..6fc045ce 100644
--- a/src/ipa/raspberrypi/controller/rpi/awb.hpp
+++ b/src/ipa/raspberrypi/controller/rpi/awb.hpp
@@ -37,6 +37,7 @@ struct AwbConfig {
 	uint16_t frame_period;
 	// number of initial frames for which speed taken as 1.0 (maximum)
 	uint16_t startup_frames;
+	unsigned int convergence_frames; // approx number of frames to converge
 	double speed; // IIR filter speed applied to algorithm results
 	bool fast; // "fast" mode uses a 16x16 rather than 32x32 grid
 	Pwl ct_r; // function maps CT to r (= R/G)
@@ -82,6 +83,7 @@ public:
 	char const *Name() const override;
 	void Initialise() override;
 	void Read(boost::property_tree::ptree const &params) override;
+	unsigned int GetConvergenceFrames() const override;
 	void SetMode(std::string const &name) override;
 	void SetManualGains(double manual_r, double manual_b) override;
 	void SwitchMode(CameraMode const &camera_mode, Metadata *metadata) override;
-- 
2.20.1