cam: Implement OptMetadata

Implement support for the new '--metadata' option by printing the
value of each metadata entry associated with a completed Request.

As sample of the output, running on raspberry pi, looks like the
following:

3050.205672 (30.01 fps) stream0 seq: 000033 bytesused: 720000
	ScalerCrop = (0x2)/3280x2460
	ExposureTime = 13969
	AeLocked = true
	DigitalGain = 1.000721
	Lux = 771.204224
	ColourGains = [ 1.561101, 1.629698 ]
	ColourTemperature = 4289
	SensorBlackLevels = [ 4096, 4096, 4096, 4096 ]
	ColourCorrectionMatrix = [ 1.691066, -0.599756, -0.091317, -0.437452, 1.983766, -0.546314, -0.083429, -0.722407, 1.805836 ]
	AnalogueGain = 2.000000
	SensorTimestamp = 3050205672000

3050.238999 (30.01 fps) stream0 seq: 000034 bytesused: 720000
	ScalerCrop = (0x2)/3280x2460
	ExposureTime = 13969
	AeLocked = true
	DigitalGain = 1.000709
	Lux = 771.232422
	ColourGains = [ 1.560868, 1.630029 ]
	ColourTemperature = 4289
	SensorBlackLevels = [ 4096, 4096, 4096, 4096 ]
	ColourCorrectionMatrix = [ 1.691081, -0.599726, -0.091362, -0.437497, 1.983627, -0.546130, -0.083420, -0.722523, 1.805943 ]
	AnalogueGain = 2.000000
	SensorTimestamp = 3050238999000

Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

src/cam/capture.cpp

@@ -10,6 +10,8 @@
 #include <limits.h>
 #include <sstream>
 
+#include <libcamera/control_ids.h>
+
 #include "capture.h"
 #include "main.h"
 
@@ -18,7 +20,8 @@ using namespace libcamera;
 Capture::Capture(std::shared_ptr<Camera> camera, CameraConfiguration *config,
 		 EventLoop *loop)
 	: camera_(camera), config_(config), writer_(nullptr), last_(0), loop_(loop),
-	  queueCount_(0), captureCount_(0), captureLimit_(0)
+	  queueCount_(0), captureCount_(0), captureLimit_(0),
+	  printMetadata_(false)
 {
 }
 
@@ -29,6 +32,7 @@ int Capture::run(const OptionsParser::Options &options)
 	queueCount_ = 0;
 	captureCount_ = 0;
 	captureLimit_ = options[OptCapture].toInteger();
+	printMetadata_ = options.isSet(OptMetadata);
 
 	if (!camera_) {
 		std::cout << "Can't capture without a camera" << std::endl;
@@ -217,6 +221,15 @@ void Capture::processRequest(Request *request)
 
 	std::cout << info.str() << std::endl;
 
+	if (printMetadata_) {
+		const ControlList &requestMetadata = request->metadata();
+		for (const auto &ctrl : requestMetadata) {
+			const ControlId *id = controls::controls.at(ctrl.first);
+			std::cout << "\t" << id->name() << " = "
+				  << ctrl.second.toString() << std::endl;
+		}
+	}
+
 	captureCount_++;
 	if (captureLimit_ && captureCount_ >= captureLimit_) {
 		loop_->exit(0);

src/cam/capture.h

@@ -47,6 +47,7 @@ private:
 	unsigned int queueCount_;
 	unsigned int captureCount_;
 	unsigned int captureLimit_;
+	bool printMetadata_;
 
 	std::vector<std::unique_ptr<libcamera::Request>> requests_;
 };