[libcamera-devel] [PATCH 2/2] libcamera: raspberrypi: Implement digital zoom

[David Plowman]

These changes implement digital zoom for the Raspberry Pi. We detect
the digital zoom control and update the V4L2 "selection" before
starting the ISP.

Libcamera metadata is always filled in by the IPAs, so we intercept it
when it comes back to the pipeline handler and update the digital zoom
region with the rectangle that we actually used.
---
 include/libcamera/ipa/raspberrypi.h           |  1 +
 src/ipa/raspberrypi/raspberrypi.cpp           | 10 ++++
 .../pipeline/raspberrypi/raspberrypi.cpp      | 59 +++++++++++++++++++
 3 files changed, 70 insertions(+)

diff --git a/include/libcamera/ipa/raspberrypi.h b/include/libcamera/ipa/raspberrypi.h
index a18ce9a..e66402e 100644
--- a/include/libcamera/ipa/raspberrypi.h
+++ b/include/libcamera/ipa/raspberrypi.h
@@ -52,6 +52,7 @@ static const ControlInfoMap RPiControls = {
 	{ &controls::Contrast, ControlInfo(0.0f, 32.0f) },
 	{ &controls::Saturation, ControlInfo(0.0f, 32.0f) },
 	{ &controls::Sharpness, ControlInfo(0.0f, 16.0f, 1.0f) },
+	{ &controls::DigitalZoom, ControlInfo(Rectangle{ 0, 0, 0, 0 }, Rectangle{ 65535, 65535, 65535, 65535 }, Rectangle{ 0, 0, 0, 0 }) },
 };
 
 } /* namespace libcamera */
diff --git a/src/ipa/raspberrypi/raspberrypi.cpp b/src/ipa/raspberrypi/raspberrypi.cpp
index bc89ab5..b4e42c1 100644
--- a/src/ipa/raspberrypi/raspberrypi.cpp
+++ b/src/ipa/raspberrypi/raspberrypi.cpp
@@ -645,6 +645,16 @@ void IPARPi::queueRequest(const ControlList &controls)
 			break;
 		}
 
+		case controls::DIGITAL_ZOOM: {
+			/*
+			 * We send the zoom info back in the metadata where the pipeline
+			 * handler will update it to the values actually used.
+			 */
+			Rectangle crop = ctrl.second.get<Rectangle>();
+			libcameraMetadata_.set(controls::DigitalZoom, crop);
+			break;
+		}
+
 		default:
 			LOG(IPARPI, Warning)
 				<< "Ctrl " << controls::controls.at(ctrl.first)->name()
diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
index 9d887b7..25cbe13 100644
--- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
+++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
@@ -37,6 +37,8 @@ namespace libcamera {
 
 LOG_DEFINE_CATEGORY(RPI)
 
+static constexpr int ISP_MIN_SIZE = 64;
+
 using V4L2PixFmtMap = std::map<V4L2PixelFormat, std::vector<SizeRange>>;
 
 namespace {
@@ -322,6 +324,13 @@ public:
 	void handleStreamBuffer(FrameBuffer *buffer, const RPiStream *stream);
 	void handleState();
 
+	void initSensorCrop(Rectangle const &crop)
+	{
+		/* The initial zoom region is the whole of the sensorCrop_. */
+		sensorCrop_ = crop;
+		zoomRect_ = Rectangle{ 0, 0, crop.width, crop.height };
+	}
+
 	CameraSensor *sensor_;
 	/* Array of Unicam and ISP device streams and associated buffers/streams. */
 	RPiDevice<Unicam, 2> unicam_;
@@ -358,6 +367,14 @@ private:
 
 	bool dropFrame_;
 	int ispOutputCount_;
+	/*
+	 * sensorCrop_ is the largest region of the full sensor output that matches
+	 * the desired aspect ratio, and therefore represents the area within
+	 * which we can pan and zoom. zoomRect_ is the portion from within the
+	 * sensorCrop_ that pan/zoom is currently using.
+	 */
+	Rectangle sensorCrop_;
+	Rectangle zoomRect_;
 };
 
 class RPiCameraConfiguration : public CameraConfiguration
@@ -763,6 +780,14 @@ int PipelineHandlerRPi::configure(Camera *camera, CameraConfiguration *config)
 
 	crop.x = (sensorFormat.size.width - crop.width) >> 1;
 	crop.y = (sensorFormat.size.height - crop.height) >> 1;
+
+	if (crop.width < ISP_MIN_SIZE || crop.height < ISP_MIN_SIZE) {
+		LOG(RPI, Error) << "Crop from sensor " << crop.width << "x" << crop.height << " is too small";
+		return -1;
+	}
+	sensorCrop_ = Size(crop.width, crop.height);
+	data->initSensorCrop(crop);
+
 	data->isp_[Isp::Input].dev()->setSelection(V4L2_SEL_TGT_CROP, &crop);
 
 	ret = configureIPA(camera);
@@ -1226,6 +1251,13 @@ void RPiCameraData::queueFrameAction(unsigned int frame, const IPAOperationData
 		handleStreamBuffer(buffer, &isp_[Isp::Stats]);
 		/* Fill the Request metadata buffer with what the IPA has provided */
 		requestQueue_.front()->metadata() = std::move(action.controls[0]);
+		ControlList &metadata = requestQueue_.front()->metadata();
+		/*
+		 * The IPA sends the zoom metadata back to us, but we're the ones who
+		 * actually know what we used, so must fill it in correctly.
+		 */
+		if (metadata.contains(controls::DigitalZoom))
+			metadata.set(controls::DigitalZoom, zoomRect_);
 		state_ = State::IpaComplete;
 		break;
 	}
@@ -1548,6 +1580,33 @@ void RPiCameraData::tryRunPipeline()
 	 */
 	Request *request = requestQueue_.front();
 
+	if (request->controls().contains(controls::DigitalZoom)) {
+		Rectangle rect = request->controls().get<Rectangle>(controls::DigitalZoom);
+		/*
+		 * If a new digital zoom value was given, check that it lies within the
+		 * available sensorCrop_, coercing it if necessary.
+		 */
+		if (rect.width && rect.height) {
+			zoomRect_ = rect;
+			if (zoomRect_.width < ISP_MIN_SIZE)
+				zoomRect_.width = ISP_MIN_SIZE;
+			else if (zoomRect_.width > sensorCrop_.width)
+				zoomRect_.width = sensorCrop_.width;
+			if (zoomRect_.height < ISP_MIN_SIZE)
+				zoomRect_.height = ISP_MIN_SIZE;
+			else if (zoomRect_.height > sensorCrop_.height)
+				zoomRect_.height = sensorCrop_.height;
+			if (zoomRect_.x + zoomRect_.width > sensorCrop_.width)
+				zoomRect_.x = sensorCrop_.width - zoomRect_.width;
+			if (zoomRect_.y + zoomRect_.height > sensorCrop_.height)
+				zoomRect_.y = sensorCrop_.height - zoomRect_.height;
+		}
+		Rectangle sensorRect = zoomRect_;
+		sensorRect.x += sensorCrop_.x;
+		sensorRect.y += sensorCrop_.y;
+		isp_[Isp::Input].dev()->setSelection(V4L2_SEL_TGT_CROP, &sensorRect);
+	}
+
 	/*
 	 * Process all the user controls by the IPA. Once this is complete, we
 	 * queue the ISP output buffer listed in the request to start the HW
-- 
2.20.1