Add Python bindings

Add libcamera Python bindings. pybind11 is used to generate the C++ <->
Python layer.

We use pybind11 'smart_holder' version to avoid issues with private
destructors and shared_ptr. There is also an alternative solution here:

https://github.com/pybind/pybind11/pull/2067

Only a subset of libcamera classes are exposed. Implementing and testing
the wrapper classes is challenging, and as such only classes that I have
needed have been added so far.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

11 files changed, 845 insertions, 1 deletions

diff --git a/meson.build b/meson.build
index ea0a4200..6d7d3ca6 100644
--- a/meson.build
+++ b/meson.build
@@ -177,6 +177,7 @@ summary({
             'Tracing support': tracing_enabled,
             'Android support': android_enabled,
             'GStreamer support': gst_enabled,
+            'Python bindings': pycamera_enabled,
             'V4L2 emulation support': v4l2_enabled,
             'cam application': cam_enabled,
             'qcam application': qcam_enabled,
diff --git a/meson_options.txt b/meson_options.txt
index 2c80ad8b..ca00c78e 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -58,3 +58,8 @@ option('v4l2',
         type : 'boolean',
         value : false,
         description : 'Compile the V4L2 compatibility layer')
+
+option('pycamera',
+        type : 'feature',
+        value : 'auto',
+        description : 'Enable libcamera Python bindings (experimental)')
diff --git a/src/meson.build b/src/meson.build
index e0ea9c35..34663a6f 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -37,4 +37,5 @@ subdir('cam')
 subdir('qcam')
 
 subdir('gstreamer')
+subdir('py')
 subdir('v4l2')
diff --git a/src/py/libcamera/__init__.py b/src/py/libcamera/__init__.py
new file mode 100644
index 00000000..0d7da9e2
--- /dev/null
+++ b/src/py/libcamera/__init__.py
@@ -0,0 +1,84 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+# Copyright (C) 2022, Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
+
+from ._libcamera import *
+
+
+class MappedFrameBuffer:
+    def __init__(self, fb):
+        self.__fb = fb
+
+    def __enter__(self):
+        import os
+        import mmap
+
+        fb = self.__fb
+
+        # Collect information about the buffers
+
+        bufinfos = {}
+
+        for i in range(fb.num_planes):
+            fd = fb.fd(i)
+
+            if fd not in bufinfos:
+                buflen = os.lseek(fd, 0, os.SEEK_END)
+                bufinfos[fd] = {'maplen': 0, 'buflen': buflen}
+            else:
+                buflen = bufinfos[fd]['buflen']
+
+            if fb.offset(i) > buflen or fb.offset(i) + fb.length(i) > buflen:
+                raise RuntimeError(f'plane is out of buffer: buffer length={buflen}, ' +
+                                   f'plane offset={fb.offset(i)}, plane length={fb.length(i)}')
+
+            bufinfos[fd]['maplen'] = max(bufinfos[fd]['maplen'], fb.offset(i) + fb.length(i))
+
+        # mmap the buffers
+
+        maps = []
+
+        for fd, info in bufinfos.items():
+            map = mmap.mmap(fd, info['maplen'], mmap.MAP_SHARED, mmap.PROT_READ | mmap.PROT_WRITE)
+            info['map'] = map
+            maps.append(map)
+
+        self.__maps = tuple(maps)
+
+        # Create memoryviews for the planes
+
+        planes = []
+
+        for i in range(fb.num_planes):
+            fd = fb.fd(i)
+            info = bufinfos[fd]
+
+            mv = memoryview(info['map'])
+
+            start = fb.offset(i)
+            end = fb.offset(i) + fb.length(i)
+
+            mv = mv[start:end]
+
+            planes.append(mv)
+
+        self.__planes = tuple(planes)
+
+        return self
+
+    def __exit__(self, exc_type, exc_value, exc_traceback):
+        for p in self.__planes:
+            p.release()
+
+        for mm in self.__maps:
+            mm.close()
+
+    @property
+    def planes(self):
+        return self.__planes
+
+
+def __FrameBuffer__mmap(self):
+    return MappedFrameBuffer(self)
+
+
+FrameBuffer.mmap = __FrameBuffer__mmap
diff --git a/src/py/libcamera/meson.build b/src/py/libcamera/meson.build
new file mode 100644
index 00000000..edf4a629
--- /dev/null
+++ b/src/py/libcamera/meson.build
@@ -0,0 +1,52 @@
+# SPDX-License-Identifier: CC0-1.0
+
+py3_dep = dependency('python3', required : get_option('pycamera'))
+
+if not py3_dep.found()
+    pycamera_enabled = false
+    subdir_done()
+endif
+
+pycamera_enabled = true
+
+pybind11_proj = subproject('pybind11')
+pybind11_dep = pybind11_proj.get_variable('pybind11_dep')
+
+pycamera_sources = files([
+    'pyenums.cpp',
+    'pymain.cpp',
+])
+
+pycamera_deps = [
+    libcamera_public,
+    py3_dep,
+    pybind11_dep,
+]
+
+pycamera_args = [
+    '-fvisibility=hidden',
+    '-Wno-shadow',
+    '-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT',
+    '-DLIBCAMERA_BASE_PRIVATE',
+]
+
+destdir = get_option('libdir') / ('python' + py3_dep.version()) / 'site-packages' / 'libcamera'
+
+pycamera = shared_module('_libcamera',
+                         pycamera_sources,
+                         install : true,
+                         install_dir : destdir,
+                         name_prefix : '',
+                         dependencies : pycamera_deps,
+                         cpp_args : pycamera_args)
+
+run_command('ln', '-fsT', '../../../../src/py/libcamera/__init__.py',
+            meson.current_build_dir() / '__init__.py',
+            check: true)
+
+install_data(['__init__.py'], install_dir : destdir)
+
+# \todo Generate stubs when building. See https://peps.python.org/pep-0484/#stub-files
+# Note: Depends on pybind11-stubgen. To generate pylibcamera stubs:
+# $ PYTHONPATH=build/src/py pybind11-stubgen --no-setup-py -o build/src/py libcamera
+# $ mv build/src/py/libcamera-stubs/* build/src/py/libcamera/
diff --git a/src/py/libcamera/pyenums.cpp b/src/py/libcamera/pyenums.cpp
new file mode 100644
index 00000000..b655e622
--- /dev/null
+++ b/src/py/libcamera/pyenums.cpp
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2022, Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
+ *
+ * Python bindings - Enumerations
+ */
+
+#include <libcamera/libcamera.h>
+
+#include <pybind11/smart_holder.h>
+
+namespace py = pybind11;
+
+using namespace libcamera;
+
+void init_pyenums(py::module &m)
+{
+	py::enum_<StreamRole>(m, "StreamRole")
+		.value("StillCapture", StreamRole::StillCapture)
+		.value("Raw", StreamRole::Raw)
+		.value("VideoRecording", StreamRole::VideoRecording)
+		.value("Viewfinder", StreamRole::Viewfinder);
+
+	py::enum_<ControlType>(m, "ControlType")
+		.value("None", ControlType::ControlTypeNone)
+		.value("Bool", ControlType::ControlTypeBool)
+		.value("Byte", ControlType::ControlTypeByte)
+		.value("Integer32", ControlType::ControlTypeInteger32)
+		.value("Integer64", ControlType::ControlTypeInteger64)
+		.value("Float", ControlType::ControlTypeFloat)
+		.value("String", ControlType::ControlTypeString)
+		.value("Rectangle", ControlType::ControlTypeRectangle)
+		.value("Size", ControlType::ControlTypeSize);
+}
diff --git a/src/py/libcamera/pymain.cpp b/src/py/libcamera/pymain.cpp
new file mode 100644
index 00000000..84829e63
--- /dev/null
+++ b/src/py/libcamera/pymain.cpp
@@ -0,0 +1,649 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2022, Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
+ *
+ * Python bindings
+ */
+
+/*
+ * \todo Add geometry classes (Point, Rectangle...)
+ * \todo Add bindings for the ControlInfo class
+ * \todo Add bindings for the PixelFormat class
+ */
+
+#include <mutex>
+#include <stdexcept>
+#include <sys/eventfd.h>
+#include <unistd.h>
+
+#include <libcamera/base/log.h>
+
+#include <libcamera/libcamera.h>
+
+#include <pybind11/functional.h>
+#include <pybind11/smart_holder.h>
+#include <pybind11/stl.h>
+#include <pybind11/stl_bind.h>
+
+namespace py = pybind11;
+
+using namespace libcamera;
+
+template<typename T>
+static py::object valueOrTuple(const ControlValue &cv)
+{
+	if (cv.isArray()) {
+		const T *v = reinterpret_cast<const T *>(cv.data().data());
+		auto t = py::tuple(cv.numElements());
+
+		for (size_t i = 0; i < cv.numElements(); ++i)
+			t[i] = v[i];
+
+		return std::move(t);
+	}
+
+	return py::cast(cv.get<T>());
+}
+
+static py::object controlValueToPy(const ControlValue &cv)
+{
+	switch (cv.type()) {
+	case ControlTypeBool:
+		return valueOrTuple<bool>(cv);
+	case ControlTypeByte:
+		return valueOrTuple<uint8_t>(cv);
+	case ControlTypeInteger32:
+		return valueOrTuple<int32_t>(cv);
+	case ControlTypeInteger64:
+		return valueOrTuple<int64_t>(cv);
+	case ControlTypeFloat:
+		return valueOrTuple<float>(cv);
+	case ControlTypeString:
+		return py::cast(cv.get<std::string>());
+	case ControlTypeRectangle: {
+		const Rectangle *v = reinterpret_cast<const Rectangle *>(cv.data().data());
+		return py::make_tuple(v->x, v->y, v->width, v->height);
+	}
+	case ControlTypeSize: {
+		const Size *v = reinterpret_cast<const Size *>(cv.data().data());
+		return py::make_tuple(v->width, v->height);
+	}
+	case ControlTypeNone:
+	default:
+		throw std::runtime_error("Unsupported ControlValue type");
+	}
+}
+
+template<typename T>
+static ControlValue controlValueMaybeArray(const py::object &ob)
+{
+	if (py::isinstance<py::list>(ob) || py::isinstance<py::tuple>(ob)) {
+		std::vector<T> vec = ob.cast<std::vector<T>>();
+		return ControlValue(Span<const T>(vec));
+	}
+
+	return ControlValue(ob.cast<T>());
+}
+
+static ControlValue pyToControlValue(const py::object &ob, ControlType type)
+{
+	switch (type) {
+	case ControlTypeBool:
+		return ControlValue(ob.cast<bool>());
+	case ControlTypeByte:
+		return controlValueMaybeArray<uint8_t>(ob);
+	case ControlTypeInteger32:
+		return controlValueMaybeArray<int32_t>(ob);
+	case ControlTypeInteger64:
+		return controlValueMaybeArray<int64_t>(ob);
+	case ControlTypeFloat:
+		return controlValueMaybeArray<float>(ob);
+	case ControlTypeString:
+		return ControlValue(ob.cast<std::string>());
+	case ControlTypeRectangle: {
+		auto array = ob.cast<std::array<int32_t, 4>>();
+		return ControlValue(Rectangle(array[0], array[1], array[2], array[3]));
+	}
+	case ControlTypeSize: {
+		auto array = ob.cast<std::array<int32_t, 2>>();
+		return ControlValue(Size(array[0], array[1]));
+	}
+	case ControlTypeNone:
+	default:
+		throw std::runtime_error("Control type not implemented");
+	}
+}
+
+static std::weak_ptr<CameraManager> gCameraManager;
+static int gEventfd;
+static std::mutex gReqlistMutex;
+static std::vector<Request *> gReqList;
+
+static void handleRequestCompleted(Request *req)
+{
+	{
+		std::lock_guard guard(gReqlistMutex);
+		gReqList.push_back(req);
+	}
+
+	uint64_t v = 1;
+	size_t s = write(gEventfd, &v, 8);
+	/*
+	 * We should never fail, and have no simple means to manage the error,
+	 * so let's use LOG(Fatal).
+	 */
+	if (s != 8)
+		LOG(Fatal) << "Unable to write to eventfd";
+}
+
+void init_pyenums(py::module &m);
+
+PYBIND11_MODULE(_libcamera, m)
+{
+	init_pyenums(m);
+
+	/* Forward declarations */
+
+	/*
+	 * We need to declare all the classes here so that Python docstrings
+	 * can be generated correctly.
+	 * https://pybind11.readthedocs.io/en/latest/advanced/misc.html#avoiding-c-types-in-docstrings
+	 */
+
+	auto pyCameraManager = py::class_<CameraManager>(m, "CameraManager");
+	auto pyCamera = py::class_<Camera>(m, "Camera");
+	auto pyCameraConfiguration = py::class_<CameraConfiguration>(m, "CameraConfiguration");
+	auto pyCameraConfigurationStatus = py::enum_<CameraConfiguration::Status>(pyCameraConfiguration, "Status");
+	auto pyStreamConfiguration = py::class_<StreamConfiguration>(m, "StreamConfiguration");
+	auto pyStreamFormats = py::class_<StreamFormats>(m, "StreamFormats");
+	auto pyFrameBufferAllocator = py::class_<FrameBufferAllocator>(m, "FrameBufferAllocator");
+	auto pyFrameBuffer = py::class_<FrameBuffer>(m, "FrameBuffer");
+	auto pyStream = py::class_<Stream>(m, "Stream");
+	auto pyControlId = py::class_<ControlId>(m, "ControlId");
+	auto pyRequest = py::class_<Request>(m, "Request");
+	auto pyRequestStatus = py::enum_<Request::Status>(pyRequest, "Status");
+	auto pyRequestReuse = py::enum_<Request::ReuseFlag>(pyRequest, "Reuse");
+	auto pyFrameMetadata = py::class_<FrameMetadata>(m, "FrameMetadata");
+	auto pyFrameMetadataStatus = py::enum_<FrameMetadata::Status>(pyFrameMetadata, "Status");
+	auto pyTransform = py::class_<Transform>(m, "Transform");
+	auto pyColorSpace = py::class_<ColorSpace>(m, "ColorSpace");
+	auto pyColorSpacePrimaries = py::enum_<ColorSpace::Primaries>(pyColorSpace, "Primaries");
+	auto pyColorSpaceTransferFunction = py::enum_<ColorSpace::TransferFunction>(pyColorSpace, "TransferFunction");
+	auto pyColorSpaceYcbcrEncoding = py::enum_<ColorSpace::YcbcrEncoding>(pyColorSpace, "YcbcrEncoding");
+	auto pyColorSpaceRange = py::enum_<ColorSpace::Range>(pyColorSpace, "Range");
+
+	/* Global functions */
+	m.def("log_set_level", &logSetLevel);
+
+	/* Classes */
+	pyCameraManager
+		.def_static("singleton", []() {
+			std::shared_ptr<CameraManager> cm = gCameraManager.lock();
+			if (cm)
+				return cm;
+
+			int fd = eventfd(0, 0);
+			if (fd == -1)
+				throw std::system_error(errno, std::generic_category(),
+							"Failed to create eventfd");
+
+			cm = std::shared_ptr<CameraManager>(new CameraManager, [](auto p) {
+				close(gEventfd);
+				gEventfd = -1;
+				delete p;
+			});
+
+			gEventfd = fd;
+			gCameraManager = cm;
+
+			int ret = cm->start();
+			if (ret)
+				throw std::system_error(-ret, std::generic_category(),
+							"Failed to start CameraManager");
+
+			return cm;
+		})
+
+		.def_property_readonly("version", &CameraManager::version)
+
+		.def_property_readonly("efd", [](CameraManager &) {
+			return gEventfd;
+		})
+
+		.def("get_ready_requests", [](CameraManager &) {
+			std::vector<Request *> v;
+
+			{
+				std::lock_guard guard(gReqlistMutex);
+				swap(v, gReqList);
+			}
+
+			std::vector<py::object> ret;
+
+			for (Request *req : v) {
+				py::object o = py::cast(req);
+				/* Decrease the ref increased in Camera.queue_request() */
+				o.dec_ref();
+				ret.push_back(o);
+			}
+
+			return ret;
+		})
+
+		.def("get", py::overload_cast<const std::string &>(&CameraManager::get), py::keep_alive<0, 1>())
+
+		/* Create a list of Cameras, where each camera has a keep-alive to CameraManager */
+		.def_property_readonly("cameras", [](CameraManager &self) {
+			py::list l;
+
+			for (auto &c : self.cameras()) {
+				py::object py_cm = py::cast(self);
+				py::object py_cam = py::cast(c);
+				py::detail::keep_alive_impl(py_cam, py_cm);
+				l.append(py_cam);
+			}
+
+			return l;
+		});
+
+	pyCamera
+		.def_property_readonly("id", &Camera::id)
+		.def("acquire", &Camera::acquire)
+		.def("release", &Camera::release)
+		.def("start", [](Camera &self, py::dict controls) {
+			/* \todo What happens if someone calls start() multiple times? */
+
+			self.requestCompleted.connect(handleRequestCompleted);
+
+			const ControlInfoMap &controlMap = self.controls();
+			ControlList controlList(controlMap);
+			for (const auto& [hkey, hval]: controls) {
+				auto key = hkey.cast<std::string>();
+
+				auto it = std::find_if(controlMap.begin(), controlMap.end(),
+						       [&key](const auto &kvp) {
+								return kvp.first->name() == key;
+						       });
+
+				if (it == controlMap.end())
+					throw std::runtime_error("Control " + key + " not found");
+
+				const auto &id = it->first;
+				auto obj = py::cast<py::object>(hval);
+
+				controlList.set(id->id(), pyToControlValue(obj, id->type()));
+			}
+
+			int ret = self.start(&controlList);
+			if (ret) {
+				self.requestCompleted.disconnect(handleRequestCompleted);
+				return ret;
+			}
+
+			return 0;
+		}, py::arg("controls") = py::dict())
+
+		.def("stop", [](Camera &self) {
+			int ret = self.stop();
+			if (ret)
+				return ret;
+
+			self.requestCompleted.disconnect(handleRequestCompleted);
+
+			return 0;
+		})
+
+		.def("__str__", [](Camera &self) {
+			return "<libcamera.Camera '" + self.id() + "'>";
+		})
+
+		/* Keep the camera alive, as StreamConfiguration contains a Stream* */
+		.def("generate_configuration", &Camera::generateConfiguration, py::keep_alive<0, 1>())
+		.def("configure", &Camera::configure)
+
+		.def("create_request", &Camera::createRequest, py::arg("cookie") = 0)
+
+		.def("queue_request", [](Camera &self, Request *req) {
+			py::object py_req = py::cast(req);
+
+			/*
+			 * Increase the reference count, will be dropped in
+			 * CameraManager.get_ready_requests().
+			 */
+
+			py_req.inc_ref();
+
+			int ret = self.queueRequest(req);
+			if (ret)
+				py_req.dec_ref();
+
+			return ret;
+		})
+
+		.def_property_readonly("streams", [](Camera &self) {
+			py::set set;
+			for (auto &s : self.streams()) {
+				py::object py_self = py::cast(self);
+				py::object py_s = py::cast(s);
+				py::detail::keep_alive_impl(py_s, py_self);
+				set.add(py_s);
+			}
+			return set;
+		})
+
+		.def("find_control", [](Camera &self, const std::string &name) {
+			const auto &controls = self.controls();
+
+			auto it = std::find_if(controls.begin(), controls.end(),
+					       [&name](const auto &kvp) {
+							return kvp.first->name() == name;
+					       });
+
+			if (it == controls.end())
+				throw std::runtime_error("Control '" + name + "' not found");
+
+			return it->first;
+		}, py::return_value_policy::reference_internal)
+
+		.def_property_readonly("controls", [](Camera &self) {
+			py::dict ret;
+
+			for (const auto &[id, ci] : self.controls()) {
+				ret[id->name().c_str()] = std::make_tuple<py::object>(controlValueToPy(ci.min()),
+										      controlValueToPy(ci.max()),
+										      controlValueToPy(ci.def()));
+			}
+
+			return ret;
+		})
+
+		.def_property_readonly("properties", [](Camera &self) {
+			py::dict ret;
+
+			for (const auto &[key, cv] : self.properties()) {
+				const ControlId *id = properties::properties.at(key);
+				py::object ob = controlValueToPy(cv);
+
+				ret[id->name().c_str()] = ob;
+			}
+
+			return ret;
+		});
+
+	pyCameraConfiguration
+		.def("__iter__", [](CameraConfiguration &self) {
+			return py::make_iterator<py::return_value_policy::reference_internal>(self);
+		}, py::keep_alive<0, 1>())
+		.def("__len__", [](CameraConfiguration &self) {
+			return self.size();
+		})
+		.def("validate", &CameraConfiguration::validate)
+		.def("at", py::overload_cast<unsigned int>(&CameraConfiguration::at),
+		     py::return_value_policy::reference_internal)
+		.def_property_readonly("size", &CameraConfiguration::size)
+		.def_property_readonly("empty", &CameraConfiguration::empty)
+		.def_readwrite("transform", &CameraConfiguration::transform);
+
+	pyCameraConfigurationStatus
+		.value("Valid", CameraConfiguration::Valid)
+		.value("Adjusted", CameraConfiguration::Adjusted)
+		.value("Invalid", CameraConfiguration::Invalid);
+
+	pyStreamConfiguration
+		.def("__str__", &StreamConfiguration::toString)
+		.def_property_readonly("stream", &StreamConfiguration::stream,
+		                       py::return_value_policy::reference_internal)
+		.def_property(
+			"size",
+			[](StreamConfiguration &self) {
+				return std::make_tuple(self.size.width, self.size.height);
+			},
+			[](StreamConfiguration &self, std::tuple<uint32_t, uint32_t> size) {
+				self.size.width = std::get<0>(size);
+				self.size.height = std::get<1>(size);
+			})
+		.def_property(
+			"pixel_format",
+			[](StreamConfiguration &self) {
+				return self.pixelFormat.toString();
+			},
+			[](StreamConfiguration &self, std::string fmt) {
+				self.pixelFormat = PixelFormat::fromString(fmt);
+			})
+		.def_readwrite("stride", &StreamConfiguration::stride)
+		.def_readwrite("frame_size", &StreamConfiguration::frameSize)
+		.def_readwrite("buffer_count", &StreamConfiguration::bufferCount)
+		.def_property_readonly("formats", &StreamConfiguration::formats,
+		                       py::return_value_policy::reference_internal)
+		.def_readwrite("color_space", &StreamConfiguration::colorSpace);
+
+	pyStreamFormats
+		.def_property_readonly("pixel_formats", [](StreamFormats &self) {
+			std::vector<std::string> fmts;
+			for (auto &fmt : self.pixelformats())
+				fmts.push_back(fmt.toString());
+			return fmts;
+		})
+		.def("sizes", [](StreamFormats &self, const std::string &pixelFormat) {
+			auto fmt = PixelFormat::fromString(pixelFormat);
+			std::vector<std::tuple<uint32_t, uint32_t>> fmts;
+			for (const auto &s : self.sizes(fmt))
+				fmts.push_back(std::make_tuple(s.width, s.height));
+			return fmts;
+		})
+		.def("range", [](StreamFormats &self, const std::string &pixelFormat) {
+			auto fmt = PixelFormat::fromString(pixelFormat);
+			const auto &range = self.range(fmt);
+			return make_tuple(std::make_tuple(range.hStep, range.vStep),
+					  std::make_tuple(range.min.width, range.min.height),
+					  std::make_tuple(range.max.width, range.max.height));
+		});
+
+	pyFrameBufferAllocator
+		.def(py::init<std::shared_ptr<Camera>>(), py::keep_alive<1, 2>())
+		.def("allocate", &FrameBufferAllocator::allocate)
+		.def_property_readonly("allocated", &FrameBufferAllocator::allocated)
+		/* Create a list of FrameBuffers, where each FrameBuffer has a keep-alive to FrameBufferAllocator */
+		.def("buffers", [](FrameBufferAllocator &self, Stream *stream) {
+			py::object py_self = py::cast(self);
+			py::list l;
+			for (auto &ub : self.buffers(stream)) {
+				py::object py_buf = py::cast(ub.get(), py::return_value_policy::reference_internal, py_self);
+				l.append(py_buf);
+			}
+			return l;
+		});
+
+	pyFrameBuffer
+		/* \todo implement FrameBuffer::Plane properly */
+		.def(py::init([](std::vector<std::tuple<int, unsigned int>> planes, unsigned int cookie) {
+			std::vector<FrameBuffer::Plane> v;
+			for (const auto &t : planes)
+				v.push_back({ SharedFD(std::get<0>(t)), FrameBuffer::Plane::kInvalidOffset, std::get<1>(t) });
+			return new FrameBuffer(v, cookie);
+		}))
+		.def_property_readonly("metadata", &FrameBuffer::metadata, py::return_value_policy::reference_internal)
+		.def_property_readonly("num_planes", [](const FrameBuffer &self) {
+			return self.planes().size();
+		})
+		.def("length", [](FrameBuffer &self, uint32_t idx) {
+			const FrameBuffer::Plane &plane = self.planes()[idx];
+			return plane.length;
+		})
+		.def("fd", [](FrameBuffer &self, uint32_t idx) {
+			const FrameBuffer::Plane &plane = self.planes()[idx];
+			return plane.fd.get();
+		})
+		.def("offset", [](FrameBuffer &self, uint32_t idx) {
+			const FrameBuffer::Plane &plane = self.planes()[idx];
+			return plane.offset;
+		})
+		.def_property("cookie", &FrameBuffer::cookie, &FrameBuffer::setCookie);
+
+	pyStream
+		.def_property_readonly("configuration", &Stream::configuration);
+
+	pyControlId
+		.def_property_readonly("id", &ControlId::id)
+		.def_property_readonly("name", &ControlId::name)
+		.def_property_readonly("type", &ControlId::type);
+
+	pyRequest
+		/* \todo Fence is not supported, so we cannot expose addBuffer() directly */
+		.def("add_buffer", [](Request &self, const Stream *stream, FrameBuffer *buffer) {
+			return self.addBuffer(stream, buffer);
+		}, py::keep_alive<1, 3>()) /* Request keeps Framebuffer alive */
+		.def_property_readonly("status", &Request::status)
+		.def_property_readonly("buffers", &Request::buffers)
+		.def_property_readonly("cookie", &Request::cookie)
+		.def_property_readonly("has_pending_buffers", &Request::hasPendingBuffers)
+		.def("set_control", [](Request &self, ControlId &id, py::object value) {
+			self.controls().set(id.id(), pyToControlValue(value, id.type()));
+		})
+		.def_property_readonly("metadata", [](Request &self) {
+			py::dict ret;
+
+			for (const auto &[key, cv] : self.metadata()) {
+				const ControlId *id = controls::controls.at(key);
+				py::object ob = controlValueToPy(cv);
+
+				ret[id->name().c_str()] = ob;
+			}
+
+			return ret;
+		})
+		/*
+		 * \todo As we add a keep_alive to the fb in addBuffers(), we
+		 * can only allow reuse with ReuseBuffers.
+		 */
+		.def("reuse", [](Request &self) { self.reuse(Request::ReuseFlag::ReuseBuffers); });
+
+	pyRequestStatus
+		.value("Pending", Request::RequestPending)
+		.value("Complete", Request::RequestComplete)
+		.value("Cancelled", Request::RequestCancelled);
+
+	pyRequestReuse
+		.value("Default", Request::ReuseFlag::Default)
+		.value("ReuseBuffers", Request::ReuseFlag::ReuseBuffers);
+
+	pyFrameMetadata
+		.def_readonly("status", &FrameMetadata::status)
+		.def_readonly("sequence", &FrameMetadata::sequence)
+		.def_readonly("timestamp", &FrameMetadata::timestamp)
+		/* \todo Implement FrameMetadata::Plane properly */
+		.def_property_readonly("bytesused", [](FrameMetadata &self) {
+			std::vector<unsigned int> v;
+			v.resize(self.planes().size());
+			transform(self.planes().begin(), self.planes().end(), v.begin(), [](const auto &p) { return p.bytesused; });
+			return v;
+		});
+
+	pyFrameMetadataStatus
+		.value("Success", FrameMetadata::FrameSuccess)
+		.value("Error", FrameMetadata::FrameError)
+		.value("Cancelled", FrameMetadata::FrameCancelled);
+
+	pyTransform
+		.def(py::init([](int rotation, bool hflip, bool vflip, bool transpose) {
+			bool ok;
+
+			Transform t = transformFromRotation(rotation, &ok);
+			if (!ok)
+				throw std::invalid_argument("Invalid rotation");
+
+			if (hflip)
+				t ^= Transform::HFlip;
+			if (vflip)
+				t ^= Transform::VFlip;
+			if (transpose)
+				t ^= Transform::Transpose;
+			return t;
+		}), py::arg("rotation") = 0, py::arg("hflip") = false,
+		    py::arg("vflip") = false, py::arg("transpose") = false)
+		.def(py::init([](Transform &other) { return other; }))
+		.def("__str__", [](Transform &self) {
+			return "<libcamera.Transform '" + std::string(transformToString(self)) + "'>";
+		})
+		.def_property("hflip",
+			      [](Transform &self) {
+				      return !!(self & Transform::HFlip);
+			      },
+			      [](Transform &self, bool hflip) {
+				      if (hflip)
+					      self |= Transform::HFlip;
+				      else
+					      self &= ~Transform::HFlip;
+			      })
+		.def_property("vflip",
+			      [](Transform &self) {
+				      return !!(self & Transform::VFlip);
+			      },
+			      [](Transform &self, bool vflip) {
+				      if (vflip)
+					      self |= Transform::VFlip;
+				      else
+					      self &= ~Transform::VFlip;
+			      })
+		.def_property("transpose",
+			      [](Transform &self) {
+				      return !!(self & Transform::Transpose);
+			      },
+			      [](Transform &self, bool transpose) {
+				      if (transpose)
+					      self |= Transform::Transpose;
+				      else
+					      self &= ~Transform::Transpose;
+			      })
+		.def("inverse", [](Transform &self) { return -self; })
+		.def("invert", [](Transform &self) {
+			self = -self;
+		})
+		.def("compose", [](Transform &self, Transform &other) {
+			self = self * other;
+		});
+
+	pyColorSpace
+		.def(py::init([](ColorSpace::Primaries primaries,
+				 ColorSpace::TransferFunction transferFunction,
+				 ColorSpace::YcbcrEncoding ycbcrEncoding,
+				 ColorSpace::Range range) {
+			return ColorSpace(primaries, transferFunction, ycbcrEncoding, range);
+		}), py::arg("primaries"), py::arg("transferFunction"),
+		    py::arg("ycbcrEncoding"), py::arg("range"))
+		.def(py::init([](ColorSpace &other) { return other; }))
+		.def("__str__", [](ColorSpace &self) {
+			return "<libcamera.ColorSpace '" + self.toString() + "'>";
+		})
+		.def_readwrite("primaries", &ColorSpace::primaries)
+		.def_readwrite("transferFunction", &ColorSpace::transferFunction)
+		.def_readwrite("ycbcrEncoding", &ColorSpace::ycbcrEncoding)
+		.def_readwrite("range", &ColorSpace::range)
+		.def_static("Raw", []() { return ColorSpace::Raw; })
+		.def_static("Jpeg", []() { return ColorSpace::Jpeg; })
+		.def_static("Srgb", []() { return ColorSpace::Srgb; })
+		.def_static("Smpte170m", []() { return ColorSpace::Smpte170m; })
+		.def_static("Rec709", []() { return ColorSpace::Rec709; })
+		.def_static("Rec2020", []() { return ColorSpace::Rec2020; });
+
+	pyColorSpacePrimaries
+		.value("Raw", ColorSpace::Primaries::Raw)
+		.value("Smpte170m", ColorSpace::Primaries::Smpte170m)
+		.value("Rec709", ColorSpace::Primaries::Rec709)
+		.value("Rec2020", ColorSpace::Primaries::Rec2020);
+
+	pyColorSpaceTransferFunction
+		.value("Linear", ColorSpace::TransferFunction::Linear)
+		.value("Srgb", ColorSpace::TransferFunction::Srgb)
+		.value("Rec709", ColorSpace::TransferFunction::Rec709);
+
+	pyColorSpaceYcbcrEncoding
+		.value("Null", ColorSpace::YcbcrEncoding::None)
+		.value("Rec601", ColorSpace::YcbcrEncoding::Rec601)
+		.value("Rec709", ColorSpace::YcbcrEncoding::Rec709)
+		.value("Rec2020", ColorSpace::YcbcrEncoding::Rec2020);
+
+	pyColorSpaceRange
+		.value("Full", ColorSpace::Range::Full)
+		.value("Limited", ColorSpace::Range::Limited);
+}
diff --git a/src/py/meson.build b/src/py/meson.build
new file mode 100644
index 00000000..4ce9668c
--- /dev/null
+++ b/src/py/meson.build
@@ -0,0 +1 @@
+subdir('libcamera')
diff --git a/subprojects/.gitignore b/subprojects/.gitignore
index 391fde2c..0e194289 100644
--- a/subprojects/.gitignore
+++ b/subprojects/.gitignore
@@ -1,3 +1,4 @@
 /googletest-release*
 /libyuv
-/packagecache
\ No newline at end of file
+/packagecache
+/pybind11
diff --git a/subprojects/packagefiles/pybind11/meson.build b/subprojects/packagefiles/pybind11/meson.build
new file mode 100644
index 00000000..1be47ca4
--- /dev/null
+++ b/subprojects/packagefiles/pybind11/meson.build
@@ -0,0 +1,7 @@
+project('pybind11', 'cpp',
+    version : '2.9.1',
+    license : 'BSD-3-Clause')
+
+pybind11_incdir = include_directories('include')
+
+pybind11_dep = declare_dependency(include_directories : pybind11_incdir)
diff --git a/subprojects/pybind11.wrap b/subprojects/pybind11.wrap
new file mode 100644
index 00000000..e8037a5d
--- /dev/null
+++ b/subprojects/pybind11.wrap
@@ -0,0 +1,9 @@
+[wrap-git]
+url = https://github.com/pybind/pybind11.git
+# This is the head of 'smart_holder' branch
+revision = aebdf00cd060b871c5a1e0c2cf4a333503dd0431
+depth = 1
+patch_directory = pybind11
+
+[provide]
+pybind11 = pybind11_dep