README.rst - chromiumos/third_party/libcamera - Git at Google


            
            .. SPDX-License-Identifier: CC-BY-SA-4.0


            .. section-begin-libcamera


            ===========

            
             libcamera

            
            ===========


            **A complex camera support library for Linux, Android, and ChromeOS**


            Cameras are complex devices that need heavy hardware image processing

            
            operations. Control of the processing is based on advanced algorithms that must

            
            run on a programmable processor. This has traditionally been implemented in a

            
            dedicated MCU in the camera, but in embedded devices algorithms have been moved

            
            to the main CPU to save cost. Blurring the boundary between camera devices and

            
            Linux often left the user with no other option than a vendor-specific

            
            closed-source solution.


            To address this problem the Linux media community has very recently started

            
            collaboration with the industry to develop a camera stack that will be

            
            open-source-friendly while still protecting vendor core IP. libcamera was born

            
            out of that collaboration and will offer modern camera support to Linux-based

            
            systems, including traditional Linux distributions, ChromeOS and Android.


            .. section-end-libcamera

            
            .. section-begin-getting-started


            Getting Started

            
            ---------------


            To fetch the sources, build and install:


            .. code::


              git clone https://git.libcamera.org/libcamera/libcamera.git

            
              cd libcamera

            
              meson setup build

            
              ninja -C build install


            Dependencies

            
            ~~~~~~~~~~~~


            The following Debian/Ubuntu packages are required for building libcamera.

            
            Other distributions may have differing package names:


            A C++ toolchain: [required]

            
                    Either {g++, clang}


            Meson Build system: [required]

            
                    meson (>= 0.60) ninja-build pkg-config


            for the libcamera core: [required]

            
                    libyaml-dev python3-yaml python3-ply python3-jinja2


            for IPA module signing: [recommended]

            
                    Either libgnutls28-dev or libssl-dev, openssl


                    Without IPA module signing, all IPA modules will be isolated in a

            
                    separate process. This adds an unnecessary extra overhead at runtime.


            for improved debugging: [optional]

            
                    libdw-dev libunwind-dev


                    libdw and libunwind provide backtraces to help debugging assertion

            
                    failures. Their functions overlap, libdw provides the most detailed

            
                    information, and libunwind is not needed if both libdw and the glibc

            
                    backtrace() function are available.


            for device hotplug enumeration: [optional]

            
                    libudev-dev


            for documentation: [optional]

            
                    python3-sphinx doxygen graphviz texlive-latex-extra


            for gstreamer: [optional]

            
                    libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev


            for Python bindings: [optional]

            
                    libpython3-dev pybind11-dev


            for cam: [optional]

            
                    libevent-dev is required to support cam, however the following

            
                    optional dependencies bring more functionality to the cam test

            
                    tool:


                    - libdrm-dev: Enables the KMS sink

            
                    - libjpeg-dev: Enables MJPEG on the SDL sink

            
                    - libsdl2-dev: Enables the SDL sink


            for qcam: [optional]

            
                    libtiff-dev qtbase5-dev qttools5-dev-tools


            for tracing with lttng: [optional]

            
                    liblttng-ust-dev python3-jinja2 lttng-tools


            for android: [optional]

            
                    libexif-dev libjpeg-dev


            for Python bindings: [optional]

            
                    pybind11-dev


            for lc-compliance: [optional]

            
                    libevent-dev libgtest-dev


            for abi-compat.sh: [optional]

            
                    abi-compliance-checker


            Basic testing with cam utility

            
            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


            The ``cam`` utility can be used for basic testing. You can list the cameras

            
            detected on the system with ``cam -l``, and capture ten frames from the first

            
            camera and save them to disk with ``cam -c 1 --capture=10 --file``. See

            
            ``cam -h`` for more information about the ``cam`` tool.


            In case of problems, a detailed debug log can be obtained from libcamera by

            
            setting the ``LIBCAMERA_LOG_LEVELS`` environment variable:


            .. code::


                :~$ LIBCAMERA_LOG_LEVELS=*:DEBUG cam -l


            Using GStreamer plugin

            
            ~~~~~~~~~~~~~~~~~~~~~~


            To use the GStreamer plugin from the source tree, use the meson ``devenv``

            
            command.  This will create a new shell instance with the ``GST_PLUGIN_PATH``

            
            environment set accordingly.


            .. code::


              meson devenv -C build


            The debugging tool ``gst-launch-1.0`` can be used to construct a pipeline and

            
            test it. The following pipeline will stream from the camera named "Camera 1"

            
            onto the OpenGL accelerated display element on your system.


            .. code::


              gst-launch-1.0 libcamerasrc camera-name="Camera 1" ! queue ! glimagesink


            To show the first camera found you can omit the camera-name property, or you

            
            can list the cameras and their capabilities using:


            .. code::


              gst-device-monitor-1.0 Video


            This will also show the supported stream sizes which can be manually selected

            
            if desired with a pipeline such as:


            .. code::


              gst-launch-1.0 libcamerasrc ! 'video/x-raw,width=1280,height=720' ! \

            
                   queue ! glimagesink


            The libcamerasrc element has two log categories, named libcamera-provider (for

            
            the video device provider) and libcamerasrc (for the operation of the camera).

            
            All corresponding debug messages can be enabled by setting the ``GST_DEBUG``

            
            environment variable to ``libcamera*:7``.


            Presently, to prevent element negotiation failures it is required to specify

            
            the colorimetry and framerate as part of your pipeline construction. For

            
            instance, to capture and encode as a JPEG stream and receive on another device

            
            the following example could be used as a starting point:


            .. code::


               gst-launch-1.0 libcamerasrc ! \

            
                    video/x-raw,colorimetry=bt709,format=NV12,width=1280,height=720,framerate=30/1 ! \

            
                    queue ! jpegenc ! multipartmux ! \

            
                    tcpserversink host=0.0.0.0 port=5000


            Which can be received on another device over the network with:


            .. code::


               gst-launch-1.0 tcpclientsrc host=$DEVICE_IP port=5000 ! \

            
                    multipartdemux ! jpegdec ! autovideosink


            .. section-end-getting-started


            Troubleshooting

            
            ~~~~~~~~~~~~~~~


            Several users have reported issues with meson installation, crux of the issue

            
            is a potential version mismatch between the version that root uses, and the

            
            version that the normal user uses. On calling `ninja -C build`, it can't find

            
            the build.ninja module. This is a snippet of the error message.


            ::


              ninja: Entering directory `build'

            
              ninja: error: loading 'build.ninja': No such file or directory


            This can be solved in two ways:


            1. Don't install meson again if it is already installed system-wide.


            2. If a version of meson which is different from the system-wide version is

            
               already installed, uninstall that meson using pip3, and install again without

            
               the --user argument.
	.. SPDX-License-Identifier: CC-BY-SA-4.0

	.. section-begin-libcamera

	===========
	libcamera
	===========

	A complex camera support library for Linux, Android, and ChromeOS

	Cameras are complex devices that need heavy hardware image processing
	operations. Control of the processing is based on advanced algorithms that must
	run on a programmable processor. This has traditionally been implemented in a
	dedicated MCU in the camera, but in embedded devices algorithms have been moved
	to the main CPU to save cost. Blurring the boundary between camera devices and
	Linux often left the user with no other option than a vendor-specific
	closed-source solution.

	To address this problem the Linux media community has very recently started
	collaboration with the industry to develop a camera stack that will be
	open-source-friendly while still protecting vendor core IP. libcamera was born
	out of that collaboration and will offer modern camera support to Linux-based
	systems, including traditional Linux distributions, ChromeOS and Android.

	.. section-end-libcamera
	.. section-begin-getting-started

	Getting Started
	---------------

	To fetch the sources, build and install:

	.. code::

	git clone https://git.libcamera.org/libcamera/libcamera.git
	cd libcamera
	meson setup build
	ninja -C build install

	Dependencies
	~~~~~~~~~~~~

	The following Debian/Ubuntu packages are required for building libcamera.
	Other distributions may have differing package names:

	A C++ toolchain: [required]
	Either {g++, clang}

	Meson Build system: [required]
	meson (>= 0.60) ninja-build pkg-config

	for the libcamera core: [required]
	libyaml-dev python3-yaml python3-ply python3-jinja2

	for IPA module signing: [recommended]
	Either libgnutls28-dev or libssl-dev, openssl

	Without IPA module signing, all IPA modules will be isolated in a
	separate process. This adds an unnecessary extra overhead at runtime.

	for improved debugging: [optional]
	libdw-dev libunwind-dev

	libdw and libunwind provide backtraces to help debugging assertion
	failures. Their functions overlap, libdw provides the most detailed
	information, and libunwind is not needed if both libdw and the glibc
	backtrace() function are available.

	for device hotplug enumeration: [optional]
	libudev-dev

	for documentation: [optional]
	python3-sphinx doxygen graphviz texlive-latex-extra

	for gstreamer: [optional]
	libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev

	for Python bindings: [optional]
	libpython3-dev pybind11-dev

	for cam: [optional]
	libevent-dev is required to support cam, however the following
	optional dependencies bring more functionality to the cam test
	tool:

	- libdrm-dev: Enables the KMS sink
	- libjpeg-dev: Enables MJPEG on the SDL sink
	- libsdl2-dev: Enables the SDL sink

	for qcam: [optional]
	libtiff-dev qtbase5-dev qttools5-dev-tools

	for tracing with lttng: [optional]
	liblttng-ust-dev python3-jinja2 lttng-tools

	for android: [optional]
	libexif-dev libjpeg-dev

	for Python bindings: [optional]
	pybind11-dev

	for lc-compliance: [optional]
	libevent-dev libgtest-dev

	for abi-compat.sh: [optional]
	abi-compliance-checker

	Basic testing with cam utility
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	The ``cam`` utility can be used for basic testing. You can list the cameras
	detected on the system with ``cam -l``, and capture ten frames from the first
	camera and save them to disk with ``cam -c 1 --capture=10 --file``. See
	``cam -h`` for more information about the ``cam`` tool.

	In case of problems, a detailed debug log can be obtained from libcamera by
	setting the ``LIBCAMERA_LOG_LEVELS`` environment variable:

	.. code::

	:~$ LIBCAMERA_LOG_LEVELS=*:DEBUG cam -l

	Using GStreamer plugin
	~~~~~~~~~~~~~~~~~~~~~~

	To use the GStreamer plugin from the source tree, use the meson ``devenv``
	command. This will create a new shell instance with the ``GST_PLUGIN_PATH``
	environment set accordingly.

	.. code::

	meson devenv -C build

	The debugging tool ``gst-launch-1.0`` can be used to construct a pipeline and
	test it. The following pipeline will stream from the camera named "Camera 1"
	onto the OpenGL accelerated display element on your system.

	.. code::

	gst-launch-1.0 libcamerasrc camera-name="Camera 1" ! queue ! glimagesink

	To show the first camera found you can omit the camera-name property, or you
	can list the cameras and their capabilities using:

	.. code::

	gst-device-monitor-1.0 Video

	This will also show the supported stream sizes which can be manually selected
	if desired with a pipeline such as:

	.. code::

	gst-launch-1.0 libcamerasrc ! 'video/x-raw,width=1280,height=720' ! \
	queue ! glimagesink

	The libcamerasrc element has two log categories, named libcamera-provider (for
	the video device provider) and libcamerasrc (for the operation of the camera).
	All corresponding debug messages can be enabled by setting the ``GST_DEBUG``
	environment variable to ``libcamera*:7``.

	Presently, to prevent element negotiation failures it is required to specify
	the colorimetry and framerate as part of your pipeline construction. For
	instance, to capture and encode as a JPEG stream and receive on another device
	the following example could be used as a starting point:

	.. code::

	gst-launch-1.0 libcamerasrc ! \
	video/x-raw,colorimetry=bt709,format=NV12,width=1280,height=720,framerate=30/1 ! \
	queue ! jpegenc ! multipartmux ! \
	tcpserversink host=0.0.0.0 port=5000

	Which can be received on another device over the network with:

	.. code::

	gst-launch-1.0 tcpclientsrc host=$DEVICE_IP port=5000 ! \
	multipartdemux ! jpegdec ! autovideosink

	.. section-end-getting-started

	Troubleshooting
	~~~~~~~~~~~~~~~

	Several users have reported issues with meson installation, crux of the issue
	is a potential version mismatch between the version that root uses, and the
	version that the normal user uses. On calling `ninja -C build`, it can't find
	the build.ninja module. This is a snippet of the error message.

	::

	ninja: Entering directory `build'
	ninja: error: loading 'build.ninja': No such file or directory

	This can be solved in two ways:

	1. Don't install meson again if it is already installed system-wide.

	2. If a version of meson which is different from the system-wide version is
	already installed, uninstall that meson using pip3, and install again without
	the --user argument.