ae7419869a
The mojo parser is fine if there are types that are used in array/map
members that it does not know about. These are usually caught by the C++
compiler, because the generated code refers to unknown types. This
feature is necessary for us for supporting FrameBuffer::Plane as an
array/map member, since as long as the type has an IPADataSerializer and
the struct defined in C++, the generated code will run fine
(FrameBuffer::Plane is not defined anywhere in mojom but is used as an
array member in IPABuffer).
The types that are defined in controls.h (or any header included in
ipa_interface.h) will all be compiled by the C++ compiler fine, since
the generated files all include controls.h. The types that are there
that are not ControlInfoMap or ControlList (like ControlValue) will
still fail at the linker stage. For example:
struct A {
array<ControlValue> a;
};
will compile fine, but will fail to link, since
IPADataSerializer<ControlValue> doesn't exist. This behavior, although
not the best, is acceptable.
The issue is that if ControlInfoMap or ControlList are used as array/map
members without the libcamera prefix, the compiler will not complain, as
the types are valid, and the linker will also not complain, as
IPADataSerializer<ControlList> and IPADataSerializer<ControlInfoMap>
both exist. However, the code generator will not recognize them as
types that require a ControlSerializer (since mojo doesn't recognize
them, so they are different from the ones that it does recognize with
the libcamera namespace), and so the ControlSerializer will not be
passed to the serializer in the generated code. This is the cause of the
FATAL breakage:
FATAL IPADataSerializer ipa_data_serializer.cpp:437 ControlSerializer
not provided for serialization of ControlInfoMap
Since ControlInfoMap and ControlList are the only types that will run
into this issue, we solve this by simply detecting if they are used
without the prefix, and produce an error at that point in the code
generator. As the code generator stage no longer has information on the
source code file and line, we output the struct name in which the error
was found (ninja will output the file name).
Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
.. 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:
::
git clone git://linuxtv.org/libcamera.git
cd libcamera
meson 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 (>= 0.55) ninja-build pkg-config
If your distribution doesn't provide a recent enough version of meson,
you can install or upgrade it using pip3.
.. code::
pip3 install --user meson
pip3 install --user --upgrade meson
for the libcamera core: [required]
python3-yaml python3-ply python3-jinja2
for IPA module signing: [required]
libgnutls28-dev openssl
for the Raspberry Pi IPA: [optional]
libboost-dev
Support for Raspberry Pi can be disabled through the meson
'pipelines' option to avoid this dependency.
for device hotplug enumeration: [optional]
libudev-dev
for documentation: [optional]
python3-sphinx doxygen graphviz
for gstreamer: [optional]
libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev
for cam: [optional]
libevent-dev
for qcam: [optional]
qtbase5-dev libqt5core5a libqt5gui5 libqt5widgets5 qttools5-dev-tools libtiff-dev
for tracing with lttng: [optional]
liblttng-ust-dev python3-jinja2 lttng-tools
for android: [optional]
libexif libjpeg libyaml
Using GStreamer plugin
~~~~~~~~~~~~~~~~~~~~~~
To use GStreamer plugin from source tree, set the following environment so that
GStreamer can find it.
export GST_PLUGIN_PATH=$(pwd)/build/src/gstreamer
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 default video display element on your system.
.. code::
gst-launch-1.0 libcamerasrc camera-name="Camera 1" ! videoconvert ! 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.