1aa49db823
Relying on the application event loop to process all our internal events is a bad idea for multiple reasons. In many cases the user of libcamera can't provide an event loop, for instance when running through one of the adaptation layers. The Android camera HAL and V4L2 compatibility layer create a thread for this reason, and the GStreamer element would need to do so as well. Furthermore, relying on the application event loop pushes libcamera's realtime constraints to the application, which isn't manageable. For these reasons it's desirable to always run the camera manager, the pipeline handlers and the cameras in a separate thread. Doing so isn't too complicated, it only involves creating the thread internally when starting the camera manager, and synchronizing a few methods of the Camera class. Do so as a first step towards defining the threading model of libcamera. The event dispatcher interface is still exposed to applications, to enable cross-thread signal delivery if desired. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
.. 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}
for libcamera: [required]
meson (>= 0.47) ninja-build python3-yaml
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 device hotplug enumeration: [optional]
pkg-config libudev-dev
for qcam: [optional]
qtbase5-dev libqt5core5a libqt5gui5 libqt5widgets5
for documentation: [optional]
python3-sphinx doxygen
.. section-end-getting-started