Jacopo Mondi
c82f944399
The CameraDevice::streams_ vector of CameraStream instances is currently mostly accessed by index. The current implementation creates all the CameraStream during the first loop that inspects the camera3_stream instances and then update the index of the StreamConfiguration associated with the CameraStream during a second loop that inspects MJPEG streams. A third loop creates the JPEG encoder associated with camera streams that produce MJPEG format. As the index-based association is hard to follow and rather fragile, rework the creation and handling of CameraStream: 1) Make the StreamConfiguration index a constructor parameter and a private struct member. This disallows the creation of CameraStream without a StreamConfiguration index assigned. 2) Create CameraStream only after the associated StreamConfiguration has been identified. The first loop creates CameraStream for non-JPEG streams, the second for the JPEG ones after having identified the associated StreamConfiguration. Since we have just created the CameraStream, create the JPEG encoder at the same time instead of deferring it. This change removes all accesses by index to the CameraDevice::streams_ vector. No functional changes intended, but this change aims to make the code easier to follow and more robust. Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Hirokazu Honda <hiroh@chromium.org> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
.. 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}
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 documentation: [optional]
python3-sphinx doxygen
for gstreamer: [optional]
libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev
for IPA module signing: [required]
libgnutls28-dev openssl
for qcam: [optional]
qtbase5-dev libqt5core5a libqt5gui5 libqt5widgets5
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 and 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