Laurent Pinchart b3987620aa libcamera: camera_sensor: Relax restriction on sizes
The CameraSensor class assumes that camera sensors support the exact
same list of sizes of all media bus codes. While allowing a simpler API,
this assumption is incorrect and is blocking usage of some camera
sensors.

Relaxing the constraint is possible without changes to the CameraSensor
API syntax, but requires changing its semantics. The sizes() function
now returns the list of all sizes for all media bus codes, and the
getFormat() function now searches in all supported media bus codes. The
former is likely not the most useful option for pipeline handlers, but
the sizes() function is currently unused. Designing a better API will
require inspecting current and expected future use cases in pipeline
handlers to determine proper heuristics.

While at it, fix a small typo in an unrelated comment.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2020-05-03 17:49:51 +03:00

.. 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
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