external_libcamera/Documentation/runtime_configuration.rst

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

Runtime configuration
=====================

The libcamera behaviour can be tuned through a configuration file or
environment variables. This document lists all the configuration options
and describes their usage.

General rules
-------------

The configuration file is looked up in the following locations, in this
order:

- $XDG_CONFIG_HOME/libcamera/configuration.yaml
- LIBCAMERA_SYSCONF_DIR/configuration.yaml
- LIBCAMERA_DATA_DIR/libcamera/configuration.yaml

The first configuration file found wins, configuration files in other
locations are ignored.

Settings in environment variables take precedence over settings in
configuration files. This allows overriding behaviour temporarily
without the need to modify configuration files.

Configuration options
---------------------

Here is an overview of the available configuration options, in the YAML
file structure:

::

  configuration:
    ipa:
      force_isolation: # true/false
      config_paths:
        - ... # full path to a directory
      module_paths:
        - ... # full path to a directory
    pipelines_match_list:
      - ... # pipeline name
    pipelines:
      simple:
        supported_devices:
          - driver: # driver name, e.g. `mxc-isi`
            software_isp: # true/false
    software_isp:
      copy_input_buffer: # true/false
      measure:
        skip: # non-negative integer, frames to skip initially
        number: # non-negative integer, frames to measure
      mode: # cpu/gpu
      threads: # integer >= 1, number of render threads to use, default 2

Configuration file example
--------------------------

::

   ---
   version: 1
   configuration:
     ipa:
       config_paths:
         - /home/user/.libcamera/share/ipa
         - /opt/libcamera/vendor/share/ipa
       module_paths:
         - /home/user/.libcamera/lib
         - /opt/libcamera/vendor/lib
       proxy_paths:
         - /home/user/.libcamera/proxy/worker
         - /opt/libcamera/vendor/proxy/worker
       force_isolation: true
     pipelines_match_list:
       - rkisp1
       - simple
     pipelines:
       simple:
         supported_devices:
           - driver: mxc-isi
             software_isp: true
     software_isp:
       copy_input_buffer: false
       measure:
         skip: 50
         number: 30
       mode: gpu
       threads: 2

List of variables and configuration options
-------------------------------------------

LIBCAMERA_LOG_FILE
   The custom destination for log output.

   Example value: ``/home/{user}/camera_log.log``

LIBCAMERA_LOG_LEVELS
   Configure the verbosity of log messages for different categories (`more <Log levels_>`__).

   Example value: ``*:DEBUG``

LIBCAMERA_LOG_COLOR
   Control the coloring of log messages (`more <Notes about debugging_>`__).

LIBCAMERA_IPA_CONFIG_PATH, ipa.config_paths
   Define custom search locations for IPA configurations (`more <IPA configuration_>`__).

   Example value: ``${HOME}/.libcamera/share/ipa:/opt/libcamera/vendor/share/ipa``

LIBCAMERA_IPA_FORCE_ISOLATION, ipa.force_isolation
   When set to a non-empty string, force process isolation of all IPA modules.

   Example value: ``1``

LIBCAMERA_IPA_MODULE_PATH, ipa.module_paths
   Define custom search locations for IPA modules (`more <IPA module_>`__).

   Example value: ``${HOME}/.libcamera/lib:/opt/libcamera/vendor/lib``

LIBCAMERA_IPA_PROXY_PATH, ipa.proxy_paths
   Define custom full path for a proxy worker for a given executable name.

   Example value: ``${HOME}/.libcamera/proxy/worker:/opt/libcamera/vendor/proxy/worker``

LIBCAMERA_PIPELINES_MATCH_LIST, pipelines_match_list
   Define an ordered list of pipeline names to be used to match the media
   devices in the system. The pipeline handler names used to populate the
   variable are the ones passed to the REGISTER_PIPELINE_HANDLER() macro in the
   source code.

   Example value: ``rkisp1,simple``

LIBCAMERA_RPI_CONFIG_FILE
   Define a custom configuration file to use in the Raspberry Pi pipeline handler.

   Example value: ``/usr/local/share/libcamera/pipeline/rpi/vc4/minimal_mem.yaml``

LIBCAMERA_<NAME>_TUNING_FILE
   Define a custom IPA tuning file to use with the pipeline handler `NAME`.

   Example value: ``/usr/local/share/libcamera/ipa/rpi/vc4/custom_sensor.json``

LIBCAMERA_SOFTISP_MODE, software_isp.mode
   Select if the software ISP should use GPU or CPU image processsing,
   one of ``cpu`` or ``gpu``. When set to ``gpu`` and EGL is not available
   the software ISP will automatically fall back to the CPU.

   Example value: ``gpu``

pipelines.simple.supported_devices.driver, pipelines.simple.supported_devices.software_isp
   Override whether software ISP is enabled for the given driver.

   Example `driver` value: ``mxc-isi``

   Example `software_isp` value: ``true``

software_isp.copy_input_buffer
   Define whether input buffers should be copied into standard (cached)
   memory in software ISP. This is done by default to prevent very slow
   processing on platforms with non-cached buffers. It can be set to
   false on platforms with cached buffers to avoid an unnecessary
   overhead.

   Example value: ``false``

software_isp.measure.skip, software_isp.measure.number
   Define per-frame time measurement parameters in software ISP. `skip`
   defines how many initial frames are skipped before starting the
   measurement; `number` defines how many frames then participate in the
   measurement.

   Set `software_isp.measure.number` to 0 to disable the measurement.

   Example `skip` value: ``50``

   Example `number` value: ``30``

software_isp.threads
   Number of render threads the software ISP uses when using the CPU.
   This must be between 1 and 8 and the default is 2.

   Example value: ``2``

Further details
---------------

Notes about debugging
~~~~~~~~~~~~~~~~~~~~~

The environment variables ``LIBCAMERA_LOG_FILE``, ``LIBCAMERA_LOG_LEVELS`` and
``LIBCAMERA_LOG_COLOR`` are used to modify the default configuration of the
libcamera logger.

By default, libcamera logs all messages to the standard error (std::cerr).
The ``LIBCAMERA_LOG_COLOR`` environment variable can be used to control whether
the messages will be colored or not. The possible values are: ``auto``, ``yes``,
and ``no``. The default value is ``auto``, which enables coloring if the standard
error is connected to a TTY.

The default log destination can also be directed to a file by setting the
``LIBCAMERA_LOG_FILE`` environment variable to the log file name. This also
disables coloring.

Log levels are controlled through the ``LIBCAMERA_LOG_LEVELS`` variable, which
accepts a comma-separated list of 'category:level' pairs.

The `level <Log levels_>`__ part is mandatory and can either be specified by
name or by numerical index associated with each level.

The optional `category <Log categories_>`__ is a string matching the categories
defined by each file in the source base using the logging infrastructure. It
can include a wildcard ('*') character at the end to match multiple categories.

For more information refer to the :doxy-int:`API documentation <log.h>`.

Examples:

Enable full debug output to a separate file, for every `category <Log categories_>`__
within a local environment:

.. code:: bash

   :~$ LIBCAMERA_LOG_FILE='/tmp/example_log.log' \
       LIBCAMERA_LOG_LEVELS=0 \
       cam --list

Enable full debug output for the categories ``Camera`` and ``V4L2`` within a
global environment:

.. code:: bash

   :~$ export LIBCAMERA_LOG_LEVELS='Camera:DEBUG,V4L2:DEBUG'
   :~$ cam --list

Log levels
~~~~~~~~~~

This is the list of available log levels, notice that all levels below
the chosen one are printed, while those above are discarded.

-  DEBUG (0)
-  INFO (1)
-  WARN (2)
-  ERROR (3)
-  FATAL (4)

Example:
If you choose WARN (2), you will be able to see WARN (2), ERROR (3) and FATAL (4)
but not DEBUG (0) and INFO (1).

Log categories
~~~~~~~~~~~~~~

Every category represents a specific area of the libcamera codebase,
the names can be located within the source code, for example:
`src/libcamera/camera_manager.cpp <https://git.libcamera.org/libcamera/libcamera.git/tree/src/libcamera/camera_manager.cpp#n35>`__

.. code:: cpp

   LOG_DEFINE_CATEGORY(Camera)

There are two available macros used to assign a category name to a part of the
libcamera codebase:

LOG_DEFINE_CATEGORY
   This macro is required, in order to use the ``LOGC`` macro for a particular
   category. It can only be used once for each category. If you want to create
   log messages within multiple compilation units for the same category utilize
   the ``LOG_DECLARE_CATEGORY`` macro, in every file except the definition file.
LOG_DECLARE_CATEGORY
   Used for sharing an already defined category between multiple separate
   compilation units.

Both macros have to be used within the libcamera namespace of the C++ source
code.

IPA configuration
~~~~~~~~~~~~~~~~~

IPA modules use their own configuration files to store parameters. The format
and contents of the configuration files is specific to the IPA module. They
usually contain tuning parameters for the algorithms, in JSON format.

The ``LIBCAMERA_IPA_CONFIG_PATH`` variable can be used to specify custom
storage locations to search for those configuration files.

`Examples <https://git.libcamera.org/libcamera/libcamera.git/tree/src/ipa/rpi/vc4/data>`__

IPA module
~~~~~~~~~~

In order to locate the correct IPA module for your hardware, libcamera gathers
existing IPA modules from multiple locations. The default locations for this
operation are the installed system path (for example on Debian:
``/usr/local/x86_64-pc-linux-gnu/libcamera``) and the build directory.
With the ``LIBCAMERA_IPA_MODULE_PATH``, you can specify a non-default location
to search for IPA modules.