.. SPDX-License-Identifier: CC-BY-SA-4.0 Environment variables ===================== The libcamera behaviour can be tuned through environment variables. This document lists all the available variables and describes their usage. List of variables ----------------- 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_IPA_CONFIG_PATH Define custom search locations for IPA configurations (`more <IPA configuration_>`__). Example value: ``${HOME}/.libcamera/share/ipa:/opt/libcamera/vendor/share/ipa`` LIBCAMERA_IPA_FORCE_ISOLATION When set to a non-empty string, force process isolation of all IPA modules. Example value: ``1`` LIBCAMERA_IPA_MODULE_PATH Define custom search locations for IPA modules (`more <IPA module_>`__). Example value: ``${HOME}/.libcamera/lib:/opt/libcamera/vendor/lib`` Further details --------------- Notes about debugging ~~~~~~~~~~~~~~~~~~~~~ The environment variables ``LIBCAMERA_LOG_FILE`` and ``LIBCAMERA_LOG_LEVELS`` are used to modify the destination and verbosity of messages provided by libcamera. The ``LIBCAMERA_LOG_LEVELS`` variable 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 `API documentation <https://libcamera.org/api-html/log_8h.html#details>`__. 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 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/raspberrypi/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.