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| -rw-r--r-- | Documentation/environment_variables.rst | 134 | ||||
| -rw-r--r-- | Documentation/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/meson.build | 1 |
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diff --git a/Documentation/environment_variables.rst b/Documentation/environment_variables.rst new file mode 100644 index 00000000..01294d79 --- /dev/null +++ b/Documentation/environment_variables.rst @@ -0,0 +1,134 @@ +.. 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: ``${HOME}/.libcamera/share/ipa:/opt/libcamera/vendor/share/ipa`` + +LIBCAMERA_IPA_MODULE_PATH + Define custom search locations for IPA modules (`more <#ipa-module>`__). + + Example value: ``${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 <http://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. diff --git a/Documentation/index.rst b/Documentation/index.rst index ff697d4f..c49db18d 100644 --- a/Documentation/index.rst +++ b/Documentation/index.rst @@ -17,3 +17,4 @@ Application Writer's Guide <guides/application-developer> Pipeline Handler Writer's Guide <guides/pipeline-handler> Tracing guide <guides/tracing> + Environment variables <environment_variables> diff --git a/Documentation/meson.build b/Documentation/meson.build index 26a12fcd..0cd5729a 100644 --- a/Documentation/meson.build +++ b/Documentation/meson.build @@ -52,6 +52,7 @@ if sphinx.found() 'conf.py', 'contributing.rst', 'docs.rst', + 'environment_variables.rst', 'index.rst', 'guides/introduction.rst', 'guides/application-developer.rst', |