Environment variables — libcamera v0.0.2 documentation

# 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).

  Example value: `*:DEBUG`

LIBCAMERA_LOG_NO_COLOR

  Disable coloring of log messages (more).

LIBCAMERA_IPA_CONFIG_PATH

  Define custom search locations for IPA configurations (more).

  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).

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

## Further details

### Notes about debugging

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

By default, libcamera logs all messages to the standard error (std::cerr). Messages are colored by default depending on the log level. Coloring can be disabled by setting the `LIBCAMERA_LOG_NO_COLOR` environment variable.

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 part is mandatory and can either be specified by name or by numerical index associated with each level.

The optional category 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.

Examples:

Enable full debug output to a separate file, for every category within a local environment:

    :~$ 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:

    :~$ 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

    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

### 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.