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uchardet

uchardet is an encoding and language detector library, which takes a sequence of bytes in an unknown character encoding without any additional information, and attempts to determine the encoding of the text.

uchardet started as a C language binding of the original C++ implementation of the universal charset detection library by Mozilla. Since this far-away time, it can now detect more charsets, and much more reliably than the original implementation. Moreover it also work as a very good language detector, while still staying reasonably fast.

Supported Languages/Encodings

Installation

Debian/Ubuntu/Mint

apt-get install uchardet libuchardet-dev

Mageia

urpmi libuchardet libuchardet-devel

Fedora

dnf install uchardet uchardet-devel

Gentoo

emerge uchardet

Mac

brew install uchardet

or

port install uchardet

Windows

Binary packages are provided in Fedora and Msys2 repositories. There may exist other pre-built packages but I am not aware of them. Nevertheless the library is very easily and quickly compilable under Windows as well, so finding a binary package is not necessary. Some did it successfully with the CMake Windows installer and MinGW. It should be possible to use MinGW-w64 instead of MinGW, in particular to build both 32 and 64-bit DLL libraries).

Note also that it is very easily cross-buildable (for instance from a GNU/Linux machine; crossroad may help, this is what we use in our CI).

Build from source

Releases are available from: https://www.freedesktop.org/software/uchardet/releases/

If you prefer a development version, clone the git repository:

git clone https://gitlab.freedesktop.org/uchardet/uchardet.git

The source can be browsed at: https://gitlab.freedesktop.org/uchardet/uchardet

cmake .
make
make install

Build with flatpak-builder

Here is a working "module" section to include in your Flatpak's json manifest:

"modules": [
    {
        "name": "uchardet",
        "buildsystem": "cmake",
        "builddir": true,
        "config-opts": [ "-DCMAKE_INSTALL_LIBDIR=lib" ],
        "sources": [
            {
                ...
            }
        ]
    }
]

Build with CMake exported targets

uchardet installs a standard pkg-config file which will make it easily discoverable by any modern build system. Nevertheless if your project also uses CMake and you want to discover uchardet installation using CMake exported targets, you may find and link uchardet with:

project(sample LANGUAGES C)
find_package ( uchardet )
if (uchardet_FOUND)
  add_executable( sample sample.c )
  target_link_libraries ( sample PRIVATE uchardet::libuchardet )
endif ()

Note though that we recommend the library discovery with pkg-config because it is standard and generic. Therefore it will always work, even if we decided to change our own build system (which is not planned right now, but may always happen). This is why we advise to use standard pkg-config discovery.

Some more CMake specificities may be found in the commit message which implemented such support.

Usage

Command Line

uchardet comes with a command line tool which obviously uses its own library. It can be considered as a demo of libuchardet even though one can find it very useful on its own right to inspect files.

uchardet Command Line Tool
Version 0.1.0

Authors: BYVoid, Jehan
Bug Report: https://gitlab.freedesktop.org/uchardet/uchardet/-/issues

Usage:
 uchardet [Options] [File]...

Options:
 -v, --version         Print version and build information.
 -h, --help            Print this help.
 -V, --verbose         Show all candidates and their confidence value.
 -w, --weight          Tweak language weights.

Library

See uchardet.h

History

As said in introduction, this was initially a project of Mozilla to allow better detection of page encodings, and it used to be part of Firefox. If not mistaken, this is not the case anymore (probably because nowadays most websites better announce their encoding, and also UTF-8 is much more widely spread) and the original code has been abandoned.

It is to be noted that a lot has changed since the original implementation, yet the base concept is still the same, basing detection not just on encoding rules, but most importantly on analysis of character statistics in languages.

Original code of universalchardet by Mozilla can still be retrieved from the Wayback machine.

  1. Mozilla code was extracted and packaged into a standalone library under the name uchardet by BYVoid in 2011, in a personal repository.
  2. Starting 2015, I (i.e. Jehan) started contributing, "standardized" the output to be iconv-compatible, added various encoding/language support and streamlined generation of sources for new support of encoding/languages by using texts from Wikipedia as statistics source on languages through Python scripts. I soon became co-maintainer.
  3. In 2016, uchardet became a freedesktop project.
  4. Since 2015, the number of supported encoding continuously increased, in particular version 0.0.6 (2016) and especially 0.0.7 (2020) added a lot of new supported charset-language couples.
  5. In 2021, I added language detection support.

Techniques used

Techniques used originally by universalchardet are described at: https://www-archive.mozilla.org/projects/intl/universalcharsetdetection

As said in the "History" section, the base algorithm is still there, helping detection of charset with analysis of character statistics in languages.

This is also why it could evolve in a quite efficient language detector.

Furthermore it does not use any dictionary, doesn't do semantics, or nothing of the sort. The drawback of this is that it can be wrong sometimes, especially on very short texts (a few words) when we don't have enough data to differentiate while a word search in a dictionnary could have done the trick. The advantages are that it makes it perform much faster, with very small memory usage while still being extremely performant on discriminating among a lot of charsets and languages when your text is long enough.

Supporting the project financially

I don't have a specific job around uchardet but I work on making Free Software exclusively. In particular I develop GIMP and other Free Software within ZeMarmot project. Thus uchardet is just one of the many FLOSS code I make.

So if you want to support my Free Software code, I suggest to donate to ZeMarmot in one of these ways:

It might sound weird to fund a Libre Art animation film (Creative Commons by-sa) to support the development of uchardet, but this is exactly what happens if you do, as part of the donation go into salary for me. And we need more funding to continue working on Free Software for a living.

Related Projects

Some of these are bindings of uchardet, others are forks of the same initial code, which has diverged over time, others are native port in other languages. This list is not exhaustive and only meant as point of interest. We don't follow the status for these projects.

Used by

Licenses

See the file COPYING for the complete text of these 3 licenses.

Code of Conduct

The uchardet project is hosted by freedesktop.org and as such follows its code of conduct. In other words, it means we will treat anyone with respect and expect anyone to do the same.

Please read freedesktop.org Code of Conduct.

In case of any problem regarding abusive behavior in uchardet project, please contact the maintainer (Jehan) or create a bug report (possibly private if needed).