# Overview

The libtracker-extract library is the foundation for Tracker metadata extraction of embedded data in files. Tracker comes with extractors written for the most common file types (like MP3, JPEG, PNG, etc.), however, for more special cases, 3rd party applications may want to write their own plugin to extract their own file formats. This documentation describes how to do that.

## Compiling applications

To compile applications using libtracker-extract, you need to tell the compiler where to find the proper header files and libraries. This is done with the pkg-config utility.

The following interactive shell session demonstrates how pkg-config is used (the actual output on your system may be different):

    $ pkg-config --cflags tracker-extract-0.12
    -pthread -I/usr/include/tracker-0.12 -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I/usr/include/tracker-0.12/libtracker-sparql

    $ pkg-config --libs tracker-extract-0.12
    -Wl,--export-dynamic -pthread -ltracker-extract-0.12 -ltracker-sparql-0.12 -lgio-2.0 -lgobject-2.0 -lgmodule-2.0 -lgthread-2.0 -lrt -lglib-2.0

The simplest way to compile a program is to use the "backticks" feature of the shell. If you enclose a command in backticks (not single quotes), then its output will be substituted into the command line before execution:

     $ cc `pkg-config --cflags --libs tracker-extract-0.12` hello.c -o hello