Rippix is a fork of ripperX, a fast and easy to use CD ripper. While ripperX does a good job of ripping and encoding songs from a CD, it uses a rather outdated user interface. Rippix tries to fill this gap. This includes porting Rippix to GTK+ 3. Additionally, a lot of deprecated code will be rewritten and documentation will be added. The reason for a fork is that after some hacking on the ripperX code, it appeared that more modifications were necessary in order to port to GTK+ 3 conveniently than what could be appreciable by ripperX devs, like removing all the XPM images (including the logo) from the UI.
id3j is a lightweight and easy-to-use library to create and add ID3 metadata tags to MP3 files. It only concerns itself with ID3 version 3.2.0 and only handles the most common types of information, but creating a tag and adding it to a file is much easier than with many other solutions. It also has one fairly esoteric feature that is interesting from a algorithmical standpoint, which is the ability to create CRC32 neutral ID3 tags. That means that you can add such a tag to any MP3 file and the CRC32 sum of the resulting MP3 file with the tag will be the same as the file without the tag.