Over the past few months there has been significant interest and development in a project to replace the firmware on iPods and other digital music players with a fully open-source alternative.

This project, known as Rockbox, is based around Linux code, and is beginning to offer some tempting features that are not provided by the manufacturers’ standard firmwares.

The firmware is the code on the player that controls how it works. In essence it is a small operating system for the player’s hardware. Rockbox replaces this with its own code, completely changing the way the player operates.

Some of the new features include full support for many audio formats, such as Ogg Vorbis, Flac, mp3, Wav and Aac; gapless playback for audio formats that support it, cross-fading, an advanced equaliser, and a huge number of plug-ins including many games and utilities (see picture).

Rockbox is heavily in development, but the daily builds are very stable. There may be a few issues, but you won’t do any damage by installing it, and just as with installing Linux onto a computer, you can dual-boot the player with the manufacturer’s original firmware.

Here we look at installing Rockbox onto a fourth-generation (clickwheel) iPod, and how to remove if it you decide to go back to the old firmware.

There are a few steps involved in setting up Rockbox. Although not very intuitive, they are systematic and can be followed easily. The first step is to back up the iPod’s boot partition, which contains the original firmware image.

Next is to extract the firmware from this partition and then combine it with Rockbox’s bootloader. After that the new image is written back to the iPod and the final step is to install the Rockbox system itself.

Note that Rockbox works only with Fat-formatted iPods. If you have a Mac-formatted one, restore using Windows or Linux.

Head to Rockbox’s website and click on the Documentation link, followed by ‘iPod instructions for Windows users’. On this page you will find several bootloader binary files. Download the appropriate one for your iPod model.

In this example it is bootloader-4g.bin, since this is a fourth-generation iPod. Next, head to the Linux iPod installation instructions and download the ipod_fw.c file. This is the utility needed to extract and combine the firmware image. Compile the code with gcc:

$ gcc -o ipod_fw ipod_fw.c

You will need the gcc compiler installed to perform this step; on Ubuntu Linux enter ‘sudo apt-get install build-essentials’ to pick up this and several other related packages.

With the files downloaded you are ready to start the installation. First, back up the iPod’s boot partition. The iPod has two partitions in total: the first is the boot partition (usually about 40-80MB in size), and the remainder of the disk is taken up with a Fat-formatted data partition.