RSO files are an audio format used by Lego's Mindstorms NXT system. The program lets users design custom built robots using the popular Lego building blocks. By converting MP3s and other audio files into the RSO format, users can add personalised speech, sound and music to their robot's soundtrack. Unfortunately, it is not possible to convert directly from MP3 to RSO, so files need to first be made into the WAV format, which is easily then made into RSO.
Download MP3-to-WAV conversion software. There are a few free programs available to accomplish this task, but the most widely is likely iTunes.
Open iTunes. Add the file you wish to convert to your play list.
Click on the file you wish to convert. Select "Edit" and then "Preferences."
Click on "Import Settings" and select "WAV Encoder" from the drop-down list. Click "OK." Wait for iTunes to update.
Right-click on the file you want to convert and select "Create WAV Version." Wait a moment as the file is created as a WAV.
Download a WAV-to-RSO conversion program. The most popular of these is SourceForge's Wav2Rso software. It's free to download and says exactly what it does in its name.
Click "File" and select the WAV file you previously converted from MP3.
Click "Convert to" and select "RSO." The new RSO file will be in same folder as the Wav2Rso program.