As it turns out in a few steps you can actually convert a DRM-free song into a ringtone using only iTunes in Windows. The trick also works for Mac users, but using GarageBand is a lot simpler so we’re focusing primarily on the Windows side.
What is DRM?
DRM stands for Digital Rights Management. In a nutshell, a song with DRM is meant to keep you from giving it to someone else. If you’re using Windows XP, you can right-click on a song file, and choose Properties. Under the Summary tab, click the Advanced >> button if it’s there. Under the Origin heading, you will see an entry named ‘Protected’. If it says No, then the song does not have a DRM. If it says Yes, well, you may be able to pay Apple money to convert the song to an iTunes Plus track, which will be DRM-free.
Let see what you need to do:-
1. Start iTunes and find the [DRM-free] song you want to convert to a ringtone. Right-click on it and select the Get Info option.
2. On the Options tab locate the Start Time and End Time options. This is where you want to specify the portion of the song you wanted converted into a ringtone. Check both of the boxes, and make sure your ringtone is under 30-seconds. Press OK when finished.
3. Right-click on the song you just modified, and choose the Convert to AAC option. If you don’t see this in the context menu navigate to Edit -> Preferences -> Advanced -> Importing, and make sure the AAC Encoder is selected in the Import Using menu.
6. Copy the music file (with the .M4A extension) to your desktop. Once you’ve done that rename the file’s extension to .M4R which will make iTunes recognize it as a ringtone. Make sure there are no symbols (underscores, hyphens, etc…) in the file name.
7. In iTunes go to File -> Add File to Library, and then browse for the file from step 6. Once you’ve selected it press the Open button. iTunes will place the ringtone in the respective section in your library: