I’ll just say up front that mp3unicode converts mp3 tags between encodings. And to be clear, we’re talking about text encodings, not audio formats.
If that doesn’t seem to make sense to you, or if encodings are a bit fuzzy for you (as they are for me), then probably you don’t have much use for mp3unicode.
Which doesn’t make it less important, since encodings can be the bane of your existence if you lean toward one and you’re forced to use another. That I can empathize with.
mp3unicode behaves much like you might expect, except that it doesn’t sense the current encoding: You have to supply it.
As you might imagine, that can cause a little stress if you’re not sure what the encoding is to start with. But it will also back off from converting, if it thinks it’s already in Unicode.
I don’t see mp3unicode in Debian-Ubuntu-Mint. So you might have to build it yourself, if you’re not using Arch.
I’ll admit this is an esoteric tool. But you never know how important a tool like this is … until you need it. 😐