Bulk Rename Utility

I wish to change the filenames of several songs - specifically, those with brackets in the title. I intend to process all my files with "Title" case, and manually cleaning-up any titles that need capitals (ie: DJ , ABBA etc). The issue I have is that I want the text inside the brackets to be lower-case, eg:

ABBA - Dancing Queen (extended version).mp3
Green Day - American Idiot (radio edit).mp3

...and so on.

Essentially, how do I tell BulkRename that I only want the text in the brackets processed ? Obviously they are not all at the same character position so I'm looking for an "ignore until (" option...

Thanks in advance.

Think I've got this sorted - I can do it via MP3Tag which is what I use to manage my songs. It allows you to case-change after/between specific characters