converting mp3s

I'm looking for a script that can find all the mp3s within a folder and all it's sub-directories that either have a bit rate greater than 192kb/s or are vbr, convert them to 192kb/s, and in the case of the vbr ones, remove the bigger of the two. If possible it would be really be nice if I could retain the id3v2 tags as well, as it would save some work afterwords. I don't care what you use to make it work, as long as it's relitively easy to find and compile. I'm currently using arch linux if that makes any difference.

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