MP3 or AAC mixing in compressed/coded domain

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Subject: MP3 or AAC mixing in compressed/coded domain
From: Yadong Wang <ydwang@xxxxxxxxxxx>
Date: Sat, 28 Feb 2009 21:19:40 -0500
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Anybody can point to me any literatures or any guide for me?

Basically, I would like to mix two MP3 (or AAC) in compressed domain directly.

Yadong