I've just written an AAC encoder plugin for ADRipper. It can encode either as a raw stream of data, or with an ADTS header (the latter can be played fine in WinAmp, WMP or Media Player Classic; no support in Amiga players yet, I'm afraid).

What I'd now like to do is mux the AAC data into an M4A container, to make the file more usable. I know I can use FFMPEG but it's terrible overkill for such a small task, and the resulting plugin size would be enormous. Would anybody know of a more "lightweight" way to mux AAC into M4A?