mkv to avi command line?

[boombastic]

I'd like to convert a number of mkv files into avi:the video is encoded in xvid so ther's no problem, while the audio is in aac.
I'd like to create a batch file to demux the audio and video parts,convert the aac audio into mp3 and mux them back into avi.
I managed to control via command line mkvextractgui to extract the streams but now i don't know what app to use to convert the audio and mux the avi,can you advice me some?

[HQ-LQ]

you must install "mkvtoolnix"
mkvextract -h
mkvextract.exe tracks %1 1:"%~dpn1_track01.raw" 2:"%~dpn1_track02.raw" 3:"%~dpn1_track03.raw" ...
mkvextract.exe chapters %1 -s > "%~dpn1_chapters.txt"

[boombastic]

I managed to control via command line mkvextractgui to extract the streams but now i don't know what app to use to convert the audio and mux the avi,can you advice me some?

i already know how to extract the streams via commandline with mkvtoolnik and mkvextract now the problem is to batch convert aac (to wav) to mp3 and re-mux into avi.
Do you know how to do it?

[Doom9]

it would be much smarter to just extract the video, but re-encode the audio source for better quality. Going AC3 -> AAC -> MP3 is clearly much worse than AC3 -> MP3

[boombastic]

I know that would be smarter but i don't have the original ac3....

[Doom9]

Then what exactly is your source? I'm not used to seeing free content distributed via MKV.

[boombastic]

it's a cam capture of the phd thesis of a friend of mine which i first converted into mkv thinking of play it only on a Pc but now that we have both a divx SAP we'd like to convert into avi.
I read time ago that avimuxgui can accept commandline parameter but i can't find any information about that,can someone provide a link?