Hi Gurus Some help needed File search and processing

So i have got :
1)Folder with incomming files (C:\in)
example :
aaa.m2v
aaa_R.wav
aaa_L.wav
aaa_M.wav

Before i recive files in this Folder i dont know exact names ,but structure is same ****.m2v and ****_L.wav
After files recived it need to be sent to convert tool

2)video convert tool
works in cmd by atribbutes
example :
coder.exe  C:\In\aaa.m2v C:\Output\aaa.lxf -wav0:D:\In\aaa_L.wav -wav1:D:\In\aaa_R.wav -format:0 -drop:0
After converter end it task it stops in CMD with words Wrap Complete and waits for input(Enter key) then takes next file .

My Solution
1 txt files  (File listing)
1 bat script (takes txt file 1 line by one and send to coder.exe)
1 Autoit Script (starts Cmd and sends in loop Enter key)

Main Problem is in sorting files
I need some logics like
Step 1 Dir files in dir
Step 2 if in folder there is :
aaa.m2v and aaa_L.wav and aaa_R.wav then do this in cmd
coder.exe  C:\In\aaa.m2v C:\Output\aaa.lxf -wav0:D:\In\aaa_L.wav -wav1:D:\In\aaa_R.wav -format:0 -drop:0

if aaa.m2v , aaa_M.wav then do this in cmd

coder.exe  C:\In\aaa.m2v C:\Output\aaa.lxf -wav0:D:\In\aaa_M.wav -wav1:D:\In\aaa_M.wav -format:0 -drop:0

Auto it

#include <Process.au3>

$pr = "c:\scripts\mono.bat"
_RunDOS("start " & $pr  )
$a = 1
While $a =1
WinWaitNotActive("Administrator:  mono","",15)
Sleep(15000)
ControlSend("Administrator:  mono","","","{ENTER}")
Sleep(15000)
WEnd

mono.bat

@echo off
title mono

@echo on
for /f %%i in (c:\scripts\mono.txt) do @start C:\Program Files (x86)\Coder\Coder.exe D:\In\media.dir\mon\%%i.m2v C:\Output\%%i.lxf -wav0:C:\In\%%iM.wav -wav1:C:\In\%%iM.wav -format:0 -drop:0

for Stereo changing is only TITLe and wav0:aaa_L.wav and wav1:aaa_R.wav


Maybe anybody can help me to automize it better ?
can pay (paypal) 2-5 $