Extract aac audio from a video file. Default audio track is 3 (0-index).

extractAudio.bat

@echo off
set "inputfile=%1"
set "filename=%1"
shift
set track=3

:loop
if not "%1"=="" (
  if "%1"=="-t" (
    set "track=%2"
    shift
  )
  if "%1"=="-o" (
    set "filename=%2"
    shift
  )
  shift
  goto :loop
)

ffmpeg -i "%inputfile%" -map 0:a:%track% "%filename%".aac