on open objects
	repeat with obj in objects
		set tgPath to getPosixPath(obj)
		set aacPath to Replace(tgPath, "mp4", "aac")
		set cmd to "/Applications/ffmpeg -i " & tgPath & " -vn -acodec copy " & aacPath & ""
		do shell script cmd
		set m4aPath to Replace(tgPath, "mp4", "m4a")
		set cmd to "/Applications/mp4box -add " & aacPath & " " & m4aPath & ""
		do shell script cmd
		set aacPath to Replace(obj as string, "mp4", "aac")
		tell application "Finder" to delete alias aacPath
	end repeat
end open

to getPosixPath(theFile)
	return quoted form of POSIX path of theFile
end getPosixPath

on Replace(src, tg, rp)
	
	set oldDel to AppleScript's text item delimiters
	set AppleScript's text item delimiters to tg
	set myList to text items of src
	set AppleScript's text item delimiters to rp
	set myText to myList as string
	set AppleScript's text item delimiters to oldDel
	return myText
	
end Replace