Editing a soundtrack from a movie

i recently got a video caSSEtte tape with a movie i wanted on it.when i made a
dvd with my dvd recorederthe result was great picture wise.the sound however
was a little distorted.i want to edit the sound…i was told that i can do it with
neros wave editor.then id have to confiture it into the movie itself.is there a 3rd
party software that can get that i was told i needed??let me no.thanks