How to fix a burnt DVD to have the audio and video match?

I have an mp4 that I converted to a wmv to burn to a dvd. On my itunes the video and audio matches. But when I watched the dvd about half way though the video and audio became separate (the mouths didn’t match with the audio) they were a couple seconds off. How can I fix this? Any help or info would be helpful.
Thanks in advance!