So little information to go on.
What do you want to do with it? Is it for the web? Is it
going to play from a laptop or desktop? Audio and video
muxed together is called Program Stream (vs Elementary Stream for
unmuxed, separate files, like for normal DVD use).
If you're creating a DVD for DVD player use, you do want to have
the audio and video separate. But we can't guess these things,
you need to tell us what you're trying to do.