Annoying Problem

[Bebi]

Im trying to encode a film to a DVD and slap it onto a DVD-RW and play it on my dvd player but the most annoying thing is, when I to code it with tmpgenc it says its using like 14.94 over 100% of disk space at its lowest bitrate which is pissing me off so is there anyway round it? ive heard if I can convert the audio it makes the file size smaller, but I have no idea how to do it and I think it requires virtualdub which I have

[Bebi]

I just saved thw wav file so what tools do I need to convert its bitrate and will this reduce file size?