DVD-R Recording time (Using Sonic MYDVD)

[sunray]

I am try to create some home movies of old 8mm cassette. I am using Sonic MYDVD. When I capture and save the videos, I see mpeg files are created. When I burn the DVD, I can only burn for approximately 40 to 45 minutes. But the DVD says 4.7gig and 120minutes.
So even to copy one 8mm tape, looks like I need 2 to 3 dvds. Is there anyway I can get 2 hours worth of recording on single DVD?

Is it something to do with the software?


Thanks

[MOVIEGEEK]

Sonic MyDVD uses LPCM audio(uncompressed) which uses about one third of a DVD,you might try Ulead DVD Moviefactory it allows MP2 audio(compressed).One problem with MP2 audio is it won't play on all NTSC DVD players.