It depends on the encoding rate used for the MPEG,
as well as how many audio files and subtitles are used.
(That's why you should do a Bit Budget, to calculate
the usable encoding rates properly!)
In general, at an encoding rate of around 4.5 Mbps, assuming
one stereo Dolby Digital soundtrack and No subtitles,
about 2-2.25 hours can be fit, more or less.
If you can successfully lower your encode rate to around 3-3.5 Mbps, you can put 3 hours more or less on a DVD-5, BUT
an MPEG2 picture usually has degraded too far at this rate.
Some kinds of video, however, like static (locked-down) shots
or low-motion video may be usable at this rate.
In extreme cases, using MPEG-1 at an encode rate of 1.5 Mbps
will allow you to create a DVD with about 6 hours of content,
but the pictures in MPEG1 don't look nbearly as good as those
in MPEG2, all things being equal.
For your reference, to fit 90 minutes on your disc,
you can successfully encode at around 6 Mbps (no more!)
An encoding rate of 8 Mbps will only allow you to put
60 minutes on your DVD-R disc, and, in addition.
MAY CAUSE PLAYBACK PROBLEMS DUE TO EXCESSIVE DATA RATE!
