I thought maybe some practical examples might help. From our library here:
- The Shawshank Redemption, 2h16m, produces a 2.75GB file. Two pass encode into Handbrake's AppleTV profile, which is ~2500kbps MPEG-4 Main profile. This movie has 6ch sound, encoded directly from the original AC3 5.1 into six discrete AAC-LC channels.
- Gosford Park, 2h11m, produces an 897MB file. One pass encode into Handbrake's iPod Highres profile, which is ~1500kbps MPEG-4 Basic profile. This movie has a Dolby ProLogic II surround soundtrack, mixed from the original AC3 5.1 soundtrack, stored in two AAC-LC channels.
These two examples are probably the top and bottom ends of the scale for SD material from your own DVDs. The first encode produces an output file of exceptional quality, almost indistinguishable from the DVD original. The second encode produces a small, iPod-compatible file at the minimum quality I would consider watchable on a large format display.
Both of these files include about 100kb of metadata atoms, including cover art. In the future, it's likely that these numbers will go up as we work out how to produce the MPEG-4 files used by the AppleTV to provide AC3 5.1 sound.