Hey, Nick,

Keep in mind image size is only half of the equation. Bitrate is the other half. A 720x480 video file encoded at a bitrate of 500KBps will look like crap, while one encoded at 1Mbps or 1.5Mbps will look much, much better. And the codec you use for encoding, as well as the source file also make huge differences in the quality of the finished product.


Basschick, DVDs are encoded using the MPEG-2 codec at somewhere between 3000 and 8000 Kbps; the reduction from .AVI or mini-DV (both pretty much the same source resolution) is somewhere around 1:8 to 1:20 depending on the final MPEG bitrate.

The bitrate you encode at is dependent on the total program length and what format of DVD you're producing; DVD-5 (single layer) can hold only about 4.5 gigs of data, while DVD-9 (double layer, single sided) can hold a bit over 7 gigs, so a 60 minute program with few extras will easily fit at a very high bitrate (6500-8000) on a DVD-5, while a 120 minute DVD with lots of extras (previews/bloopers/etc) will need to be compressed much more, maybe as low as 3000-3500, or will have to go on DVD-9 which is both more complicated to author and more expensive to manufacture.

Most of our DVDs are encoded at between 4500-6000Mbps, which looks decent even on a 42" plasma TV; if you get below about 3500-4000, you typically start to see artifacting on a big screen TV. (It also depends on the program; video shot against a white wall will compress much better than video shot with a bunch of leaves and branches in the background blowing in the wind)

Transcoding from MPEG-2 to any other compressed format will undoubtedly cause artifacting because MPEG is already a very lossy format, so any artifacts introduced by MPEG compression will be amplified by re-encoding to another media. So transcoding to anything (WMV, Real, Quicktime, Divx, etc) from ripped DVDs will never produce as good a quality as transcoding from either AVIs, full-resolution Quicktime files, or DV video.