I have just begun downloading avi files and converting them to mpg using MainConcept MPEG Encoder, then using TMPGEnc DVD author and the writing tool to put it on a dvd-r. When I watch the DVD's on my DVD player, the quality is low. Should I use different programs or are the avi file that I am downloading low-quality?
This depends on a number of factors, but the bottom line is that an AVI file is a highly compressed cource to begin with, and is not an ideal source for conversion to DVD if quality is of prime importance.
Some AVIs will still look pretty good when converted to DVD (see 3 below), but this depends on several things:
1) What was the quality of the original AVI? A two hour+ movie encoded to a 700MB AVI file may look OK on your computer, but is not going to yield a very crisp DVD picture. When going from a lower quality source, the conversion will lower the quality a little more still.
2) What size is your TV? The larger your TV, the more noticeable this deterioration will be.
3) What is your criteria? Were you expecting DVD quality? Were you expecting VCD quality - in most cases AVI to DVD gets you VCD quality at the best (often less).
In terms of what you can do to improve the picture quality there are two things I can think of:
1) Encode the MPEG2 file at a lower resolution of 320 x 480. This is still DVD compliant. As most AVI files are encoded at small resolutions (often around 320 x 240), the process of enlarging them can cause a lot of deterioration. Similarly, using the 320 x 480 allows your DVD bitrate to be spread less thinly.
2) I don't know anything about the MainConcept encoder, but if there are quality settings, you may want to try a re-encode at a higher setting. (In TMPGEnc, for instance, you have the choice of faster encoding /lower quality or slower encoding/higher quality.)
That being said, you have to remember the cardinal rule: re-encoding can't improve on the quality of the original (and the original may not be of as high quality as it looks on your computer monitor).
