As mentioned, your results can depend heavily on the content. I have authored DVDs that long before with very acceptable results, but mostly talking head type of footage. Would not attempt with a wedding reception with lots of motion and flashing lights for instance, image would self-destruct! The calculator Harm suggested looks pretty neat, just tried it. Got the same result using an old rule of thumb, which is 560/minutes=bitrate.
Before spending hours encoding the entire program, I would try encoding a short sample using the suggested bitrate, which is about 3.3, using 2-Pass VBR encoding. Burn the sample to disc and check it out and if you are happy with it, then do the whole thing.
Also, I don't always trust the size estimate in the lower corner of AME because I believe that is figuring PCM audio, and not the actual Dolby AC-3 at 192Kbps that Encore will be using, which produces a much smaller size audio file on the disc.
Your are really pushing the limits of the DVD format at 170 minutes, but it is possible it will look ok depending on the material being encoded.
Jeff Pulera
Safe Harbor Computers
