What happens if your DVD project is over 1 hour long

Question

I know that to get the highest quality image on your DVD that your project should be 1 hour. What happens if your project is longer than that? let's say one hour ane 10 minutes for example. Will Encore still pop out a DVD only with lower quality images?

Answer 1

Hi Terry.
Of course it won't, although I understand where your concerns come from - blame marketing speak for this!.
It's basically nonsense - Hollywood have been outputting films on DVD running well past the 1 hour mark for over a decade now.
What determines the final image quality on any DVD has much, much more going on than simple running time.
Initially, you should start with the highest quality assets available to you. A lot of the time, this will be SD Video - Standard Definition Video - at 720x480 pixels if in NTSC regions, or 720x576 in PAL regions. If it is higher than this, it is a form of High(er) Definition video. That would introduce our first variable, as high definition source material needs to be correctly scaled or reduced in resolution to SD.
Then it needs to be transcoded into a DVD compliant compressed data format called MPEG-2, standing for the Motion Picture Experts Group, although some wags would claim it really stads for "moving pictures by educated guesswork". There are many encoders out there, and some are frankly better than others at all settings, whilst others work well in some cases but not in others. It's a bit of a minefield. Encore's MainConcept encoder is pretty good.
Quality here depends on the available bitrate, which depends on running time divided by available disc space, with added complexity caused by quality of source, quality of encoder & rapidity of motion in the source.
Basically, the more action in the film (or explosions, fires - anything difficult to encode because of fast motion etc) the more bits that section will need so another trick is using VBR or CBR - Variable bitrate will use fewer bits when it can in order to use more when it has to. VBR will always vary the bitrate to maintain quality. CBR uses the same number of bits, regardless of content, and will only ever vary the quality or (in best case scenario) waste disc space.
If using Dolby Digital Audio, which is 0.192kbps for stereo, this leaves you with up to 9,500kbps for film.
A DVD9 has 65,000 avalable MegaBits for use (after subtracting an overhead) so a 3 hour film would run for 10,800 seconds.
Audio MegaBits used we cancalculate as it is a fixed bitrate, so 0.192 x 10,800 = 2073.6MegaBits.
65,000 - 2073.6 = 62926.4 MegaBits remaining
This gives you a video bitrate of 62926.4/10800 = 5.83Mbps, or 5,830kbps for your video bitrate. That's almost 6Mbps, and a lot of hollywood come in at less than this. a 2-pass VBR would be your best fit, with the minimum at 2,000, the maximum at 6,000 and the target at 5,000 (Some encoders cheat here and set the maximum internaly to the spec limits - I do not recommend trying this in settings though).
A well-encoded film at an average bitrate of 5,000 kbps is not going to look terrible by any stretch although a lot does depend on those variables.
Hope this helps