First, I have to admit I don't really use DVDA for burning DVD's at this point...I use DLP Pro. Once I get a chance to learn the program, I'll probably start using it...

Having said all that, 1080P was not in the format list of supported formats for DVD's nor the ATSC specification when it was released and standardized...It hadn't been developed then, and there weren't any displays that could handle it.

Besides numerous other aspect ratios, the main 16x9 formats were 1080i and 720p. The difference is, with an interlaced signal you're still dealing with fields...30 field ones, and 30 field twos. This gives you a total of 60 pictures in a given second. The 720p has 60 pictures displayed in one second, but they are not interlaced. The 60 pictures per second was based on compatibility with the line frequency (in the US, 25/50 in the UK), and is basically a hold-over from NTSC where flicker and hum bars were reduced by the interlace and by keeping the scan rate close to the power line frequency. When color came around, it changed from 60Hz to 59.97Hz with the Horizontal changing to 15.734Khz..This allowed the color subcarrier (3.579545MHz) and the sidebands it created to be interleaved properly to reduce bandwidth and eliminate cross-color artifacting.

The 1080p displays that are out now look real good...So do the 1080i displays, as do the 720p displays. As the formats for content delivery continue to be improved, the capabilities of the displays will really be put to use...Right now, a lot of what people are looking at on these wonderful displays is actually good old 480i program material that has been upconverted either by the broadcaster, or by the DVD player, or the TV itself. All things considered, it still looks pretty good.

1080i was chosen again, to save on bandwidth of the transmitted signal...By going interlaced, you kept the bandwidth needed for the interlaced signal close to that of the non-interlaced format even though the actual picture is larger.

It's all about bandwidth, and that was what the concerns were about as the transition from analog to digital broadcasting was being developed...They wanted to at the very least, use the same bandwidth, or less than what was currently being used. Some of the early formats considered actually required the receiver to pick up 2 channels simultaneously with the bandwidth of the 2 channels combined to make up the picture for one show stream...Glad THAT didn't happen...

I haven't started mesing around with Blu-Ray yet, but when I do I'll stick with formats that have been standardized...The Blu-Ray formats are still in a state of flux, and I can't justify buying a burner that can be obsoleted by the stroke of a pen by some guy in a suit in Japan...


Cheers!

edited for additional content...

Thanks for the reply. I knew most of what you said, and a little I didn't.

Unless I didn't read into enough, I don't think it answered my question.

If I have a rendered project with AVC 1280x720 @29.97fps.....then which template should I choose for burning?

Brad, are you saying you rendered your project to an mp4 format? In Vegas Pro 8c, 'Render As', if I select 'Main Concept AVC / ACC, it shows an mp4 file association, with only two aspect sizes, of 640x480 being the larger of the two. Are you making this for playback on an Ipod?