why use half d1?

[vandakeg]

I was reading through the posts awhile ago, and read somewhere that the frame size in mpeg-2 video makes no difference in the outputted file size.
My question is, if bitrate is the only determining factor as far as size and quality, why would anyone even use half d1 standards? Does the lower resolution allow you to get away with lower bitrates, w/o the loss of quality?

[adam]

Does the lower resolution allow you to get away with lower bitrates, w/o the loss of quality?

That's exactly it. Also one may choose to make a CVD (Basically the same as a SVCD but uses half D1 res) instead of a standard SVCD because that way they can later transfer their footage over to DVD without having to re-encode the video, because half D1 res complies with the DVD standard and the SVCD compliant resolution of 480x480/576 doesn't.

[pixel]

Half D1 resolution is also used by most people when making DVD's to watch on TV because normal TV's can't see much higher resolutions than this.

[FulciLives]

Well it boils down to quality and the amount of video you can fit on a single DVD recordable.

With full D1 (720x480 NTSC or 720x576 PAL) you generally do not want the bitrate to ever fall below 4000kbps. Of course the higher the better.

But with half D1 (352x480 NTSC or 352x576 PAL) you can use bitrates as low as 2500kbps and still get very good quality.

When I use half D1 I like to use 2 Pass VBR with an average of 3000kbps and a max of 5000kbps. If I were to use those values at full D1 the quality would not be as good.

Also when you capture from sources such as cable TV or VHS etc. you rarely will get better quality at resolutions above half D1 so to use full D1 is a waste.

So while it is true that bitrate determines the overall FILE size it is also true that resolution will play a part in the overall QUALITY. So in short a higher resolution will NOT always look better than a lower resolution IF the bitrate is too low for the given higher resolution.

So again half D1 is used mostly for video capture from "low" quality sources ... it can also be used on high quality sources as a way to squeeze more video on a single DVD recordable at "good" quality. Of course quality is relative to an extent but half D1 with a high enough bitrate (like 3000 to 3500) will look DAMN excellent on just about any TV unless you have a monster 50" or bigger TV display. Then the limited resolution of half D1 (despite a proper bitrate for that limited resolution) might start to be noticeable.

So again another way of putting it ... a "high" bitrate half D1 encoding can look better than a "low" bitrate full D1 encoding.

It boils down to balance and the fact that a DVD recordable disc can only hold so much.

- John "FulciLives" Coleman