What is the difference between "dimensions" and "display size"?

[zz5]

When you bring up "Video Program Information" for a video file, there are two sizes for the video. One is "dimensions" and the other is "display size". Some of the 1080i video files are reported as having both dimensions and a display size of 1920x1080. Others have dimensions of 1920x1088 and a display size of 1920x1080.

Are there actually two different video sizes contained in the header information? I've opened the files with other programs and VideoRedo is the only one that reports more than one video size.

[DanR]

In the MPEG world, all dimensions must be multiple of 16. Since 1920 x 1080 video is actually encoded as 1920 x 1080i with the last 8 lines usually being recorded as black or gray.

So, VideoReDo reports both the encoding dimensions 1088 as well as the display dimensions, 1080.

[zz5]

Thanks very much for your help, DanR.

The reason I posted was that I'm getting ready to start doing a lot of archiving HD to DVD (just copying files to DVD's, not DVD authoring), and I wanted to make sure that I was doing it right. I didn't want to archive a lot, and then find out later that there were problems playing back on hardware devices I might have in the future just because of header values. Right now the only device that I have that can play HD other than my cable box is my computer. Eventually, I want to be able to stream HD files over my home network to a hardware device.

On avsforum and other places, there is a lot of discussion about changing the dimensions in the header to 1080 from 1088 to allow HD DVD authoring to work and allow the video to be played without scaling when played back on a native 1080 display. Why are the dimensions of some files reported as 1080 while others are 1088 in VideoRedo? Aren't all 1080i files encoded at 1088? If a file has dimensions of 1088, but the display area in the header data is 1080, am a I safe to just leave 1088 for the dimensions? No other program that I know of reports two sets of dimension like VideoRedo does.

I've been trying to figure this out for a few days, but it's really hard to find anyone who knows very much about this, so I'm hoping you will be able to recommend what to do. Should I just trim the files with VideoRedo and leave the header information intact, or should I also use some utility to change the header information from 1088 to 1080?

Thanks very much for your help.