What is the nature of the DVD output?

[WMcD]

Not an audio question, but I submit it to the brain trust here.

What is the nature of the output of a DVD player?

Some of e-mail buddies say they can't see the difference between HDTV and a good NTSC montior.

Now I'll admit that HDTV and DVD don't advertise to be the same.

None the less, I've seen some rear projection wide screen displays at the Sony showroom, and a Toshiba at a Tweeter. In both cases, the feed was from a DVD player.

Can it be this is NTSC letterbox format enhanced with line doubling and progressive scan? It sure looked very good to me.

A link to a website would be fine.

Regards,

Gil

[mwiener]

William,

I am going to take a stab at this. DVD is mastered using 480I, 240 lines of resolution on the screen 60 times per second. Each 240 lines of resolution is called a field. 2 fields of 240 lines of resolution are collectively referred to as a frame. Each 480i frame is actually 2 240 line fields. Since they are displayed so fast, the 2 240 line fields appears as one frame to the human eye. If you divide the 60/2 you still are producing 30 frames per seconds ( from the 60 fields ) of 480 lines of resolution, but not all 480 lines of resolution are on the screen at the same time.

If you were displaying a full 480 ( instead of the 240 for 480i )lines of resolution on the screen for each field 60 times per second, you would be displaying progressive scan DVD output.

As far as line doublers, you are correct. 480i on most HDTVs is upconverted ( line doubled ) to a higher resolution. On my TV it goes to 960i. But there is a price to pay for the upconversion. Line doubling of 480i takes the 240 actual lines of resolution per field ( remember 60 fields per second, 2 fields make a 480i frame ) and ups the number of lines of resolution in the field from 240 to 480. Just take the 480i example and double everything.

When the line doubling is done, it looks wonderful on things that are not moving. However, through the line doubling manipulation, you create motion artifacts. Sometimes called jaggies, or just areas that do not look right.

Progressive scan gets around this because no line doubling is being done on progressive scan DVD.

I am using a HTPC now to show DVDs. I am actually scaling them up to 960 x 540 progressive resolution on the PC, then displaying that on my HD RPTV. The results are quite impressive, but I still need to tweek a bit. I think I will skip the whole progressive scan DVD phase.

As far as HDTV, it is 1080i or 540 lines of resolution per field, 60 times per second. The big difference in HDTV is the source actually has more resolution than DVD does, so no manipulation is required.

Mike.

[WMcD]

Mike,

Thanks for your response. I'm gonna read it carefully and do some more investigation.

Regards,

Gil

[mwiener]

I edited the message to make a few points clearer. I thought it was clear when I posted it. But after re reading, I could see where it would be confusing.

This is a confusing topic that took me a long while to figure out. Let me know if you have any questions after re reading the post.

Mike.