[opendtv] 1080i vrs 720P

Last Saturday we had a surprise party for my Father-in--Law, who was 
celebrating his 80th birthday. The part took place while Florida was 
playing Kentucky - the game was in HD on CBS.

The room was filled with Florida fans, and I was forced to sit in a 
chair about three feet from the 50" screen, to the side. At normal 
viewing distances the pictures looked very good. I think CBS has 
improved their production processes, and their HD sports no longer 
look like a compromise between the SD and HD audience. But at three 
feet, i was amazed at how bad the pictures looked.

Since my display is 720P, I expected so artifacts from the 
inter-format conversion from the 1080i source. But I was amazed at 
how pronounced the interlace artifacts were at this distance. The 
small area twitter was quite pronounced, and I would often see 
tearing and hash in graphics. But this was not as bad as the 
compression artifacts.

There were three major types of video that fell apart into visible 
blocking artifacts:

1. Anything with a dissolve in and out of replays with DVE zoom 
effects would fall apart. And any other dissolve would fall apart.

2. Any close-ups with players moving through the field of view would 
fall apart. This was especially noticeable on tight close-ups, even 
if slightly out of focus.

3. Many graphics would fall apart, especially when they were being 
flown in and out.

What was most annoying was the huge differences in quality; sometime 
the pictures would be sharp, and at other times they would just fall 
apart.

Just now I pulled up a game from ESPN-HD that was recorded on the 
PVR. The game was the FSU Boston College game of two weeks ago. An 
interesting side story with this one. The game was supposed to be in 
HD, but "due to technical difficulties" the first half was presented 
in 4:3. What was interesting is that it looked like 4:3 HDTV. They 
managed to get things working during half-time and the second half 
was in 16:9 at 720P - the images were not sharper, they just filled 
the screen.

So I sat in the same chair at the same distance and watched some of 
the game in 720P. The difference was remarkable. First, there were no 
interlace artifacts. Second, the pictures rarely if ever showed 
blocking artifacts. What did happen was the SNR would spike up during 
more difficult scenes - the picture would become a bit noisy, but did 
not break up.  All of the problems I had seen with the CBS 1080i feed 
were MUCH less pronounced with the 720P feed.

This is the first time I have had the luxury to compare formats on my 
HD display, thanks to the PVR. It was quite revealing. Now if our 
local ABC affiliate would get their DTV station on the air...

Regards
Craig

 
 
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