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Discussion Starter #1
What does the 480I digital signal really look like with OTA? Does it compare to a DVD picture, or a satellite picture? Thankyou for your input.
 

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It depends on your local affiliates but for the most part its better than Satellite but not as good as DVD. Some programs and channels are different than others.
 

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Expanding on what bmello said...

Some locals must have fantastic upconverters. For some reason, I think that commercials and the local news cast on our ABC affiliate looks almost better than DVD -- my screen is probably too small and too low rez to really tell.


To me, the local SD PQ received OTA is much better than satellite.


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Broadcast analog NTSC has 330 horizontal lines of resolution. A DVD has 480 horizontal lines. Digital ATSC 480i has 640 horizontal lines. So digital has the capability of being much better. However, the digital is only as good as its original source. I too have observed that local news has excellent resolution from the in studio shots as there is no retransmission from a lower quality source.


Rick
 

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I have dish, OTA digital/HDTV and cable. On my Sony 53HS10 OTA digital from WPIX-DT (all widescreen) looks better than any of the dish channels including the premium channels. PBS-HD looks better than WPIX-DT. NBC-DT primtime (Friends, Will & Grace) look as good as WPIX-DT. I would rate these DVD quality for primetime.


ABC-DT, Fox-DT and UPN-DT dont look that good bc they are 4:3 and not as clear as WPIX and NBC. CBS of course looks very good for HDTV channels but regular DTV is not widescreen.


Overall clarity wise most OTA DTV is better or on par with dish with some programming DVD quality (primetime)

Dish premium channels sometimes approach DVD quality as well depending on the show/movie.



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Eram
 

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Suffice to say if you're considering using an HD STB with a conventioanl NTSC TV (preferably through an S-video or component connection), you won't be disappointed (at least until you spring for an HD display). I am doing exactly that with my 36" set, and the CBS primetime, PBS HD feeds, and ABC's NYPD Blue (unsure what resolution it's boradcast in) are DVD virtual quality. So was FOX' The Lone Gunmen, and I hope that show is set to return this fall. I've had neighbors say they'd never seen HD before. It broke my heart to admit to them they still haven't... Other programming that's filmed or taped originally for SD looks essentially like what you'd see on DBS - some quite acceptable, some downright soft.
 

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Live local news will often look better than the other programming because it is first generation. Almost everything else is off tape or video server, often recorded from a satellite feed that also came off tape or server. When you see it on the monitors at the station the quality is really very good and with Digital you are getting to see that. It would look good even without upconversion.


Tony
 

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Discussion Starter #8
Ray H,Rick R :

Your information has given me this thought. I might hook up a NTSC-TV to a STB. If the 480i digital signal is this good I will wait on HD set.Ray H ;How much better was picture quality than analog 480i?I am very tempted to get 43 inch analog RPTV and try this. Thanks for input.
 

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In my area (Portland OR), the channel witht the BEST NTSC upconvert (FOX) is exactly equal to the analog. The rest of the channels are worse. I NEVER watch the digital upconverts.


However, in your area things may be quite different. If the stations in your area are component digital all the way, the result can be very very nice.


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STOP DVI/HDCP; Boycott JVC
 

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wpix is actually zooming the 4:3 picture to fill the 16:9 window. It looks excellent and Ive never been bothered with the tops and bottoms cut off. Although it is a 480I source, I must admit it is the best sd signal Ive ever seen.


All of the ota upconverts look better than the local stations I get from dish. My ota reception has been stable enough that I think I will unsubscribe to dish's local package and save myself 5 bucks a month. The local stations especially seems to me more compressed on these dbs services.


I guess you can compare the signal to a nonanamorppic widescreen dvd. Wpix though is stunning, even on cartoons. Do a search in the programming forum for more details.


K
 

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Broadcast analog NTSC has 330 horizontal lines of resolution. Text


Scan lines and horizontal resolution can be confusing.


That 330 lines means vertical lines stacked next to each other across the screen like teeth of a comb.


Analog NTSC has 525 scan lines from top to bottom (but that's broken into two fields of 267.5 horizontal scan lines each, called interlaced scanning). Also, the vertical interval has 21 lines of blanking, so active video only has 504 scan lines from top to bottom.


And analog NTSC actually has much more lines of resolution prior to being broadcast by the NTSC transmitter. In the U.S. the video is low-passed before the transmitter to fit within the 6 MHz bandwidth; end result: 330 lines.


NTSC pictures in TV Studios and Control Rooms looks way better before being funneled through analog US TV transmitters...600 lines is typical, 800 lines is common.


On the other hand, U.S. digital television (ATSC) has 18 different scanning schemes per FCC "Table 3." Some are called 1080i, 720p, and 480i. Then there are 16x9 or 4x3 aspect ratios and interlaced or progressive scanning.


But 1080i is the nickname of 16 by 9 video with 1080 interlaced horizontal scan lines and 1920 square pixels across and you can see 960 teeth of a comb from left to right.


720p is the nickname of 16x9 with 720 progressive horizontal scan lines and 1280 square pixels across: 640 comb teeth.


480i has both 4x3 and 16x9 ratios; both have 480 horizontal scan lines from top to bottom but 4x3 has 640 square pixels across and 16x9 has 853 square pixels across.


It has become popular for DTV stations to simulcast their NTSC channel in 480i 4x3 on one stream of their DTV channel. If you can, compare their analog and digital pictures to see the difference in resolution.




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George at WNDU
 

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I've noticed that some digital broadcasts look terrible. I think I'm seeing MPEG artifacts. One example is Late Night with Conan O'Brien on WRC Channel 4 in Washington DC. I'm using a Samsung SIR-T150. I've tried setting it to 480i, 480p, 720p and 1080i, but haven't noticed any difference. Is this a result of poor MPEG conversion by the local station?
 

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Quote:
Originally posted by George Molnar:


That 330 lines means vertical lines stacked next to each other across the screen like teeth of a comb.
No, that's not across the screen, it's only across a horizontal distance equal to the height of the picture. Across an entire 4x3 aspect ratio screen it's 440 lines. Since the resolution of analog formats is usually measured across a horizontal distance equal to the picture height, and digital sources are measured across the entire pixel grid, one or the other has to be corrected before you can compare them to each other.

Quote:
Also, the vertical interval has 21 lines of blanking, so active video only has 504 scan lines from top to bottom.
Again, this is incorrect. The blanking occurs in every field, therefore the total number of visible scan lines is 485, not 504.

Quote:
480i has both 4x3 and 16x9 ratios; both have 480 horizontal scan lines from top to bottom but 4x3 has 640 square pixels across and 16x9 has 853 square pixels across.
Wrong again. There are two 480p formats, the 640x480 is 4x3 only, the 704x480 can be either 4x3 or 16x9. Both of the 704x480 formats are anamorphic the pixels are non-square.


-Jonathan
 
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