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bk jackson 07-03-2007 08:15 PM

720P vs 1080i?
Why is HD broadcast 720P OR 1080I? All of the sales people in the big box stores say that 720P is better than 1080i due to progressive. If that is true, why did they even come out with 1080i? Who decides and why which shows are shot in which format? What can I do to get the best HD broadcast picture through Comcast? Will all broadcasts go to 1080P someday?

Lots of questions but very eager to learn,


LXIX 07-06-2007 09:06 AM

Re: 720P vs 1080i?
This could take a while to answer.

Our ATSC standard has 18 different broadcast formats when you factor resolution, aspect ratio and frame rate. For sake of brevity you can narrow it down to these 5 resolutions:

480i, 480p, 720p 1080i and 1080p/24fps

Why does ATSC have so many resolutions and frame rates? Bureaucracy, with so many cooks in the kitchen (computer companies wanted 480p so that the extra spectrum could be used for data casting. TV manufacturers wanted 1080i since at the time TV's could be easily converted to this standard) the decision was made to offer all the formats and let the broadcasters decide.

In theory, the idea was to use 480i/p broadcasts to allow multicasting of 4 channels on 1 channels spectrum. This would allow a broadcaster to collect extra ad revenue. When primetime hours begin, they could switch to HDTV and shut off the multicasting.

As to the 720p vs. 1080i debate, it is stupid and pointless. If you own a TV that is 1080i/p then a 1080i broadcast will look better than a 720p broadcast. If you own a 720p TV then a 720p broadcast is preferable.

Both 720p and 1080i have their pluses and minuses: 1080i will have a definite perceived resolution advantage while 720p will handle the movement of text on the screen better (and motion in general). But none of this matters because there are no TV's that are multi-scan and can support the native resolution of both formats (some front projectors can do this but are supper spendy). Since this display doesn't exist, we cannot do a fair comparison of the formats. I feel that you would need a display that is larger than 90" while sitting 14 feet away to see a difference anyways.

In the end, if broadcasters were to switch to 1080p/24 then this would be the best for resolution but then you have the juddery look of 24 frames per second. 1080p 60 would be the best but we do not have an approved ATSC broadcast for this resolution.

I am afraid that this most likely created more questions than it answered but hey, I took my shot.


JerryDelColliano 07-06-2007 10:26 AM

Re: 720P vs 1080i?
If people behind home theater and HDTV content made things understandable for the consumer - they might sell more but they NEVER do that. Seemingly there is a lot of bad feelings left over from past format wars etc...

Content providers would WAY rather sell you more 1080i channles than better looking 1080p ones. Until the bandwidth gets REALLY wide (think 5 to 10 years down the road) expect to see more of the iPods effect - more options with lower quality. Consumers (not us) seem to want that.

The think I am excited about is DirecTVs claim of 150 HD channels. Dish has more HD now but that could be eclipsed soon assuming DirecTV gets thier bird launched soon. I heard the rocket they planed on using blew up on another mission thus the delay. I am not sure of that however.

whatchel1 07-13-2007 09:24 PM

Re: 720P vs 1080i?
With present technology satellite doesn't have enough bandwidth to transmit 1080p. If Directv gets the channel Dish will in most cases get the channel as well. Direct has 1 of it's new birds up and will be functioning soon (special dish required). Dish will have 1 of it's new birds up before to long as well. So the competition will continue. Of course the biggest thing is there are not that many nets to broadcast in HD. Both providers are moving to MPEG 4 which will help. BTW Directv is saying up to 150 channels. They aren't saying how soon they will have them up & running.

JerryDelColliano 07-15-2007 07:23 AM

Re: 720P vs 1080i?
I heard that the new sat for DirecTV is delayed because the rocket blew up trying to send another sat into space (from the ocean) for another client.

DirecTV says they will have 150 channels in HD. That will be a HUGE deal for HD.

TheMoose 07-15-2007 08:44 AM

Re: 720P vs 1080i?

Originally Posted by JerryDelColliano (Post 1246)
I heard that the new sat for DirecTV is delayed because the rocket blew up trying to send another sat into space (from the ocean) for another client.

Not true according to This press release from DirecTV

EL SEGUNDO, Calif.--(BUSINESS WIRE)--July 7, 2007--The DIRECTV 10 satellite soared into space yesterday, beginning the first leg of its mission to dramatically expand HD programming for millions of DIRECTV customers nationwide and establish DIRECTV as the industry's HD pace-setter.

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