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I know that a high definition(1080i or 720p) signal is transmitted digitally with a 16:9 aspect ratio. What about SDTV(480i) and EDTV(480p)? Are they transmitted digitally with a 16:9 aspect ratio?
 

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What about SDTV(480i) and EDTV(480p)? Are they transmitted digitally with a 16:9 aspect ratio?
Standard definition is transmitted/received in a 4:3 aspect ratio. It may be analog or digital. Enhanced Definition is transmitted in a 4:3 aspect ratio but "unfolded" to display in a 16:9 screen with standard (relatively poor) resolution. Although digital, it is not HDTV. This is very much like putting a 8-1/2x11" piece of paper in a 4x6" envelope.
 

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Originally posted by Phil P
I know that a high definition(1080i or 720p) signal is transmitted digitally with a 16:9 aspect ratio. What about SDTV(480i) and EDTV(480p)? Are they transmitted digitally with a 16:9 aspect ratio?
480i is normally 4:3, but that doesn't mean that you don't see some 16:9, but it is not very common. 480p on the other hand, which is DVD quality can be both 4:3 or 16:9. But in broadcasting, a 480p signal is usually sent 16:9. I can't think of a single 480p that is 4:3, but I can think of quite a few 480i in 16:9.


True 480p does look better than 480i whether it is 4:3 or 16:9. It is NOT HD, but it is better than SD. And contrary to what some people believe, 480p is a viable format for certain programming. Certainly sports and movies look better in HD, but for news programming and the tabloid talk shows like Jerry Springer, 480p is very acceptably quality.


Does that mean that those programs would not benefit from HD, No, but is it really worth the extra pixels for pictures (news programming) that is shot in bad lighting and under extreme conditions? As has been pointed out here on AVSForum, when sports is being shown, if the lightning is bad, the HD looks bad and these guys have a week to get it right. In a hot war zone, for instance, you will not have good lighting (maybe none!) and the lower res 480p works just fine.


Now in my book I will take 16:9 480p over 480i 4:3 any day on any programming if HD is not available. YMMV
 

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Question from a newbie:


Is a 1080i signal necessarily 16:9? When I get the OTA digital channels (1080i or 720p) for a non-HD show, they are showing up in what appears to be 4:3 ratio (black bars on the sides of the picture of my Hitachi 51s700). The only aspect options my tv gives me in these instances are 16:9 or 16:9 zoom, and to "get rid of" the black bars, I have to choose the zoom option. Just wondering if this is standard for a non-HD signal or if, more likely, it's something set-specific or some kind of user error. Thanks for any help.
 

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There is nothing wrong with your set. The network must be broadcasting in HD to get 16:9, if they are not broadcasting it in HD it will show up in 4:3 like the commercials. Even if the national network is offering it in HD, your local still must pass it on. Depending on your local station this may or may not be a problem, sometimes my ABC local forgets to flip the switch but CBS is always reliable.
 

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aces,


The stations that broadcast HD use a single scanrate for all broadcasts on that channel, whether they are true HD sources or not.


This scanrate is either 720p or 1080i with a 16/9 aspect ratio. When the program being broadcast is not HD (local news, commercials, any non-HD programming) the picture is sent out at the HD scanrate in a 16/9 format.

Since the non-HD programming is 4/3, the station adds the black bars to the sides of the 4/3 image.


So a 1080i signal IS necessarily 16:9 and is broadcast as such, but if the program is not HD the station adds black bars to the sides of the 4/3 picture as part of that 16:9 image. Your tv sees this as a 16/9 image, not a 4/3 image, and thus your aspect ratio choices from the tv itself are eliminated or restricted. Most sets won't alter an incoming HD image at all, so you're lucky you have the 16:9 zoom on yours.
 
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