# do all HD channels broadcast in 1080i signal?



## Mikoyan (Jun 10, 2007)

do all HD channels broadcast in 1080i signal? 

any way to tell if the HD channel is in 720p or 1080i? 

I'm not sure why, but my HDTV sometimes look a lot better if I choose 720p on my HR10. This only works for certain stations/shows.


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## bonscott87 (Oct 3, 2000)

In general:

ABC, Fox, ESPN variants are 720p
NBC, CBS, HDNet and most others are in 1080i


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## JimSpence (Sep 19, 2001)

What's the native resolution for your HDTV? I'll guess that it is 720 (actually 768), so with the TV set to 1080i the TV has to downconvert to 720p. Different models of HDTVs do this conversion better than others. Letting the HR10 do the conversion is giving you a better picture.


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## xtc (Jan 22, 2005)

so what setting is better to have on my TV 720P or 1080i? I was told 720P is better for Sports or Fast Action and everything else its about the same?


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## bonscott87 (Oct 3, 2000)

xtc said:


> so what setting is better to have on my TV 720P or 1080i? I was told 720P is better for Sports or Fast Action and everything else its about the same?


Set the resolution on your receiver that matches the native resolution of your TV. That will be best for 95% of the people out there. If you don't do that then you're doing a lot of up and down converting that typically makes thing worse.


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## Mikoyan (Jun 10, 2007)

bonscott87 said:


> Set the resolution on your receiver that matches the native resolution of your TV. That will be best for 95% of the people out there. If you don't do that then you're doing a lot of up and down converting that typically makes thing worse.


yup, that's what I'm doing right now. the picture looks much better when I set HR10 to 720p, sending signal to my 720p TV.

However, I've noticed the following show look a lot better when I set 1080i on my HR10, using the same 720p Tv: Jay Leno, HDNet movies, Letterman, 
NASA on HDNet, as well as pay-per-view HD movies. ???


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## rminsk (Jun 4, 2002)

If you are talking about a DirecTV signal then it is most likely HD Lite which is not 1080i how you now it to be. Instead of being 1920x1080i they are resampled to 1440x1080i or 1280x1080i.


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## TyroneShoes (Sep 6, 2004)

BTW, MyTV is also 720p.



Mikoyan said:


> ...I'm not sure why, but my HDTV sometimes look a lot better if I choose 720p on my HR10...


There is one instance that can make a difference, and that is how well your TV deinterlaces. There are a couple of general ways to do this, and in 2004 only certain models from about 3 manufacturers did it the good way, the majority doing it in a way that can cause jaggies when you rescale to 1080 in your HR10. By 2006 most sets were doing it the proper way, but if you have a set that doesn't, 720p display will give you a better result since it avoids deinterlacing in the set. The HR10 seems to deinterlace 720p properly before rescaling to 1080i (and just before your set reinterlaces it to progressive, and possibly rescales it).

This of course affects 1080i content as well as 720p content, as the HR10 rescales everything (it has no native passthrough mode, which although the HR20 does, that doesn't appear to improve things at all). This means that the HR10 effectively rescales 1080i to 1080i using a 1:1 algorithm, which is probably as transparent as a true native passthrough would be.

Of course there is some potential loss of rez when using 720p output on 1080i content, but images are rarely resolved beyond 720p-rez even when broadcast as 1080, due to a lot of mitigating factors. I can notice it only if there is super-fine detail in the content. For instance, the "stars" on the curtain behind Conan seem slightly more distinct when my HR10 is set to output at 1080. Since that kind of detail is rare (and bad deinterlace is constant at that setting on my Sony) 720p works better for me.

But it's important not to get bogged down in any confusion between broadcast resolution and output resolution of the HR10, as they are two very different things. Many feel they have to continually change their output rez to match the broadcast rez, but they don't, and it really doesn't make any difference if you do. Set the output resolution once and forget it, usually to match the native rez of your display.

Also, "downconverting" from 1080 to 720 or back is somewhat of a misnomer. The proper term is "crossconverting". Not only that, but the "converting" part seems to imply some degratory process, which rescaling (what the process is called in a display and is therefore probably the most accurate term) does not imply. Rescaling between 480/720/768/1080 is exceptionally transparent in modern displays.


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