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1080i versus 720P

jkizer1
04-06-2007, 08:39 AM
I recently bought a Sharp Aquos 37 inch LCD. For some reason, when using HDMI connect I recieve a 720 P broadcast, and when using component I get 1080i on HD programming. Can anyone explain why this is, and which, if either, produces a better picture quality?

davecramer74
04-06-2007, 11:19 AM
well, seems a little weird to me unless you have one device using 1080i and one device using 720p. My tv displays what i tell it to. My xbox360, i have setup via componant. It has display settings that let me choose 1080i. My cable box same thing, i go into the settings and it displays any HD at 1080i.

Im not quite clear on this, are you saying that you have the same device, you tried both cables, and they display different modes. Or do you have one device hooked up componant and getting 1080i and another device hooked up HDMI and getting 720p.

Your tv should be displaying whatever the device hooked up to it tells it to.

davecramer74
04-06-2007, 11:54 AM
When using component cables, your device can't tell your TV what to do. It relies on settings.
Hi def Jeff

Ya they can. Explain how my xbox360 changes displays then when i change them? Its componant, they dont even make hdmi for it. My HD dvr from comcast i had hooked up via componant before i put hdmi on it. It changed as well. If i change to 720p on sports, my tv said 720p. If i changed it back to 1080i for movies, it showed 1080i. So im not clear on what your saying.

Type A
04-06-2007, 12:48 PM
Everything you see is 720p, because that is your native resolution. You can send the tv either 1080i or 720p, but it will still only display 720p. It may say 1080i, but thats just an indication of what kind of signal its recieving, not what is being displayed. Setting the proper source output resolutions according to your display native resolution are kinda a thing of the past...nowadays most displays will accept either format, but it will still only display one format, its native.

jkizer1
04-06-2007, 12:54 PM
Same device is being connected in both cases, a comcast digital cable box. With the HDMI cord, the set display indicates 720p, with component, 1080i.

Type A
04-06-2007, 01:03 PM
Its the device, outputs are set to output differnt resolutions, and probably just a glitch from your cable company. Luckily it doesnt make a differnce as I doubt you can tell any differnce between sending your display 720 or 1080. Just use the cable you want to use, as long as you get hd, it wont matter either way whether its 720 or 1080.

highdefjeff
04-06-2007, 03:25 PM
is part of the "video picture" you are watching, not necessarily a "readout" or assessment by the TV.

deadhead68
04-06-2007, 04:48 PM
Its the device, outputs are set to output differnt resolutions, and probably just a glitch from your cable company.

Exactly. Though it may not be a glitch. My moto 3412 can have the component and HDMI outputs independently set. So it could be operating just fine, just that the STB's component is set to 1080i and the HDMI is set to 720p.

DeadHead68

BobY
04-10-2007, 06:53 PM
HDMI is a bi-directional communication port, unlike Component Video, which is input-only on the display.

As part of the HDMI handshake, most likely your cable box is interrogating the display as to it's resolution, then setting it's output resolution based on the response from the display.

The cable box probably defaults to 1080i and stays that way when using Compnent Video as it has no way of determining the display resolution. The display has no problem accepting a 1080i input and converting it to the native resoltuion of the display.

peledre
04-13-2007, 02:27 PM
As part of the HDMI handshake, most likely your cable box is interrogating the display as to it's resolution,
So, who's the Good Cop and who's the Bad Cop?