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Why my HD channel show pictures in 1080i? Dead pixels?

#1
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6/22/09 at 8:59am
  • Joined: June 2009
  • Post Count: 7
Got my Samsung LN52B750 (1080p)two days ago.

I live in Maryland and I have Comcast cable TV. I watched a few HD channels and I notice that they are all 1920x1080i @ 60Hz.

Why are they not 1080p? Why are they 60Hz. Can I manually change the refresh rate?

How can I find dead pixels easily? I need advice about the TV settings, etc. in which I can easily spot dead pixels. Heard people talking about dead pixels. Kind of concerned.

Cheers!
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#2
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6/22/09 at 9:45am
  • Joined: May 2003
  • Location: Eastern NC
  • Post Count: 1,756

Re: Why my HD channel show pictures in 1080i? Dead pixels?

TV does not broadcast in 1080p. They only do 1080i and 720p. DirecTv and Dish Network offer 1080p on some of their On Demand channels. 1080p takes too much bandwidth to broadcast all HD channels that way. You need Blu ray for 1080p.

You shouldn't need to worry about dead pixels for quite awhile, having a new tv. You'll know it when you get one......

You can go to AVS Forums, and find settings for your tv. Just look for your model number.
Samsung HL61A750 (LED DLP)            Onkyo TX-SR805
Oppo BDP-83 Blu ray                                  Polk Audio LSi9
Polk Audio LSiC                                  Sony SS-MB100H
JBL PSW1200 (Sub)                        ...
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#3
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6/22/09 at 9:51am
  • Joined: April 1999
  • Post Count: 1,573

Re: Why my HD channel show pictures in 1080i? Dead pixels?

Quote:
Why are they not 1080p? Why are they 60Hz. Can I manually change the refresh rate?

TV stations only broadcast at 1080i/60hz and 720p/60hz for HD. Your cable set top box can output one or the other (it converts stations using the other format to the output format you have selected; more advanced boxes like a TivoHD have a "native" mode which passes the signal without conversion), and the TV displays what it is getting in, not what it is displaying. Although technically there are other formats allowed in the broadcast spec (like 1080p/24), stations don't use them because it's a pain for them to reconfigure their equipment, plus there are tuners/STBs out there that would choke on anything else but the ubiquitous 1080i/720p @ 60hz.

Now note that this is not what your TV actually displays. Your TV de-interlaces 1080i to 1080p, & scales 720p up to 1080p. Plus it does the frame rate conversion to the 240 hz internally. You won't ever really feed it anything but 60hz material (any TV) and 24hz material (Blu-ray given a player w/ 24p output), and it is displaying the input frame rate, not the output frame rate which is always 240 on your set. What you can control is the degree of inter-frame interpolation, the "auto motion plus" setting.

Quote:
How can I find dead pixels easily? I need advice about the TV settings, etc. in which I can easily spot dead pixels. Heard people talking about dead pixels. Kind of concerned.
You can get discs with test patterns like Avia/DVE that throw up solid frames on the screen that would allow you to spot dead pixels. Have to be above a certain number to be considered a defective panel that will be replaced under warranty. See http://www.wikihow.com/Fix-a-Stuck-P...an-LCD-Monitor
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#4
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6/22/09 at 9:59am
  • Joined: August 1998
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Re: Why my HD channel show pictures in 1080i? Dead pixels?

Quote:
Originally Posted by MDDC
Got my Samsung LN52B750 (1080p)two days ago.

I live in Maryland and I have Comcast cable TV. I watched a few HD channels and I notice that they are all 1920x1080i @ 60Hz.

Why are they not 1080p? Why are they 60Hz. Can I manually change the refresh rate?
The native resolution of the LNxxB750 is 1080p. So, you are always seeing a 1080p image. You cannot, nor is there any need to, change the refresh rate.

The "1920x1080i @ 60Hz" message you see reflects the resolution of the incoming source. For example, if you have a PS3 connected via HDMI, the source label will read "1920 x 1080 @ 60Hz." Further, if you are watching a Blu-ray disc on the same PS3, the display should change to "1920 x 1080 @24Hz." Also, the B750 series TVs display at 240Hz (as opposed to the more traditional 120Hz.) With AMP (Auto Motion Plus) you can tweak the display further by independently controlling Blur and Judder. Myself, I never use it, but many owners prefer the interpolating effect when viewing "fast action" sports programming, etc.


EDIT - - Whoops! Looks like others beat me to it. I type too slow!

Gary

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#5
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6/22/09 at 11:07am
  • Joined: June 2009
  • Post Count: 7

Re: Why my HD channel show pictures in 1080i? Dead pixels?

Thanks for all responses!

You guys are awesome.

Cheers!
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