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Discussion Starter · #1 ·
Thought I'd throw this out for the collective community:

I'm still bothered by "judder" on some comcast HD cable networks on my 70C8470U. Since switching my receiver to output 1080p (onkyo 609), I almost never notice judder. BUT, i'm constantly perusing cable HD channels like G4, FX, AMC, MGM, TNT and occasionally find a movie that judders on motion, almost all the time. I mean it's not like it okay for awhile, then judders, it's juddering - speeding up and slowing down continuously.

With the receiver upconverting it's MUCH better than it was. Before setting the AVR to output 1080p, I tried to watch transformers 1 on FX HD a couple weeks ago and it was unwatchable with CRAZY judder. Now though, Matrix 2 on AMC HD looks fantastic, War of the Worlds last night looked really good, but something I surfed onto last night (forget what it was last night) had some subtle judder in it, that just shouldn't be ther.

I'm currently running movie mode with all enhancements off (film mode, motion enhancement, pixel plus, active contrast, energy savings,...).

What might I have set incorrectly to account for this? Might it be the specific HD cable broadcast? I've not gone to another set in my house to see if I can see it (like the panny 50ST30 plasma in the bedroom), but I'd bet it doesnt' do it as i've never seen anything like this before.

My current theory is that it's doing some processing and not doing it well. I'm just not sure what it doing. The AVR is de-interlacing (1080i output from cable box to AVR, AVR converts to 1080p and outputs to the TV) so there should be nothing for the set to do but display it, right? I have read that the sharps default to 60Hz refresh rate when aquomotion is off. Is is possible that 1080p is not a native refresh rate for this set? (not likely) is it possible that 60Hz is the issue?

Any ideas how to get to the bottom of this?

Best,
jeff
 

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It sounds like you are describing normal 24hz film motion artifacts. Judder in video has a specific meaning. Can you describe what you are seeing in more detail.
 

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Discussion Starter · #3 ·
Hi,
Maybe I'm using the wrong technical term, but I was describing what I'm seeing. The images on some of the channels (fx hd was the worst) seems to speed up then slow down. I'll see if I can capture some video of the issue and post it.
Best,
Jeff
 

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Discussion Starter · #5 ·
Hi,
Yes it's the latest comcast box. I had set its output resolution to 1080i, from 1080p. I reset it to "native" last night and scanning FX HD (main offender in the past showing the issue) among others showed no speeding up/slowing down. I left the AVR outputting 1080p. I'll keep testing and post back.

My initial idea for changing the comcast box to outputting 1080i all the time was to get the display upconversion/scaling out of the equation, but that was misguided and preliminary results suggest it introduced artifacts.

Best,
jeff
 

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Native would be the place to start. Think about it, cable boxes likely do not have the latest nor most effective scaling or processing. In fact, they are likely built about as cheaply as possible and stay in use for years after they are obsolete (which is often before they get into customer's homes).
 

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I think its normal I have the same problem whith my Sharp lc-60e78un connected to the 809 and I got the Comcast hd dvr cable box now if there is a solution to that that would be nice.

Sent from my PC36100 using HT Shack
 

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Discussion Starter · #11 ·
which comcast box do you have? the usual way to get into the menu, is turn the box off, then press the "menu" button. an on screen menu should appear. Use the arrow keys on the front of the menu to navigate (up, down move you up and down through the menus. enter selects that option). look for HDMI settings of similar.
Here's a page for comcast boxes and manuals: http://customer.comcast.com/help-and-support/cable-tv/cable-box-user-manuals/

Let me know if you're still having trouble figuring out how to check the setting.
 

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Discussion Starter · #14 ·
Hi Onkyolover,

I think I finally solved the issue, although I don't understand why it works better now. If you're still bothered by jerky motion, try setting your onkyo to "through" for the monitor out output resolution. Tried to watch GI Joe, rise of cobra on FXHD tonight and it was very jerky. I had the RCVR set to 1080p, and changed it to "through" and voila it was jerk-free. I'm not sure why that should be better. the manual says that should pass input resolution through without change to the display. In my case, comcast box is outputting 720p. (I didn't test 1080i). I thought the Qdeo was a good upscaling/de-interlacing solution, but maybe it interacts badly with this display.

Anyway, try that if you've not. I'm happy now, no more jerkiness.

Best,
jeff
 

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Think of combinations of equipment like stacking filters in an audio system. Many here can relate to the complexity of the result. This is why most experienced in system design start with as little processing as possible and add it back one thing at a time to keep the variables limited.
 
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