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wallace123456
Joined: 14 Aug 2006
Posts: 2236
Location: Northwest VA area
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| Posted: Thu Aug 16, 2007 3:47 am Post subject: Judder - What's your thought on what causes it |
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Well, I have read a boat load on this and the A site regarding judder. And I may be thick headed, but I still have judder.
Without going into what I have done to try to get rid of it, I would like some thoughts on what causes it.
Blast away!!
Thanks.
wallace
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Thu Aug 16, 2007 5:22 am Post subject: |
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You need to run 72 or 96hz refresh rate, and use Reclock.
Most judder is caused by running 60hz, a 24fps multiple fixes this. Jumps are jerks are PC specific and caused by the separate sound and video clocks getting out of sync, Reclock fixes this.
That's all there is to it really.
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ecrabb
Forum Moderator
Joined: 13 Mar 2006
Posts: 15909
Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Posted: Thu Aug 16, 2007 5:27 am Post subject: |
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Judder is the visual artifact which results from trying to display material that was shot at one frame rate, at another frame rate which is not the same or an even multiple of the orignal. The cause is frames from the source necessarily being displayed for different lengths of time.
So, if you try to watch film source DVD (film shot at 24fps) @ 60hz, you'll have judder. Watch at an even multiple of 24 - say, 72hz - and with properly encoded source material, there will be no judder.
To clear up one common misconception, there is no judder at the movie theater.
SC
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Gino
Joined: 22 Apr 2006
Posts: 1363
Location: Trinity Beach, AUSTRALIA
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| Posted: Thu Aug 16, 2007 5:44 am Post subject: |
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| ecrabb wrote: | | To clear up one common misconception, there is no judder at the movie theater. |
Perhaps, but there is flicker 
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Thu Aug 16, 2007 6:35 am Post subject: |
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Cinema flicker drives me bananas.
There is judder at the cinema - not because of a frame rate mismatch, but because 24fps is not enough for smooth motion. Cinematographers have to follow all sorts of rules, to keep it from being too objectionable.
But that's what makes a movie a movie, rather than a cheap soap opera. The film look.
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ecrabb
Forum Moderator
Joined: 13 Mar 2006
Posts: 15909
Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Posted: Thu Aug 16, 2007 9:26 am Post subject: |
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| Mark_A_W wrote: | | There is judder at the cinema - not because of a frame rate mismatch, but because 24fps is not enough for smooth motion. Cinematographers have to follow all sorts of rules, to keep it from being too objectionable. |
That was my point for mentioning it... Judder specifically IS frame rate mismatch, so that's NOT judder! By incorrectly calling it judder, it confuses people into thinking it's nothing they can fix. Obviously, you can't fix the original frame rate, but you don't have to watch judder.
SC
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Tom.W
Joined: 09 Mar 2006
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WanMan
Joined: 19 Mar 2006
Posts: 10270
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| Posted: Thu Aug 16, 2007 1:44 pm Post subject: |
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Why are we still stuck on 24 and 60 in frame rates and refresh rates? Why can we not simply understand the limitations of 80-100 years ago and 'get over it'?
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ecrabb
Forum Moderator
Joined: 13 Mar 2006
Posts: 15909
Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Posted: Thu Aug 16, 2007 3:55 pm Post subject: |
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It's not just a limitation of 80 years ago. A lot of people (including me) like, or even LOVE 24p. Besides, as long as we have CRTs, we have to deal with refresh rates. As long as people are running processors and HTPCs, there's going to be a learning curve to understanding how to match the two to eliminate judder.
SC
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wallace123456
Joined: 14 Aug 2006
Posts: 2236
Location: Northwest VA area
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| Posted: Fri Aug 17, 2007 6:59 pm Post subject: |
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Good article.
I have reclock working and that helped a little. I'll mess with the refresh rate this weekend (I hope).
Any other suggestions or recommendations, I'm open to them.
wallace
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ecrabb
Forum Moderator
Joined: 13 Mar 2006
Posts: 15909
Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Posted: Fri Aug 17, 2007 8:39 pm Post subject: |
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Just remember to base your calcs on 29.97 (not 30fps) for NTSC DVD. So, your refresh rate won't be exact multiples of 24 like 48 or 72. You should use a multiple of (29.97/30)*24. So, 23.976, 47.952, or 71.928. I know somebody will say, "for pete's sake, it's only a frame out of every 1000!", but hey, we're trying to eliminate visual artifacts, we may as well not leave something in there to have another visual artifact every 42 seconds (also known as 171 hiccups per 2hr movie)!
Good luck, and report back how things work out.
SC
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Phil Smith
Joined: 08 Mar 2006
Posts: 7717
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| Posted: Wed Aug 22, 2007 1:06 am Post subject: Re: Judder - What's your thought on what causes it |
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| wallace123456 wrote: | Well, I have read a boat load on this and the A site regarding judder. And I may be thick headed, but I still have judder.
Without going into what I have done to try to get rid of it, I would like some thoughts on what causes it.
Blast away!!
Thanks.
wallace |
Are you sure it's not stutter instead of judder? Two entirely different things that sometimes get confused.
I for one am not bothered much by 60Hz judder. I don't really see it but on rare occations, or if someone points it out to me. At first this bothered me and I felt like I needed to become more attune to it. After further thought I decided it was GOOD that I rarely notice it, and I'd like to keep it that way.
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wallace123456
Joined: 14 Aug 2006
Posts: 2236
Location: Northwest VA area
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| Posted: Thu Aug 23, 2007 2:45 am Post subject: |
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Oh sh*t!!! Well, here is the stupid side of me (some will say it's all of me): Ok, so I am changing refresh rates last night. I have a eVGA GeForce 6800XT 256mb pci-e video card.
When I change them, to anything other than 23.976, the settings take place, my 1272 pj flickers like it want to accept the new setting, but it doesn't.
All the while, the htpc is asking me "do I want to keep the settings?" I say "yes", and the setting drops back to 23.976.
I have the htpc set up in "clone" mode. So, I change the output to single mode, make some changes (stupid moment coming here  ) and the windows desktop display off the screen!!! I can't get to any desktop icons, START button or anything.
Hell, now I just want to be able to get the desktop back..
Take your best shots, I deserve it...
How in the hell do I get the desktop back on either the dvi or vga output???
(Tail between my legs)
wallace
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Phil Smith
Joined: 08 Mar 2006
Posts: 7717
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| Posted: Thu Aug 23, 2007 3:35 am Post subject: |
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I've had that problem. Seems I rebooted in safe mode.
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Thu Aug 23, 2007 4:05 am Post subject: |
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You can't run a 1272 at 23.796hz, unless you are picking interlaced (48hz interlaced would be unwatchable IMO).
What res are you aiming for?
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wallace123456
Joined: 14 Aug 2006
Posts: 2236
Location: Northwest VA area
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| Posted: Fri Aug 24, 2007 2:18 pm Post subject: |
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| Phil Smith wrote: | | I've had that problem. Seems I rebooted in safe mode. |
Phil!! U R THA MAN!! Worked great. Thanks to MS for making failsafe stuff for idiots like me
| Mark_A_W wrote: | You can't run a 1272 at 23.796hz, unless you are picking interlaced (48hz interlaced would be unwatchable IMO).
What res are you aiming for? |
Any res that will get rid of the judder. I would like to display 1080i, but again, I can't get the refresh rate in th nVidia (with or without Powestrip) to stay at customized settings.
gotta go.
wallace
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Sat Aug 25, 2007 3:51 am Post subject: |
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You need to use 47.952 or 71.926.
You can't run a CRT at 24hz.
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AnalogRocks
Forum Moderator
Joined: 08 Mar 2006
Posts: 26706
Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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| Posted: Sat Aug 25, 2007 4:03 am Post subject: |
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| Mark_A_W wrote: | You need to use 47.952 or 71.926.
You can't run a CRT at 24hz. |
I did that once. It was hipnotic
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