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Discussion Starter · #1 ·
Hello,

does anybody know how to change the refresh rate of the full-screen output on the Hipix? I just bought it, and the settings only allow 60hz, which gives me migraines :(


Thanks,

-Arpad
 

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Discussion Starter · #3 ·
I know, but I was hoping since the Hipix is partially meant to be used with a monitor, that it will have the option of running at a higher refresh rate. If I remember correctly, the reason you can't really tell that TVs are running at 60hz is because the TV screen ghosts alot more than monitor screens, and fills in the gap between the refreshes.
 

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Hmmm, quite a change to the BBS since last I was here....

you probably wouldn't want to drive your TV over 60 HZ, the tube probably couldn't handle it (if it's not actually a giant computer monitor, like the Gateway "dimension" 36" monitor). But obviously you want max. HZ on your computer monitor. So, if you output to a monitor, I think you'll want to send it through the VGA out at 100 HZ +. But otherwise, the HDTV standards require 60 HZ along with the vertical and horizontal resolutions (why do people always want to make HDTV not HDTV and make their HDTV compliant hardware work at non-HDTV specs?). If you're hooking up a PC, you'll know right away with a VGA pass-through if you set the video card to display something the TV can't handle. Hope the tube survives.
 

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The HiPix takes over in fullscreen mode so the VGA card refresh becomes irrelivant.


Many computer monitors can handle well above 60hz,

so I have been "bugging" telemann for a while to include outputs with refresh above 60hz.


Maybe someday they will do it, but for now they

are optimizing for HDTV sets, not computer monitors.


Also they told me the MPEG2 decoder chip and the RAMDACs on the board have limits less than a VGA card so they cannot drive it at as high a

refresh rate.
 

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Discussion Starter · #7 ·
Thanks for the info, I'm using my 21" monitor with the Hipix, and any computer monitor with a refresh rate below 75hz gives me a migraine(though 85hz is much better), even though TVs annoy me but are still more bearable (probably because of the ghosting).


PVR do you know what the specs are on the RAMDAC?

Anything above 60hz would be a blessing... maybe there are some registry hacks?

Otherwise, I'm afraid I'm going to have to sell it, as much as I like the board so far.
 

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This is a shot in the dark, but you might want to try turning down the contrast on your monitor. Darker images persist longer on the retina. The flicker may become less noticable.


(hmm, just noticed the pun. It's not intended.)
 

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Quote:
Originally posted by mkanet
That's not a "problem". It's a standard for HDTV broadcasts.
ATSC broadcast formats say nothing about how a display might render the image - only how it is transmitted.


You could envision, for example, a monitor that displays a 24 fps picture at 72 Hz refresh rate.
 

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Arpad,


What refresh rate would you have them add?


The only modes that it _might_ make sense for them to add are anything @ 120 Hz, or 1080p @ 60 Hz.


Here's why:


Much programming is inherently 30i or 60p. In order to display these at higher than 60 Hz without adding objectionable motion judder, the refresh rate must be an integer multiple of 60.


Much programming is inherently 24p. But none of it is broadcast that way - it is always broadcast 30i or 60p. (the ATSC standard DOES support 24p directly; no one uses it so far) If you were to blindly convert a 24p program broadcast at 30i or 60p to 72 Hz, it would also introduce objectionable motion judder. The only way to convert a 24p program would be to find the original 24p frames within the 30i or 60p broadcast, and that's a problem of greater complexity than the HiPix can handle.


120 Hz is high enough that very people could use it.


1080p @ 60 Hz might be nice, but Telemann has stated that the Janus chip physically cannot support this mode. Maybe you can wait for the HiPix DTV-300.
 

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In theory what you say is true, but I have

been happy with results of DVD player software

or dScaler when the display refresh is 75hz or

above (not necessarily a multiple of 24, 30 or 60)


Perhaps if the refresh is high enough maybe your

eye can't perceive any judder anymore.


Alot of monitors can't handle 120hz.


I wish we had a way to play with the table

of variables needed to make custom resolutions.


I would love to try these and see how they work:

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

(etc)
 

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Discussion Starter · #13 ·
Balazar:

I'd love anything above 60hz. At this rate, I can't watch more than half an hour before I start feeling it. I guess I don't have any options, if it's a hardware limitation.


Qubit:

Thanks, I tried turning down the contrast, but it didn't help much :(
 

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If you can't stand 60 Hz refresh on a monitor, you might try a DLP projector or an LCD display. These should have a different duty cycle and brighness waveform than a CRT and may bother you less. (a different duty cycle is why film gets away with 24 frames per second without flickering teribly while video needs at least 60 frames per second before most people find it tolerable)
 

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Quote:
Originally posted by PVR
In theory what you say is true, but I have

been happy with results of DVD player software

or dScaler when the display refresh is 75hz or

above (not necessarily a multiple of 24, 30 or 60)


The reason that DVD looks good at anything around 85 Hz or faster is that the DVD is encoded as 24 fps on disc. ~85 Hz is several times 24 Hz, so the judder is minimal even when the refresh rate is not an exact multiple of the frame rate.


With Digital TV, in most cases you're starting with 60 fps (fields or frames), so you couldn't do arbitrary refresh rates without judder until you got above 120 Hz or so.
 

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Quote:
Originally posted by dlarsen



The bowtie shutter on modern 35mm projectors flash each film frame twice so it's 24 frames/sec but at 48Hz.


Dave
Why would they bother flashing it twice? Woudn't it be easier just to leave it on longer? The picture would be brighter too. If they are flashing each frame twice, they need a much brighter light source to get the same effective brighness as leaving the frame illuminated for 1/24th of a second.
 

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DAP,


I'm not exactly sure on the specifics, but I think it's because the film is moving at a constant speed. To "keep it on longer" would mean freezing the film in place. It'd have to have time to decelerate and accelerate, so it'd be perfectly still when frozen. I don't think that would be physically possible 24 times a second.


I think the way it actually works is by flashing for about 1/5000th of a second or less, so that the movement of the film won't create a blur.
 

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Quote:
Why would they bother flashing it twice? Woudn't it be easier just to leave it on longer?
Because then it would have objectionable 24Hz flicker. The on time is greater than the off time (the bowtie) but you do throw away some lumens. As lighthouses got more efficient, It was a compomise worth making. Sensitivity to flicker varies from person to person but most people would find 24Hz VERY objectionable.



Quote:
To "keep it on longer" would mean freezing the film in place.
It actually is. There is a loop of film at the top and bottom of the film gate. Each frame is stopped in the gate and then flashed. Twice. The sound head is offset by 18 frames (for optical) to pickoff the sound at a constant rate area. The supply and takeup reels (platters) stay in motion and the loops provide the buffer to stop the film in the gate while it is being flashed. There often is slight motion in a poorly cleaned and maintained gate and you can see it. It even shows up in telclined transfers to DVD.


Dave
 
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