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Discussion Starter · #1 ·
Hi,


I am currently testing a DreamVision MovieStar Plus (1024x768) for somebody else and have reached the following conclusions:
  • It produces tearing artifacts, which appear during horizontally panning scenes. (Tearing artifact is when the top part of the screen is the previous frame, and the bottom part of the screen is the next frame - causing a 'skew' effect during horizontal pans)
  • Its internal refresh rate is about 104 Hz (tear line becomes almost stationary during hockey games when I adjust my ROCK+ or HTPC closer to around 104 Hz. Hockey games are excellent horizontally-panning test material)
  • No tearing artifacts during 480i input directly into projector, bypassing my ROCK+ and HTPC.
  • Constant judder because of fixed-rate 104 Hz internal refresh rate. Inputting 72 Hz refresh gets converted internally by projector to the projector internal refresh rate, causing judder to reappear. (Note: Moving VGA cable back and fourth between projector and monitor causes tearing AND judder to dissapear in middle of playback)


This would seem like this is an OEM version of at least the Davis DLX650 projector electronics or a descendant thereof; The DLX650 has the identical tearing artifact flaw (with ALL outboard scalers, at ALL resolutions and refresh rates, making it unsuitable for videophiles). Incidentially, the DLX650 also has an internal refresh rate of 104 Hz.


I would like to know what the people at DreamVision has to say about this; and I want to know if there is a firmware upgrade I can install on the DreamVision MovieStar Plus to at least eliminate the tearing artifact. This is a really expensive DLP projector that shouldn't have the tearing artifact flaw, so I'm pretty curious if there's a firmware upgrade for the projector that fixes this!


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Thanks,

Mark Rejhon
www.marky.com/hometheater
Lead Software Engineer for The TAW ROCK


[This message has been edited by Mark Rejhon (edited 08-14-2001).]
 

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FYI, installing software revision 'L' on the Davis DLX650 fixes the tearing problem. But only if you run at a refresh rate of 60hz.


Mike



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Join the NYC-area HT club! Send me e-mail!


[This message has been edited by mflaster (edited 08-14-2001).]
 

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Discussion Starter · #4 ·
Hi,


Tried to contact them, but got no response so far - Do you have a phone number I could call?


I would prefer to attempt a firmware upgrade using a DreamVision sanctioned firmware upgrade if one is available! (rather than attempting the Davis firmware upgrade on a DreamVision projector, which I don't know is a safe thing to try anyway.)


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Thanks,

Mark Rejhon
www.marky.com/hometheater
Lead Software Engineer for The TAW ROCK
 

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Mark,


Very intersting post wich confirms my impressions on many DLPs. To have that problem on a costly model sold for home cinema is inadmissible. Shame on Dreamvision which communicates on « CRT like » colours and does not mention « Power point projectors tearing like ».


I did myself noticed judder and tearing on my Plus U2-1080 (XGA DLP) connected to a Quadscan. As many DLP projectors, it has a fixed internal scan rate wich, IMO, is the maximum rate specified for it (85Hz). I’m sure of that fact because when I swith from a PAL to a NTSC DVD, the speed of the wheel stays constant. I did experiment a long time ago with a Davis DL450 : the speed of the wheel was varying when changing from PAL to NTSC.



The tearing effect is sometimes visible on travellings on the Plus. If you don’t look for judder, it is not too much annoying. May be 104Hz is worse than 85 http://www.avsforum.com/ubb/wink.gif Except that, the picture is really beautiful, so I can live with these limitations.


Something is still incomprehensible to me : Why is the tearing effect only visible on travellings ? It should be far less but still noticable on much quiet scenes. Does the fast moving images are drivin’ the internal scan processor crazy (huh, I don’ know in which memory area to put that stuff, I’ll try here) ?


In an other way, it would be a nice improvment to fix the internal scan rate to 60Hz or better, to be able to choose 50 (PAL) or 60Hz (NTSC) to avoid tearing and judder, but I don’t even know if my model can receive a firmware upgrade.


I remember a great post you made on triple buffering, so, may be you have answer(s ) or further developpements.


Thanks.


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Serge Lacroix - Cherbourg - France


[This message has been edited by selac (edited 08-16-2001).]
 

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Mark I have a url for Plurison who I believe distribute the dreamvision in North America and some contact number are on the web site (Not Ian Mcaruther) though here is the link to there web site... Plurison contacts


good luck hope this helps


Milesf>


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