Line Doubler

Discussion in 'Beginners, General Questions' started by DonN, Nov 19, 2003.

  1. DonN

    DonN Auditioning

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    We are in the process of completing our home theater and are not very experienced in the equipment area. Someone mentioned a "line doubler" to me the other day and I would like some enlightenment on the subject. We are using an older Sony 1020 CRT (Red, Blue, Green) projector and projecting to a 70"x70" screen. We mostly watch dvds on our player which has "progressive scan" but also what some tv on it. Do we need a line doubler ? Will we see a great improvement in the images with one ? I do have a NextVision 5 High Definition Video Processor (still in box), is this a line doubler ? I know these questions may be elementary to some of you "pros" but we are in need of some good advice.
     
  2. JeremySt

    JeremySt Screenwriter

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    The concept of "line doubling" was something used before the days of digital displays. Today, the more common term is "scaling" If your projector is capable of accepting a progressive scan DVD player, then it can probably accept a scaler.

    However, the qualtiy of a good external scaler can be anywhere from a few hundred (companies like DVDO) to several thousand (the top of the line Farudja and Runco)

    The quality of a good progressive scan DVD player will not need much help from an external scaler, but if you want your other sources to look better (VCR, Sat, games) then a scaler would help a little.

    Im not familiar with the NextVision, but it sounds like a scler to me.
     
  3. Vince Maskeeper

    Vince Maskeeper Producer

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    1) The Sony 10xx series are mostly VIDEO GRADE ONLY projectors. Video grade projectors are those that have a horizontal scan frequency rating of below 31.2 kHz, often this will be only 15.6 kHz, as used for normal PAL and NTSC video.

    Video only projector can display normal video from a VCR, Laserdisc player, Satellite decoder or DVD player. It can't display video that has been externally processed by a line doubler or scaler. It also can't display video from a computer or progressive scan DVD player (or, specifically with the DVD player in progressive scan mode).

    Chances are 99% your 1020 won't handle a doubled imagine anyway.

    2) A "line doubler" simply makes interlaced video sources progressive video- making a smoother, more film like image. If your sony could handle this higher sync rate video, you would already have it with progressive DVD- so the DVD part of your system would require no doubling. However, TV and VHS signals would probably benefit slightly from doubling- most of these are so low resolution- they will look pretty mediocre at 70 inches anyway.

    3) The NextVision 5 High Definition Video Processor is a box from Viewsonic that is essentially a scaler- and processes incoming analog video signals (like VHS) to a higher resolution output-- this is similar to line doubling- but in the case of the NextVision, it more than doubles- and outputs a signal at 1024x768.

    This box is really cheap and designed to make TV signals compatible with computer monitors-- it's more of an "adapter" than a real image processor. This is marketed, mostly, at kids who wanna run their Xbox on their PC monitor...

    However- it outputs a 1024x768 progressive signal, which is probably not compatible with the 1020 series of Sony projectors.


    So bottom line is, line doubling- or even better SCALING is a key element of front projection and in achieving a grat image- but your projector unit must support HIGH FREQ video rates.

    -Vince
     
  4. DonN

    DonN Auditioning

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    Thanks for your input. If I understand what you are telling me is that the device would be useless on my projector. I'm glad that I didn't have to pay for it, it came free with another item I purchased. If I understand right from reading the projector manual, if the projector would work with the progressive scan dvd player it would do so thru the RGB hook ups. I have been using RCA video cable to connect to my dvd, trying to decide if the cost of component cables would be worth the expense. Any ideas on that subject? Appreciate any help you might supply.
     
  5. ChrisWiggles

    ChrisWiggles Producer

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    I'm not particularly familiar with the sony CRTs, but if it is indeed video grade only, it won't take progressive at all. Regardless, component and RGB are different, and you'd need a transcoder to get RGB to the projector with progressive scan (or higher).
     

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