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Ultra/De-interlacers

Discussion in 'Projectors, Screens & Video Processors' started by osmyth, May 4, 2005.

  1. osmyth

    osmyth
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    I am thinking about getting a new dvd player and was looking at progressive scan, but then started to think about other things.
    I have a Panasonic Viera 37pe30, so I assume on terrestrial and sky it converts the 576 signal into the 480 native screen resolution?

    Firstly, does anyone know what de-interlacer the pe30 has. I have emailed Panasonic but haven't got a reply yet.

    The Iscan Ultra seems to output 480 lines for NTSC inputs and 576 lines for PAL inputs. Is it possible to choose the lines output from either input (ie. 480 out from any input), or is this effectively what a scaler (or descaler?!) does?

    I suppose in a roundabout way i'm asking if the deinterlacer of the Ultra will be better than the pe30?! I've found out the Ultra uses the Silicon 504 and this is found in some of the good Denon DVDs, so I assume the answer will be yes.

    thanks, Owen.
     
  2. Carl Ed

    Carl Ed
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    The SiI-504 is almost certainly better than the one in you plasma, but the question is 'by how much'? Only you are really qualified to make that judgement, as how much weight one puts on deinterlacing artifacts.

    The only real recommendation I can make is that if you are acually bothered by deinterlacing artifacts (which you'll need to judge in isolation from scaling artifacts, video noise, etc), then you will benefit from a deinterlacer. Then you have to decide if its worth the money.
     
  3. osmyth

    osmyth
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    Carl, you mention scaling there, so I assume the same applies that the Iscan HD would probably do better scaling, than the plasma, of 576 source down to the 480 native screen, thus possibly bettering the picture on 2 fronts?
    Owen.
     
  4. Thunder

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    Down Scaling is unlikely to have much of a beneficial effect. We are talking about two different things here;
    1.) Deinterlacing: taking an interlaced image such as 576i which displays only the odd numbered and then the even numbered lines in each pass, and turning it into a deinterlaced or progressive image - 576p which displays all lines in each pass.
    2.) Scaling: taking say a 576p image and artificially boosting the resolution up to 768p by means of clever mathematics which effectively makes up picture information that isn't there :thumbsup:

    In fact I'm not sure if many scalers offer down scaling ( anybody with more extensive knowledge please correct me if I'm wrong :) )
     
  5. Thunder

    Thunder
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    The SIL504 only deinterlaces :thumbsup:
     
  6. osmyth

    osmyth
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    Thunder, what I was trying to get at was that if the native resolution of a screen is 480 lines, and you pass it a 576 line input (i or p) then it presumably has to do some sort of conversion (downscale?) to make it fit.
    If you externally downscale (just checked and the Iscan HD does downscale) to 480 then pass it to the plasma then I assume the plasma wouldn't have to do anything as the input would match the native res.
    So, my assumption is similar to de-interlacers, that the performance of the scaler would have an affect as well.
    Owen.
     
  7. Thunder

    Thunder
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    It could make a difference I suppose, but it depends if you can bypass the internal scaling on the panel. The best man to ask would be Gordon, but to be honest I think its a question of suck it and see :) See if you can borrow a HD or similar from some one to try :smashin:
     
  8. Carl Ed

    Carl Ed
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    The same rule applies.

    Assuming that you can bypass the internal scaler, an external scaler would probably be better than the one in your plasma, but whether it would be that much of an improvement to warrent the investment is a highly subjective thing.

    Most if not all multi-rate scalers can do down-conversion, and do it just as well as up-conversion. They'll do the 720x576->640x480 conversion needed for SD plasmas just fine.

    What you're saying is more or less correct. Just a note though; there is a little more to getting the native resolution of the display than just getting the right resolution. You also need to get the right timings and sync information (front porch, back porch, sync width, etc) to be able to bypass the internal scaler (if you even can bypass it).
     
  9. osmyth

    osmyth
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    Carl, thanks, so what kind of setup does an external scaler work best with if you can't necessarily bypass the display's scaler?
    Owen.
     
  10. Carl Ed

    Carl Ed
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    If you can't bypass it then it'll never be perfect, but you can at least pick an output from your scaler that the plasma will scale better. Conventional wisdom would suggest that this would be 576p, but in real life 1080i, 480p, or just about anything else may offer a superior result. You'll just have to play around and see.
     
  11. Joe Fernand

    Joe Fernand
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    osmyth

    Just for clarity - in addition to being multi input video switchers the:

    DVDO iScan Ultra - is a Deinterlacer.
    DVDO iScanHD - is a Deinterlacer + Scaling engine.
    DVDO iScanHD+ - is an HDCP compliant Deinterlacer + Scaling engine.

    The Deinterlacing in the iScan Ultra tends to get a 50/50 result when folk compare it to what Panasonic provide within the PWD Displays - some folk say its worth the cost some say not.

    The iScan Ultra cant 'Frame Rate Convert' your 50Hz signals to 60Hz (or vice versa) though you can perform that trick using the HD/HD+.

    You can never actually 'bypass' the Video Processing in any Display - though you can learn how to minimise any negative effects the on-board Video Processing is adding to the image you see on screen.

    Oddly enough with a Standard Definition (852x480) Panasonic Display the best option we have found (through lots of trial and error) is to 'scale' all of your sources to 1280x720P at 50 and 60Hz and then let the Display's processor 'down sample' the signal to fit on the 852x480 pixel array.

    Best regards

    Joe
     
  12. osmyth

    osmyth
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    Joe, thanks very much for the reply, as I had started thinking about the Ultra. I have a th37pe30 and I don't think it can accept higher than 576 (?) so your 'best' option using 720 wouldn't work for me!
    thanks, Owen.
     
  13. Carl Ed

    Carl Ed
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    That depends on the display. Most projectors and the occational plasma do allow people to bypass the internal scaler entirely if you feed it its native rate. Certainly not Panasonic ones via their DVI port, though.

    Why wouldn't it? Try it out with 720p and see, but it should work. It has an internal scaler after all.
     
  14. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Carl: Joe sad you cannot by-pass the video processing not the scaler.....I agree with him. All you can do is minimise the affect of the video processing and this is usually done by removing the rescaling part on HD panels, where possible. The signal is still being captured and processed by the display though but as you say if you hit correct timings the scaling section may be disabled.

    Gordon
     
  15. Carl Ed

    Carl Ed
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    To that extent that is true. Some forms of video processing are worse than others, of course.
     
  16. osmyth

    osmyth
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    Carl, I was just going by the manual!
    That says 480 and 576 inputs for the Viera pe30 only.
    I've sent an email to Panasonic, unless anyone else can say that they are passing a 576+ input to a Viera pe30, and that it scales it properly?

    thanks, Owen.
     
  17. Joe Fernand

    Joe Fernand
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    Hello all

    osmyth - the PE30 is/was a shocker as far as compatibility goes.

    Its been a while since I looked - Is it NO support at 720P via YUV or just no support for 720P at 50Hz?

    Best regards

    Joe
     
  18. osmyth

    osmyth
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    Joe, will check the manual again tonight, but don't think it mentioned 720 at all.
    Owen.
     
  19. osmyth

    osmyth
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    Apologies, my mistake!
    It mentions 480, 600, 624, 768, 870 and 1024 at various Hz between 60 and 85, but not 50, via the PC input. (no 720 I'm afraid)
    The scanning format is 525(480)/60i.60p and 625(575)/50i.50p.

    If i've undestood some of the other comments correctly, then Sky would be output at 625/50Hz and therefore I would need a scaler which could convert the 50Hz to 60Hz to be input via the PC input.
    As Joe mentions the Ultra can't do this.
    Is there generally a problem with the Viera only accepting 60Hz via the PC input, when the scanning format for Pal is 50Hz ?

    thanks, Owen.
     
  20. Carl Ed

    Carl Ed
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    What a nightmare of a display. I sure hope the picture quality is good to make up for it...


    See if you can borrow a scaler and feed it its native resolution and refersh rate via the analogue (PC) input, and see how much of an improvement it makes. That's about the only way you'll be able to find out if a video processor would actually benefit you.
     

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