50 hz v 100hz

Discussion in 'General TV Discussions Forum' started by GRAHAME, Sep 17, 2001.

  1. GRAHAME

    GRAHAME
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    HI

    THE SONY KV32FQ75U HAS THE FACILITY FOR SWITCHING BETWEEN 50 and 100 HZ - DO OTHER W/S TV'S HAVE THIS FACITILITY ??? WLD HAVE THOUGHT THAT BY HAVING THIS ABILTY IT WOULD END MOST OF THE ARGUMENTS BETWEEN THE TWO (50 v 100) ???
     
  2. Mr.D

    Mr.D
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  3. Mr.D

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  4. GRAHAME

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  6. rbooth

    rbooth
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    Lets get things straight

    A digital chassis can be used on 50hz and 100hz sets. I had a 50hz Panasonic 32PK1 which posterised badly. I now have 100hz Loewe which exhibits no posterisation I can see. Posterisation is not just seen on 100hz sets.

    50hz interlaced sets display various artifacts such as twittering and combing which you don't get on a properly implemented progressive display.

    The scan speed required on 50hz progressive and 100hz interlaced is the same and to get the best picture (50/60hz progressive) you need a chassis capable of a higher scan rate than found on 50hz interlaced sets. My Loewe displays 60 progressive for NTSC sources and 100hz interlaced Pal - this would not be possible on a slower 50hz interlaced chassis.

    Many of the highest quality line doublers/processors used for progressive displays use some form of motion compensation/interpolation. The key is how well they do the job.

    I agree that many 100hz implementations have their flaws but to suggest that 50hz interlaced is inherently superior is oversimplifying a complex subject. The best image is 50/60hz progressive which needs a faster scan (equivalent to 100hz interlaced) which cannot be done on a standard 50hz interlaced chassis/tube.

    Rob
     
  7. Jeff

    Jeff
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  8. Mr.D

    Mr.D
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    I have a panasonic TX32PK1 and it does NOT posterise thats the main reason I bought it. I did various tests for this very reason. The digital implementation on this set is solely for timing issues there is no sampling of the incoming image. ( this info was from panasonic) I'd suggest if you saw posterising on yours your source is at fault. ( early dvd player? TV out from PC?)

    I did not say that digital inherently means inferior: considering what I do for a living that wouldn't make a hell of a lot of sense would it.

    I have looked at the Loewe sets and they posterise: in this respect they seem little different to the previous model philips sets which I am led to believe have the same chassis.

    Yes there are inherent artifacts in a 50Hz interlace signal I didn't indicate otherwise.<br />However I do not consider compromised intensity scale and motion interpolation artfifacting a worthwhile trade off for flicker reduction and lack of combing. Especially when the vast majority of 100Hz/digital processing sets have little or no 2:2 or 3:2 detection capabilities and apply unnecessary primitive deinterlacing processes (ie blow away one field and smear/fill in the gaps which are primarily designed for deinterlacing field captured material) on film based material regardless.

    Neither did I mention bandwidth with regard to chassis. Of course you need a chassis with higher bandwidth if you are using a higher refresh rate , thats got nothing to do with the issues I mentioned though. Its like saying a 1.8 litre engine is quicker than a 1.1 litre what else is new ?

    I am aware that there are reasonably effective interpolation and deinterlacing processes ( use them a fair bit myself and trust me they are way better than anything you'll find in the real world they do not work in realtime yet though). I have yet to see a domestic TV that does ( in my book) an acceptable job : mainly for the reasons that I've already mentioned.( poor 2:2 3:2 detection = unnecessary damaging interpolation) A case of too much crude processing especially where its not strictly necessary( frame based material)

    The "best" way of viewing material in my book is:

    filmbased 50Hz interlace - correctly deinterlaced shown at multiples of 25fps ( 75Hz , 100Hz)

    filmbased 60Hz interlace - inverse telecined to 24fps ( removal of 3:2 pulldown) displayed in multiples of 24 ( 72Hz , 120Hz)

    field captured 50Hz - fields merged ( interpolated preferably using motion vector analysis techniques with some sort of estimated motionblurring)) to 25fps and shown again in multiples of 25 ( higher the better)

    field captured 60Hz - fields merged to 30fps and shown in multiples ( ie 60Hz , 120Hz)

    ( interpolation techniques can be argued about of course ie go 50fps and 60fps on video material by interpolating up each field instead of merging: this doesn't look as nice as fieldsmerging if you ask me and you get stretching and compressing of the edges of features)

    So to watch on your Loewe at 50Hz and 60Hz prog is only ideal if: the set has adequate 2:2 detection for filmbased and or interpolation for field based 625/50 material : again has adequate interpolation for field based 525/60 material. Its most likely not using any 3:2 pulldown detection for film based materal if its using a 60Hz refresh : if it is using 3:2 pulldown detection to get back to 24fps the non-multiple 60Hz refresh again is not ideal.( similar issues with progscan outputting dvd players)

    So you might be in with a chance with 625/50 ( although you've still got a 50Hz refresh issue which kinda defeats the point of having a 100Hz TV in the first place). 525/60 video might be OK if the interpolation is up to scratch (not in my experience on the loewes I've seen) filmbased 525/60 is never going to be ideal on this set-up.

    You might find that you are happy with its appearance but I take issue with your statement that 50/60Hz progscan is the "best" way to view: it might be the best alternative you have on your kit.

    Anyway to summarize:For all the limitations associated with traditional interlaced display I still find these far preferable to the inadequacies found in current domestic implimentations of 100Hz and other digital techniques. This may be entirely down to my particular background where I do a lot of colourspace manipulations and conversions and posterisation is anathema. I'm not too bothered by minor motion artifacting unless its really bad ie features sliding about and large breakups.<br />The most annoying thing for me is that there is not really any reason for posterisation other than sloppy design ( even cost isn't such an issue anymore)

    Thee newest panasonic range seems to do OK by the numbers and I seem to recall it mentions 3:2 pulldown detection but I've yet to see one.

    Its news to me that the 50Hz mode on the sony DRC sets isn't progressive but I'll accept what you say in absence of better info( always thought this was mainly for watching 625/50 filmbased material fail to see a reason for it otherwise)

    DRC never impressed me and readin between the bumph of Sony's press on it I strongly suspect its just anti-aliasing with a bit of pseudo 3d colour upsampling ( last bit could be beneficial if its accurate)

    Sorry for the long post but I hate it when people talk about this subject and degenerate it into the anti-100Hz = anti-digital = analogue luddite.

    Next we'll get the "personal preference , don't care what you say ...you don't have my eyeballs ( thank God!) which isn't what I'm talking about either.
     

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