HD trailers on LCD "shadows and blacks"

Discussion in 'LCD & LED LCD TVs Forum' started by Dan Gleebitz, Nov 2, 2005.

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  1. Dan Gleebitz

    Dan Gleebitz
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    Still not decided on which telly to get but I thought I'd experiment while I wait. :D

    I've got a Dell 19" monitor which has 800:1 contrast and supports upto 1280x1024 in resolution so it should run HD content with no problems. I thought I'd try out some HD trailers from apple.com.

    Generally the quality is very good with sharp edges and decent colour. However the blacks or darker areas are really bad and I'm getting a lot of pixelation and what I believe you call "Oil Painting" effect. Check out these screen captures:

    [​IMG][​IMG][​IMG]

    What is causing this and is this a problem I can expect from LCD tv's?
    Is this a contrast ratio issue?
     
  2. brakepad

    brakepad
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    I'm not sure that the effects you're describing are actually due to the LCD - although they may be more visible on an ultra-crisp TFT monitor than if you were to view it though a CRT monitor or TV set. I think the fact that the effects are captured in your screengrabs confirms that they are indeed present in the source material.

    The effect on left picture is (I believe) called macroblocking, and is an artifact of the video compression that results in step changes in areas of solid colour, rather than gradual blending which would require more bitrate in the video. Image processing hardware in TV's and post-processing filters in DVD software should reduce this effect so maybe experiment with some 'dedicated' DVD software (e.g. WinDVD) or codecs that allow postprocessing (e.g. ffdshow) to see what happens.

    I think the centre image is again showing similar effects that are simply aftifacts associated with compressed video. I can't really tell what is in the 3rd pic.

    Not an expert on video compression by any means so I'm sure someone out there can fill in the technicalities - or just tell me that I'm completely wrong! :)
     
  3. Dan Gleebitz

    Dan Gleebitz
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    But these are suppose to be 720p HD quality trailers, isn't that suppose to be better than DVD?
     
  4. kam03

    kam03
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    I get that on my sony 32" BRAVIA LCD. I have a NEC 2080UX+ 20.1" LCD and i dont notice anything like that on it. I have no idea why this is on LCDTV's or HDTV's.

    I just viewed the trailer and i seem to get similar results. I guess its the source. I did notice similar results when watching other sources which is evident on my 32" HDTV but not on my NEC.
     
  5. brakepad

    brakepad
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    Potentially yes, as they probably use a more advanced form of compression than the MPEG2 used on DVDs, but digital video encoding still suffers from artifacts of one form or another regardless of the compression technology used.

    Bitrates also vary greatly so some sources may be better than others, and high resolution video at the same bitrate as low resolution video (using the same compression technology) by definition must be more compressed and will show more artifacts. I still reckon what you are seeing is due to the source rather than the display.

    Long live Laserdisc!
     
  6. Dan Gleebitz

    Dan Gleebitz
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    You're right, I downloaded an HD trailer from divx.com and it was amazing. If it looks that good on a 40" LCD then i'll be very happy indeed. :)
     
  7. stlic

    stlic
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    I think the source idea is spot on. I was pretty disspointed with apple HD trailers, tried on both my LCD and CRT monitors to get the same effect. Other than the rediculous tearing which is apparent on .mov files played on a PC (like Apple thinks the PC can't play back perfectly) the compression artifacts are very apparent.

    Given that in the past Apple tried to pass off a Fantastic Four SD trailer which they had simply resized to 720p I don't really trust their trailer quality control.

    What makes it so much harder to swallow is the high system requirements to play 1080p H.264 video. For the rcommended specs you should expect perfect image quality but the finish just isn't there in many cases.
     
  8. RockySpieler

    RockySpieler
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    The bit rate has an affect, I have a few 720 and 1080 movies, they tend to be 24 (23.99) fps, but the bit rate and consequent file size varies.
     
  9. Onyxia

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    It is the codec without a shadow of a doubt. I can see it on my LCD too (Dell 2001FP). H264 deals with the dark areas a lot differently than other codecs, the oil painting effect appears only on the apple trailers. I have a 1080i ts version of the King Kong trailer with proper shadowing and no banding at all. I think the compression needs to be tweaked, it is a trailer after all and small filesize is desireable. Properly encoded H264 movies will not have this defect.
     
  10. David Mackenzie

    David Mackenzie
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    Yes, it's the codec. Video compression is all about compromise.
    For the record, I can't see it on any of my LCDs - you don't have the brightness set too high do you?
     
  11. samhain

    samhain
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    Where is the best online place to sample true HD footage
     

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