HDMI nightmares!

Discussion in 'LCD & LED LCD TVs Forum' started by skk3, Dec 19, 2006.

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  1. skk3

    skk3
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    Wow!

    I have just been lucky enough to audition the Denon 1930, Pioneer 989 and Arcam 137 all via HDMI into my Toshiba 32WL48. There is STILL grain on the screen with each machine! I am gutted. Then I dug out an old What HiFi mag containing a review of this TV and it is stated that the picture is better via component!!!!How can this be! Does anyone out there have a DVD connected via component to this TV and what is the picture like please. I am desperate for help!
     
  2. scouse258

    scouse258
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    i suffered similar issues with my projector but solved it by buying quality HDMI cables (Ixos)

    In my case it seemed like the picture was losing integrity due to the cables so i was glad when the cable made a difference but every so often on black scenes i can see speckles of white.

    Try the cables mate
     
  3. scouse258

    scouse258
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    you can even get a loan of some to see if the y make a difference if you ask your dealer
     
  4. skk3

    skk3
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    Thanks for your reply.

    The HDMI cable in question was VERY expensive, courtesy of the What HiFi READER RESCUE TEAM! Yes, my secret's out and I will be featured in the issue out at the end of Feb 2007. They are a great bunch of knowledgeable lads but their visit raised more questions than answers - I just do not know where to go next.
     
  5. rogerft

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    HDMI should be better than component because the signal is digital all the way to the display. SHOULD being the operative word, when HDMI first appeared some of the interface implementations were not good and things have now improved.

    On your set component may well be better.
     
  6. toycollector

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    I improved my pic by changing the tv settings from 720 to 1080.
     
  7. ianh64

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    If they are so knowledgeable, hopefully they can explain how a digital video cable can improve the image quality!

    For audio, there are technical reasons why different digital cables can sound different, but video works differently and, having scoured the HDMI specs, short of a cable introducing errors (which would be visible as random sparklies exactly as scouse258 mentions), I cannot see how video can be improved by a different HDMI cable. But I am open to a valid technical explanation.
     
  8. Joe Fernand

    Joe Fernand
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    Hello all

    Syk - take a second to consider the many possible areas where your image may be getting degraded as it passes from Source disc to the electronics that produce the image on your Display.

    An HDMI cable is unlikely to be the culprit if your seeing 'grain' across the whole image when using the Digital (HDMI) Input on your Display.

    Did your 'Rescue Team' do any form of Source to Display calibration with your existing or the potential replacement Players?

    There are lots of Displays with Digital Inputs (HDMI/DVI) that only require a single 'click' change on the Contrast settings to show or hide nasty video amplification noise; see Panasonic PDP Threads for the number of folk that see Green dots crawling all over poorly adjusted Displays.

    Its perfectly feasible to have a Display that has an inferior Digital Input - the video processing that lies behind the HDMI socket may not be top notch and may indeed be inferior to the video processing that's used for Analogue Inputs on your Display.

    If your existing player has Analogue YPbPr 'Component' Out then possibly best to try that for now - assuming it works I guess that's going to be the preferred option (the other option being to replace the Display:eek: ).

    scouse258 - you need a new HDMI cable if your seeing white speckles with your existing cable :devil:

    Best regards

    Joe
     
  9. bosque

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    Grain is a natural part of film and if you had a processor which got rid of it entirely you'd be left with an unnatural digitised non-film image. It shouldn't be confused with the artefacts that early DVDs introduced to the image. Lots of people have been complaining about the grain in the night scenes on the DVD of Michael Mann's Miami Vice and again that is a deliberate choice on the part of the director. I hope the professionals in stores are not telling you that grain is always a flaw !
     
  10. neilmcl

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    It would be helpful if the OP told us what he was seeing this "grain" on, is it one particular DVD in question, all sources? Has he compared with using a non-digital connection to see if there's any difference?
     
  11. skk3

    skk3
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    Hi All

    Grain occurs on all my DVD collection - the one we watched at the time was Galdiator. I have since watched this DVD on a friend's Akai 30 inch LCD being fed by a Sony LS500. His picture is expectionally smooth and grain free. I would draw everybody's attention again to the original What HiFi review of the Tosh when grain was reported there and again at my home - imagine shelling out for a £1200.00 Arcam and seeing grain! For the record, I could not see a massive improvement over my Sony DVP-S336 connected with a 10metre scart, I really couldn't. Maybe I am too much of a a perfectionist. I wish I have waited before I took the plunge 2 years ago - stuff is so much cheaper and better now, but I would have missed out on 24 month's enjoyment. Swings and roundabouts!!
     
  12. rogerft

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    I bought a £5 HDMI cable from LIDL which looked well made and had gold plated contacts because I felt confident that with a digital signal the cable would not make a difference.

    Because I had a credit note I had to use I bought a Tech+link HDMI cable that had 5star review stuck on it because I thought it would be useful later.

    To check it out I changed it for the LIDL cable and both the picture and sound improved, the picture was brighter and more vibrant I saw the difference and also the sound through the TV speakers (I have a wlt68) the top end improved .

    My advice now is if you have a cheap cable try a better one .... some of the prices are crazy though they must be on 300% markup.
     
  13. ianh64

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    With all due respect, I cannot see how a HDMI video cannot become more vibrant simply by changing a cable unless there is a problem with the original cable. At a simplistic level, pixel data from HDMI video is carried across 3 wires. For a image to become more vibrant, the digital data must change, and it must change consistently - ie not randomly. If it is not consistent, then you see sparklies. It is not possible for a cable to change say RGB data from 128, 128,128 to say 130, 130, 130 making the image more 'vibrant'. Even if digital data was being truncated, the fact that data for a single pixel can be split across multiple wires means that the difference would not be uniform, especially if YUV was being transmitted rather than RGB.

    Audio on the other hand is different, but I doubt that you could not hear the difference on a TV. Certainly top end would not improve. Audio may be affected by jitter (which video is immune to unless the jitter become very large in which case catastrophic failure of the picture occurs), but this would manifest itself as loss of imaging in the sound stage, not loss of detail or increase in top end etc.

    I am happy to be proved wrong, but I have taken time to analyse the HDMI specifications and play devils advocate, I could not come up with any scenario, except where the cable started to introduce random errors, that could cause the image to become more vibrant. I must stress that I am not an expert, but I have seen no expert explanation to counter this argument.
     
  14. SquintingBadger

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    I think the problems are more complicated and subtle than simple interference causing 'sparklies'. Although to get to the point where you can see sparklies, you either have a very poor cable or bucket loads of interference.
    Other problems like enhanced vibrancy are much more difficult to explain, but I wouldn't say they were impossible because I couldn't come up with a reason to explain them (very unlikely, yes). Admittedly it does seem difficult on the surface to come up with a reason for behaviour like this given the way the data is transmitted, it doesn't surprise me at all that it can happen. There are many more subtle ways a signal can be affected, and if you test the same cable in a thousand different environments you're going to get a thousand different effects on the signal - most will probably have no effect on the resulting data, some could produce some very bizarre effects - in my opinion.

    Also I suspect different receivers will react differently to different kinds of variations in the signal. I'm also not sure what effect corruption on the clock like would give. Who knows, maybe even the voltage level on the cable at the receiver will cause changes in the colour output (it shouldn't, but then no equipment is ever built perfectly). It could probably be a mix of flaws in the cable and the tv connection combining to produce unexplainable effects - which better built cables will alter. But that's just a random guess.

    Unfortunately there is no error detection, so it's very difficult to actually measure the change in signal from source to destination - it's all subjective.
     

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