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Hitachi 32LD7200 & Denon 1910 dvi problems

Discussion in 'LCD & LED LCD TVs' started by matt_p, May 10, 2005.

  1. matt_p

    matt_p
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    Hi,

    I've had the hitachi 32ld7200 now for a few weeks, and the denon 1910 for a week or so. I've had various problems that have completely confused the hell out of me, so thought I'd run it past you lot!

    Right. Initially, I had my PC connected to Hitachi DVI > DVI, with the Denon connected DVI (Denon end) > HDMI (Hitachi end). This gave mind-bogglingly bad picture quality, macroblocking aplenty, green blacks. Absolute rubbish. After researching a bit, I found that these are pretty common problems with the Denon 1910 :mad:

    So anyway, out of boredom the other night, I thought I'd give it a go with the DVI > DVI cable. A vast improvement! The macroblocking and green blacks had been reduced in severity by at least 90%, and that pretty much saved the Denon from being returned.

    At this point, the Hitachi had the setting of DVI-STB. You can choose from DVI-PC or DVI-STB, depending on whether you're putting in a PC connection or set-top-box. Naturally, the Hitachi manual tells you to set it to DVI-STB when connecting a DVD player to DVI.

    Now here's the weird thing. I was playing around with the settings again, and flicked it over to DVI-PC just to see what happened. The picture has improved ten-fold again! It is seriously jaw-droppingly good. All macroblocking has gone, blacks are perfect...

    If I compare the picture I have now to the picture I had with the DVI > HDMI cable, the difference is massive. And I don't mean that in a snooty hi-fi av expert kind of way, I mean a particularly near-sighted mole sitting 50m away would notice the difference.

    Any techie types out there care to tell me what has happened here? As far as I know, I have made the same connection three times (digital out on the denon > digital in on the hitachi), but have yielded three very different results in terms of picture quality.

    i) I thought that, in terms of video, HDMI carried the same signal as DVI, just repackaged into a different connector?

    ii) Why was there such a difference between the HDMI input and the DVI-STB input?

    iii) Why was there such a massive difference again between the DVI-STB setting and the DVI-PC setting?

    I look forward to anyone's thoughts on this one!

    cheers

    matt
     
  2. ianh64

    ianh64
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    This probably is not the answer, but I shall quickly explain the differences between DVI modes and HDMI.

    DVI is basically a PC legacy. As such, it was designed for PC use was designed to use 8 bit RGB values in the range 0..255 for black..white. This standard is called DVI-PC.

    However, PC displays are not the same as video displays, so a DVI-Video standard was devised. The range of values here are RGB 16..235 black..white.

    So in the video world, black is digital 16 and white is 235. In the PC world, black is 0 and white is 255. The problem though if you connect a DVI-Video source to a DVI-PC display is that you will never get a full black or a full white. A similar thing occurs the other way around and I believe causes a black crush - you loose dynamic range in the blacks - also the whites but it is not so visually noticable.

    HDMI is more than DVI. It is DVI-Video on steroids - it allows much more than DVI-Video in 8 bit RGB.

    So I suspect that you have been seeing the effects of a mismatch between your source and your display. I can't proove this, but it sounds like your 1910 is sending out DVI-PC level video and your display is expecting DVI-video level.

    Now I could be talking utter garbish, but you did ask for anyones thoughts, and my other thoughts are private at this time of night so there you go.

    -Ian
     
  3. jarve35

    jarve35
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    I've just bought a Denon 3910 and also the 32ld7200 which I've had running with a Pioneer 545 through scart for several weeks with very good results. I auditioned the 3910 with the Pioneer PDP435XDE plasma which was using the hdmi connection and the picture was really good. I got home connected the 3910 through a Chord silver plus HDMI cable into the 32ld7200 and expected to be wowed by the picture but in reality had the same macroblocking issue you get with the 1910. Tried all the possible changes through the hdmi connection offered by the 3910 ie 720p, 1080i, hdmi component and rgb, but all showed over saturated red and macroblocking through hdmi. Switched to a DVI cable and set as DVI STB and the picture is stunning at either 720p or 1280i. Also tried the DVI PC setting which was very good but has less colour definition.
    Not sure if this is a general issue with the HDMI interface on the 32ld7200 or Denon players with this panel, but have raised it with the supplier who I purchased the Denon from who are going to test more when they have the 32ld7200 units in stock.
     
  4. matt_p

    matt_p
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    I don't think it's an issue with the 7200, searching around the web I've found many reports of people having the same trouble with the Denon dvd players (or should I say players with the faroudja upscaling chip).From what I understand, some panels suffer more than others, but Denon have recognised the problem as being with the Faroudja chip.

    I'm pretty disappointed really, I've tweaked the settings on both the set and the player so that the macroblocking and colour problems are minimised, but they're still there to a degree. What I have found is that DVI-PC setting on the 7200 seems to 'dither out' the macroblocking, but washes colours slightly. Fingers crossed that Denon can come up with some kind of firmware fix??? :lease:
     

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