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Discussion Starter · #1 ·
Has anyone actually compared how a dvd looks through an htpc vs. a good progressive scan dvd player? If all I ever do is stay on the htpc, I am satisfied with it, UNTIL I do a side by side comparison with my panny-rp56 on the same dvd.


What I do is rip a dvd to the hard drive and play the dvd from the rp56, starting at the same time and occasionally freeze framing both images, and then switch inputs back and forth on the plv60 to compare.


Although the sharpness might be better on the htpc (vga input 1), the color is so inferior to the rp56 (component input 3) it's amazing and although I have been playing around with the color settings on the htpc and the plv60 for the last several weeks, I have not figured out a way to dial in the htpc.


The basic AVIA setup seems to do nothing for color from the VGA input, since there is no saturation and hue setting for the vga input anyway. And the color and tint patterns look spot on anyway through the blue filter (even better than the rp56), yet when compared to the rp56 on the dvd movie, the color is utterly washed-out and inferior.


Even the brightness and contrast patterns on AVIA show problems. From the rp56, there is a definate range where I can see 1 of the 2 white moving bars (contrast pattern) or 1 of the 2 black moving bars ( brightness pattern). However, from the htpc, these pairs of bars are so close in visibility, they pretty much both appear or become invisible at the same time making it very difficult to know what the correct brightness and contrast settings should be.


If anyone has any suggestions for this problem it would be greatly appreciated.
 

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The naked truth is, you can't go about it this way.


your PC setup isn't calibrated to SMPTE and NTSC standards. What many folks don't realize is, you can't simply pop Avia or VE into your PC and correctly calibrate your picture. Why? These discs are only useful calibration tools when the player they're played in is already playing by all the rules of the system. In the case of an HTPC, the "DVD player" is all of the hardware and software involved: the DVD-ROM drive and drivers, the MPEG decoding, the DVD player software and, most important, the video controller and drivers. Unless this entire chain is calibrated AS A SYSTEM to the appropriate reference standard, the calibration DVDs may not produce the truth on your display.


Video controllers in particular tend to be guilty of taking all sorts of liberties with the video signal, resulting in voltage offsets, incorrect color or gamma on any or all three channels, etc. This is commonly noted in the more in-depth magazine reviews of HTPCs.


The problem is, once the signal is in an analog component format (RGB or YPbPr but especially RGB), all of the damage is done and the display is left to pick up the pieces.


It get's worse. Whether by design or defect, your display's RGB input may also be breaking rules and sullying the video signal. But if you hook up a good transcoder to your consumer DVD player and look at the test patterns you can pretty eaily rule that out.


All of these concerns of course also apply to folks doing HDTV on HTPC, only the stakes are higher and there may not even be HD test patterns (e.g. Displaymate) in the mix - yikes!


Bottom line: a good percentage of HTPC setups aren't producing accurate pictures because they aren't calibrated to a reference standard. I'm guessing people who really care about picture accuracy are eyeballing things as best they can. Has anyone got a true reference HTPC configuration to share with us?
 

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Discussion Starter · #3 ·
Thanks for that informative responce Den. My htpc is the 'htpc special' being offered here at av-science. I was told by their tech-support that it was a well calibrated pc set according to a well callibrated plv60 and that the problem most likely has to do with my plv60 vga settings. I chose to get a professionally built and configured htpc to avoid having to worry about the pc end but maybe that was wishful thinking.
 

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Understood. If the pc is sold as calibrated, then they ought to supply a procedure to return the pc to the shipped settings. If that doesn't align the Avia patterns properly, again it could be your display's RGB input wreaking havoc; try a transcoder on the RP56 to compare. I'm certain the AV Science support team can help you get to the bottom of this - good luck.
 

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My HTPC consists of [email protected], 512MB RAM, 160GB RAID and a Geforce2MX. My results are very good, and I can calibrate the picture on the PC.


The main problem is that the controls are split. On the one hand are the contols from your software player, on the other hand are the (sometimes a bit hidden) controls from your graphics card.


I use the standard Nvidia drivers, and you have to look for nView, there you can adjust your desktop colors, contrast, gamma and several other things.

The overlay controls are the ones interesting for playing back DVDs or other media. There you can independently adjust the usual settings like brightness, contrast, color and tint.

The controls of the software player interact with these, so you have to try a lot. At least I had to! ;-)


After lots of tweaking I have good results. IMHO the PLV-60 is a very good match with a HTPC because of pixel-perfection. Not many 16:9-projectors can do that. When I think of it, isn't the PLV-60 the only one? ;-)
 

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Discussion Starter · #6 ·
My color problem is solved! And I did it in a way that nobody recommended and I never expected. I increased the ram from 128 to 512. My htpc now rocks.
 

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How bizzare! So you cracked a "well-calibrated" PC made especially for your particular model of pj and raw ram was the answer? That's scary. How much better than the RP-56 is it now? I keep thinking I should get an HTPC, but you all keep scaring the heck out of me.
 

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That sounds contrary to my belief of what should have an effect or not.. I am not disputing that it happened but it is odd...


Firstly the GFX cards settings is where I work from... Try to set your card and the release of drivers to scoped settings for black and white levels... Hue and saturation are personal levels IMHO but first work on the overlay controls.... After that make sure the SW DVD player is at defaults... Then work on the projector....


Once that is done have a careful look at the image subjectively (eg put AVIA away for a couple of movies) and see if you have any problems that need to be addressed... Also look at different sources (eg dScaler / All the SW DVD players / HD) with the same settings to see if they are all having the same issues (eg your HTPC / PJ settings need a minor tweak) or if it is related to that application only (then adjust in the SW)...


As Dennis made clear earlier the final image is a result of many items in the chain... With a HTPC you have more variables that can effect this rather than simply source / display....
 

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Discussion Starter · #9 ·
The only other explaination I can think of is that I have the pc next to the pj right now for testing. I am still using the same 50ft vga cable but it is not spanning the length of all the other wiring. Maybe it could have been the inteference from the other wiring. I won't know for sure until I put the pc back in the home entertainment center. I'll keep you posted. But right now I just thrilled to have such a good pq. The picture is clearly better than the rp56 now. More vidid, sharp, and smooth. And the color is richer. The THX and Avia setup patterns shows better grey scale tracking, and better contrast and black levels. Had to adjust the contrast and brightness way down now to get it dialed in. Shrek in a side by side comparison to the rp56 is fantastic now.
 
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