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1:1 pixel mapping?

807 Views 9 Replies 5 Participants Last post by  Drew888
I have tried searching the forums on this but for some reason the search function will not work for the past several days. My question is what exactly is 1:1 pixel mapping. Is this only available to LCD type displays? I have a 51S500 Hitachi and I presume the only resolutions that I can use are 920x500 (desktop), 1184x666 (to click ok cancel), and 1776x1000i (dvd & media file playback). Sorry for the dumb question as I usually do my research but have not had any luck with the search function for the past several days :(

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Torpid, did you find your answer?

I have a 57S700 and for the windows desktop 720x480 @60Hz (a ATIHDTV predefined resolution) worked well.

I just started hooking up and tweeking my HTPC the day before yesterday.

1776x100i huh...Hmmmm I try to choose an interlaced res. and my screen goes blank.

I am still searching for timings that work best.

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I use a DVI-D cable from my ATI 9700 Pro to my Hitachi 51S500. The resolutions I have were setup thru powerstrip. To answer your question no I have had no respose or luck finding an answer. Interlaced resolutions only work on certain Catalyst drivers. I am using version dated 8/25/2004.
1:1 pixel mapping is for fixed resolution displays like Plasma, LCD, DLP and LCoS. CRTs need not apply. When you can get your computer to output the same resolution that your TV displays, that's 1:1 pixel mapping. They are trying to avoid having the TV upscale or downscale the resolution to match and therefore degrading image quality. Get it?
If I'm reading your post correctly, I think you're asking two questions. First, what is 1:1 pixel mapping in general, and second, what is the correct resolution to run your 51S500 at?

1:1 pixel mapping is the process of matching the output of your source device (HTPC or scaling DVD player) to the native resolution of your display device. All fixed pixel displays (FPD) including LCD, DLP, and LCOS machines have a native resolution that projector will scale any input to. The advantage of 1:1 mapping is match the native resolution at the source and thus bypass the (usually) inferior scaler in the projector itself. For instance, if you have an LCD projector with a native resolution of 1280x720, but your HTPC is set to 1024x768, the scaler in the LCD projector will kick in and scale your 1024x768 image to 1280x720 resulting in a poor image. If you adjust your HTPC to 1280x720 using powerstrip then the scaler will sense the incoming signal is already scaled properly and it will not kick in. That's the short version of it. I'll leave out phase, dot clock, scanning freqs, etc. for simplicity.

The answer to your second question is slightly more complicated. The 51S500 is a CRT device, meaning it does not have a native resolution. Instead it displays everything at specific scanning frequencies. Some CRTs are multi-scan devices, meaning they can display multiple different resolutions. Some are fixed frequency devices, meaning they'll only display input signals that match a single format, and others are sort of a combo (I'm sure there's a name for this but I don't know it). Most rear projection tvs are of this combo type. They'll accept any input signal, but then they convert it to a specific scanning frequency just like the scalers do in an FPD. I don't know the specifics of the 51S500, but I would guess that it converts everything to 1080i before displaying it. I would download powerstrip and start with its built-in 1080i settings and then tweak from there until you get a sync'd signal.

If you already knew all this, sorry for being redundant. Best of luck.
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Perfect answer! Thanks thats pretty much exactly what I was looking for :) I know not to ask how to get it working but knowing what you are shooting for helps tons!!! Now to dig deeper :D

I have learned tons these last two days.

So far today is the third day after connecting my HTPC for the first time to my 57S700 Hitachi RPTV.

I have a perfect desktop image of 920x500p. Direct from Powerstrip:

PowerStrip timing parameters:


Generic timing details for 920x500:

HFP=104 HSW=80 HBP=80 kHz=34 VFP=20 VSW=1 VBP=42 Hz=60

Linux modeline parameters:

"920x500" 39.996 920 1024 1104 1184 500 520 521 563 +hsync +vsync

and I use 1920x1080i for DVD playback and so far it's looking very good;


Generic timing details for 1920x1080:

HFP=169 HSW=56 HBP=295 kHz=34 VFP=2 VSW=5 VBP=38 Hz=30

interlace +hsync +vsync

So far I have learned (from Karnis-I am cut and pasting);

All 1080i/ 540p based timings (that are safe) have a scan rate that is exactly 33.75KHz, refresh rate is 59.94Hz(or 60) and vertical line total is 563 (this value must be exact! I just forget why...it's because if your vertical line total varies just a bit from this you will loose sync. Keep the progressive vertical line total at 563 (interlaced 1125). :) for all resolutions.


I have found this on karnis' very long thread,

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Yea I use 920x500 for desktop and 1184x666 to hit buttons when I cant at my normal desktop resolution. I use to use 1920x1080i for dvd playback but have opted for 1776x1000i for much less overscan. This of course is not a big issue with Zoomplayer or Theatertek as you can modify where the video is displayed. I guess I have been doing things from the beginning correct and will continue to do so. You are connected via the ATI HDTV component dongle correct? I have been using a DVI-D cable as I use to use the dongle but found much better quality with a direct connect with the DVI cable. Thanks to all for the replies. And if you are interested in the 720p timing (1184x666) just let me know and I'll post it. It's not great for clarity as scaling artifacts are shown but works just fine to hit the OK/Cancel when needed :p


BTW Drew888 what version of Catalyst are you using now? 4.10 still?
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If you don't want to mess around, the imagine graphics cards -- www.imaginegraphics.co.uk -- have many different 16:9 resolutions. But the cards are pricey, around $350-400. I have the older PowerVR card, and it works great!
I am connected via DVI and love the picture, very vivid!

I am using the 4.9. On their site ATI suggests upgrading to SP2 and I haven't yet so I opted for 4.9 not knowing what 4.10 might be like running without SP2.

Maybe it'll be fine on SP1, I dunno.
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