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Discussion Starter · #1 ·
Greetings. The following post was originally made to the high-end projector forum, but I have since discovered this more relevant forum, so I've made some modifications to the original text and am posting it here.


I often see people mention "Home Theater PC" systems. HTPC. I have done some searches on this. Naturally, such systems come in all flavors. Some are put together by Digital Connection. A lot are homemade. It is my understanding that a HTPC solution enables the (currently) best possible video from DVDs.


I know there are FAQs aplenty on this subject, but what I'm after is straightforward and the answer doesn't seem to be all that easy to find, particularly in light of the apparent fact that most of the information / accepted knowledge on this subject is a few months out of date.


We all know how a stand alone DVD player functions. You eject the tray, plunk a DVD in, close the tray. Screen shows nothing up until this point, or perhaps the DVD manufacturer's logo. Certainly not a desktop with a mouse pointer. Once the DVD is acknowledged, it automatically starts playing, typically bringing up the menu. Full-screen, of course. Again, no mouse pointer. You do everything with a nice remote control. The audio does not stutter. Fast forwards don't chug (much). Rewinds and chapter searches and other things don't cause the unit to choke. The hardware does not blue-screen. Ejecting the disc does not cause errors; it simply brings back the manufacturer's logo, or the black screen.


This is solidity.


What is the software / hardware combination which can accomplish this?


And that's not all, of course. Things get a little more complicated. Let's cover the film refresh-rate aspect. 24fps, right? If you want the PC to display that, I've been told you need to select 48Hz, or perhaps 96Hz, and feed that to the projector. Fine, I'm sure there are hardware configurations which can handle 720x480 (or even PowerStripped 1365x1024 or whatever) at 96Hz. What I'm concerned about is what happens when you play a DVD that has non-film video. 30fps stuff. Is there a way to get the software to automatically detect this and switch over to 60Hz? Even if there is, wouldn't this cause a brief glitch? Actually, I've read that it can really confuse media-playing software. What's the solution?


(Please note: Yes, I know all about 3:2 pulldown; the point here is to skip that PQ-compromising process.)


Maybe the solution is to play everything at 120Hz (I'm thinking not). I'm not technically inclined enough to know for certain, but it seems to me that there must be limits to how well a projector is going to handle ultra-high refresh rates and oddball resolutions. It likely depends on the projector, so let's say I'm dealing with the JVC G150CL.


It's generally accepted that no projector's internal scaler (not even that of the ultra-expensive G150CL) does anywhere near as good a job as what you get with any normal PC media player. It stands to reason that the best possible video solution for ALL varieties of video - not just DVDs, but gaming consoles, DirecTV, VCRs, you name it - would be to find a way to input the video to one's HTPC, convert and scale it to the projector's full-panel resolution (ie, 1365x1024 progressive), and then pipe the results to the projector, preferably via its DVI input. This would (far as I know; correct me if I'm mistaken) even be better than using a video processor like the Faroudja NRS+, which costs thousands of dollars. (Hey, it doesn't have DVI-out, so it's not even a contender.)


It doesn't seem as though anybody has really nailed down the ultimate, fully working PC setup for this concept. I've seen solutions for DVD, of course. Easy. I've seen solutions for NTSC and HDTV, which unfortunately all seem to be based on hardware which draws video directly to the desktop, with all of the compromises that implies (such as aspect ratio issues). Haven't heard of a DirecTV solution, except the obvious idea of piping it in as NTSC. So, input solutions, numerous and confounding. Scaling solutions, unknown.


Output solutions, also not very clear. I don't even know if there IS a way to output a DVI signal from a PC.


That's about the extent of it. I've read threads which talk about PowerStrip 3.0 and Theater Tek and things like that, but they are all months old and the discussions tended to focus on wish-lists which I strongly suspect have had time to be fulfilled (things like resolution-switching to make D-ILA + Panamorph a more fulfilling combination). Maybe it's a good time to get all the pertinent facts laid down in one up to date thread.
 

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Just feeling your pain here, Colmino (and bumping your inquiry back into the light).

As a newbie, I'm faced with similar decisions, and it does seem like there are no perfect set-ups, no all-in-one(der) solutions without drawbacks. You could pack every PCI slot in your box, trying to cover all the bases, only to end up with driver conflicts :mad: .

I'm amazed that nobody seems to make a capture card that can bring in satellite HDTV!!! Is there any way to feed an HTPC from an RCA DTC-100???

I dunno....anyway, good luck in your search for the grail.


Shaun
 

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Quote:
Originally posted by Colmino
And that's not all, of course. Things get a little more complicated. Let's cover the film refresh-rate aspect. 24fps, right? If you want the PC to display that, I've been told you need to select 48Hz, or perhaps 96Hz, and feed that to the projector. Fine, I'm sure there are hardware configurations which can handle 720x480 (or even PowerStripped 1365x1024 or whatever) at 96Hz. What I'm concerned about is what happens when you play a DVD that has non-film video. 30fps stuff. Is there a way to get the software to automatically detect this and switch over to 60Hz? Even if there is, wouldn't this cause a brief glitch? Actually, I've read that it can really confuse media-playing software. What's the solution?


(Please note: Yes, I know all about 3:2 pulldown; the point here is to skip that PQ-compromising process.)


Maybe the solution is to play everything at 120Hz (I'm thinking not). I'm not technically inclined enough to know for certain, but it seems to me that there must be limits to how well a projector is going to handle ultra-high refresh rates and oddball resolutions. It likely depends on the projector, so let's say I'm dealing with the JVC G150CL.
I feel your pain, too. We're all dealing with the effects of the video/broadcast industry in a transition period combined with the convergence of video/entertainment with computers. Consumer electronics are getting more like high-end products, while computers are getting more like consumer electronics. The whole thing's kind of a mess, really when you think about all this stuff. Resolutions, refresh rates, interlaced vs. progressive, HD vs. SD, different types of connectors, ad naseum. Maybe in 10 years, we'll have DVD players, recorders, and displays that are all perfectly happy displaying a HD-DVD or whatever in 1080i (or P) and we won't have to worry about all this crap. Until then, I'm going to just play with and enjoy what I can, and try to make smart purchasing decisions (no 50" plasma displays or D-VHS recorders for me, yet!)


One note: I didn't quite get your comment about skipping the 3:2 pulldown process to improve PQ. We can skip 3:2 pulldown only when we have 24fps progressive displays *and a supporting playback medium.* Any NTSC DVD that contains material shot on film is also going to have 3:2 pulldown. To clarify, progressive-scan DVD players or HTPC's outputting a progressive-scan image, are *removing* the 3:2 pulldown, so there isn't really any way of "skipping" that process.
 

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3:2 pulldown does not sacrifice quality. It reconstructs the picture perfectly. The issue some people run into is that there is judder, especially in pans. This is something that is a larger problem with film and its low 24fps.


Ever seen Snake Eyes with Nicolas Cage where they do that 360 degree pan around the casino? I heard people groaning all around me in the theater.


Most people won't notice any problems with 3:2 pulldown, but you can do a multiple, as you said, to eliminate it. Problem is that most digital projectors work best at 60hz (or 75 for D-ILA I believe.)


Whatever your feelings upon this, there are TONS out there enjoying film based content on their HTPCs.
 

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Discussion Starter · #6 ·
> 3:2 pulldown does not sacrifice quality. It reconstructs the picture perfectly. The issue some people run into is that there is judder, especially in pans. This is something that is a larger problem with film and its low 24fps.


Yes, exactly. What I seem to recall reading, either here or elsewhere, was that some DVD playback software was capable of converting DVD-based film content into 24fps progressive video at DVD resolution (in realtime, of course), which would make it possible to eliminate the judder completely, provided it was displayed at multiple, as you say.


There seem to be conflicting perceptions of what the reality is on this subject. One person on another forum insists that 3:2 is the only way a DVD will ever be seen (and he has a unique method for making his point), but I am inclined to suspect that converting 3:2 DVD content into 24fps progressive video is a brainless process with obvious advantages, it's been done already. Especially as I'm not the only person who has specifically been seeking ways to switch to 48Hz on the fly.


> Problem is that most digital projectors work best at 60hz (or 75 for D-ILA I believe.)


Here's where I'm totally lost. I can't for the life of me begin to imagine why 75Hz is D-ILA's "sweet spot", nor how that is remotely compatible with standard 60Hz video. But then it's a completely different subject. :)
 

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"I'm amazed that nobody seems to make a capture card that can bring in satellite HDTV!!! Is there any way to feed an HTPC from an RCA DTC-100???"


Nope. Well, at least not at roughly consumer prces. Uncompressed HDTV is a lot of information. It will not pass uncompressed over the PCI bus that most of us have.
 

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Quote:
Originally posted by Namlemez
3:2 pulldown does not sacrifice quality. It reconstructs the picture perfectly. The issue some people run into is that there is judder, especially in pans. This is something that is a larger problem with film and its low 24fps.


Ever seen Snake Eyes with Nicolas Cage where they do that 360 degree pan around the casino? I heard people groaning all around me in the theater.


Most people won't notice any problems with 3:2 pulldown, but you can do a multiple, as you said, to eliminate it. Problem is that most digital projectors work best at 60hz (or 75 for D-ILA I believe.)


Whatever your feelings upon this, there are TONS out there enjoying film based content on their HTPCs.
I think one problem in discussing this issue is nomenclature. 3/2 pulldown does not sacrifice quality *OR* reconstruct the picture in any way. 3/2 pulldown is a post-production term - it's a pattern or sequencing of the film's frames to video's frames/fields during the film-to-video transfer.


A progressive-scan DVD player or computer software DVD player playing something that was shot on film *REMOVES* the 3/2 pulldown introduced in the film-video transfer, and reconstructs 24 progressive-scan frames per second from the DVD's 29.97 interlaced frames per second.


Further, you don't see judder in a theater - there isn't any. Judder happens because of mismatch in frame rates, so you'll only see it in a film to video or computer situation (how do you fit those 24 progressive frames on a display that's refreshing 60 times a second). Obviously, the timing doesn't work right, and some frames are going to spend more time on the screen than others - there's judder. If everything's working correctly, a computer should technically be able to playback a film-sourced DVD without any judder at all - that's where refresh rate comes in. If the display's refresh is set to a multiple of the film rate, then there's no frame rate mismatch, and judder shouldn't occur.


As for matching monitor refresh to DVD playback, I haven't played around with it, but from what folks here are saying, it works beautifully. A big question I have, though - is how are the two correlated? With all the stuff going in the computer, are the monitor's refresh and the DVD player application perfectly synchronized? Hmmm....


Can't wait to try it myself this fall when the HT is finished.


SC
 

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Discussion Starter · #9 ·
> If the display's refresh is set to a multiple of the film rate, then there's no frame rate mismatch, and judder shouldn't occur.

> As for matching monitor refresh to DVD playback, I haven't played around with it, but from what folks here are saying, it works beautifully.


This is precisely what I'm attempting to accomplish. More specifically, I'm trying to output the results (24fps film synced to 48Hz refresh rate), via DVI, to the projector.


My understanding is that PowerStrip will let me do this, at my desired resolution (in this case, 1368x1024, for a pixel-perfect match with the projector's panel resolution). Still haven't nailed down how I'm going to scale the image (720x480 for DVD, some other 4:3 resolution for NTSC input) to full-screen 1368x1024.


Probably the biggest remaining hurdle is the fact that not all DVD video plays at 24fps, and basically zero of the NTSC-input video will be 24fps. Instead, I believe it'll generally be 60Hz. This means that refresh rate changes will be necessitated, probably on a case-by-case basis. Meaning when it's time to play Xbox, the HTPC needs to recogzine 60Hz video and adjust the refresh rate accordingly.
 

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Colmino,


Yep, you're right. I know what you're saying about wanting to somehow sense a certain kind of material and change the refresh rate on the fly. I can't imagine how that would be possible right now. At the moment I think it's going to have to be a manual thing. Watch a film DVD, switch to 48hz - play Xbox, switch to 60 hertz. I can't really think of any easier or better way to do it at the moment.


I guess we'll be doing some experimenting! Good luck and keep us posted if find any tricks along these lines - I'll do the same.


SC
 

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Does this work? My understanding from other threads was the PowerStrip CAN NOT control timing on a DVI interface. I'm driving a Pioneer 503CMX via an ATI 7500 using DVI. The only refresh rate available to me is 60Hz.
 
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