Will HTPC improve image quality?

H

HTnovice

Guest
Hi guys,

Have just purchased my first projector, the Sanyo VLP-Z2, and am using a PAL Xbox to play DVDs (with component cables).

I have noticed a kind of artifacting effect when playing DVDs. When I use the Z2's screensaver mode, it's crystal clear and I can actually appreciate how high the resolution is. But when I play DVDs, it looks low resolution. I've found that slightly blurring the image helps cover up some of the artefacts.
Shots from a long range, such as cityscapes, tend to look most pixellated, and bright shots are more prone to it than dark shots.
It's the same thing you see on computers when playing very compressed movies - could this be because I'm playing my DVDs from a PAL Xbox ? It's not so bad that I'm not loving watching movies, but I'd like to know if there's a way to stop it.

Would building a dedicated HTPC solve this problem, or is this just a limitation of the compression inherent to DVDs? I'd rather not spend a day building a HTPC only to find that image quality isn't improved.
 

Pulsar

Well-known Member
HTnovice,

I will almost guarantee that a correctly setup HTPC will blow your XBox away for DVD playback. Just make sure that 1:1 pixel mapping is possible for the Z2 (sure it is) and then build the PC. There is lots of useful info on here, but just make sure you get a Radeon graphics card with DVI output.

Post here if you have any questions, and I will do my best to answer them.

Cheers

Rob
 

KraGorn

Novice Member
Originally posted by Spacecat
build a radeon based HTPC properly and it will blow away any DVD player or Xbox!!
Um .. it may "blow away" an X-Box, it'll not do that to a decent DVI-equipped DVD player, Component player yes, DVI no. :)

It'll be no worse and at times maybe a tad better that say a Bravo, Momitsu or such but not by much .. I have a V880 and a 9600-based TT-toting HTPC feeding my Z2 and the V880 is no worse, while my Pioneer 868 would definitely be superior on the Z2 if it could drive it at 720P ... on my Sharp Z200E the HTPC doesn't produce as sharp and detailed an image as the 868.
 

The Nightfly

Active Member
KraGorn,

What output resolution on the 868 are you using to send to the Sharp ?

That's quite a coup for the 868 if it looks better than the 1:1 pixel mapped output from the HTPC.

Allan
 
H

HTnovice

Guest
Thanks for the info guys - I'm going to build a HTPC. I've already got a Shuttle SB65G2 case, a 2.4GHz Pentium 4 and 512MB of DDR400. What video card should I use - the cheaper the better? My Z2 is capable of 720p and 1080i - will the HTPC be able to output this? I'll try out the case's onboard sound to see if it's ok, although I've got a spare Audigy 2 ZX that I could probably use if it's not.
I'll get building this week, and then find out how to map pixels 1:1 with my projector. Thanks for the info guys.
 

KraGorn

Novice Member
Originally posted by Allan Probin
What output resolution on the 868 are you using to send to the Sharp ?

That's quite a coup for the 868 if it looks better than the 1:1 pixel mapped output from the HTPC.
1280x720 and letting the Sharp down-scale which it does of course far cleaner than up-scaling. From what little experimentation I've done I think the increased PQ is coming from the superior MPEG decoding in the Pio over that of the Sonic/Radeon partnership (I'm never sure what's done in software and what in the graphics card).

I'm not saying the Pio's way better than the PC, just that unlike the V880 I used in the past with the Z2 which was on a par with the PC but no better, the 868 definitely improves on detail .. though for what reason, decoder/noise-reducer/calibration I wouldn't like to say.

Since I'm scrapping the HTPC, a decision which pre-dates the 868/Z200, I'm not going to be trying to twiddle it any more, in the end I've a program source definitely not inferior to it and that's all I need really.
 

GrahamC

Novice Member
Radeon 9600 based card will do the job for you. Also the xbox will play your DVDs but is a compromise in all areas, a htpc willl shame the thing.
 
H

HTnovice

Guest
If I do build it with a 9600 PRO, will I be able to output in 720P or 1080I, in PAL? Also, can I whack a HDTV card in the box and use it as a HDTV box as well?
 
H

HTnovice

Guest
Actually, scratch that last one. I've got a GeForce FX 5700 lying around at work - reckon that'll do the job?
 

KraGorn

Novice Member
Two potential things to consider with the FX:

1) Radeons by and large give better picture quality due to their on-board MPEG decoding support, certainly that was my experience with earlier FXs, no idea about the 5700.

2) If it's got a fan it'll be noisy, some FXs are deafening, again no idea about the 5700.

Also you don't want a Pro Radeon for HTPC, again a noisy fan buys you nothing in terms of performance you need to play DVDs.
 

The Nightfly

Active Member
KraGorn,

Thats really interesting about the Pioneer. Does it have any other resolutions up its sleeve ?

You must be scaling the signal twice: once in the Pioneer to get it to 1280x720 and then again in the Sharp to bring it down to 1024x576. And considering PAL material starts at 576 anyway that seems kind of wasteful. Does the Pioneer have an unscaled output, i.e 720x480 (NTSC) or 720x576 (PAL) ? That way you could do the scaling once-only in the projector.

If this was possible, PAL material especially should look very very good as no scaling would be required at all, anywhere in the chain, either in the Pioneer or the Sharp, for the vertical resolution.

Allan
 

keyser

Standard Member
I´m gonna build a HCPC, should I buy the 9600SE, is that about the best I can get without spending lots of cash?

What about the 9800 all in wonder?

Are any analog TV tuner cards better than others? Is it no problem to have PIP, and if I have two displays, is it possible to do one thing on one display but another on the other. Say watch TV on the projector, but play a game on the monitor?
 

KraGorn

Novice Member
Yes, the Pioneer has native 720x NTSC and PAL, but since the projector is native 1024x576 then 720x576 would still be scaled by the projector .. by upscaling beyond the projector's resolution I'm letting the projector down-scale, which in my experience introduces far less/negligible PQ degradation, rather than having it massage 720x576 into 1024x576 which would involve severe contortions .. the scaler in the 868 is far more up to that than the Z200.

I have to say I've not spent much time experimenting with the 868's scaler .. it also does 1920x1080i which at present doesn't seem of much interest .. and I've returned the Z2 for warranty repair/replacement so I can't compare the 1280x720 mode of the 868 with the PC on a non-scaling projector. I bought the 868 with an eye to getting a 1280x720 panel sometime in the not too distant future.

Sadly it's a bit fiddly to switch between output resolutions so doing A/B comparisons is a bit hard as one easily forgets the subtleties .. not a criticism of the 868, it's not something ordinarily one would want to do every few seconds .. whereas switching between PC and DVD only takes a couple of seconds and doesn't involve menu-hopping.
 

MikeTV

Well-known Member
I'm no expert, but isn't there an HDTV output capability for the Xbox? Would an HTPC still "blow away" an xbox outputting HDTV resolutions? Does it work for DVD playback?
 

KraGorn

Novice Member
Originally posted by Allan Probin
You must be scaling the signal twice: once in the Pioneer to get it to 1280x720 and then again in the Sharp to bring it down to 1024x576. And considering PAL material starts at 576 anyway that seems kind of wasteful. Does the Pioneer have an unscaled output, i.e 720x480 (NTSC) or 720x576 (PAL) ? That way you could do the scaling once-only in the projector.
Actually, after posting my first reply I've been thinking .. what I don't know is how an anamorphic DVD is output, ie. what the resolution is coming out of the DVD decoder ... is it still 720x576 or has it been already scaled to 1024x576?

Id it's the latter then your point is completely correct and 1:1 mapping is achieved without scaling.

Wonder how I find out?
 

KraGorn

Novice Member
Originally posted by MikeTV
I'm no expert, but isn't there an HDTV output capability for the Xbox? Would an HTPC still "blow away" an xbox outputting HDTV resolutions? Does it work for DVD playback?
Resolution per se isn't really the main point I don't think .. unless I'm hopelessly confused. :)

Unless the source material is the same resolution as the display device then somewhere scaling will take place, unless the source material is non-interlaced then de-interlacing will take place (except for CRTs). If both conditions are satsified then 1:1 mapping of a progressive signal is achieved and maximum quality is obtained.

Feeding a DVD to a 1280x720 'HDTV' panel involved both processes, it has to as the DVD is 720x576 (PAL) or 720x480 (NTSC) interlaced. Thus, the issue is which piece of equipment does de-interlacing and/or scaling the best.

Finally of course there's the question of DVD decoding, not all MPEG decoders are equal, maybe the X-Box is good, maybe a 'normal' PC is better (though of course an X-Box IS a PC for all intents and purposes, abeit with inferior graphics in some respects) maybe, as in the case of my Pio8686 the DVD player is at least as good.
 
H

HTnovice

Guest
Update:

I haven't built my HTPC yet, but I did hook up my girlfriend's cheap DVD player. Lo and behold this thing supported 575P, and the picture quality was simply amazing compared to the Xbox. Considering I can pick up the same DVD player for AU$99, I'm not sure whether to simply buy one of these or build a theatre PC. I've already got most of the components for a HTPC, but don't know if it's worth the hassles...
 

KraGorn

Novice Member
HTPC's can be relatively hassle-free if you use some sort of front-end like MyHTPC, however I frankly prefer a normal DVD player for sheer convenience.

However, some things to consider:

1) Using software an HTPC can allow you to play DVDs and remove those annoying 'User Operation Prohibitions' like skipping copyright warning [email protected], ads, trailers etc. which Hollywood try to force you to watch.

2) You can rip DVDs to hard disk and play them from there, meaning you don't have to ferret the DVD out from behind the chair where it fell to last time. :D

3) You can watch other disk-based material like the *cough* illegal HDTV copies *cough* which need Media Player 9.

So, an HTPC does give you more than just good PQ if these facilities are important to you.
 

MikeTV

Well-known Member
I haven't built my HTPC yet, but I did hook up my girlfriend's cheap DVD player. Lo and behold this thing supported 575P, and the picture quality was simply amazing compared to the Xbox.
I think this is the crux. The player is progressive, and not PAL interlaced (although I fully agree with all KraGorn's advice on scaling). However, if you used the HDTV capability of the xbox, it would be noticebly better than the xbox via scart (pal interlaced), and the differences between the xbox and a progressive player, may then be neglible.

My understanding is that dvd players will output 720x576p, even for widescreen. So I don't think you can completely avoid scaling, because the projector will be scaling to 1024 (and dvd's are encoded at 720), even when using a progressive dvd player. But at least it is only in the horizontal direction.

Were it me, I think I might be inclined to try the xbox hdtv option, because then you'd get hdtv for games too. And you can probably hack the xbox to be a media player. I'm not sure how much the hdtv adaptors cost though. And the projector will be scaling, as KraGorn says. However scaling from 540p to 576p probably isn't noticeable - the projector may just use 540 lines, without scaling the vertical at all (but who knows?). In the horizontal direction, perhaps it just uses 960 pixels. In this way, it would be unlikely to introduce scaling artefacts (this is all just speculation).

I know someone who is using an xbox in this way, and is very happy with the results, using a 800x600 dlp projector (but all things are not equal). However, the standalone progressive player would probably give the best results, with the hdtv xbox a close second, and an xbox via interlaced a poor third, I'd imagine.
 

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