Digital video?

Posted by: spiffnme

Digital video? - 10/15/03 05:36 PM

I'm not totally sure if I understand DVI...here's what I think it is.

Your DVD player would convert the digital data from the disc to 720p then it would send that digital signal to your digital tv. The signal would never undergo a digital to analog conversion. Where as most DVD players would need to take the digital data from the disc, convert it to analog, and send it via your component video cables to your TV. You know what...as I'm trying to explain how I understand it, I'm realizing I don't understand it. Anyone care to give me a bare bones "Digital Video for Dummies" explaination of 480p 480i 720p 1080i and 1080p? DVI vs Component?
Posted by: sushi

Re: Digital video? - 10/15/03 06:28 PM

Craig, you got it right regarding the DVI (DVI-D) versus Component connections. With the DVI-D connection, the video signal remains in the digital domain from start to finish, eliminating the possible degradation due to D/A and A/D conversions.

Regarding 480p, 480i, 720p, et al., the number designate the horizontal resolution or pixel counts. The "p" and "i" subscripts are for "progressive" and "interlaced," respectively. In the interlaced format, a half of the entire image content, consisting of odd-numbered horizontal scan lines only, is sent first, followed by another half of the image consisting of even-numbered scan lines sent 1/60 second later. These two image "fields" will make up one complete image "frame" every 1/30 second. In the progressive format, a complete image (frame) is simply sent every 1/30 second. The interlaced format is invented early in the history of TV broadcast, in order to prevent CRT screen flickers.

In this era of big-screen TVs, however, the problem of interlaced video format is the fact that the objects in the scene can move between the two consecutive fields (i.e., within 1/60 second), resulting in the nasty "combing" artifacts. This wasn't a big deal when the TV screen was small and the picture quality was compromised anyway by other factors such as the artifacts associated with the analog over-the-air broadcasting.

The "native" format of DVD media is 480i. When a 24-frame-per-second film material is converted onto DVD, they perform what's called 2:3 pulldown -- the first film frame is copied into three consecutive 60-fps interlaced DVD fields, the second film frame into two following DVD fields, the third film frame into the next three, etc... That way, two 24-fps film image frames are converted to five 60-fps interlaced DVD fields in order to preserve the final frame rate (you need a bit of math to understand this: 24/2 = 60/(2+3) ).

All fixed-pixel digital displays (plasmas, DLPs, LCDs...) are inherently progressive. In order to display the 480i DVD image on a big-screen TV with a good image quality, you need to "deinterlace" the 480i signal to the 480p, 720p, or 1080p progressive format. A good deinterlacer chip will automatically detect the 2:3 pulldown sequences of film-based materials, and reverse the pulldown process to generate the 480p video sequence in which the original film frames are perfectly restored. Deinterlacing the video-based materials is MUCH more complicated, because you have to intelligently interpolate between the consecutive 480i fields and compensate for the motion artifacts (combing). The Faroudja DCDi and other reputable deinterlacers are extremely good at doing these tricks, in addition to correctly detect the 2:3 pulldown sequences.

The most common HDTV format (either satellite, cable, or over-the-air) in the US is 1080i, followed by 720p as a distant second. SDTV broadcast is always 480i, same as DVD.
Posted by: spiffnme

Re: Digital video? - 10/15/03 06:42 PM

Cool...I understood most of that before. I guess I'm not as dumb as I thought.

I guess my next question is what's compatible with what. If I get a DVD player, I'm going to want a DVI output for the best possible PQ, right? BUT, I'll also need a TV that has DVI inputs as well, no?

What about HD-DVD and 1080p? I know the new LCOS TV's are suppossedly able to handle 1080p.


Posted by: Zarak

Re: Digital video? - 10/15/03 06:45 PM

So 1080P would be the best you can get? (does anything do this?) Is there currently anything above 1080? I'm trying to keep up with all of this stuff so I have some idea of what I'm looking at as far as that part goes when it comes time to get a new TV....oooppps, sorry Sushi, I mean a FP (only if I ever decide to finish the basement)
Posted by: Semi_On

Re: Digital video? - 10/15/03 06:50 PM

In reply to:

I guess my next question is what's compatible with what. If I get a DVD player, I'm going to want a DVI output for the best possible PQ, right? BUT, I'll also need a TV that has DVI inputs as well, no?




In theory, yes.

In reply to:


What about HD-DVD and 1080p? I know the new LCOS TV's are suppossedly able to handle 1080p.




HD-DVD hasn't really been defined yet so there's nothing but speculation at this point.
Posted by: sushi

Re: Digital video? - 10/15/03 07:10 PM

Yes, Craig, for the best possible image quality, you want a DVD player and a display device both equipped with a DVI-D port. I believe that many latest big-screen TVs and plasmas, as well as most front projectors, are DVI-savvy. Same for the latest satellite/OTA HDTV tuners.

On the player side, however, only a few (including a Samsung unit and the Bravo D1, made by the obscure V, Inc.) are available at this time. One political/regulatory obstacle that's been hindering the production of DVI-savvy players is the sticky issue of digital copyrights.

In part for the same reasons, very few, if any, AV receivers are equipped with a DVI-video selector at this time. The new flagship ES receiver from Sony (costing ~$5K) is the ONLY one that I am aware is capable of DVI switching. The current state of the market really sucks in these regards...

The new LCoS TVs are by no means unique in the 1080p capability. Quite a few front projectors including my own, as well as some latest RPTVs and plasmas, are capable of handing the 1080i and 1080p signals (although there is no use, unless you set up an HTPC).

I am not very familiar with HD-DVD (yet), and wish somebody else to fill in here. But I believe that the proposed HD-DVD media format is capable of 720p, 1080i and 1080p.
Posted by: sushi

Re: Digital video? - 10/15/03 07:29 PM

Zarak, I don't think anybody is producing in 1080p. So the 720p and 1080i are the best you can get at this time. I believe that in order to do 1080p the existing infrastructure has to be updated with respect to bandwidth. So I don't think it's coming to town very soon (read, not for many years -- think about how long it's been taking for them to get to 1080i).
Posted by: mhorgel

Re: Digital video? - 10/15/03 07:35 PM

What I don't get is why I can get 1080i and 720p via a component cable from my digital cable box, but I need a DVI to get the same resolution from a DVD. Are there going to be any DVD players that outbut 720p or 1080i via component cables? My TV doesn't have DVI connections.

Mark
Posted by: spiffnme

Re: Digital video? - 10/15/03 07:48 PM

The new Denon DVD-5900 has DVI out.
Posted by: twopecker

Re: Digital video? - 10/15/03 07:50 PM

I was happy to see this thread here, I was about to start something very similar.

I am thinking of putting together an HTPC to mainly use as a dvd player. I have a Sanyo Z1 projetor, with a native resolution of 964x544. the Z1 does not have a DVI connector, just a vga.

Now I am an uber computer nerd, but havent played much in the HTPC arena, so have a few questions. Its my understanding that I can force my video card to output 964x544, to match the native resolution of my projector. Now will this look any better than say an average everyday progressive dvd player? I am using a pioneer non-progressive right now, and I can either replace this w/ a progressive unit, or go w/ an HTPC.

Any input on this would be appreciated....was it saturn who has one hooked up to his X1?
Posted by: twopecker

Re: Digital video? - 10/15/03 07:55 PM

I guess the projector can use a max resolution of 1024x768 as well. Now if I put the projector in this resolution, would I actually take full use of the 768 lines, or would a dvd only play at 480?

HELP!!!!
Posted by: Semi_On

Re: Digital video? - 10/15/03 11:30 PM

In reply to:

What I don't get is why I can get 1080i and 720p via a component cable from my digital cable box, but I need a DVI to get the same resolution from a DVD.




You'll never get that resolution from DVD. The format doesn't support it.

In reply to:

Are there going to be any DVD players that outbut 720p or 1080i via component cables?




The DVD standard does not include resolutions above 640x480. You will never get better than that from a DVD. You may get an HTPC or DVD player that uses a scaler to output in that format but the information itself is still 640x480.

In reply to:

My TV doesn't have DVI connections.




For DVD, unless your TV is inherently digital (plasma, LCD, etc), I don't believe you'll see a difference. At that point, the only advantage would be transporting the information digitally so that the end product has a pure source. At 480p, I doubt enough degradation can occur in component to make a difference.
Posted by: Saturn

Re: Digital video? - 10/16/03 12:25 AM

Hey twopecker;

I believe you can sync a HTPC to your Z1 by using Powerstrip. Unfortunately I do not know those settings but it should be easily found on avsforum. Matching your output to source will present a native signal to your projector and supposedly give the best picture possible. Some people say that this may not look any better than the average progressive DVD player which is 720x480p....true if you have your projector set to Native aspect ratio. But since your HTPC is set to 964x544 like your projector the scaling capabilities of your video card will scale up your 720x480p to 964x544. There will be interpolation to smooth out jaggies and such to give a better looking (possibly softer) picture. Some other people use really great Scalers such a DSCALER (Semi knows about this stuff) But for me the built in driver of my video card and my NVIDIA NVDVD software scales it nice and clean. So for my X1 the Powerstrip settings are set to sync with the X1 and present the picture in its native format. There are other advocates that actually upscales the HTPC resolution to like 1024x576 or even 1280x720 and then the projector downscales them to its native res. And they claim to get even a better picture because the scaler on the HTPC cleans it up and gives a nice smooth picture at high resolutions and then the projector downscales the picture to its native resolution so by then the picture is free of jaggies and it looks much smoother and very slightly softer but the overall picture quality is fantastic. I have not yet tried this out yet but i was going to try this actually soon. Someone on AVSFORUM gave me the codes for Powerstrip to set it up properly to sync with the projector at those higher resolutions.
In my opinion yes the HTPC gives the best picture...but at a price of tweaking, upgrades, hours of setup, making it WAF friendly such as programming learnig remote with keyboard keystrokes to control the HTPC. A Progressive DVD does also gives a nice picture with less hassles. I opted with a HTPC to tweak out every last detail. But once you dialed it in correctly your done.

Saturn
if you havent seen already...here are pics of my setup with pics taken of the X1 in action.
http://www.spacelofts.com/x1/

Posted by: sushi

Re: Digital video? - 10/16/03 08:06 AM

In reply to:

For DVD, unless your TV is inherently digital (plasma, LCD, etc), I don't believe you'll see a difference. At that point, the only advantage would be transporting the information digitally so that the end product has a pure source. At 480p, I doubt enough degradation can occur in component to make a difference.



Today's TVs and RPTVs often process video signals digitally even though the final imaging device is analog (CRT). So there is theoretical and practical advantage in feeding them digitally.

Also, many people, at the very least those with front projectors, seem to attest that DVI-D connection does improve the DVD picture quality over component connection, often quite dramatically (although I haven't yet tried DVI myself).
Posted by: alan

Re: Digital video? - 10/16/03 09:28 AM

Hi sushi,

We are getting into the realm of visible nuances here. In comparisons, there is little or no difference in the visible clarity and sharpness of a 720p vs. 1080i picture. I haven't seen a DVI picture output comparison, although a former colleague, David Ranada at Sound&Vision, raves about it.

Would you agree, sushi, re the former?
Posted by: sushi

Re: Digital video? - 10/30/03 05:45 PM

Alan,

To be honest, I've never watched a native 720p material yet. So I cannot comment on that one.