| AudioREVIEW's Forum Archives - Home Theater |
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|   Various questions, random thoughts, miscellaneous ramblings | topspeed
Nov 11, 2003 1:55 PM | | My Sony DVD changer is giving up the ghost or at the very least becoming increasingly schizophrenic during playback so I'm writing to Santa to bring me some new toys. Here's my questions for all you experts.
1) Is there a visual difference between Faroujda, Crystal, or Silicone Tech chips? If so, which is the one I should be aiming for? Why?
2) I also use the DVD player as my cd transport and was considering a universal player like the Denon 2900. Good idea or am I better off with a good dedicated cd/sacd player and separate dvd/dvd-a player? I'm not really into hi-rez per se but you never know. Better options?
3) Where can I find info describing the difference between 1080i, 480p, etc? Interlaced? Progressive? That is all latin to me. What should I be looking for?
4) Finally, I'll be replacing my tv at the same time. I was intrigued by the 60" Samsung DLP but read they haven't got a handle on the tech yet. My local shop swears that the best picture is still made not by plasma, lcd, or dlp, but good 'ol CRT and states the 40" XBR Wega has the best black level and definition. I really wanted something between 50-60" and refuse to go plasma. I currently have a 32" Hitachi Ultravision and am still impressed by the picture but I'm certainly no expert (as if that wasn't evident already!) Any opinions on this?
Sorry about all the questions guys/gals. While I can hold my own in audio, when it comes to video I'm about as bright as a small appliance bulb. Thank God for this place! I don't really want to spend more than $4-5k for both the source and video.
Thanks for your help. |
| Interlaced vs Progressive. | Smokey
Nov 11, 2003 2:27 PM | | Interlaced is basically showing you 30 full frame per second. It will show you 60 half frame (called fields which only consist of either even, or odd scan lines) in 1 second. It will show a field (1/60 of a second) with only even scan lines, and then it will complete the full frame by showing the odd scan lines. So every 1/30 of second, a full frame (with both even and odd scan lines) are shown.
Progressive is different in that it will show 60 full frame per second and it doesn't skip even or odd scan lines like interlace does. It will show both lines at one run every 1/60 of second.
The same concept apply either in regular or HD signal ;) |
| Interlaced vs Progressive. | topspeed
Nov 11, 2003 4:18 PM | | Thanks Smoke,
So does that mean that a 480p @ 60fps will appear just as good as a 1080i @ 30fps? Also, what is the highest resolution in progressive and is that limited by the source's processor, the TV, or the satellite/dvd signal? I'm sorry if these questions seem mundane but I've tried to get answers at the local Suckit City/Worst Buy to no avail. |
| Interlaced vs Progressive. | Monstrous Mike
Nov 12, 2003 9:44 AM | | <b>So does that mean that a 480p @ 60fps will appear just as good as a 1080i @ 30fps? </b>
In general, 1080i has over twice the resolution so it will give you a sharper picture. However, severe motion in the picture is better done by progressive scan so there may be an instance where the 480p might look better.
<b>Also, what is the highest resolution in progressive and is that limited by the source's processor, the TV, or the satellite/dvd signal? </b>
The highest resolution as per digital TV standards is 720p. There is talk about 1080p but I think that is still for the lab for awhile. You'll find that there a few TVs capable of 720p but they are not the average rear projection 60" ones from the mass market brands. The limiting factor is that 720p needs a very high scan rate. This requires more complex electronics. |
| Some minor corrections, Mike | woodman
Nov 12, 2003 12:21 PM | | b "In general, 1080i has over twice the resolution so it will give you a sharper picture. However, severe motion in the picture is better done by progressive scan so there may be an instance where the 480p might look better."
In this response, you're equating the number of scanning lines with "resolution". While the number of scan lines DOES equal and define
i vertical resolution,
it's actually the
i horizontal resolution
that is the major contributor to the "Hi-Def" images that we're calling HDTV. It's also the one parameter that can vary from one signal format to another AND from one video display device to another.
b "The highest resolution as per digital TV standards is 720p. There is talk about 1080p but I think that is still for the lab for awhile. You'll find that there a few TVs capable of 720p but they are not the average rear projection 60" ones from the mass market brands. The limiting factor is that 720p needs a very high scan rate. This requires more complex electronics."
The scan rate for conventional NTSC television that's been in use for the past 60 years has been 15,734. Now that we're moving into
i digital television,
we will be using higher scanning rates. The scanning rate for 720p is 43,200 scan lines per second. For 1080i it's 32,400. 1080p will require a scan rate of 64,800 - which is a bit too much for conventional CRTs to handle. There are now several models of LCoS-based display RPTVs from Toshiba on the market that natively display everything in 1080p format, but of course these displays do not "scan" lines as in a CRT, but activate the pixels in a different manner altogether.
Just a "heads-up" for you, Mike.
woodman |
| 1080i does require more bandwidth than 720p. | Smokey
Nov 12, 2003 12:57 PM | | Since 1080i have more pixel per scan lines (1920 pixels) than 720p (1280 pixels), then it require more bandwidth to carry 1080i, although 720p show more scan lines per second than 1080i.
Here is the mathematical breakdown:
Bandwidth 1080i=scan lines x pixel per scan lines (per second)
Bandwidth 1080i=32,400 x 1920=62 million pixels shown per second.
Bandwidth 720p=43,200 x 1280=55 million pixels shown per second.
Since one cycle can be used to represent two pixels, then 62 million pixels equal to 31 MHz bandwidth (1080i), while 55 million pixels equal to 27.5 MHz bandwidth (720p :) |
| Didja ever hear the expression ....... | woodman
Nov 12, 2003 2:40 PM | | ... "a little knowledge can be a dangerous thing"?
In this case, you've tripped over some totally inappropriate math.
Hear me now - and believe me later, Smokey-san:
THERE IS NO DIFFERENCE IN "BANDWIDTH" BETWEEN 720P AND 1080I WHATSOEVER.
Also:
BOTH FORMATS MUST FIT INTO A 6MHZ "BANDWIDTH" WHICH IS ALL THAT IS ALLOWED TO A TV BROADCASTER TO TRANSMIT WITHIN.
If your math was correct, then please tell me how a TV broadcaster could ever transmit a "Hi-Def" image within the 6MHz channel that is allotted to them by the FCC?
woodman
P.S. The answer to this enigma lies in the fact that a "data reduction" codec called MPEG2 is used to make the whole scheme viable. |
| That number holds true if signal is not compressed (analog). | Smokey
Nov 12, 2003 3:15 PM | | For analog HD video signal which is inputted to TV, the bandwidth numbers which I stated does hold true. But as you said for transmission purposes, Mpeg technology is used for "data reduction" since signal is digital. But once the digital signal is received and decoded to analog, the bandwidth is back up to where it was stated (at least theoretically :) |
| Allow me to say ....... SO WHAT?????????? | woodman
Nov 12, 2003 3:55 PM | | The number is totally, absolutely, irrevocably meaningless AND irrelevant!
As I've stated on numerous occasions at this board and elsewhere, there is no possible video image which would require ALL of the 2,073,600 pixels on the screen to be differently illuminated from those on either side of each. None - never - never, ever - cannot happen - period - end of conversation. Every video image - no matter how detailed and Hi-Def it may be, would never require such a scenario. So, as I already stated ... "theoretically" is actually meaningless and irrelevant. In the world of digital video (and audio), compression will ALWAYS be in play ... no reason why it wouldn't. The days of analog video and audio are definitely numbered - and dwindling!
woodman |
| Smokey, you are mixing two different concepts. | Monstrous Mike
Nov 13, 2003 6:13 AM | | You are confusing to concept of the amount of digital video information and its conversion to the compressed MPEG-2 video format with the scan rate of displaying that video on the TV itself.
As woodman has said, it is virtually physically impossible for an HDTV image (or any digital TV image) to have every pixel different in which case it would not compress. So by doing some mathematical probabilities, it is very rare for the HDTV signal not to be able to pass through a 6 mHz transmission medium.
The other parameter you mentioned is the scan rate. This has nothing to do with the transmission or the transmission bandwidth. It has to do with how capable the TV is when it needs to display the HDTV signal. As it happens, 720p requires the greatest scan rate and thus any HDTV with the capability of displaying 720p will be more expensive and will be more capable than an HDTV that can only play 1080i. |
| Did some more research... | topspeed
Nov 13, 2003 11:39 AM | | and noticed that Hitachi and Toshiba seem to be the highest rated RPTV's. They both seem to be using proprietary lens systems and who knows which is better. It would appear that DVI input for HD is the more accepted method, no? Unfortunately, it also seems one of them uses IEEE while the other uses DVI. Is this a big deal or are they both pretty easy to match with satellite boxes? Also, I couldn't even find a TV that had 720p. The best I could find was 560p (or thereabouts). Any recommendations? |
| Let me ask you a simple question. | Smokey
Nov 13, 2003 3:40 PM | | What would the bandwidth of analog component signal (especially the luminance "Y") that is coming out of HD decoder for a 1080i signal that is fed to TV? |
| re: Various questions, random thoughts, miscellaneous ramblings | woodman
Nov 11, 2003 3:18 PM | | Regarding the TV choice:
b "Finally, I'll be replacing my tv at the same time. I was intrigued by the 60" Samsung DLP but read they haven't got a handle on the tech yet. My local shop swears that the best picture is still made not by plasma, lcd, or dlp, but good 'ol CRT and states the 40" XBR Wega has the best black level and definition. I really wanted something between 50-60" and refuse to go plasma. I currently have a 32" Hitachi Ultravision and am still impressed by the picture but I'm certainly no expert (as if that wasn't evident already!) Any opinions on this?"
You bet yer bippy! Whatever you do, do
b not
listen to what your local shop is telling you - at least in regard to the 40" Sony beast that is. They are quite correct in that CRT-based displays DO offer the best black level and very likely the best "resolution" as well. But a 40" CRT is just a huge gamble, and not one that I'd ever consider myself. Should that tube fail (not common but definitely possible) you're left with a VERY expensive door-stop! Replacing the tube is NOT an option!
So, I'd suggest that you concentrate on CRT-based RPTVs from such companies as Toshiba or Hitachi. Pioneer, Mitsubishi, Sharp, or Panasonic could also be worth considering - depending on where you buy it and just how good the technical support (warranty) you can get from them.
I concur with those that have told you that DLP technology hasn't been around long enough to establish its long term reliability. Ditto plasma. Also, plasma displays - unless you spend a humongous amount of cash will NOT give you true Hi-Def images.
Hope this helps you
woodman |
| Thanks Woodman | topspeed
Nov 11, 2003 4:22 PM | | I heard about the recalls on Sony's RPTV's because of bleeding problems but didn't realize the quality issues included their CRT's. I'd love to get either a LCD or dlp simply because they are a helluva lot easier to move. However quality comes before back pain. What do you think of LCD technology. Is it any good? Can it do HD? |
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