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Discussion Starter · #1 ·
Hi. I posted this one as a part of my reply in another thread, but I thought my question is valid enough that I should post it as a new thread and open it to get a more broader feedback.


Please keep in mind that the LS110/Cinema 12SF pj and Panasonic RP-56 DVD player BOTH have the Faroudja chip built in.

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Now, let me throw something at you that I've been pondering for awhile. The Marantz DLP has 27(!) Faroudja chips working inside it that deinterlaces the picture and gives it that "smooth, velvety consistency." I'm wondering if both the Faroudja's in the 12SF AND the Panny RP-56 are working SIMULTANEOUSLY just like the Marantz to give that nice picture I was talking about above (when I keep the progressive mode "on" in the DVD player). Because I know whatever signal you feed into the 12SF, it will automatically be deinterlaced.


So....if you run the DVD player in interlaced mode, the pj's Faroudja is doing the deinterlacing (dim, muddy picture if brightness/contrast is not tweaked on the Panny). But if you run the Panny itself in "progressive" mode (bright, clear, crisp picture), does that mean both the DVD player AND the pj is working to deinterlace the picture?!?! I have NO idea. All I know is the picture looks FANTASTIC! I just thought it would be working the same way as the Marantz in this case.


--> Consequently, when I was shopping for a progressive DVD player, I performed a shootout between the Panasonic RP-56 vs. Sony N7000 (?). Guess what?! Both gave the exact same picture results as mentioned above when I ran comparisons between progressive and interlaced modes with the 12SF projector. Something's going on here that I really don't have the full grasp of.
 

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The picture can't be deinterlaced twice...think about it. It simply means that the DVD player deinterlaces better. All the projector does then is scale the picture.


I'm not so sure how the Faroudja chips work. If they can be flag-based, the deinterlacing in the DVD player would be much easier than doing it externally with a raw video signal.
 

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Joel,


The Marantz has 3 Faroudja chips, I believe. Only two of these matter to the LS110 when playing anamorphic DVD as the third chip is for scaling. Since the LS110 is 848x480 native, the scaler is not needed for DVD.


The other chips are for NTSC decoding and de-interlacing. These should be the same that the LS110 has.


I can't explain why the the interlaced vs. progressive looked so different. I expect that the 12SF was an early model. I know there have been several different firmware updates. I haven't seen and RP-56 paired up with a LS110.


-phil
 

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I'll try to answer the question without delving too deep into the technological details. However I am handicapped by an EE degree, so be kind. Part of the explanation involves talking about how TV sets have worked ever since vacuum tubes were new technology, but I'll keep it as light as possible by omitting a lot of detail.


The data on the DVD is actually stored as two "frames" which are 240 lines, with each line being 702 pixels wide. (The numbers are for NTSC television in the USA, the numbers change for other TV systems in other countries, but the principles don't.) Every other frame is "Even" (containing image data from lines 2,4,6,...,480) and between those are the "Odd" frames (containing image data from lines 1,3,5,...479).


In a normal TV broadcast, these frames are broadcast alternately and the "persistence" of the phosphors on the front of the CRT fools the eye into thinking the two overlapping frames are one image with a higher 480 lines of vertical resolution. This is called an "interlaced" signal, and the interlacing technique came about to allow relatively high resolution images from the inexpensive receiving tubes of the 1940's, on displays which were a very large vacuum tube called a CRT (Cathode Ray Tube). The maximum frequency used is the horizontal sweep frequency of 15.75Khz - which made possible inexpensive TV sets full of cheap tubes.


An interlaced DVD player simply reads the data frames (702 pixels wide by 240 lines) and outputs them as an analog signal we refer to as 480i (for interlaced). The signal contains both image data and "sync" information used to control the "sweep" movement of an electron beam across a CRT display, and the maximum frequency is that same 15.75Khz. The rate the image data is being output is 240 lines/frame X 702 pixels/line X 60 frames/sec = 10.1 million pixels/sec (approximately).


A progressive DVD player combines the "odd" and "even" data frames togather into one frame which is 480 lines high by 702 pixels wide, and outputs this at 60 frames/sec. The term for combining the digital data frames (in the digital domain) is "de-interlacing", aka "line doubling" sometimes. On a more modern CRT display like a computer monitor, the electron beam sweeps twice as fast (because modern solid-state devices are better than vacuum tubes) and paints the entire 480 lines 60 times per second - in the computer teminology, 60Hz refresh. The name for such an analog signal is 480p (for progressive), and the sweep frequency has doubled to 31.5Khz. The data rate of the resulting image is 480 lines/frame X 702 pixels/line X 60 frames/sec = 20.2 million pixels/sec (approximately).


Note that the progressive 480p signal has twice as much image data as the interlaced 480i signal, one of two reasons "progressive DVD" looks better than "interlaced DVD" - and the most important reason.


However, there is another consideration. The projectors "de-interlacer" must work with digital data, and the 480i signal, in addition to being at half the data rate of the 480p signal, has been converted to analog.


(Optional paragraph) It doesn't matter whether it's composite video, S-video, or component video, all these are just descriptions of different electrical standards for transporting the 480i signal. Component video is preferable, because it has three coaxial signal wires versus two for S-video or one for composite video, but the bottom line is all three electrical signals were constrained to half the 480p data rate "up front" in the interlaced DVD player. The three coaxial lines of "component video" will support twice the data rate of 480i and can therefore be used for 480p - although composite video and S-video will NOT suffice for 480p.


The projector will convert the incoming 480i back to digital data for line doubling/de-interlacing. When it's done, it will transform back to an analog video signal. Note that the original DVD digital data was converted from digital to analog to digital to analog - a total of three conversions. Every conversion is imperfect and further degrades the image. This is the second of two reasons that 480p images are superior to 480i - the 480p image was "de-interlaced" as digital data, and only got transformed once to analog.


All other things being equal, 480p should always look better than 480i on a "progressive" mode display like a computer monitor or projector. In the first couple of years of DVD technology, it was indeed possible to externally de-interlace a high-quality 480i signal and get better results than a lower quality 480p signal. But technology has advanceed since then, and today a decent 480p signal is nearly always superior.


As a matter of fact, all that "sweep" information for controlling electron beams on CRTs is useless for progressive displays like projectors or any flat panel technology - therefore we have new digital video interfaces that omit such information, and transfer the digital data without transformation to analog - they are called DVI, Firewire, and SDI among others. These digital signals are superior because they avoid the image degradation associated with digital to analog (D/A) and analog to digital (A/D) conversions.


Gary
 

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Gary,


Kudos an a very informative post, but I am still left with a serious question. On paper, your assesment of whether or not to bypass a DVD players interlacer looks pretty clear, but so far I have never seen the benefit unless using a projector or TV with an inferior interscaler.


For instance, just this last weekend I took my 12SF to the HTA projector shootout held in Austin and they were using a Sony DVP-9000ES DVD player connected via component displaying images from Video Essentials.


First we ran it with the DVD player sending out a progressive signal and there was easily noticable stair stepping and jaggies in the picture, especially with the scene of the American flag waving in the wind.


We then switched off the progressive mode on the DVD player and VOILA, the picture looked as smooth as silk. The rest of the picture was unchanged, still same level of brightness, color, contrast, etc. The only diference was in the interlacing between what the DVD player was able to do VS what the projector was able to do.


I have made similar comparisions using the following progressive scan DVD players: Toshiba SD-6200, Pioneer Elite DV 36, and Pioneer DV-C603


All had the same effect as when we used the Sony 9000ES.


If what you say is true, then the results should have been the other way around, right?


Any idea why I am getting a far better picture by sending the projector an interlaced signal vs a progressive? All I can think of is that by sending a progressive signal to the 12SF it then bypasses the internal Faroudja DCDi chip set thus I am seeing the diference between the Faroudja and the DVD player's interpolator.
 

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(According to the references I have, anamorphic dvd is 720x480.)


Unfortunately it's a little more complicated than this. Much of the material on DVD's is from film, and film is 24 frames/second, so there is the issue of 3:2 pulldown to deal with. If a progressive scan dvd player has access to the raw data stream, and can examine the flags, and IF the flags were set correctly by the dvd authoring process, the dvd player could do a really nice job of deinterlacing. However, in reality what most progressive scan dvd players have in them is an inexpensive de-interlacing chip, which is looking at the output of the mpeg decoder, and the flags are not available. So, the chip has to do 3:2 pulldown detection on its own, and it often doesn't get it right. That's one problem.


My experience has been that if you have a display device capable of displaying 480p, and no other scaler, you'll may find the progressive scan output of the dvd player to be an improvement. However, if you have an external scaler, especially a good one like a Faroudja, I find the interlace output of the dvd player to be much better.


So while on paper the progressive scan dvd player may sound like a guaranteed improvement, in reality it's often not.


William
 

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Joel:


I am not sure if you are joking or serious. The only place 27 chips has ever been mentioned that I am aware of is in my bogus review of "5 Projectors I Haven't Seen". Why are you quoting that number in your thread, which otherwise seems serious, and where someone might actually believe it?
 

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AustinTexas,


The Sony9000ES is a well-regarded DVD player, but has two flaws with regard to modern player designs.


Firstly, it has the chroma upsampling bug described in the series of articles Tryg pointed you at.


Secondly the deinterlacer is the Genesis chipset, which has been found to be considerably inferior to the Sage/Faroudja chipset I thought we were discussing.


I'm not familiar with the other DVD players you mentioned, but perhaps you can find their test results in the shootout articles linked to the article above. However, if your projector does have the Sage/Faroudja de-interlacer, I'm not surprised that it outperforms multiple progressive players with lesser deinterlacer designs.


However, I would also expect that if you drove it with a standalone DVD player with the Sage/Faroudja de-interlacer, you would see another increase in image quality due to the lack of additional A/D and D/A conversions.


Reading back to your original post, I see you did indeed try a Panasonic RP-56, which has both the superior de-interlacing and no chroma bug. Forgive me for suggesting this, but the common errors I see people make are menu setup errors in the players (like setting the player for interlaced output) or assuming that the S-video output is progressive (it's always interlaced regardless of the player menu setting which only switches the component video from interlaced to progressive).


The ultimate quality in theory comes from also bypassing the internal scaler of the projector and driving it at the native panel resolution. I believe for your Marantz that is 1280X720 - but every player you threw at it was outputting 702X480. I don't know for sure but perhaps after de-interlacing, the Marantz scales digitally to 1280X720 before converting back to analog video signals. In the case of a 480p signal, it does the same number of conversions but perhaps the scaler works better with that source - who knows.


I can't fault your overall process - try the different alternatives and use what looks best to your own eyes.


Gary
 

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Gary,


I couldn't tell who or what message you were refering to regarding some of your recent comments.


you wrote:

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Reading back to your original post, I see you did indeed try a Panasonic RP-56, which has both the superior de-interlacing and no chroma bug. Forgive me for suggesting this, but the common errors I see people make are menu setup errors in the players (like setting the player for interlaced output) or assuming that the S-video output is progressive (it's always interlaced regardless of the player menu setting which only switches the component video from interlaced to progressive).

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As my message says, all connections were via component cables, but perhaps you are talking about BSN (aka Joel)?



you also wrote:

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The ultimate quality in theory comes from also bypassing the internal scaler of the projector and driving it at the native panel resolution. I believe for your Marantz that is 1280X720 - but every player you threw at it was outputting 702X480.

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I don't have a Marantz. I have a Cinema 12SF which also has the Faroudja DCDi chip set but displays DVD material in its native resolution - no scaleing needed.


Considering that so far, no DVD player outputing a progressive signal has yet matched, let alone equaled the clarity and smoothness when compared to outputting the DVD's native interlaced signal to my 12SF's and allowing the Faroudja to do the interpolating. I can only assume that what ever conversions may be going on, its obviously not having any impact on the image as shown on my 12SF.
 

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Go ask Dan Miller in the guest speaker forum! Its nice having a guest from Marantz to ask how their products work, and maybe he can answer, or find an answer, to your question.
 

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Quote:
Any idea why I am getting a far better picture by sending the projector an interlaced signal vs a progressive? All I can think of is that by sending a progressive signal to the 12SF it then bypasses the internal Faroudja DCDi chip set thus I am seeing the diference between the Faroudja and the DVD player's interpolator.
Sounds like you were watching "video" material. In such a case, the Faroudja chip will always look better compared to the Genesis and other chips regardless of whether the deinterlacing is taking place in the projector or in the DVD player. With film-based material, as long as the DVD player can do 3-2, it should be about even.
 

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Discussion Starter · #13 ·
@ Austin:



That is so STRANGE! We both have the same projector (12SF) but completely different results !? Your post above states that you actually have a BETTER picture with an interlace signal coming from the DVD player and letting the pj do the line-doubling. I, on the other hand, have the opposite whereas the Faroudja chip in my DVD player (RP-56) does a better job de-interlacing the picture (progressive mode is "on").


What's going on?

P.S. Never mind...I just read your answer in the other thread. ;)
 

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Discussion Starter · #14 ·
@ QQQ:


My bad. I'm no expert on the Marantz and I guess I just quoted you unconsciously when I was writing out my question. The Marantz does indeed have 3 chips built in.;)
 
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