# 622 HDMI worse than component



## knealy (Jul 6, 2002)

The HDMI connection on my 622 produces a fuzzier and duller image than the component hookup does. My 921 was much clearer with the DVI connection. Has anyone else noticed that the HDMI picture is worse than the component one?


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## Ron Barry (Dec 10, 2002)

I have not noticed that to be the case. I am using HDMI on both My TVs. What is your TV make and model. Maybe someone else has that model and can pipe in with their experiences.


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## boylehome (Jul 16, 2004)

knealy said:


> The HDMI connection on my 622 produces a fuzzier and duller image than the component hookup does. My 921 was much clearer with the DVI connection. Has anyone else noticed that the HDMI picture is worse than the component one?


It looks like component is the same in quality as the HDMI here. The audio through the HDMI is better than the RCA connectors for the component.


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## jsanders (Jan 21, 2004)

knealy said:


> The HDMI connection on my 622 produces a fuzzier and duller image than the component hookup does. My 921 was much clearer with the DVI connection. Has anyone else noticed that the HDMI picture is worse than the component one?


Maybe you should get an eye exam or something.

There should be no difference between an HDMI and DVI connections as far as picture quality goes. They are the same interface, HDMI adds sound, that is it.

The digital to analog conversion happens in your TV with these interfaces. Unless you changed TVs in the process, there is no difference, you are using the same digital to analog converter in your TV in both cases!


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## bobukcat (Dec 20, 2005)

jsanders said:


> Maybe you should get an eye exam or something.
> 
> There should be no difference between an HDMI and DVI connections as far as picture quality goes. They are the same interface, HDMI adds sound, that is it.
> 
> The digital to analog conversion happens in your TV with these interfaces. Unless you changed TVs in the process, there is no difference, you are using the same digital to analog converter in your TV in both cases!


I think you missed his point, he's saying that the HDMI looks worse than the component on his 622 but on his 921 the DVI provided better quality than component. I don't think it is at all unbelievable that the OP's 622 could show worse video quality than his 921 with DVI. It could be something about the specific combination of reciever and monitor, it could be a less than ideal 622, or maybe the OP does need an eye examination.


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## wcswett (Jan 7, 2003)

knealy said:


> The HDMI connection on my 622 produces a fuzzier and duller image than the component hookup does. My 921 was much clearer with the DVI connection. Has anyone else noticed that the HDMI picture is worse than the component one?


Yes, I have the same problem. The HDMI image is clear but the colors are washed out and it lacks anything close to "black". The component connection is fine. I have only checked this on one of my two 622's.

--- WCS


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## jsanders (Jan 21, 2004)

bobukcat said:


> I think you missed his point, he's saying that the HDMI looks worse than the component on his 622 but on his 921 the DVI provided better quality than component.


HDMI is a digital signal, it spits out zeros and ones.
DVI is a digital signal, it spits out zeros and ones.

The television takes those numbers, and converts those numbers to an analog signal internally.

Both connections use the *same* Digital to Analog converter, the DVI/HDMi connection makes no difference because they are both spitting out bits.

The component outputs on the 921 and 622 have have their own D/A conversion in them. If you say that the HDMI looks worse than component on the 622, but DVI looked better than component on the 921, you might be looking at it backwards.

The DVI/HDMI should give exactly the same picture (unless the scaler changed in the unit which I think is unlikely). It could mean that the 622 has a better D/A converter than the 921. Look at it from the reference of the component looking better or worse than HDMI/DVI, not HDMI/DVI looking better or worse than component.


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## olgeezer (Dec 5, 2003)

In other words, its best to send 0s and 1s as far down the pipe as possible, which would be the display. If component looks better on the display than HMDI or DVI, it means that the STB does a better D/A conversion than your display. This is unusual, but not overly unusual.


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## lujan (Feb 10, 2004)

With my Mitsubishi TV, I'm able to change the settings (color, contrast, brightness, etc.) separately for each input (component, HDMI, etc.). I had to change the HDMI input settings drastically so that the picture would look as good as the component picture. WCSWETT is right, before I made all the setting changes, the HDMI picture looked washed out. I was amazed at all the changes I had to make to get the HDMI to look as good as the component.


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## ebaltz (Nov 23, 2004)

HDMI to DVI on my Pany looks amazing and better than componant. It works perfectly and looks great.


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## David_Levin (Apr 22, 2002)

jsanders said:


> The television takes those numbers, and converts those numbers to an analog signal internally.


Actually, I think this is only true if the display is CRT based. LCD, Plasma, DLP, LCOS, etc wouldn't need a conversion to analog,

This is where I'd expect the digital cable to do better.


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## jsanders (Jan 21, 2004)

David_Levin said:


> Actually, I think this is only true if the display is CRT based. LCD, Plasma, DLP, LCOS, etc wouldn't need a conversion to analog,
> 
> This is where I'd expect the digital cable to do better.


This isn't that movie, "The Matrix", you don't watch numbers on your screen that represent pictures, whether it be LCD, Plasma, DLP, LCOS, or anything else.

Something has to take those numbers and translate them into their corresponding wavelengths of light that emit from the television. The light that forms the picture that you see coming from the television is *analog*. You have to convert those numbers being sent to the television into the light produces the TV picture. There is always a digital to analog conversion.


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## LtMunst (Aug 24, 2005)

jsanders said:


> Something has to take those numbers and translate them into their corresponding wavelengths of light that emit from the television. The light that forms the picture that you see coming from the television is *analog*. You have to convert those numbers being sent to the television into the light produces the TV picture. There is always a digital to analog conversion.


I don't think that is what was meant by a digital TV not doing a digital-analog conversion. Of course the light we see is analog. A digital TV, however, does not have to convert a digital signal into analog in order to fire the pixels (unlike a CRT). The pixel matrix is controlled entirely by digital commands (ie pixel #... on/off at ...intensity).


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## jsanders (Jan 21, 2004)

Let's see what you are saying here...

You were talking about Digital TVs, with digital inputs. A digit is representative of a finger on your hand, namely a digit. The number system on the TV is base 2, not base ten that humans use. In other words, the TV has only one finger, instead of ten found on the human hands.

With reference to the TV picture, you said,


LtMunst said:


> "Of course the light we see is analog".


Then you said,


LtMunst said:


> I don't think that is what was meant by a digital TV not doing a digital-analog conversion.


Why should I even bother with arguing this point? You contradict yourself.

If you have digital bits coming in, and you have analog light coming out, then you *must* convert from digital to analog. How can you possibly have analog coming out and digital going in without doing some kind of D/A conversion?? You are defying the laws of physics!



LtMunst said:


> I don't think that is what was meant by a digital TV


That is where the mistake is, you use the word, "I". Why not look up what is meant by digital TV, and get the real definition instead of a personal definition.

Digital TV does not refer to the TV being digital all the way through. Digital TV (DTV) is referring to the broadcast signal (8VSB in the United States) being digtial and not analog. It has nothing to do with what happens inside the television.


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## jsanders (Jan 21, 2004)

olgeezer said:


> In other words, its best to send 0s and 1s as far down the pipe as possible, which would be the display. If component looks better on the display than HMDI or DVI, it means that the STB does a better D/A conversion than your display. This is unusual, but not overly unusual.


Yes! Olgeezer got it right! This is because the analog signal properties, while they do have more resolution than digital signals, degrade over distance and time without the possibility of being able to be regenerated to their original state. Digital signals can be regenerated and repeated over distances without loosing any data, which is in this case correlates to picture quality. By doing your conversion to analog at the last possible stage, you are insuring the best possible reproduction of the source without loss of quality.


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## abricko (Mar 1, 2006)

I've noticed HDMI output is off a bit, the Black Levels appear to be crushed over HDMI... just because it's a full digital signal it doesn't mean the receiver is outputting properly, it means that you will not have added analog noise (over component out)...


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## SaltiDawg (Aug 30, 2004)

jsanders said:


> ...
> 
> There should be no difference between an HDMI and DVI connections as far as picture quality goes. They are the same interface, HDMI adds sound, that is it.
> 
> ...


D'oh.

I don't think he was suggesting a difference because of DVI vs HDMI, but rather that the digital output of his *921* was better than the analog. Now with the *622* on *the same TV* the analog looks better than the digital.


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## TechnoCat (Sep 4, 2005)

olgeezer said:


> In other words, its best to send 0s and 1s as far down the pipe as possible, which would be the display. If component looks better on the display than HMDI or DVI, it means that the STB does a better D/A conversion than your display. This is unusual, but not overly unusual.


That's not quite correct. First off, digital signals along HDMI attrit more quickly than analog do - it's just that for the first three metres or so it's below the error-correction floor. But more importantly, there are several factors in Component vs HDMI... and digital vs. analog is NOT one of them.

Yes, component is analog. But it's three pipes; it has plenty of bandwidth for 720p and for 1080i. THERE'S NO MEASURABLE OR PERCEPTABLE LOSS IN NORMAL DISTANCES OVER COMPONENT. The primary distinction between using component and HDMI is simply this: Where does the scaling happen? (Or how often?)

Scaling will always happen on a Plasma regardless, simply because no mass-market plasma has a 1920x1024 panel (1080) nor do they match the 720 spec exactly either. So if you send an HDMI signal, you've already scaled on the receiver and now you have to scale again.

MPEG is a compression technology. That's an important term, because it compresses in several dimensions. It's not just "map this color to this number" - although it does that. It's not just "turn these close-together colors into one", although it does that too. It's also "turn these 17 pixels that are the same color or real close, into a single big blobby pixel" and also "turn the area from 212,32 to 254,56 that don't change for 14 frames into a single image once rather than 14 times.

The important part of that here is that the definition of a "pixel" is fluid in MPEG. (And in JPEG.) There is a native resolution going in, but much less so coming back out. And so what happens next, on either signal? It has to be sampled for rescaling. Which completely obliterates any theoretical "pure-digital" advantage to HDMI.

So which is better? Both work fine. Certainly one cable (HDMI) is more convenient than 4 (3 component plus digital audio), though the Component will carry the signal further. But the big choice you're left with is the quality of the source scaler. Many televisions have good ones for HD and crappy for SD. Which would put you much better off using Component than HDMI because the receiver can upscale, essentially, better to a point where the TV can downscale effectively. Not typically an HD issue because that's where the bucks/sex/sales are (and it's a smaller resolution change), but try it with SD and you may see a difference.


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## jsanders (Jan 21, 2004)

SaltiDawg said:


> D'oh.
> 
> I don't think he was suggesting a difference because of DVI vs HDMI, but rather that the digital output of his *921* was better than the analog. Now with the *622* on *the same TV* the analog looks better than the digital.


Actually, the way he stated it, he was using the analog as the reference in the two receivers to quantify the digital. That is backwards. The digital is the same, he needs to use the digital as a reference on both boxes, and use that as a reference to compare the analog signals on both boxes, as the 622 and 921s will have different D/A converters, but digitally they will spit out the same bits.


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## LtMunst (Aug 24, 2005)

jsanders said:


> Why should I even bother with arguing this point? You contradict yourself.
> 
> If you have digital bits coming in, and you have analog light coming out, then you *must* convert from digital to analog. How can you possibly have analog coming out and digital going in without doing some kind of D/A conversion?? You are defying the laws of physics!


Dude, noone is arguing that there is a final D/A conversion as a result of the creation of light waves. In this respect everthing we see and hear is always analog. That is not the question.

The original poster I referenced simply stated that unlike a CRT, an LCD/DLP does not have to internally convert/process the digital signal to an analog wave. A CRT requires an analog wave signal to funtion. A LCD/DLP chip works with digital commands. And yes, the final result of both is an analog light wave.

Minor semantics issue.. no need to get worked up over it. :nono2:


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## jsanders (Jan 21, 2004)

TechnoCat said:


> Yes, component is analog. But it's three pipes; it has plenty of bandwidth for 720p and for 1080i. THERE'S NO MEASURABLE OR PERCEPTABLE LOSS IN NORMAL DISTANCES OVER COMPONENT. The primary distinction between using component and HDMI is simply this: Where does the scaling happen? (Or how often?)


Doesn't HDMI have a handshake mechanism, and checksums to make sure the bits are correct? If your HDMI hits the maximum length, it can be repated. The differences between analog and component is where does the D/A conversion happen. You had better set the output on your receiver to do the native resolution of your TV so that it doesn't scale twice. If you don't, it will rescale, *regardless* of whether you are using component or HDMI.



TechnoCat said:


> Scaling will always happen on a Plasma regardless, simply because no mass-market plasma has a 1920x1024 panel (1080) nor do they match the 720 spec exactly either. So if you send an HDMI signal, you've already scaled on the receiver and now you have to scale again.


There are plenty of plasmas out there that do 1024x1024, but there are ones out there that do 720p native resolutions. While what you said may be true of some plasmas, it is not true of all plasmas. Under the scenario of a 1024x1024 plasma, *regardless* of what you use, component, or DVI, the TV will still have to scale a second time if the source mode doesn't match the output mode of the receiver. It is moot point.



TechnoCat said:


> MPEG is a compression technology. That's an important term, because it compresses in several dimensions. It's not just "map this color to this number" - although it does that. It's not just "turn these close-together colors into one", although it does that too. It's also "turn these 17 pixels that are the same color or real close, into a single big blobby pixel" and also "turn the area from 212,32 to 254,56 that don't change for 14 frames into a single image once rather than 14 times.


You should learn more about MPEG compression before you try to explain it. The Motion Picture Encoding Group (MPEG) compresses the signal with a Discrete Cosine Transform which puts as much information in the left hand corner of the screen as possible. This reduces spatial redundancy. The compression technique you are speaking of is very rudimentary and not nearly efficient enough to do the job.



TechnoCat said:


> But the big choice you're left with is the quality of the source scaler. Many televisions have good ones for HD and crappy for SD. Which would put you much better off using Component than HDMI because the receiver can upscale, essentially, better to a point where the TV can downscale effectively. Not typically an HD issue because that's where the bucks/sex/sales are (and it's a smaller resolution change), but try it with SD and you may see a difference.


With dish's compressed up the wazoo SD signals, there isn't enough information to do a good job scaling the picture. Oddly enough, I've found that using the composite cable on the compressed SD picture works well, and precisely because everything gets combined and things get smeared a bit. The result is that smeared colors look better to me than blotching and solarization.

Aside from what you have said TechnoCat, olgeezer was correct in what he said.


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## saweetnesstrev (Oct 8, 2005)

HDMI looks alot better then Component on my 411,, HDMI much sharper and brighter and bolder..


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## jsanders (Jan 21, 2004)

LtMunst said:


> The original poster I referenced simply stated that unlike a CRT, an LCD/DLP does not have to internally convert/process the digital signal to an analog wave.


Can you show me where the original poster said that??


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## olgeezer (Dec 5, 2003)

I hoped what I said wasn't confusing. It apparently was. I just google the first article that popped up from Ecoustics and am pasting their take on what I thought I said:

"The upshot of this article--in case you're not inclined to read all the details--is that it's very hard to predict whether a digital DVI or HDMI connection will produce a better or worse image than an analog component video connection. There will often be significant differences between the digital and the analog signals, but those differences are not inherent in the connection type and instead depend upon the characteristics of the source device (e.g., your DVD player) and the display device (e.g., your TV set). Why that is, however, requires a bit more discussion"


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## SaltiDawg (Aug 30, 2004)

jsanders said:


> Actually, the way he stated it, he was using the analog as the reference in the two receivers to quantify the digital. ...


It is *two different STB's.* Are you are suggesting that *all* STB's when presented with the same (compressed) satellite data stream provide *identical* outputs?


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## harsh (Jun 15, 2003)

jsanders said:


> If you have digital bits coming in, and you have analog light coming out, then you *must* convert from digital to analog. How can you possibly have analog coming out and digital going in without doing some kind of D/A conversion?? You are defying the laws of physics!


Actually, with respect to non-CRT technologies, the video signal is digital until your brain processes what strikes your retina.

Non-CRT displays all create varying brightness using your vision's perception of something that is flashing on and off very rapidly as being less bright than a continuous light with the same intensity. The ratio of on to off determines the relative brightness.

It is likely that the only analog processing taking place is in the audio subsystem.

Don't even bring up the concepts of photons and lightwaves.


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## jsanders (Jan 21, 2004)

SaltiDawg said:


> It is *two different STB's.* Are you are suggesting that *all* STB's when presented with the same (compressed) satellite data stream provide *identical* outputs?


I don't understand why so many on this thread are having trouble with these concepts.

The 921 and 942 and 622 receive the same satellite data stream.

The 921 and 942 and 622 have the same MPEG-2 decoding algorithm, they all use the broadcomm chipset to do it.

The 921 and 942 and 622 all spit out the same MPEG-2 decoded bits through the DVI/HDMI outputs, provided that they are all set to the same output resolution. This is because these are digital outputs. It puts out numbers, and it is uncompressed, not MPEG-2 compressed.

The 921 and 942 and 622 will have variations from each other on their component outputs. This is because they all go through unique, biased, DACs (Digital to Analog converters).


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## LtMunst (Aug 24, 2005)

jsanders said:


> Can you show me where the original poster said that??


This is what the post in question said "Actually, I think this is only true if the display is CRT based. LCD, Plasma, DLP, LCOS, etc wouldn't need a conversion to analog,
..."

As I said, he was simply stating that the LCDs/DLPs etc did not have to convert the digital signal to analog in order to display. You then went off on the tangent about there ALWAYS being a D/A conversion when light is emitted.


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## jsanders (Jan 21, 2004)

harsh said:


> Actually, with respect to non-CRT technologies, the video signal is digital until your brain processes what strikes your retina.
> 
> Non-CRT displays all create varying brightness using your vision's perception of something that is flashing on and off very rapidly as being less bright than a continuous light with the same intensity. The ratio of on to off determines the relative brightness.
> 
> It is likely that the only analog processing taking place is in the audio subsystem.


Harsh, you don't even know the word for what you are describing. The "ratio of on to off" is called a "duty cycle".

However, that isn't how LCDs work.

You have a florescent back plane, which emits light through a polarized piece of glass. This emits white light. There are thin film transistors in groups of three (red, green, and blue) which make up each individual pixel element. These transistors cause liquid crystals to untwist, the amount of untwisting correlates to the amount of light which is allowed to pass through. Doing this will give you the hughes of red, green, and blue which make up the desired color of the pixel on the screen.

Here is a question for some in this thread....

How do you take the incoming numbers from the HDMI/DVI signal, and use those to control the individual transistors which allow filtered light to pass through the screen? You use a Digital to Analog Converter (DAC)!

What comes out of your TV really is analog. Digital TV doesn't mean digital out. It means it is receiving a digitally broadcast signal!


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## LtMunst (Aug 24, 2005)

jsanders said:


> I don't understand why so many on this thread are having trouble with these concepts.
> 
> The 921 and 942 and 622 receive the same satellite data stream.
> 
> ...


What makes you think the scaler is the same for all 3 receivers?? Those receivers all add some level of processing to downscale/upscale the signal for whatever output resolution the box is set to. There is alot of variation in the way different scalers will process identical streams. To insist that all 3 receivers must process and output the HDMI/DVI signal exactly the same is not necessarily true.


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## LtMunst (Aug 24, 2005)

jsanders said:


> Here is a question for some in this thread....
> 
> How do you take the incoming numbers from the HDMI/DVI signal, and use those to control the individual transistors which allow filtered light to pass through the screen? You use a Digital to Analog Converter (DAC)!


Where do you get this DAC idea for LCD's, etc??? There is no DAC in these systems. The processor uses digital instructions to determine which parts of the LCD matrix to send voltage to as well as how much voltage to apply. There is no analog wave used in this process.


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## jsanders (Jan 21, 2004)

LtMunst said:



> This is what the post in question said "Actually, I think this is only true if the display is CRT based. LCD, Plasma, DLP, LCOS, etc wouldn't need a conversion to analog,
> ..."
> 
> As I said, he was simply stating that the LCDs/DLPs etc did not have to convert the digital signal to analog in order to display. You then went off on the tangent about there ALWAYS being a D/A conversion when light is emitted.


Okay. David_Levin said that in post #11. He isn't the "original poster" (your words from post #20), knealy is the original poster.

The tangent was started when you disagreed with me in post #13 by stating:


LtMunst said:


> A digital TV, however, does not have to convert a digital signal into analog in order to fire the pixels (unlike a CRT).


That isn't true. It has to do a D/A conversion when it sends displays the pixel. I explained how that happens for LCDs in post #29.


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## jsanders (Jan 21, 2004)

LtMunst said:


> Where do you get this DAC idea for LCD's, etc??? There is no DAC in these systems. The processor uses digital instructions to determine which parts of the LCD matrix to send voltage to as well as how much voltage to apply. There is no analog wave used in this process.


It appears you don't know what digital and analog signals are. You just described a digital to analog conversion process.

Consider the transisitor loading curve.

A transisitor can be used as a switch, or an amplifier. Let's take an old TTL circuit because they are very simple.

When the transisitor is in saturation, above 1.5 volts, the switch is on. When the transisitor is below the base to emitter diode voltage (0.7 volts), the transisitor is off. Anything in between is undefined. That is the basis of the simplest digital signal.

An analog signal is where the transisitor is used as an amplifier. The entire range of the transistor loading curve has distinct meaning.

In the thin film transisitor (TFT) displays, the transistors that control the amount of light to pass through the red, green, and blue sub-pixels. The sub-pixels are being used as amplifiers, not switches. They are fed by *analog* signals!

For your information, a digital signal switches things on and off. Voltages that exceed a threshold activate a swtich, and voltages below a different threshold deactivate a switch. There is also a histresis curve too, but that is a little more complicated.

The analog signal is not set by voltage thresholds. The analog signal is what is controlling those transistors that act as amplifiers in the LCD display.

If those transistors were digital switches, you would only get 8 colors because the transistors could only be on or off (no hues).

You could get the following combinations of colors because each sub-element only switches on or off:

red (off) + green (off) + blue (off)
red (off) + green (off) + blue (on)
red (off) + green (on) + blue (off)
red (off) + green (on) + blue (on)
red (on) + green (off) + blue (off)
red (on) + green (off) + blue (on)
red (on) + green (on) + blue (on)

You need more than just switches to get your millions of colors that are detectable to the human eye. You need to control intensity of each sub-pixel. In order to do that, the transistor needs to act as an amplifier. In order to do that, the transistor sub-pixel needs to be fed an *analog* signal.


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## jsanders (Jan 21, 2004)

LtMunst said:


> What makes you think the scaler is the same for all 3 receivers?? Those receivers all add some level of processing to downscale/upscale the signal for whatever output resolution the box is set to. There is alot of variation in the way different scalers will process identical streams. To insist that all 3 receivers must process and output the HDMI/DVI signal exactly the same is not necessarily true.


They all use the same broadcom chips in those receivers. Most likely, they all have the same scaler. It would be less likely if the receivers were not all from the same company, but in this case, they are!

For arguments sake, why not just take the scaler out of the picture. ABC outputs in 720p. Have the receiver ouput 720p to your display. Under that scenario, no scaler is used. The people that are complaining will most likely still complain about their pictures looking different.

The problem is likely that they don't have their inputs calibrated properly.


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## LtMunst (Aug 24, 2005)

jsanders said:


> You need more than just switches to get your millions of colors that are detectable to the human eye. You need to control intensity of each sub-pixel. In order to do that, the transistor needs to act as an amplifier. In order to do that, the transistor sub-pixel needs to be fed an *analog* signal.


This is really a semantics debate. What you describe is not the common definition of a DAC. A DAC as most define it would convert the digital video signal into a complete analog wave. This is not done in LCD/DLP etc. By your definition, virtually every process within a computer would be a digital to analog conversion. Writing from RAM to the Hardrive would require a DAC since variable voltages are required to move the write arm across the platter.


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## LtMunst (Aug 24, 2005)

jsanders said:


> They all use the same broadcom chips in those receivers. Most likely, they all have the same scaler. It would be less likely if the receivers were not all from the same company, but in this case, they are!
> 
> For arguments sake, why not just take the scaler out of the picture. ABC outputs in 720p. Have the receiver ouput 720p to your display. Under that scenario, no scaler is used. The people that are complaining will most likely still complain about their pictures looking different.
> 
> The problem is likely that they don't have their inputs calibrated properly.


Ok..leaving out the scaler. There are differences in the Video drivers. Same chipset or not, the software video drivers play a large role in the final output. If you think the video drivers are identical in these receivers, you are absolutely wrong.


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## knealy (Jul 6, 2002)

OK, here's the original poster back to see the fray that I've started.

First let me say that I'm using the same pair of eyes to evaluate what I'm seeing, so getting them examined might improve my sight, but shouldn't change my comparison (unless someone wants to go off on a tangent on this as well!).

Second. I'm not arguing about the technologies. I'm merely observing what I see. If anyone wants to tell me what I saw was impossible, then fine, but that's what I saw.

Third. I was indeed comparing the DVI output of the 921 with the HDMI output of the 622. The component outputs of both receivers produce comparable results, -neither noticeably different from the other. But the digital outputs look markedly different even though they are connected to the same input on the TV (which BTW is a SONY Grand Wega KF-42WE610 LCD Projection HD Monitor - sorry for leaving out that info to start with).

I tried different HDMI cables. I tried adjusting the picture settings on the SONY. While I can improve on the picture quite a bit by adjusting brightness, contrast, sharpness, whatever, on the SONY I can't get the brilliant and well defined images with my 622 that I got with my 921 (which had plenty of it's own troubles, as we all know).

My only conclusion is that the 622 is doing something different than my 921 did since they're getting the same source material. The choices left to me are that they are indeed different in their outputs or I'm crazy. I choose the former.

Hope I didn't waste all of your time. And I wish people could keep their comment civil.


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## knealy (Jul 6, 2002)

BTW, I hate it when technical people tell me what I'm looking at is impossible or not true. I'm here looking at it. Who are they to say what I'm looking at. It may be that I'm misinterpreting it, or looking at something different than what they think, but please don't tell me what I can see and you can't.


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## jsanders (Jan 21, 2004)

LtMunst said:


> This is really a semantics debate. What you describe is not the common definition of a DAC. A DAC as most define it would convert the digital video signal into a complete analog wave. This is not done in LCD/DLP etc. By your definition, virtually every process within a computer would be a digital to analog conversion. Writing from RAM to the Hardrive would require a DAC since variable voltages are required to move the write arm across the platter.


No, it is not a semantics debate at all. You do not know what an analog signal is when compared to a digital signal. A DAC can be used in anything, video or otherwise. It is this analog wave that you speak of which controls the three red, green, and blue transistors that make up a pixel in your tv.

I guarantee you that a DAC is used in an LCD TV screen. If it was all digital, you would have two to the power of three, or 8 colors because you would only have three switches instead of three amplifiers. If your TV only shows the 8 primary colors, then great. If not, you have a DAC in your TV!

Writing and reading RAM, or ROM involves purely digital signals. Why? Because these signals have only two states to them. A 'zero' is less than 0.7V, and a 'one' is a voltage greater than 1.5 volts. That is using the old TTL logic of VCC being 5v. To reduce power and heat, they have improved on this and reduced all of these thresholds. A digital signal is defined as a signal with detectable voltage states which are defined by thresholds.

Writing to a hard drive does have some D/A conversion in it. In fact, it is a very complicated process. The digital signal tells the drive controller what sector it wants to go to. Then, there is an automatic control loop that moves the head accross the platter. They typically use something like a 9 pole filter to control that drive head quickly and produce a critically damped response. That is what they have to do in order to get the "seek time" spec on the drive.

You are very wrong on this topic LtMunst. If you want to learn how it works, we can continue to the discussion. If you still think you are right, then please tell us how you think it works. How does the TV convert an uncompressed digital video stream of zeros and ones into the millions of colors of light that you see on your tv screen? Do you design TVs or computers or something? I haven't heard your explanation yet. Please tell us how it works, I would like to know.


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## jsanders (Jan 21, 2004)

LtMunst said:


> Ok..leaving out the scaler. There are differences in the Video drivers. Same chipset or not, the software video drivers play a large role in the final output. If you think the video drivers are identical in these receivers, you are absolutely wrong.


Video drivers have nothing to do with this. The video driver is what allows the 921/942/622 to put menus and program guides and such on the screen. If the receivers are just doing video playback, then the video driver isn't used and the MPEG-2 decoder output spits right out the HDMI/DVI port. The driver is just an interface between the application running on a computer and the display controller.


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## harsh (Jun 15, 2003)

jsanders said:


> Harsh, you don't even know the word for what you are describing. The "ratio of on to off" is called a "duty cycle".


I fully understand the term duty cycle, but I didn't bring it up because of possible confusion by an unfamiliar term. That exercise is left to those who might use those terms to shock and awe (or don't understand the audience).


> How do you take the incoming numbers from the HDMI/DVI signal, and use those to control the individual transistors which allow filtered light to pass through the screen? You use a Digital to Analog Converter (DAC)!


Why would you want to convert from digital to analog (except for CRT)? The kinds of transistors found in LSI and VLSI chips are typically not amplifiers -- they are binary switches. If they need to vary something, they do it using duty cycle.


> What comes out of your TV really is analog.
> 
> 
> > Only if your TV is a CRT based device.
> ...


The signal is modulated into sinus radio frequencies. This is an analog process. Computer people might recognize this as something very much like a MODEM only at a much higher frequency.

As for your understanding of how LCD works, here's an explanation from the leader in the use of the technology for TVs:

http://sharp-world.com/sc/library/lcd_e/s2_1_1e.htm

The key is not the twisting, but rather the spinning of the rods to an endwise orientation which allows the light to pass.


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## jsanders (Jan 21, 2004)

knealy said:


> BTW, I hate it when technical people tell me what I'm looking at is impossible or not true. I'm here looking at it. Who are they to say what I'm looking at. It may be that I'm misinterpreting it, or looking at something different than what they think, but please don't tell me what I can see and you can't.


Okay knealy, I believe that you see what you see! I apologise if I gave you the impression that you were crazy or anything.

Let me ask you a couple of questions.

You are using a DVI output on the 921.
When you connect the 622, are you going HDMI to HDMI, or are you using an HDMI to DVI converter on your TV? Are you plugging the thing in the exact same plug on the back of the TV, that being a DVI socket on your Sony in both cases?


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## jsanders (Jan 21, 2004)

harsh said:


> The kinds of transistors found in LSI and VLSI chips are typically not amplifiers -- they are binary switches. If they need to vary something, they do it using duty cycle.The signal is modulated into sinus radio frequencies. This is an analog process. Computer people might recognize this as something very much like a MODEM only at a much higher frequency.


We aren't talking about chips here. We are talking about an LCD TV panel that is huge! We are not talking LSI, or VLSI. We are talking three transistors per pixel on a 1080i LCD panel. If anything it is VSSI (Very Small Scale Integration) because you have only 6 million transistors (not even a gate) on a panel that is at least 45 inches in diagonal!

I think I mis-read what you said there the first time I glanced at it. I think I get what you are trying to say. The transistors on the display are switches that are driven with a duty cycle to modulate intenisty. There has to be one more element to make that work right. If you are varying the switching by modulating duty cycle, then there needs to be something to do the averaging. That would suggest that there either needs to be either a capacitor in there, or the LCD elements that twist need to not be able to react fast enough to the individual switches to do the averaging. If this is the case, then the D/A conversion is done by a process of switching via duty cycle and averaging either by a capacitor or the physical limiations of the liquid crystal twisting.



harsh said:


> As for your understanding of how LCD works, here's an explanation from the leader in the use of the technology for TVs:
> 
> http://sharp-world.com/sc/library/lcd_e/s2_1_1e.htm
> 
> The key is not the twisting, but rather the spinning of the rods to an endwise orientation which allows the light to pass.


In your link, I don't see the word "spin", or "rod", or "endwise", although your explantion sounds okay. I did find "twist" though.

Here are a few quotes from your link:

"Light passes through liquid crystals, following the direction in which the molecules are arranged. When the molecule arrangement is _twisted_ 90 degrees as shown in the figure, the light also twists 90 degrees as it passes through the liquid crystals."

"This figure depicts the principle behind typical _twisted_ nematic (TN) liquid crystal displays"

"The molecules along the upper plate point in direction 'a' and those along the lower plate in direction 'b,' thus forcing the liquid crystals into a _twisted_ structural arrangement."

Light bends 90 degrees as it follows the _twist_ of the molecules

When voltage is applied to a combination of two polarizing filters and _twisted_ liquid crystal, it becomes a LCD display

"A combination of polarizing filters and _twisted_ liquid crystal creates a liquid crystal display."


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## knealy (Jul 6, 2002)

jsanders said:


> Okay knealy, I believe that you see what you see! I apologise if I gave you the impression that you were crazy or anything.
> 
> Let me ask you a couple of questions.
> 
> ...


As I mentioned, I am plugging into the same input on the TV. It is DVI. So I'm using a DVI male to HDMI male cable which goes from the TV to the 622. In the case of the 921 I used a DVI male to DVI male (same input on the TV, -DVI). So for the 622 I had to use a different cable, but no adapter.

I've tried two different DVI to HDMI cables, one from Gefen, who specializes in such things, and the other from Monster who also made the DVI to DVI cable I was using with the 921. Both brands produced the same results on the 622, -dull and not as clear as the component connection.


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## harsh (Jun 15, 2003)

jsanders said:


> "This figure depicts the principle behind typical *twisted* nematic (TN) liquid crystal displays"


The "twisting" is what gives an LCD increased opacity when not charged (flaccid?).

The key sentence from the link was the last one:


Sharp website said:


> In other words, the voltage acts as a trigger causing the liquid crystals to function like the shutter of a camera.


What your suggesting is that the voltage is varied to force a behavior more like an iris. While LCD's can be grayed by tinkering with the voltage, it is somewhat difficult to control uniformity. A few pages later, Sharp explains that a TFT (Thin Film Transistor) is a switching transistor (diode).

http://sharp-world.com/sc/library/lcd_e/s2_4_3e.htm

(the active matrix diagram)


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## harsh (Jun 15, 2003)

knealy said:


> Both brands produced the same results on the 622, -dull and not as clear as the component connection.


I would be asking Dish for an advance replacement of your ViP622.


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## jsanders (Jan 21, 2004)

harsh said:


> The "twisting" is what gives an LCD increased opacity when not charged (flaccid?).
> 
> The key sentence from the link was the last one:What your suggesting is that the voltage is varied to force a behavior more like an iris. While LCD's can be grayed by tinkering with the voltage, it is somewhat difficult to control uniformity. A few pages later, Sharp explains that a TFT (Thin Film Transistor) is a switching transistor (diode).
> 
> http://sharp-world.com/sc/library/lcd_e/s2_4_3e.htm


Nuts! I tried to edit my post when I got home from work, but it was already replied to. You can see my edited post there. It does say that it is a switching transistor. I still do think that changing the voltage acts like an iris, one of the previous pages seemed to hint at this. I think that because it is a switching transistor that varying a duty cycle will do the same thing as changing the voltage. If you vary the duty cycle fast enough, the liquid crystal twisting may not be able to twist back all the way between pulses. It takes time to move mass. This could be a natural way of doing the averaging via a duty cycle. I don't see any capacitors in the diagram, however, there may be some sort of capacitance in there too. It sounds like doing high speed duty cycle type switching and averaging with the effects of the liquid crystals twisting and untwisting are doing the digital to analog conversion.


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## jsanders (Jan 21, 2004)

knealy said:


> As I mentioned, I am plugging into the same input on the TV. It is DVI. So I'm using a DVI male to HDMI male cable which goes from the TV to the 622. In the case of the 921 I used a DVI male to DVI male (same input on the TV, -DVI). So for the 622 I had to use a different cable, but no adapter.
> 
> I've tried two different DVI to HDMI cables, one from Gefen, who specializes in such things, and the other from Monster who also made the DVI to DVI cable I was using with the 921. Both brands produced the same results on the 622, -dull and not as clear as the component connection.


Are you watching the same channel on both the 622 and 921? For instance, if you are watching an MPEG-4 encoded channel on the 622 that would not be good because the bits coming out of the unit would be different from the different encoding/decoding schemes.

Is there a way that you could temporarily take the component pictures out of your test and just compare the DVI on the 622 against the DVI on the 921? It is entirely possible that the component outputs are biased differently on the two units.

Have you tried viewing a test pattern on the two units? HDNet has a test pattern that runs at 5am on Tuesday mornings that lasts for ten minutes. I don't know if that is still the same time for it. The tests weren't as good as video essentials, but it might give you a more controlled basis for comparison.


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## knealy (Jul 6, 2002)

jsanders said:


> Are you watching the same channel on both the 622 and 921? For instance, if you are watching an MPEG-4 encoded channel on the 622 that would not be good because the bits coming out of the unit would be different from the different encoding/decoding schemes.
> 
> Is there a way that you could temporarily take the component pictures out of your test and just compare the DVI on the 622 against the DVI on the 921? It is entirely possible that the component outputs are biased differently on the two units.
> 
> Have you tried viewing a test pattern on the two units? HDNet has a test pattern that runs at 5am on Tuesday mornings that lasts for ten minutes. I don't know if that is still the same time for it. The tests weren't as good as video essentials, but it might give you a more controlled basis for comparison.


Well the 921 was sent back for my $200 credit. I had also returned a 501 for a replacement. Unfortunately they gave me a $25 credit for the 501 in exchange for the 622. So it took quite a while to straighten out that mess. They claimed they hadn't received a 921. But I had the UPS tracking info showing that they signed for it two days before the 501 arrived. Then they said it only indicated that they'd got a package, but not what was in it. So I asked them to tell me what was in it. Finally they relented and told me I'd be getting the credit.

Now to answer your question. Yes, I used the same channels, HD and SD to check the results. I also paused the HD picture so I'd be sure to have the same image.

Don't know where to go from here except just to use the component video.


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## Mr. Crowley (Apr 27, 2006)

You guys need to realize DVI is 8-bit and HDMI is 10-bit, so there will be a difference when using the DVI input. If you want to read further read this (just add www at the beginning):

avsforum.com/avs-vb/showthread.php?t=556134


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## Jeff McClellan (Apr 22, 2002)

On a Sony LCD-RP, component does have a better picture with the 622 then HDMI. For now at least.


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## LtMunst (Aug 24, 2005)

jsanders said:


> Video drivers have nothing to do with this. The video driver is what allows the 921/942/622 to put menus and program guides and such on the screen. If the receivers are just doing video playback, then the video driver isn't used and the MPEG-2 decoder output spits right out the HDMI/DVI port. The driver is just an interface between the application running on a computer and the display controller.


This is nuts. You are trying to say that software drivers have nothing to do with the video output?  Wonder how software updates have been able to fix video issues in the past (like the 942 smearing issue)? Guess the updates somehow changed out the chipset. :lol:

All 3 of these receivers are specialized computers running on the Linux operating system. Just like your home PC, anything displayed on your monitor is the result of both hardware and software processing. There is no straight pipe from the MPEG decoder chipset to the HDMI output.


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## LtMunst (Aug 24, 2005)

jsanders said:


> Digital TV does not refer to the TV being digital all the way through. Digital TV (DTV) is referring to the broadcast signal (8VSB in the United States) being digtial and not analog.


Ok...lets play semantics a little more. There is NO SUCH THING as a digital broadcast signal. Last I checked, all radio transmissions are in the form of an analog sine wave. Can that analog wave carry digital info?....sure. But that requires an A/D conversion.

Carrying this even further....Every process within the receiver or TV is completed using an electrical current based on a 60hz alternating sine wave. In this respect, ALL functions are analog.

Bottom line is that you are mis-applying the term DAC. A DAC, as used in audio/visual components performs one of two functions.

#1 Converts digital instructions into a single audio sine wave which is directly amplified by a speaker.

#2 Converts digital instructions into a single sine wave used by a cathode ray to progressively scan across a phosphor matrix.

That's it.

An LCD does not use #2. To create a picture on an LCD, the processor creates a digital map of the pixel matrix for each frame identifying which subpixels need to be turned on and at what intensity. These instructions are then sent to the matrix at one time. The matrix is not refreshed line by line. There is no single analog wave driving the pixel refresh. Are individual analog signals sent to specific electrical components to make this happen?...Sure. It is not DAC, though.


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## SaltiDawg (Aug 30, 2004)

jsanders said:


> They all use the same broadcom chips in those receivers. Most likely, they all have the same scaler. ...


After your numerous pompous and arrogant posts, suggesting a lack of understanding of the issue, you have the cajones to admit this?

Ploink!:nono2:


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## olgeezer (Dec 5, 2003)

knealy said:


> The HDMI connection on my 622 produces a fuzzier and duller image than the component hookup does. My 921 was much clearer with the DVI connection. Has anyone else noticed that the HDMI picture is worse than the component one?


Let's see if we can make any sense. I'm not an engineer, which may be good, but I am a salesman which is 2 steps above pond scum. This is what I think. Your eyes are always the best judge. Nothing has changed in your set up except the receiver. The only possibilities that are left are: 921 better HMDI/DVI than 622, unlikely to be different. 622 better D/A conversion than 921 possible. Display and cables have remained constant so that D/D or A/D conversion changes on display are unlikely. If your DVI/HMDI cabling are greater than 7 meters, there is a possibility of working on one but not the other, but that normally is a cliff not a gradual decline. The 921 was DVI the 622 is HMDI. Another possibility is the HMDI cable. The only thing you can change is the cable. I have a 622 on a analog rear projection. I did notice an improvement on component although not enough to disconnect my DVI/HMDI. At work on 7 digital displays from a 411 I've seen an improvement on component. My best guess would be that the 622 has better D/A conversion than the 921.


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## TechnoCat (Sep 4, 2005)

jsanders said:


> Doesn't HDMI have a handshake mechanism, and checksums to make sure the bits are correct? If your HDMI hits the maximum length, it can be repated.


True but completely irrelevant. Data loss doesn't tend to be a one-time thing, and HDMI signals are far more fragile than Component ones.



jsanders said:


> The differences between analog and component is where does the D/A conversion happen. You had better set the output on your receiver to do the native resolution of your TV so that it doesn't scale twice. If you don't, it will rescale, *regardless* of whether you are using component or HDMI.


Yes, that's one of the points I made, but then you added...


jsanders said:


> There are plenty of plasmas out there that do 1024x1024, but there are ones out there that do 720p native resolutions.


Name 5 in the top 10 of plasma sales. The typical 42" plasma panel is 1024 x 768. 720p is 1280x720.



jsanders said:


> While what you said may be true of some plasmas, it is not true of all plasmas. Under the scenario of a 1024x1024 plasma, *regardless* of what you use, component, or DVI, the TV will still have to scale a second time if the source mode doesn't match the output mode of the receiver. It is moot point.


Did you even READ my post, or did you just decide to argue with every sentence? That's pretty much what I said - that they have to rescale on the monitor side.



jsanders said:


> You should learn more about MPEG compression before you try to explain it.


I've worked in that field, even developing codecs. From your desire to argue rather than read already demonstrated, I don't think you have a real good concept of what I said. And I was simplifying dramatically for comprehension; fully describing what it really does requires a LOT of VERY complex math.



jsanders said:


> With dish's compressed up the wazoo SD signals, there isn't enough information to do a good job scaling the picture. Oddly enough, I've found that using the composite cable on the compressed SD picture works well, and precisely because everything gets combined and things get smeared a bit. The result is that smeared colors look better to me than blotching and solarization.


Decent scaling takes care of blotching/etc., as would antialiasing or a number of other techniques that are usually built into the scaling. Not that they can fix over-compression, but our cable company was far worse, and so was the DirecTV images I saw last year.


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## dave1234 (Oct 9, 2005)

Mr. Crowley said:


> You guys need to realize DVI is 8-bit and HDMI is 10-bit, so there will be a difference when using the DVI input. If you want to read further read this (just add www at the beginning):
> 
> avsforum.com/avs-vb/showthread.php?t=556134


But all Mpeg2 is 8 bit so in the end it doesn't matter if HMDI is 10bit and DVI is 8 bit.


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## jsanders (Jan 21, 2004)

LtMunst said:


> This is nuts. You are trying to say that software drivers have nothing to do with the video output?  Wonder how software updates have been able to fix video issues in the past (like the 942 smearing issue)? Guess the updates somehow changed out the chipset. :lol:
> 
> All 3 of these receivers are specialized computers running on the Linux operating system. Just like your home PC, anything displayed on your monitor is the result of both hardware and software processing. There is no straight pipe from the MPEG decoder chipset to the HDMI output.


You're right LtMunst, software does write to control registers for the decoders and scalers and such, and that can have a huge effect on what is viewed. That code, while it is probably part of a driver doesn't have to be in a driver. As far as chipsets being changed on the fly may sound laughable, it can happen (I'm not suggesting the 622 is this way though)! If you recall, however, the 921 has programmable hardware in it. They got software updates in it that programmed FPGAs. Those chips are generally expensive and used mainly for development, but there are a fair number of shipping products with them.

As far as the there being no straight pipe from the decoder chip to the digital output goes, you might want to think about that a bit. You are right, these receivers are computers running Echostar DVR software. These computers do not have the processing power to to be in the critical path between the decoder chipset and the video output. The software may put menus and programming guides on the screen by writing to video memory, that software does not process all of the bits going from the decoder to the digital output.


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## jsanders (Jan 21, 2004)

LtMunst said:


> Ok...lets play semantics a little more. There is NO SUCH THING as a digital broadcast signal. Last I checked, all radio transmissions are in the form of an analog sine wave. Can that analog wave carry digital info?....sure. But that requires an A/D conversion.
> 
> Carrying this even further....Every process within the receiver or TV is completed using an electrical current based on a 60hz alternating sine wave. In this respect, ALL functions are analog.
> 
> ...


The LCD doesn't use #1, or #2. There are more kinds of DACs though.

How about #3, 
The Pulse Width Modulator, the simplest DAC type. A stable current (electricity) or voltage is switched into a low pass analog filter with a duration determined by the digital input code.

In this case, the pulse width modulator (PWM) is what is happening in your LCD. The low pass filter is accomplished via the physical properties of the twisting liquid crystals in the display's pixel.


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## jsanders (Jan 21, 2004)

TechnoCat said:


> I've worked in that field, even developing codecs. From your desire to argue rather than read already demonstrated, I don't think you have a real good concept of what I said. And I was simplifying dramatically for comprehension; fully describing what it really does requires a LOT of VERY complex math.


Cool! Maybe you can enlighten us a bit then. What codecs have you developed? I'm aware that the DCT based compression is complicated. Could you take a couple of paragraphs to give us a bit more details? I'm interested to know. Why do they do Discrete Cosine Transforms instead of Discrete Fourier Transforms? It seems that they are similar in what they do.


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## jsanders (Jan 21, 2004)

SaltiDawg said:


> After your numerous pompous and arrogant posts, suggesting a lack of understanding of the issue, you have the cajones to admit this?
> 
> Ploink!:nono2:


I guess we all have good days and bad days SaltiDawg. :rolling: Yesterday wasn't one of my better days. Didn't mean to come off as "pompous and arrogant". Sorry about that!


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## jsanders (Jan 21, 2004)

knealy said:


> Well the 921 was sent back for my $200 credit. I had also returned a 501 for a replacement. Unfortunately they gave me a $25 credit for the 501 in exchange for the 622. So it took quite a while to straighten out that mess. They claimed they hadn't received a 921. But I had the UPS tracking info showing that they signed for it two days before the 501 arrived. Then they said it only indicated that they'd got a package, but not what was in it. So I asked them to tell me what was in it. Finally they relented and told me I'd be getting the credit.
> 
> Now to answer your question. Yes, I used the same channels, HD and SD to check the results. I also paused the HD picture so I'd be sure to have the same image.
> 
> Don't know where to go from here except just to use the component video.


I've got one more question for you knealy.

CNet.com said that the specs on your TV's native resolution is 1386 x 788. Is this true?

What are you setting your tv output too?

Have you tried comparing the digital to component on your screen with the output set to 480p, 720p, and 1080i? Does the component look better than the digital in all three cases? Does the quality change at all for either output in all three cases?


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## gsalem (Feb 4, 2004)

jsanders said:


> Cool! Maybe you can enlighten us a bit then. What codecs have you developed? I'm aware that the DCT based compression is complicated. Could you take a couple of paragraphs to give us a bit more details? I'm interested to know. Why do they do Discrete Cosine Transforms instead of Discrete Fourier Transforms? It seems that they are similar in what they do.


DCTs can be easily computed with 16 bit integers; this makes it an easy problem to throw silicon at, seeing all of the 8x8 DCTs that MPEG (or H.26x) requires. DFTs
require floating points intermediates, even though the start points are just 8 bit
integer (PEL) values. (And actually, DCT isn't complicated. The complicated parts
are doing Motion Estimation efficiently and parallelizing bit encodings).

;-)

Seriously, my objective eye tells me the opposite. I had a 921 with DVI. At least
on my native 720p plasma, the 622 with an HDMI/DVI cable gives a better picture.


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## jsanders (Jan 21, 2004)

gsalem said:


> DCTs can be easily computed with 16 bit integers; this makes it an easy problem to throw silicon at, seeing all of the 8x8 DCTs that MPEG (or H.26x) requires. DFTs
> require floating points intermediates, even though the start points are just 8 bit
> integer (PEL) values. (And actually, DCT isn't complicated. The complicated parts
> are doing Motion Estimation efficiently and parallelizing bit encodings).
> ...


Oh, that is cool! So, the DCT does real numbers then if it is just an integer. Makes a lot of sense that they would use it if you can avoid complex numbers.

Motion estimation is difficult? At first thought, it seems like it would be as easy as doing the sum of an XOR on all of the bits between frames. The more that changed, the bigger the result would be. I guess that probably isn't a good estimator of motion though.

You have a native 720p plasma, eh? I guess they really do exist! 

It is hard to guess what knealy's problem is. His monitor isn't a native 720p, 480p, or 1080i display, that makes it harder to guess what he is seeing! He was also not comparing DVI to HDMI between the 921 and 622, but the comparison between component and digital between the two machines. It just makes it hard to guess what the problem is.


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## nataraj (Feb 25, 2006)

jsanders said:


> This isn't that movie, "The Matrix", you don't watch numbers on your screen that represent pictures, whether it be LCD, Plasma, DLP, LCOS, or anything else.
> 
> Something has to take those numbers and translate them into their corresponding wavelengths of light that emit from the television. The light that forms the picture that you see coming from the television is *analog*. You have to convert those numbers being sent to the television into the light produces the TV picture. There is always a digital to analog conversion.


This is funny. Isn't it the age old question of waves vs photos 

Anyway, DLPs are as digital as we will get in displays. Even the intensity of light at a pixel is output digitally by the display (how many times the mirror is "on" vs how many times its "off") and our eye/brain does the integration.


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## saweetnesstrev (Oct 8, 2005)

Ill take photos to prove hdmi is better then component. if ya guys want.


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## jsanders (Jan 21, 2004)

nataraj said:


> Anyway, DLPs are as digital as we will get in displays. Even the intensity of light at a pixel is output digitally by the display (how many times the mirror is "on" vs how many times its "off") and our eye/brain does the integration.


I can't argue with that one nataraj. You're right, the DLP does flash the light at the viewer's eye with differing frequencies to vary intensity. The viewer's eye does do the averaging in that case.

One must also note that with this technology, not everyone's brain does the averaging very well. Some people see the dreadded "rainbow effect" because their brain starts to see the individual colors from the color wheel flashing at their eye through each mirrored pixel.


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## jsanders (Jan 21, 2004)

saweetnesstrev said:


> Ill take photos to prove hdmi is better then component. if ya guys want.


This is with a 921, or a 622? Ideally, we are looking for pictures of DVI via the 921 being compared with pictures of the HDMI via the 622.

However, anything you would like to show us might be interesting. Just make sure you tell us what your TV is, what the native resolution of the TV is, what the output resolution is of your PVR, and what PVR you have.

For the comparison to be of any use at all, you need to make sure that both inputs on your TV have been properly calibrated to meet ISF specifications.


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## nataraj (Feb 25, 2006)

jsanders said:


> One must also note that with this technology, not everyone's brain does the averaging very well. Some people see the dreadded "rainbow effect" because their brain starts to see the individual colors from the color wheel flashing at their eye through each mirrored pixel.


The problem of rainbow is purely because the current cheaper projectors use one chip. With 3 chippers they go away. Also with the current year models from Samsung etc. which use LEDs instead of UHP, they go away - not just that they can also increase the color space to something that has not been possible in any other technology.


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## jsanders (Jan 21, 2004)

nataraj said:


> The problem of rainbow is purely because the current cheaper projectors use one chip. With 3 chippers they go away. Also with the current year models from Samsung etc. which use LEDs instead of UHP, they go away - not just that they can also increase the color space to something that has not been possible in any other technology.


You forgot to mention that the new Samsungs, in addition to getting rid of the lightbulb and color wheels and replaced them with red, green, and blue LEDs, also got rid of that stupid wobilation technology! It will be capable of natively showing 1080p source material (without wobbling the whole chip) if anyone decides to offer that format.

It should be a great TV when it comes out!


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## harsh (Jun 15, 2003)

saweetnesstrev said:


> Ill take photos to prove hdmi is better then component. if ya guys want.


If you do this, make sure you set a relatively slow shutter speed. Most modern cameras have far too short an exposure time to catch a whole frame.


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## harsh (Jun 15, 2003)

jsanders said:


> One must also note that with this technology, not everyone's brain does the averaging very well. Some people see the dreadded "rainbow effect" because their brain starts to see the individual colors from the color wheel flashing at their eye through each mirrored pixel.


The portion of the population that has a problem doing intensity averaging tend to wear sunglasses under flourescent lighting. The color wheel issue is a much higher frequency yet afflicts a much larger percentage of the population. Today's el-cheapo color wheel displays three colors at 120Hz (60rps*2 sets of R-G-B/revolution).

Of course this isn't an issue with three chip DLP.

I recall reading that the DLP intensity cycle is about 50KHz; well above the 50Hz that fools most PAL and SECAM viewers.


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## harsh (Jun 15, 2003)

jsanders said:


> You forgot to mention that the new Samsungs, in addition to getting rid of the lightbulb and color wheels and replaced them with red, green, and blue LEDs, also got rid of that stupid wobilation technology!


You can't do away with wobbulation in 1080p DLP until such time as TI ships 2MP chips. Samsung has NOT done away with wobbulation in 1080p now nor in the near future. Given the performance of the current technology, it is unlikely that they'll bother going there.

The manufacturers need to spend their time incorporating better scalers as they've pretty much topped out on the HDTV display resolution issue.


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## boylehome (Jul 16, 2004)

harsh said:


> Samsung has NOT done away with *wobbulation* in 1080p now nor in the near future.


Wobbulation, what is it? Thanks


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## harsh (Jun 15, 2003)

boylehome said:


> Wobbulation, what is it?


Try your favorite search engine. Wikipedia also has a tidy definition:

http://en.wikipedia.org/wiki/Wobulation



Lao Tzu said:


> Give a man a fish and you feed him for a day. Teach him how to fish and you feed him for a lifetime.


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## boylehome (Jul 16, 2004)

harsh said:


> Try your favorite search engine. Wikipedia also has a tidy definition:
> 
> http://en.wikipedia.org/wiki/Wobulation


harsh, thanks for the url. Good information.


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## hdaddikt (Jul 2, 2005)

jsanders said:


> I've got one more question for you knealy.
> 
> CNet.com said that the specs on your TV's native resolution is 1386 x 788. Is this true?
> 
> ...


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## jsanders (Jan 21, 2004)

harsh said:


> You can't do away with wobbulation in 1080p DLP until such time as TI ships 2MP chips. Samsung has NOT done away with wobbulation in 1080p now nor in the near future. Given the performance of the current technology, it is unlikely that they'll bother going there.
> 
> The manufacturers need to spend their time incorporating better scalers as they've pretty much topped out on the HDTV display resolution issue.


I got that "no wobulation" info on the Samsung from this link:

http://www.engadget.com/2006/01/06/samsung-hl-s5679w-dlp-with-led-backlight/

I did a bit more digging and found that it is in fact wrong on that detail, someone misrepresented what it could do. They had an argument thread on that detail at cNet.com. For some reason engadget hasn't corrected their website. Arghhh!


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## auburn2 (Sep 8, 2005)

jsanders said:


> Let's see what you are saying here...
> 
> You were talking about Digital TVs, with digital inputs. A digit is representative of a finger on your hand, namely a digit. The number system on the TV is base 2, not base ten that humans use. In other words, the TV has only one finger, instead of ten found on the human hands.
> 
> ...


There is no D to A in a DLP or LCD TV. Actually if you use component cables it goes from analog back to digital after it enters the TV. The only analog component of what you see is the light itself (either a bulb or array of lights/LEDs). In these sets the light is always on. The technology is a little different, but both are digital displays, what they output is entirely digitally controlled.

In the single chip DLPs the light goes through a spinning color wheel which puts color on it. As with the bulb, the wheel is always spining, the colored light reflects off the inidividual micromirrors which are turned "on" or "off" through digital commands. This rapidly changing colored light passed through a lens to the screen and on to your eye. Your brain integrates the changing colors to create the image you see. What you see with a DLP is actually an optical illusion, the image you see is not really even there.

In an LCD the light passes through a series of LCD panels. Individual crystals in the panels turn on and off to filter the light and create the image you see. Again the control for the LCD panels is entirely digital "on/off".


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## jsanders (Jan 21, 2004)

auburn2 said:


> There is no D to A in a DLP or LCD TV. Actually if you use component cables it goes from analog back to digital after it enters the TV. The only analog component of what you see is the light itself (either a bulb or array of lights/LEDs). In these sets the light is always on. The technology is a little different, but both are digital displays, what they output is entirely digitally controlled.
> 
> In the single chip DLPs the light goes through a spinning color wheel which puts color on it. As with the bulb, the wheel is always spining, the colored light reflects off the inidividual micromirrors which are turned "on" or "off" through digital commands. This rapidly changing colored light passed through a lens to the screen and on to your eye. Your brain integrates the changing colors to create the image you see. What you see with a DLP is actually an optical illusion, the image you see is not really even there.
> 
> In an LCD the light passes through a series of LCD panels. Individual crystals in the panels turn on and off to filter the light and create the image you see. Again the control for the LCD panels is entirely digital "on/off".


That is only half true. We've been through this before.

Pulse width modulation with a low pass filter to do averaging is the simplest form of D/A conversion.

DLP is a digital display, because the mirror is either reflecting at the screen, or it is reflecting somewhere else. The DLP is actually doing half of the D/A conversion, it does the pulse width modulation, the viewer's eye does the averaging. It is okay to call DLP an all digital display.

The LCD screen, however, is different. It has a PWM input, and it also has a low pass filter in that the liquid crystals twist or, as harsh put it, they spin. They don't move very fast, they are slow, and this does the averaging in the display. This low pass filter actually changes with aging. This is why you have problems with response time of the LCDs. When LCDs get older, they get even slower, and while static pictures still look fine, fast movement doesn't. If you could look at the transfer function of an LCD element over time, you would see that it acts as a low pass filter that looses bandwidth over time. You see smearing and/or trails when LCDs get slower. This is because the low pass filter in the LCD itself looses bandwidth. LCDs are doing a PWM D/A conversion. The PWM input doesn't change over time, the LCD elements slow down in their averaging of the PWM and that causes problems. It is also evidence that LCDs are in fact acting as a low pass filter and, thus completing the D/A conversion in the panel.


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## nataraj (Feb 25, 2006)

harsh said:


> You can't do away with wobbulation in 1080p DLP until such time as TI ships 2MP chips.


TI has been shipping full 1080p chips. Thats what goes into 1080p single chip front projectors that were announced last year. AVSForum >3500$ projectors forum should give you all the details.

There is some confusion about whether the new samsung rptvs use these or some other chips - I'm not sure that has been confirmed one way or the other yet.


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## harsh (Jun 15, 2003)

nataraj said:


> TI has been shipping full 1080p chips.


DLP Cinema is pretty much reserved for commercial projectionists. I think you'll find that DLP Cinema equipped gear goes for tens of thousands of dollars. The new "low-end" Barco sports redundant 2,200 watt lamps and will light up a 15 meter screen.

This is not something that you'll find in a Samsung consumer rig. The CES report on the Samsung LED lit unit says that it features the wobbulated array. Samsung does claim that their HL-R7178W has 2MP, but I'm dubious. They claimed at the Winter CES that their 1080p stuff used the latest TI chip, but they didn't say which latest chip.

Not citing the specifications about TI chips seems to be a condition of licensing the technology. It forces the TV manufacturers to spend considerable time and energy trademarking names to differentiate their product from everyone elses.


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## koralis (Aug 10, 2005)

jsanders said:


> You forgot to mention that the new Samsungs, in addition to getting rid of the lightbulb and color wheels and replaced them with red, green, and blue LEDs, also got rid of that stupid wobilation technology! It will be capable of natively showing 1080p source material (without wobbling the whole chip) if anyone decides to offer that format.
> 
> It should be a great TV when it comes out!


As an owner of a wobbulated tv, I've just got to say that I think it looks great. You might not like the idea of it strictly from a technology-purist point of view, but the end result is just fine.


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## nataraj (Feb 25, 2006)

harsh said:


> DLP Cinema is pretty much reserved for commercial projectionists.


Not talking about that. Optoma HD81 that is coming out next month ...

Optoma HD81 1080p DLP official discussion


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