Advantage of using digital video input/output

[Ken]

What is the basic reason for using digital input/output as opposed to
analog signal? The application is for AutoCad with both 2D and 3D
display. Is the main advantage of digital input for gaming and movies?

Thanks
Ken K

 

[Rod Speed]

What is the basic reason for using digital input/output as opposed to analog signal?

Digital doesnt get degraded by the cable etc.

The application is for AutoCad with both 2D and 3D display. Is the main advantage of digital
input for gaming and movies?

Nope, anything where you want to maintain image quality.
The degradation happens most at the higher bandwidths,
so at the higher screen resolutions.

 

[Ken]

Rod Speed said the following on 1/1/2007 1:16 PM:

Digital doesnt get degraded by the cable etc.


Nope, anything where you want to maintain image quality.
The degradation happens most at the higher bandwidths,
so at the higher screen resolutions.

Rod, I just googled DVI to try to understand the DVI-I and DVI-D, single
and dual.

The present issue is that we have a monitor that, I am told, has some
blue lines randomly appearing when running non-intensive apps but
mega-problems when my daughter runs AutoCad. (She is about 250 miles
away). She swapped monitors, cable, etc., and the issue is with her
monitor on the analog circuit (the monitor is just fine on her
roommate's computer with either one's VGA cable.

Her monitor has the VGA adapter and a DVI-I dual link receptacle. Her
video card has VGA and DVI-I receptacles. As I understand it, the DVI-I
allows for both VGA and digital signals to be passed to the monitor.
Correct? I do not understand monitors well enough to know if there are
two VGA and one digital circuits. My thought is this: if we can bypass
the VGA circuit by purchasing a DVI cable, then, assuming there is no
digital circuit problem, that would solve her present problem. If that
is true, then I am unclear whether to use a DVI-I or DVI-D cable and
whether to use a single or dual link cable. So that adds a second
question: when does one use a single versus a dual link cable? Clearly
only one monitor connector can be hooked into one DVI-D connector.

This is a bit confusing. I hope I am able to communicate my lack of
understanding well enough!!

Thanks
Ken K

 

[Rod Speed]

Rod Speed wrote

Rod, I just googled DVI to try to understand the DVI-I and DVI-D, single and dual.

And had a melt down between the ears |-)
One of the clearer descriptions is
http://en.wikipedia.org/wiki/Dvi

The present issue is that we have a monitor that, I am told, has some blue lines randomly
appearing when running non-intensive apps but mega-problems when my daughter runs AutoCad.

That isnt the sort of problem you normally get
with a cable, its normally a video card problem.
So nothing to do with your original question.

(She is about 250 miles away). She swapped monitors, cable, etc., and the issue is with her
monitor on the analog circuit (the monitor is just fine on her roommate's computer with either
one's VGA cable.

The VGA cable is an analog cable. Presumably you
mean that the problem is with the DVI analog cable.

Her monitor has the VGA adapter and a DVI-I dual link receptacle. Her video card has VGA and
DVI-I receptacles. As I understand it, the DVI-I allows for both VGA and digital signals to be
passed to the monitor. Correct?
Correct.

I do not understand monitors well enough to know
if there are two VGA and one digital circuits.

No there isnt two VGA circuits, just the VGA circuitry is connected to
both the VGA connector and the appropriate pins of the DVI-I connector.

My thought is this: if we can bypass the VGA circuit by purchasing a DVI cable, then, assuming
there is no digital circuit problem, that would solve her present problem.

Maybe. We dont actually know whether
the problem is with the digital circuitry tho.

If that is true, then I am unclear whether to use a DVI-I or DVI-D cable

If you want to eliminate the analog signals, you can do that with a DVI-D cable.

and whether to use a single or dual link cable.

That depends on the resolution you are running the monitor at.

So that adds a second question: when does one use a single versus a dual link cable?

For the higher monitor resolutions.

Clearly only one monitor connector can be hooked into one DVI-D connector.

Sure, but it isnt dual in the sense of dual monitors, its dual in the sense
of two digital channels, that can carry twice as much information. A single
digital channel cant go fast enough for the higher monitor resolutions.

This is a bit confusing. I hope I am able to communicate my lack of understanding well enough!!

Yes, its clear what you are having a problem with.

 

[Ken]

Rod Speed said the following on 1/1/2007 4:58 PM:

And had a melt down between the ears |-)
One of the clearer descriptions is
http://en.wikipedia.org/wiki/Dvi


That isnt the sort of problem you normally get
with a cable, its normally a video card problem.
So nothing to do with your original question.

Hmmm.... I realized I forgot one piece of information. The reason for
the video card that we installed a couple of days ago is that the
problem with the lines began when the video was attached to the on-board
VGA controller on her ASUS mb. I think it is an Intel graphics
accelerator. The new card did not solve the problem.

Experiments:
Her monitor/on-board video controller/her cable---> random video lines
made worse by AutoCad or Adobe Illustrator

Her monitor/video card (radeon x800 with 128MB RAM)/cable---> random
video lines made worse when she uses AutoCad/Adobe Illustrator

Other monitor/her video card/her cable. All is well.

Her video card/other cable/her monitor. Same problem.

Other computer and video card/either cable/her monitor Same problem.

Seems like the common factor is the monitor, not the video card, as the
video card is just fine running the app with a different monitor and the
problem began before the new video card. No? Sorry I forgot that last
bit of info.

The VGA cable is an analog cable. Presumably you
mean that the problem is with the DVI analog cable.

No, the VGA cable. She does not have a DVI cable. That is what I am
looking to purchase as a trial to see if the problem is just with the
VGA circuit in her monitor. I think the way to go, then, is with a
DVI-D dual link to maximize the digital signal throughput and eliminate
the VGA circuit presumably. Reasonable? I think the native resolution
of her monitor is about 1280 x 1024.

No there isnt two VGA circuits, just the VGA circuitry is connected to
both the VGA connector and the appropriate pins of the DVI-I connector.


Maybe. We dont actually know whether
the problem is with the digital circuitry tho.


If you want to eliminate the analog signals, you can do that with a DVI-D cable.


That depends on the resolution you are running the monitor at.


For the higher monitor resolutions.


Sure, but it isnt dual in the sense of dual monitors, its dual in the sense
of two digital channels, that can carry twice as much information. A single
digital channel cant go fast enough for the higher monitor resolutions.


Yes, its clear what you are having a problem with.

After what I wrote above with the different experiments do you still
feel it is the video card and not the monitor?

 

[Rod Speed]

Rod Speed wote

Hmmm.... I realized I forgot one piece of information. The reason
for the video card that we installed a couple of days ago is that the
problem with the lines began when the video was attached to the
on-board VGA controller on her ASUS mb. I think it is an Intel
graphics accelerator. The new card did not solve the problem.

Yeah, I'd forgotten that you had said that previously.

It certainly changes things.

Experiments:
Her monitor/on-board video controller/her cable---> random video lines made worse by AutoCad or
Adobe Illustrator

Her monitor/video card (radeon x800 with 128MB RAM)/cable---> random video lines made worse when
she uses AutoCad/Adobe Illustrator

Other monitor/her video card/her cable. All is well.

Looks like a monitor problem, its sensitive to what is being displayed
and produces that problem based on what is being displayed.

Her video card/other cable/her monitor. Same problem.

Other computer and video card/either cable/her monitor Same problem.

Seems like the common factor is the monitor, not the video card,
Yes.

as the video card is just fine running the app with a different monitor and the problem began
before the new video card. No?
Yes.

Sorry I forgot that last bit of info.

Yeah, and I didnt remember you previously mentioned it until now too.

That likely means that the two PCs arent using the same video mode,
which is why her monitor works fine on the other PC. Presumably you
arent actually running Autocad on the roommate's PC.

No, the VGA cable. She does not have a DVI cable. That is what I am looking to purchase as a
trial to see if the problem is just with the VGA circuit in her monitor.

Yes, well worth trying.

I think the way to go, then, is with a DVI-D dual link to maximize the digital signal throughput

Depends on whether the video card supports the dual mode.
No problem in using a dual link cable if it doesnt tho.

and eliminate the VGA circuit presumably. Reasonable?
Yes.

I think the native resolution of her monitor is about 1280 x 1024.

You need to specify the refresh rate to know
if a single DVI-D link will be fast enough.

After what I wrote above with the different experiments do you still feel it is the video card and
not the monitor?

Nope, its definitely the monitor and a DVI cable is well worth trying.

The monitor may well just have a problem on the analog inputs.