# Will multiple HDMI connections lose quality?



## Hogger

Running HDMI from my DVD to my projector.
The easy way would be a single cable with little holes in the wall and ceiling.
The other way would be a short cable from DVD to a wall plate, then a long cable from wall plate up to the ceiling plate at the projector, then another short cable from ceiling plate to projector.
Will I lose image quality running three different cables, and multiple connections?


----------



## dyohn

HDMI is digital. As long as you have a signal then you have a signal, it is either there or it's not. Running through multiple connectors will not degrade the signal unless it stops it altogether.

Be aware that HDMI has a length limitation of about 50 feet. If your run is longer than that you will probably need to use an amplifier of some sort...


----------



## Hogger

50' I didn't know that. I'm looking at about a 25' run.
Thanks for the help, now I can install it the clean looking way.


----------



## selden

Make sure the cables are all certified category 2. Even medium length runs can have problems if low quality cables are used. HDMI is very sensitive to cable quality.

It probably would be appropriate to test the cables and wall panels by using them before you spend a lot of time pulling cabling though the walls.


----------



## Toby Jack

You say that the signal is either there or its not. I am a little confused on this one. So at long HDMI lengths there is the potential for signal degradation if am not mistaken. I was under the impression that signal degradation meant loosing some of the 0's & 1's and would therefore degrade the overall image on the screen. But what you are saying is that at a certain point in a long HDMI cable the component (Television) either receives all of the digital information or none at all? I'm confused:huh:


----------



## glaufman

Hogger said:


> 50' I didn't know that. I'm looking at about a 25' run.
> Thanks for the help, now I can install it the clean looking way.





selden said:


> Make sure the cables are all certified category 2. Even medium length runs can have problems if low quality cables are used. HDMI is very sensitive to cable quality.
> 
> It probably would be appropriate to test the cables and wall panels by using them before you spend a lot of time pulling cabling though the walls.


Some equipment is more sensitive to the longer runs also.


Toby Jack said:


> You say that the signal is either there or its not. I am a little confused on this one. So at long HDMI lengths there is the potential for signal degradation if am not mistaken. I was under the impression that signal degradation meant loosing some of the 0's & 1's and would therefore degrade the overall image on the screen. But what you are saying is that at a certain point in a long HDMI cable the component (Television) either receives all of the digital information or none at all? I'm confused:huh:


What happens is that if 0's and 1's start getting lost, the communcation protocol breaks down, the equipment on the receiving end can't figure out what it's being told, and "gives up"...
Often the HDCP is the first thing to go, in which case the source equipment gets scared and closes the city gates...


----------



## selden

What greg said!

One of the intermediate failure states is for some framerates and resolutions to work, but others not. Switching from 1080p/24 movie and menu content on a BD to 1080p/60 extras content often causes the loss of the image, for example.


----------



## Toby Jack

It's sure is great having experts on this forum


----------



## selden

Many of us have become "experts" by having been burned by the problems you're smart enough to ask about ahead of time!

In my case, I was lucky enough that my projector has "greater than 15 meters" cable setting. It saved me from spending another $200-300 on an HDMI cable extender. I was using a high quality (AudioQuest X) 15 meter cable, but the projector (Mitsubishi HC3800) simply couldn't sync reliably, which would often cause it to go into an automatic shutdown.


----------



## bootman

dyohn said:


> HDMI is digital. As long as you have a signal then you have a signal, it is either there or it's not. Running through multiple connectors will not degrade the signal unless it stops it altogether.
> 
> Be aware that HDMI has a length limitation of about 50 feet. If your run is longer than that you will probably need to use an amplifier of some sort...


There is a bit more to the 'bits is just bits" argument.
All digital cables carry analog like waves at very high frequencies.

I'll try to put it as simply as possible without going deep into digital transmission theory.

An analog wave has a positive and negative swing.
(picture a simple sine wave)

A digital signal is represented like a square wave where the peaks are extended through time.
This is how the zeros and ones are represented in the digital world.
example:
A positive voltage can equal "one" or "on".
A negative voltage can equal "zero" or "off"

How both types of signals travel through a medium (copper, fiber, air, etc) is exactly the same.

The higher in frequency you go the faster you can stream the ones and zeros.
But as you increase the frequency of the signal it gets harder for that same signal to go through a given medium without changing due to different factors like resistance and outside interference.

With an analog signal, changes in the wave results in distortions which become visible or audible. (depending on the type of signal)

Now with digital, changes in the wave results in data loss.
Error correction circuits attempt to compensate for this loss.
However, when the errors become so great that the ECC cannot fully replicate the signal, you start to get interesting results.

With video, you can start seeing things like picture freezes or macro blocking.
Then there will come a point if things get bad enough that you will get no picture at all.


I haven't even scratched the surface of digital transmission but hopefully you can visualize how once the digital signal hits the cable, it basically behaves like an analog one.
It's only "ones and zeros" while it is in the transistors.
(and even that is not 100% accurate  )


----------



## glaufman

selden said:


> Many of us have become "experts" by having been burned by the problems you're smart enough to ask about ahead of time!
> 
> In my case, I was lucky enough that my projector has "greater than 15 meters" cable setting. It saved me from spending another $200-300 on an HDMI cable extender. I was using a high quality (AudioQuest X) 15 meter cable, but the projector (Mitsubishi HC3800) simply couldn't sync reliably, which would often cause it to go into an automatic shutdown.


For me, I was lucky enough that the cousin I was doing the install for doesn't really care that he's only getting DD equivalent audio! (issues only when sending hdmi thru avr...)


----------

