Would multiple connected HDMI cable negatively impact image quality? - AVS Forum
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post #1 of 14 Old 03-21-2013, 08:56 AM - Thread Starter
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Hi,

 

I need to run about 30-35ft HDMI cable through the conduit in the ceiling in my HT room, to connect a blue-ray player to projector for 2D/3D 1080p movies. I could run a single 35ft cable that connects the blueray player directly to the projector, or, use wall plates to make it look neater. But with wall plates on both ends, and two more HDMI cables, It would add 4 additional cables in the connection, compared to the single 35ft cable. Would the extra connections negatively impact the image quality, or it doesn't matter for digital signals?

 

thanks,

 

Jason

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post #2 of 14 Old 03-21-2013, 09:01 AM
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‘Would the extra connections negatively impact the image quality’ – not impact on image quality but may impact on your system being able to deliver a stable image free from visual artifacts or suffering intermittent dropout.

Where possible I’d go with a single cable with no unnecessary breaks in the cable run.

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post #3 of 14 Old 03-21-2013, 09:32 AM
 
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Jason, Joe has given you some good advice for both of your questions.

I wanted to take a step back and make sure I understand what you are trying to do. You have a single Blu-Ray player going to both a TV and a projector. The projector implies a large screen, which brings up the question of how are you handling the audio?

Remember that HDMI can only send one audio and one video stream at any time. By the HDMI spec, that audio and video stream has to be compatible with *everything* active in your HDMI network. So if, for instance, you use the splitter/dist amp you mentioned and only your projector is 3D compatible, then you will not get 3D on either device. This is called the lowest common denominator.

The same thing is true with audio. If you hook up a 2-channel TV directly to your Blu-Ray player, then only 2-channel audio will be sent out.

In terms of the split cable / wall connections. When possible you want to stay with one cable. However, wall plates and small cables have advantages both from an aestetics reason and a prevent-damage reason. One long cable can also be pulled causing damage to whatever is being pulled. I'd rather break a wall plate than damage a piece of equipment (of course, I'd rather do neither).

Bottom line to all of this is to try it. If you are getting errors, you'll know it. They will be obvious on the screen such as lines or sparkles or no picture. It won't be subtle like muted colors or a less sharp picture. Of course for a long term compatibility standpoint, you want to make sure you use certified High Speed cables. At 35' you are greater than the maximum passive HDMI high speed cable length. However, active cables (such as Redmere) or converting to Cat 6 wiring would give you high speed throughput at 35'.
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post #4 of 14 Old 03-21-2013, 01:51 PM - Thread Starter
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Quote:
Originally Posted by Joe Fernand View Post

‘Would the extra connections negatively impact the image quality’ – not impact on image quality but may impact on your system being able to deliver a stable image free from visual artifacts or suffering intermittent dropout.

Where possible I’d go with a single cable with no unnecessary breaks in the cable run.

Joe

 

by "image quality", I did mean to include those things, like visual artifacts or dropouts. Thanks for the advice!

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post #5 of 14 Old 03-21-2013, 02:02 PM - Thread Starter
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Originally Posted by alk3997 View Post

Jason, Joe has given you some good advice for both of your questions.

I wanted to take a step back and make sure I understand what you are trying to do. You have a single Blu-Ray player going to both a TV and a projector. The projector implies a large screen, which brings up the question of how are you handling the audio?

Remember that HDMI can only send one audio and one video stream at any time. By the HDMI spec, that audio and video stream has to be compatible with *everything* active in your HDMI network. So if, for instance, you use the splitter/dist amp you mentioned and only your projector is 3D compatible, then you will not get 3D on either device. This is called the lowest common denominator.

The same thing is true with audio. If you hook up a 2-channel TV directly to your Blu-Ray player, then only 2-channel audio will be sent out.

In terms of the split cable / wall connections. When possible you want to stay with one cable. However, wall plates and small cables have advantages both from an aestetics reason and a prevent-damage reason. One long cable can also be pulled causing damage to whatever is being pulled. I'd rather break a wall plate than damage a piece of equipment (of course, I'd rather do neither).

Bottom line to all of this is to try it. If you are getting errors, you'll know it. They will be obvious on the screen such as lines or sparkles or no picture. It won't be subtle like muted colors or a less sharp picture. Of course for a long term compatibility standpoint, you want to make sure you use certified High Speed cables. At 35' you are greater than the maximum passive HDMI high speed cable length. However, active cables (such as Redmere) or converting to Cat 6 wiring would give you high speed throughput at 35'.

 

Thanks for putting some thoughts in this. Here is what my setup will be - one blueray player, using a HDMI spliter, one cable goes to HDTV (2D only), and one goes to projector (3D 1080p). The audio is an optical cable going from blueray to a receiver, which controls 5.1 sound system.

 

You brought up a point I forgot to state in my original post - as high speed HDMI is certified only up to 25ft, the advantage of using a wall plate plus another short cable on either or both ends is, I thought, is I could use a 25ft cable instead of 30 or 35ft cable, plus two 3-6ft table, this way all cables are certified high speed. But I also accept the more cables and more connections lead to more points for potential issues. Maybe I'll do what you suggest - try it.

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post #6 of 14 Old 03-21-2013, 02:14 PM
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Quote:
Originally Posted by seafan View Post

I could use a 25ft cable instead of 30 or 35ft cable, plus two 3-6ft table, this way all cables are certified high speed.
No, a 25' high speed HDMI cable plus two 6' high speed HDMI cables does not equal a 37' high speed cable. If it did, there would be 37' high speed HDMI cables.
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post #7 of 14 Old 03-21-2013, 03:02 PM
 
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Quote:
Originally Posted by seafan View Post

Thanks for putting some thoughts in this. Here is what my setup will be - one blueray player, using a HDMI spliter, one cable goes to HDTV (2D only), and one goes to projector (3D 1080p). The audio is an optical cable going from blueray to a receiver, which controls 5.1 sound system.

You brought up a point I forgot to state in my original post - as high speed HDMI is certified only up to 25ft, the advantage of using a wall plate plus another short cable on either or both ends is, I thought, is I could use a 25ft cable instead of 30 or 35ft cable, plus two 3-6ft table, this way all cables are certified high speed. But I also accept the more cables and more connections lead to more points for potential issues. Maybe I'll do what you suggest - try it.

So what will happen with a 1x2 splitter is that the Blu-Ray player will see the TV's limited capabilities and then output to the TV and Projector only what the TV can handle. So, no 3D. There are matrix splitters (for more money) that allow you to "tinker" with what TV capabilities are reported to the Blu-Ray player. But in that case, you'll send out a 3D video signal that your projector can handle but your TV cannot.

With the S/PDIF, you'll be limited to DVD quality sound. Dolby Digital, DTS and 2-channel LPCM. The high resolution audio for Blu-Ray, such as Dolby TrueHD and DTS-HD MA cannot be sent out over S/PDIF due to bandwidth limitations of the S/PDIF connection.

Just wanted to make sure you knew the limitations going in.

I think trying the cables is a good idea. Just make sure to get a good return policy in case it doesn't work out.
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post #8 of 14 Old 03-21-2013, 03:23 PM
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As Andy points out with a 3D capable Source plus 1 x 3D capable and 1 x non-3D capable Display you will want to ensure your 1x2 DA has the ability to ‘spoof’ the Source (using EDID management) so that the Source believes it is always connected to a 3D capable Display otherwise with the non-3D Display connected to the system (even if it is in Standby) you will be limited to 2D Output from the Source.

http://www.octavainc.com/HDMI%20distribution%20amp_splitter%202%20port.html

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post #9 of 14 Old 03-21-2013, 03:26 PM - Thread Starter
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Quote:
Originally Posted by alk3997 View Post


So what will happen with a 1x2 splitter is that the Blu-Ray player will see the TV's limited capabilities and then output to the TV and Projector only what the TV can handle. So, no 3D.

 

I should add that I won't be using the TV and the projector at the same time, does that change the situation? I mean, if I use the spliter, and hook up to both, but turn off TV while watching projector, will I get 3D?

 

The thought of using a spliter is that I won't need to keep unplug/plug the HDMI cable everytime I watch the projector.

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Unfortunately, it's not whether you are using them at the same time, it's whether they are connected to the splitter at the same time. That "off" button is really a standby button on *most* new TVs. So even when the TV is "off", it's still sending its EDID over the HDMI cable. If there are any TVs out there that don't do this, you would have to search reviews to find out. But, for the most part, "off" is not off.

Unplugging the HDMI cable is not a good long term solution since it really shouldn't be hot plugged either and that can lead to connector damage. There really isn't a cheap solution to the problem. Joe can tell you about matrix switchers which bypass the problem by changing the EDID.
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post #11 of 14 Old 03-22-2013, 07:29 AM - Thread Starter
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Originally Posted by alk3997 View Post

Unfortunately, it's not whether you are using them at the same time, it's whether they are connected to the splitter at the same time. That "off" button is really a standby button on *most* new TVs. So even when the TV is "off", it's still sending its EDID over the HDMI cable. If there are any TVs out there that don't do this, you would have to search reviews to find out. But, for the most part, "off" is not off.

Unplugging the HDMI cable is not a good long term solution since it really shouldn't be hot plugged either and that can lead to connector damage. There really isn't a cheap solution to the problem. Joe can tell you about matrix switchers which bypass the problem by changing the EDID.

 

If I turn off the blue-ray player when I plug/unplug HDMI cable to switch between TV and projector, (without using any spliter) would that still be considered "hot plug" that may lead to connector damage?

 

If I upgrade the blue-ray player to one with dual HDMI output, (such as Panasonic BDT-500) so one goes to 2D TV and the other goes to 3D projector, would that solve the problem of 2D TV disabling 3D signal to the projector?

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post #12 of 14 Old 03-22-2013, 09:52 AM
 
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Originally Posted by seafan View Post

If I turn off the blue-ray player when I plug/unplug HDMI cable to switch between TV and projector, (without using any spliter) would that still be considered "hot plug" that may lead to connector damage?

Yes. Even with the Blu-Ray player in the off position, it's actually in standby so there is still "juice" coming out of the HDMI port. That's the electrical side. The mechanical side is that over time repeated unplug/plug cycles can physically damage the connector, whether or not it is plugged into the AC socket.
Quote:
Originally Posted by seafan View Post

If I upgrade the blue-ray player to one with dual HDMI output, (such as Panasonic BDT-500) so one goes to 2D TV and the other goes to 3D projector, would that solve the problem of 2D TV disabling 3D signal to the projector?

Yes, either the Panasonic you mentioned or the later OPPOs will solve that problem with their independent HDMI ports.
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post #13 of 14 Old 03-22-2013, 10:01 AM - Thread Starter
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No, a 25' high speed HDMI cable plus two 6' high speed HDMI cables does not equal a 37' high speed cable. If it did, there would be 37' high speed HDMI cables.

 

Ok, so I gather that the limit is on the overall distance the signal travels thru HDMI cable, not the physical length of each cable?

 

on the other hand,  could we speculate that a single 37' cable is equivalent of 5 connected cable adding up to the same length (if we count the two wall plates, which is basically a very short cable), no better no worse?

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post #14 of 14 Old 03-22-2013, 10:33 AM
 
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No. The connectors and any wall plates will (perhaps slightly) change the distance you can achieve for full bandwidth.

This is a situation where try-it and see if it works applies. Of course, if you are worried about 4K or other high-bandwidth situations then trying it may not be sufficient. But, for 1080p/60 (or 1080p/24 3D), a good thick (24awg or thicker) standard speed HDMI cable will actually work at 35 feet. If you throw in Deep Color enabled, then it probably will work. I'm using a combined 62 feet (maybe 66 feet) of HDMI cable to reach one TV. The middle 50' cable is standard speed while the other two are high speed. Two wall plates are also included.

Without Deep Color enabled, I have no errors. With Deep Color I have handshaking issues that eventually get resolved but I can tell that bit errors are starting to occur. One day I'll replace the 50 foot in-wall with a Redmere cable but no need to now since everything that I'm currently using works.
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