# HDMI bit errors? How to measure / observe?



## sawyer (Feb 10, 2013)

What is the quality of HDMI for reproducing Audio Signal
How do you know?
How do you test?
can you extend quality audio digitally with hdmi?

What is the result of using HDMI to extend an otherwise analog signal
The following actually has application in my whole house multi-receiver setup. just put here to provide a theoretical example
Suppose you have source with hdmi splitter and hdmi extender (ie powered using cat6) providing the same input two identical A/V Receivers. There is a room with speakers for a 7.4 setup . One receiver drives front, surround, and two powered subs. The other A/V Receiver drives surround back and two powered subs (ie sub takes preout).

Let's say the front to back speaker distance is 30' however the wiring run is 120'.

Ignoring any difference in the cost to deploy assuming 12awg wiring for speakers and preout to subs is 75ohm impedance,RG6/U 22pf/foot capacitance wiring in either case.

I would expect that the hdmi method of distribution would produce in this case exact the difference of 100' of cable length
That is assuming that a dual av receiver implementation required a 20' analog - 
as opposed to 120' analog run to surround back and pair of subs required for a single av receiver


the point being and the question being raised is how does one measure/identify the quality of an hdmi signal?
Visually if there are "sparkle's present then it is apparent.
Is there a low cost option to get the bit error rate? or equivalent


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## NBPk402 (Feb 21, 2012)

I have no idea... Subscribed to see what the answer is. :T


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## gazoink (Apr 17, 2013)

sawyer said:


> What is the quality of HDMI for reproducing Audio Signal
> How do you know?


 You don't. It works, or it doesn't.


sawyer said:


> How do you test?


If it works and doesn't periodically fail, it's working.


sawyer said:


> can you extend quality audio digitally with hdmi?


 Yes, but I wouldn't. Extending HDMI is more expensive and more prone to problems than extending analog audio.


sawyer said:


> the point being and the question being raised is how does one measure/identify the quality of an hdmi signal?
> Visually if there are "sparkle's present then it is apparent.
> Is there a low cost option to get the bit error rate? or equivalent


No. The only HDMI test options are the basic continuity testers or the many kilobuck ($30K+) industrial HDMI test systems. It's one of the (many) failings of the HDMI concept: no field qualification. However, for between $1200 and $2000 you can get Cat5/Cat6 qualifiers that do measure important transmission characteristics of those cables, which, if you use them in your extender and test the wire before and after you pull, you've done all you can practically do. Except, $2000 for a cable qualifier isn't practical either.

You might look at extending just the digital audio bitstream, which depending on your AVRs, may or may not be possible. 

I would probably look first at extending line level audio, like if the primary AVR has pre outs. A Cat5 balun at each end, you're golden, solid, cheap.


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## rab-byte (Feb 1, 2011)

Is this theoretical or are you grappling with a practical application?

As stated above HDMI testers are available on the market. Check Atlona and Sencore, both will set you back a lot of money. They're really only useful if your working in the industry at a high level.


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## rab-byte (Feb 1, 2011)

The question of testing sound quality has given rise to snake oil cables and lofty claims about materials and construction. The poor mans test is still to plug it in and see if it works. HDMI extenders are useful, cat-6 or fiber, for tight runs and 50'+ runs. Outside these conditions a quality (not determined by price) HDMI cable is great.


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## gazoink (Apr 17, 2013)

rab-byte said:


> As stated above HDMI testers are available on the market. Check Atlona and Sencore, both will set you back a lot of money. They're really only useful if your working in the industry at a high level.


There are three levels of HDMI cable test systems: 1, basic continuity...just looking for a broken wire or bad connector. Cheap, but not very useful. 2. the Atlona/Sencore solutions, which test for "connectivity issues", which is not a test of cable performance, but rather a test for the result. The don't qualify a cable, they test for proper communication between devices, which involves cables. And 3. Real HDMI cable profiling test systems. These fit only into manufacturing and test labs. The profile the actual characteristics of a cable in terms of a few basics like bandwidth, return loss, and others. They are basically a "network analyzer" (that's electrical circuit networks, not computer networks), and thus are horrifically costly. These are actually what installers need, but because of cost and the depth of knowledge required to operate them, can't have. 

HDMI remains serious overkill for audio only. I could gripe and moan about what a complete mess HDMI is for many pages, but there's really no point. We have it, we're stuck with it until something better comes along, it's a poorly though-out, badly implemented top-heavy solution foisted on the consumer in the guise of a "one-cable connection", when in actuality, it's all about copy prevention. You can tell by how features keep getting added on with somewhat limited backward-compatibility. 

Not a fan, stuck with it, fight with it on a daily basis. Fortunately the average guy can plug in a 6' HDMI cable and have it work. It's just a mess for distribution, switching, and long runs.


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