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Do HDMI Cables Matter?

by Amit Thakar November 05, 2008
Do HDMI Cables Matter?

Do HDMI Cables Matter?

That's the big questions. Do HDMI cables matter? If you were to pose this question in an AV forum, the answer you’d likely get from a lot of folks would probably be a resounding "no." And you couldn’t blame them for thinking so. After all, a quick online search for high definition multimedia interface (HDMI) cable reviews shows that cheap, no-name HDMI cables seem to perform just as well as more expensive, branded cables. The logic assumes that since HDMI is a digital signal, the cable just pushes the bits through, and, unlike analog cables, the cable itself can’t really make the video look any better. While there is a kernel of truth in this, it’s not really that simple.

The recent HDMI 1.3 specification brought significant changes over HDMI 1.2. The most important change was the doubling of single-link bandwidth from 165MHz to 340MHz. This equates to a data rate of 10.2Gbps on the HDMI link (3.4Gbps per data channel). This increase in data rate means that HDMI can scale to support higher resolutions beyond 1080p, such as WQXGA (2560 x 1600), higher color depths such as 12-bit and 16-bit Deep Color (up from 8-bit today), and higher resolutions up to 120Hz (up from 60Hz today).

To help installers and consumers differentiate cable performance, HDMI Licensing, LLC,

the agent responsible for licensing the HDMI specification, announced that cables will be tested as Category 1, or standard speed, and Category 2, or high speed. Category 1 cables are tested at 75MHz, or 720p/1080i resolution, while Category 2 cables are tested at full-rate HDMI 1.3 speeds, or 340MHz, which includes 1080p resolution and beyond. HDMI Authorized Test Centers (ATC) conduct the testing, and cables that pass receive a certificate similar to Figure 1. While the ATC tests cable performance, another entity called Simplay Labs tests and certifies cables (and other HDMI equipment like sources and sinks) for compatibility and interoperability in real-world usage scenarios. Passing ATC certification is a prerequisite for Simplay HD testing.

ATC certificate
Figure 1. HDMI Category 2 Certificate

However, the vast majority of HDMI cables sold in the market today are not Category 2 certified and are marketed as just “1080p compatible.” If you were to plug these cables into a Blu-ray player, chances are they would work just fine with today’s 1080p content. But all bets are off as soon as you plug these cables into future hardware and content capable of full-rate HDMI 1.3 at higher resolutions, color depths and refresh rates. This is due to the fact that as data rates increase, it becomes increasingly difficult for cables to transmit a signal reliably. To help ensure adequate performance, the HDMI specification defines the amount of jitter that is permitted at the transmitter and receiver. Jitter relates to the amount of uncertainty in interpreting 1s as 1s and 0s as 0s. With an increase in data rate, meeting the jitter requirements becomes increasingly difficult. One major limiting factor for sending high-speed data over conductors is the “skin effect,” which is the tendency of an alternating electric current (AC) to flow mostly on a conductor’s surface (skin) at high frequencies. This causes the effective resistance of the conductor to increase. As seen in Figure 2, the net effect is increased signal jitter, which makes it much more difficult for a receiver to correctly determine the 1s or 0s in the digital signal, leading to pixel errors, loss of audio and visual artifacts such as snow and streaks across the screen.

HDMI cable loss
Figure 2. Impact of Cable Loss on Digital Signals

All other conditions being equal, thinner- and longer-length cables cause higher loss. Since there are a variety of potential cable manufacturers, materials, and link distances, each multimedia installation can experience different levels of loss. As mentioned above, this loss can lead to visual artifacts such as snow or streaks, and even loss of audio since HDMI carries audio information. A solution to this, especially at longer distances, is to use actively powered technology to combat the loss and reduce the jitter. Gennum’s ActiveConnectä technology was designed specifically for this purpose. It is the only actively powered solution that can be integrated into a cable (within the HDMI connector), or in a standalone extender to enable HDMI 1.3 Category 2 performance over long reach cables. End products from cable and HDMI extender manufacturers integrate ActiveConnect technology to ensure high performance and robust signal integrity.

So what does all of this mean for a consumer? If you’re in the market for cables today, you want to be sure those cables can scale and handle future bandwidth increases, especially if you’re placing them behind walls. So while the content available today might play just fine, the same might not hold true once 12-bit and 16-bit Deep Color content becomes available (major manufacturers have already started releasing hardware capable of 12-bit). Shorter cables of less than 5 meters in length will likely be okay, but if you need anything longer, it’s important to buy HDMI 1.3 Category 2 certified cables from trusted manufacturers. This should be kept in mind before planning any installation and will save you considerable frustration, as well as money, in the long run.

Additional resources:

By Amit Thakar, Product Manager, Analog & Mixed Signal Products, Gennum Corporation


Bill_Bright posts on January 01, 2009 17:38
I hear ya! Fortunately, this is already paid for, and since the house is wired, I don't see a urgent need for more any time soon.
mtrycrafts posts on January 01, 2009 16:17
Bill_Bright, post: 503035

I gave up on Monster long ago due to lousy quality (and wild claims too). .

Well, I did not give up completely, I do have a couple bulk rolls of their speaker cable, but I put my own ends on.

Well, you may want to reconsider and give up on them completely. Just read some of the other threads here about Monster Cable and their bullying business tactics
Bill_Bright posts on January 01, 2009 11:49
I thought I would breathe some life back into this thread… arriving here through Do I Need 120 Hertz HDMI Cables?

As a retired ATC radio communications technician for the Air Force (well qualified to teach soldering techniques and cable making), I am reminded that cheap has two definitions that must not be forgotten. While certainly it means inexpensive, it also means lousy quality.

I gave up on Monster long ago due to lousy quality (and wild claims too). The last straw was a Monster S-Video cable I bought, excited to see some serious video improvement over the current composite connection I was using. The picture was incredibly sharp with great contrast, in B&W only. Not happy. Giving the connections a push to ensure they were tight, the color popped in and out. Upon opening the connector, I found blobs of solder, stray wire strands, birdcaging, and cold solder joints - in one connector! The opposite end was hardly better.

Quality parts + poor soldering techniques - Quality Control = cheap cables.

I did what I should have done in the first place - I ran up to Radio Shack and got their much less expensive but quality-made S-Video cable - I then let Monster know they need slash the overly imaginative marketing department and create an obviously lacking Quality Assurance department.

Well, I did not give up completely, I do have a couple bulk rolls of their speaker cable, but I put my own ends on.
highfigh posts on November 08, 2008 21:08
They matter, but in some cases, the cheaper ones have less problems with losing the handshake and causing dropouts.

I have a customer who asked about better audio interconnects to feed his Audio Research power amp and we discussed max price. I found what I could in that range and when I got them, I gave him my opinion of the materials quality and he just said I should use them, even though I offered to return them. I actually apologized for spending his money on them. No-name XLR ends, braided wires with a pearlescent white nylon mesh, $400/2M. What a joke. My 25' Audio-Technica mic cables sounded as good and I don't think I paid more than $20 each.

I'm fine with profits, too but marketing with BS is a real problem for me. Munster Cable annoys me and this same customer had another dealer in town install some equipment previously, using some big, fat-jacketed speaker wires. I would say ‘cable’ but that's not what it was. I pulled the “pants” off to clean up the ends and what I found was really offensive. 12 AWG stranded with an 18AWG solid wrapped around it “because highs and lows travel at different speeds”. Yeah- in 20', the signal on one conductor might arrive a microsecond sooner than the other and that translates to less about 12“. Since the wrapped wire is far less than 12” longer, the difference is much less than a microsecond. How audible is that?
FirstReflection posts on November 05, 2008 21:45
A good article.

It's important to stress that almost all HDMI cables that are short in length (around 15 feet or shorter) will almost certainly be able to handle 8-bit 1080p content, which is the highest signal quality in common use today. In other words, if all you're doing is connecting your DVD player to your TV, you're almost certainly fine with almost any HDMI cable.

This article's warning mostly applies to in-wall installations, or other installations where it would be difficult and/or expensive to replace the existing cable run. Only in that sort of situation are you likely to be using a longer than 15 foot length of HDMI cable and only in that sort of situation would it be likely that you could not easily and inexpensively replace the cable if there ever comes a time when far greater bandwidth is being used by common signals.

Thankfully, even if you are in need of a long length HDMI cable and one that is already fully tested and certified to comply with bandwidth usage far in excess of today's common signals, you do NOT have to pay an expensive price!

Both monoprice.com and bluejeanscable.com offer HDMI 1.3 Category 2 tested and certified cables in both short and long lengths for very reasonable prices.

The obvious and worst offender of spreading misinformation and charging far higher than necessary prices is Monster Cable. Much like Bose, Monster Cable's business and profits depend entirely upon misinforming the mass market and convincing the mass market through advertising that their products are superior to others and worth their extremely high margin prices. Retailers gladly go along with this despicable practice because the margins allow for greater retailer profits as well.

I'm fine with profits. In fact, I applaud Monster Cable and Bose because they are exceptionally good businesses in the sense that they make tremendous profit. What I object to is the amoral and dishonest aspect of achieving these profits through misinformation and lies.

Sadly though, the responsibility lies with consumers to uncover instances where they are being ripped off. It is not Monster Cable's nor Bose's job to conduct business in a fair and honest manner. It is consumers' job to demand fairness and honesty. And the only way to make that demand is through use of the open market. In other words, stop buying over-priced, under-performing products and instead, buy fairly priced, honestly performing products.

Consumer education is the key, which is why Monster Cable and Bose spend so much money on advertising. Advertising is nothing more than “education” for the mass market, but when that advertising is spreading misinformation, “education” becomes “propaganda”.
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