rAVe Reviews! HDMWhy?

HDMI-Uncensored-Paperback-Featured2One of my previous articles on my HDMI Extender Shootout at InfoComm13 yielded a few comments.  One of those came form Jason Griffing at DSI in Los Angeles, and asked if I had read “HDMI Uncensored” by Boccaccio and Flickinger.  I related that I hadn’t but that I was familiar with Mr. Boccaccio and needed to get the book.

Well, wouldn’t you know it, Mr. Boccaccio must have read the comments, because a couple weeks ago, a package showed up at my door, and inside was a signed complimentary copy of the book!  (Who said blogging doesn’t pay and that no one reads the comments?)

I promptly dug in to the text and was illuminated to all the inner workings of the HDMI format.  Given the addressable market for the book itself, and the amount of time and energy that must have went into writing it, Boccaccio and Flickinger did this more as a service to integrators than they did to make a buck on a book.  It is well worth the cover price, and every integration firm should own a copy, (get one here).

So given the fact that I’ve written on HDMI before, and likened it to Lampoon’s Cousin Eddie, (you know the in-law you tolerate during the holidays because you have to but would rather never see again),  I had to relate what I thought of the book.

The major take away was that HDMI cables all have different perfomance signatures, as do HDMI devices.  As you add more pieces to the chain, extenders, DAs, etc, the reliability of your HDMI connection really becomes the composite of all these performance signatures, meaning that its a crap shoot at that point.  Even Boccaccio and Flickinger state that

“The only concern that any user will ever have with HDMI is its reliability.”

Why is that exactly?  It’s not because it can’t work, but more because manufacturer’s can, as the book states, “do pretty much anything they want” when it comes to configuring their products as long as “they fall within HDMI’s operating window guidleines.”  This is a major issue.

One of the other interesting things to learn, is that the standard HDMI connector we all know and love, the Type A connector, has 19 pins/wires.  12 pins transport video and time data, 3 pins transport DDC channel data (EDID, HDCP, and Infoframes), 1 pin is for control, 2 pins are for power and plug and play return, and one is for ethernet.

The reason I found this especially interesting, is that in my AV experience, anytime I hear the word “converter” I run for the hills.  I don’t know how many headaches I had converting one signal to another.  It was always best to leave conversion out of the picture.  So when you buy an extender that uses 1 or 2 Cat5e/Cat6 cables to “extend” HDMI, what are you actually doing?  It’s not an extender actually, as an extender would need 19 wires, these devices use 8 or 16 wires for the 1 or 2 CatX versions respectively.  It is really converting the signal, combining data from several wires inside the HDMI cable to move them across long distances, and then converting the data back on the other end.  If they called these devices long range converters, what they actually are, at least I never would have expected them to work consistently in the first place, and would have built in extra hours of labor for onsite troubleshooting from the get go.

The book is a wealth of knowledge on all the issues related to varying reliability.  Get it and read it, you’ll learn a TON.

However it does not actually answer the question as to how we got stuck with HDMI as a standard in the first place, a question that even my clients used to ask me all the time.

The book does a great job of explaining the need for a digital standard and the bottleneck analog represents.  It even goes through the genesis of the IT based digital video standards from Firewire to DVI to HDMI.  However one thing I wish it would have dove into more was the existing SDI standard for broadcast.

It does briefly talk about standard SDI, mentioning that it needed two connections for 1080p and “was restricted to non-encrypted digital content.”  However, SDI progressed to 3G-SDI amd currently is used on cinema servers and cinema projectors, devices that utilize much higher quality content than Blu-Ray.  This means that content used in that environmant has a much higher risk of being used for high resolution content copying and distribution.  So why does the Hollywood crew allow it?  It is actually encrypted after all.  It just uses a separate ethernet connection and encryption method.  Hmmm.

To take things a little further, another point that the book makes is that High Definition Copyright Protection or HDCP, (you know, the reason everyone tells us HDMI is necessary), is not even tied to the HDMI standard.  It is a whole different standard, owned by a whole different group, being DCP, LLC.  It was developed before HDMI and just happened to be integrated into that cable once it was created.  HDMI is not necessary for HDCP.  In fact, the book relates that HDCP can even be used across other formats including “TCP/IP and any compatible wired or wireless connection including WiFi, Ethernet, or USB.”  Another HMMM.

So we know that SDI can work with encryption, even if it is another type in cinema.  We know that HDCP can work over ethernet per the standards of HDCP itself, and doesn’t need HDMI.  So why couldn’t SDI with ethernet be used to deliver HD and HDCP?  Were integrators clamoring for an easier way?  I mean even if you had 2 SDI connections and an ethernet connection, that is less work than the old 5 wired RGBHV isn’t it?  That would have been an improvement in itself, let alone the increased quality and bandwidth associated with it.

The thing I want to know the MOST about HDMI, (and we all should), is what Boccaccio and Flickinger glance over on page 7 in the beginning.  They state that they don’t want to bore us “with the politics” of “this new digital interface” and how the architecture was decided.  I am begging you to please bore me!   That is the part that I want to be “Uncensored” here.

In my opinion, the promise of and desire for a simplified connection was not for the integrator.  It was aimed at the consumer.  There was a desire to create a connection that would make setup so easy that the consumer could do it themselves.  This would bypass the need for an integrator, someone who in the eyes of a TV manufacturer is adding extra cost to their product through attached professional installation, therefore limiting their addressable market.

So in the effort to sell more standalone TVs in homes, distributed video systems suffer still.  HDBaseT or AVB, (Firewire II, read the book) seem to have the promise to eliminate our dependence on HDMI in the future as HDBaseT and AVB ports are added to source and sink devices for direct CatX connections.  Hopefully that will take place and we won’t have to worry about HDMI in distributed video anyway.  It can be relegated to the home market in a 1 to 1 short range configuration where it actually works. . .most of the time.

Thanks again gentlemen for the book.  It is an awesome read even if it doesn’t explain how we all got left holding the bag on this one.

I know that we are past the point of return here, I get it.  I still however ask, “HDMWhy?”  We may never really know.