Talk about HDMI

So, more specifically, what is HDMI? HDMI - High Definition Multimedia Interface - is actually just a logical progression on top of DVI. The video segment of the HDMI signal is actually compatible pin for pin with DVI, but in a much different package. HDMI improves on DVI by transmitting digital audio on the same interface, adding support for HDCP and also better DDC options for manufacturers.

HDMI provides 5Gbps over copper interconnects up to 15 feet - that's enough headroom for a 1080p signal and 8 channel audio. For those who like to do the math, a 1080p raw video signal and eight 192kHz audio channels require less than 4Gbps. So, there is a significant portion of unused overhead built into the HDMI specification. We've seen demonstrations of hooking your DVD player, receiver, and PVR each with a single cable at shows like CES and the word is that adoption of HDMI is going even faster than originally planned.

Below, you can see a cross-section of what the 19-pin HDMI cable looks like. The smaller, sturdier cable was designed with laptops and slimmer devices in mind. The DVI cable on the right shows the large difference in size.

Click to enlarge.

Right now, HDMI cables, like the original DVI cables, are very expensive. High quality cables easily retail for more than $100 each, although middle of the pack HDMI cables in the one and two meter range can be had for less than $20.

Remember the interoperability and quality issues with older DVI connectors on video cards? Since DVI is a relatively loose protocol, manufacturers are not strictly enforced to adhere to design principles. Signal quality on DVI connectors hit a low point in 2001/2002, but fortunately, it seems that awareness of the problem has started to rectify these issues. Since Silicon Image had a significant influence on the original DVI and HDMI specifications, they have taken it upon themselves to set up their own quality control laboratories, PanelLink Cinema (PLC). New devices will go through a very stringent verification process to assure that the next generation interfaces don't have the same problems which plagued DVI. The lab also works directly with Intel's HDCP spinoff licensor, Digital Content Protection, to assure that HDMI-ready devices adhere to the HDCP guidelines. Copy protection is a large facet in the HDMI specification, so it only makes sense that Intel and Silicon Image have so much invested in building trust with the content providers.

Today, the largest factor that plagues HDMI in the living room is whether or not devices are actually taking advantage of 8 channel audio. Many of the first generation HDMI ready devices only utilized two channels with the thought that TVs in particular would not need anymore than 2 channels. As a result, many new devices still ship with separate stereo inputs just as they do with DVI, but obviously, the push will be for new devices to drop these inputs in favor of digitally-protected high fidelity capabilities built in the cable specification. Stereo would just be a fall back.

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  • Tujan - Monday, January 17, 2005 - link

    The FCC and these proprieties mistake 1. The inaliable nature that 'broadcast in this way is 'illegal search and seizure...and 2.Representatives of 'media, are not representative of 'copyright law, or the authors of wich copyright law represents.

    A third can be added in wich would only 'mention of fact,but would actually deal with copyright itself. In that 'copyright is something relational to 'authors. It is not a business contract of a questionable 'first sale contract wich these broadcasts do their illegal deed through our premises,without our person to define them being so. Without our person to delegate the relationship of our equipment,or the functionality of person in wich this type of 'contract clause,deals usury within its blackmail of device,and copyright.

    The asset of copyright in second of person,is that of wich has its possession.Neither broadcast,nor FCC has this possession.And there is no specification known through copyright wich is tentative,or soon deliberated,wich is of and part of that assumed under copyright for author within its purpose.

    Conducting business association through this type of law,is still illegall search and seizure.While this is a physical connection in a specification true.The relationship of author/authors within copyright is the subject of the works copyright portrays solely for author in premise,and criteria. The subject of wich a criteria in media and device,the FCC should not be making itself party to without realizing its effects have resolved both author,and person of use in 'fair-use,of their own relationship to copyrighted materials conductive through them.In either asset (1),or asset(2).Author/person of use respecively.

    ))))))))))))))))) All comments and materials submitted to the Forums shall be considered non-confidential and the property of Anandtech, unless otherwise agreed in advance in writing by Anandtech. These Forums use moderators and administrators to monitor the content and appearance of messages posted in our Forums. However, considering the realtime nature of this bulletin board, it is impossible for us to monitor or review every message. Therefore, you agree that neither these Forums, nor any person or entity associated with them, will be held responsible for the contents, accuracy, completeness or validity of any information posted in them.< This statement as transposed is inproper english. If the FCC wishes to conduct the same procession w/o the person of its destinguishment in its 'effect. Then a relationship will have to be gained in its statement of effect. Since there is 'no effect,if there is no 'effect in its equivalency.

    Statements such as this are a 'null detail,of less importance here at a simple signing of a clause to enter a forum. However,when it comes to a person,this statement is an illegal one.When there is functional detail in an effect denied through its reception.

    Whatever Anantech does in its relationship to anantech for example remains its own person to do so. But without participation,a statement cannot be made so that an agreement lacks its person.Therefore cannot be an agreement.

    But Im discharging anantech of any responsibility for this agreement.Since certainly without my statement it would not matter anyway.

    Jan 16 2005
  • KristopherKubicki - Monday, January 17, 2005 - link

    ShadowVlican: The cable design is mostly intended for inputs sources to a receiver - which just so happens to also have the ability to go to any other devices like a TV, DVD player, Tivo, whatever. It's just a newer idea to replace all of the cables in the back - RCA, S-Video, DVI, component - in one swoop.

    But then again the DRM things are a different animal on their own. I don't personally enjoy the idea of more DRM, but with so much of the industry behind the technology I have a hard time thinking it wont become universally accepted.

  • ShadowVlican - Monday, January 17, 2005 - link

    oh yea. i agree with everyone that's saying Display devices (CRT, LCD, Plasma, etc) will never be combined with your sound setup... combining those 2 technologies are just plain stupid...

    how will we get surround sonud if the speakers are stuck to the damn TV.. what's the point of this stoopid new cable other than taking our rights away :@
  • ShadowVlican - Monday, January 17, 2005 - link

    what's wrong with dvi and separate audio connectors... they just want to make more money selling new useless products that actually DON'T benefit us now... i wonder what will happen to all those people who invested in HDTVs... Reply
  • shabby - Monday, January 17, 2005 - link

    #31 i'll bet the mpaa/riaa had something to do with that. Reply
  • ksnider - Monday, January 17, 2005 - link

    I have a new LCD TV with HDMI input and HDCP support.
    It also comes with schematics (on CD).

    I studied the schematics and was astonished by what I found: the HDMI digital input is terminated at a special purpose chip that deserializes and deframes the data, decrypts the HDCP, and converts the R, G and B to ANALOG!

    So on the output of this chip there is a normal RGB (plus sync) signal. This is fed to the switching matrix (where it is combined with all other inputs the TV supports) and then this analog RGB signal is again digitized and fed to the scaler that scales it up or down to drive the LCD panel.

    Of course, they do this because the whole point of HDMI is to protect the *signal*, not the picture quality. If the HDMI chip sent a digital signal to the LCD, it wouldn't serve it's purpose. In order to protect the digital signal, it *has* to output analog.

    This means, you're actually going to end up with a WORSE picture!
  • rika13 - Monday, January 17, 2005 - link

    dont bitch about it here, bitch about it to your elected officials, dumping about 50,000 letters (yes letters, as in dead trees) on your senator's desk will get his attention

    problem isnt they are taking rights away, its that its being done steathily, and circuit shitty, best lie, and others arent refusing to sell that crap
  • KristopherKubicki - Monday, January 17, 2005 - link

    Noli: I believe all HDMI inputs are HDCP compliant.

  • ProviaFan - Monday, January 17, 2005 - link

    Once the CBDTPA passes, you can kiss your "rights" goodbye, because even if you try to exercise them, the RIAA will call the FBI on your rear, and they'll be carting you off to federal pound-me-in-the-@#$ prison for 768 years about 5 minutes after you download illegal free/open source software to make a backup of your new notCD so you can play it in your car.

    I'm sorry, but I just don't submit to this "you all must give up your rights to control your own equipment because a few people abuse the capabilities of said equipment." Bite me, RIAA! :disgust;
  • bersl2 - Monday, January 17, 2005 - link

    #26: You mean "former current laws." Reply

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