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I continue to be amazed at the growing number of input jacks one finds on the back (and front) of today's HDTV sets. This all started in the mid 1980's with the advent of the first audio/video components such as VCR's and early videodisc players. These devices gave rise to the "monitor/receiver" with one or two sets of composite (Right, Left, Video) RCA jacks. With the introduction of S-Video, another jack was added along with audio output jacks for the rising audio receiver market. The final addition to the analog complement was the "component" inputs (Y, Pr, Pb or YUV). This interface allowed the coupling of the wider bandwidth video information from DVD players to pass directly to the display, resulting in sharper pictures. However, because of the possibility of being able to copy high definition video via this interface, very few, if any, external HDTV decoder boxes use component connections. With the digital revolution and the increasing convergence of both TV and computer technologies, not only are we blessed with a plethora of multiple legacy analog jacks, but a whole new collection of digital interfaces, all with their own special purpose. This must be confusing to the HDTV retail selling force and most likely their customers. Most customers and retail sales personnel do not have a college degree in electrical engineering and computer science to fully understand what all of these holes and their complementary hoses do. The instruction books help and are probably the best reference, but it seems a little more in-depth knowledge is needed to make full use of the capabilities of these multiple digital interface features. I am not going to dwell on the analog connections as these are now well known, but let's take a moderately hard look at the various digital interfaces that are now (or will be) used in today's HDTV sets and related equipment. Because of the growing convergence of HDTV with computer and telephone technologies, the more salient interfaces related to both HDTV and computer equipment will also be included. HDMI Technical Identification - High Definition Multimedia Interface DVI Technical Identification - Digital Video Interface SPDIF Technical Identification - Sony/Philips Digital Interconnect Format FIREWIRE (iLink) Technical Identification - IEEE 1394 DTV LINK Technical Identification - IEEE 1394 plus 5C content protection ETHERNET Technical Identification - IEEE 802.3 or 10 -100BaseT (Mbps over Twisted Pair) The above descriptions are of the most salient digital connections found on today's HDTV receivers and associated components. However, because of that aforementioned increasing convergence of traditional consumer electronics and all information technologies, i.e. computers, games et al, other emerging connection technologies are certain to be embraced by HDTV equipment. Therefore, for completeness, I have added a summary of the most important of these emerging and expanding connection technologies. USB Technical Identification - Universal Serial Bus 1.1 and 2.0 Wi-Fi Technical Identification - IEEE 802.11b, a, g, and n WiMax Technical Identification - IEEE 802.16a Technical Identification - IEEE 802.15 At this time there are at least five different inter-industry groups working on DTV/HDTV network standards. Hopefully, there will be some convergence of thought from these groups that will result in a robust, secure HDTV A/V interconnectivity standard. The tremendous pace of evolving technology is sometimes a nemesis to developing and establishing technical standards. Further, the longer the network standards process takes, the harder it becomes to accommodate legacy equipment. The best consumer strategy is to protect the investment in the display system (i.e. monitor), which should have a lifetime of at least ten years. Separate signal delivering devices (i.e. boxes) are much less expensive to replace than the display. HDMI is probably the most stable connection technology as we look to the future. That's why I listed it first, and the more you have, the merrier. Ed *Also known as Digital Transmission Licensing Administration (DTLA). The "5C" refers to the five companies that developed and comprise the licensing group.
Posted by Ed Milbourn, March 7, 2006 11:41 AM
Reader Commentary >>>The final addition to the analog complement was the "component" inputs (Y, Pr, Pb or YUV). This interface allowed the coupling of the wider bandwidth video information from DVD players to pass directly to the display, resulting in sharper pictures. However, because of the possibility of being able to copy high definition video via this interface, very few, if any, external HDTV decoder boxes use component connections. So does this mean that since my new costco 'economy' HD LCD Screen doesn't have digital inputs that I am S.O.L. when it comes to viewing HD content on my TV?? Currently my cable provider (Charter) doesn't provide an HD option, but I will be moving to an area covered by Comcast and i had looked forward to getting the few HD channels that are available... Homer Brown... Hi, I was under the impression that DVI and HDMI were equal in the video area but while reading a DVD player shootout I read this, Aside from the macroblocking issue, the Faroudja continues to be one of our favorite de-interlacing/scaling solutions. It is one of only a few true 10 bit video processing chips available, and its diagonal line processing is still the best in the industry. Since the S77 has an HDMI output, it can deliver a true 10 bit video signal if the output is never converted to DVI. There is a common misconception in the electronics world that DVI and HDMI are identical except for HDMI’s ability to carry multi-channel audio signals on top of video. This is not true. DVI outputs 8 bit RGB signals only and cannot carry 10 bit video like HDMI can. In fact, HDMI is actually capable of 12 bit transmission as well. What does this buy you? Well if you are lucky enough to have a display with an HDMI input, you can significantly reduce the contouring artifacts that are c... The final addition to the analog complement was the "component" inputs (Y, Pr, Pb or YUV). This interface allowed the coupling of the wider bandwidth video information from DVD players to pass directly to the display, resulting in sharper pictures. However, because of the possibility of being able to copy high definition video via this interface, very few, if any, external HDTV decoder boxes use component connections. Hi homerbr, Not sure how this happened but the last line is incorrect. While I could speculate on what he meant it is best Ed provide the explanation. At this time and likely for the next few years the component analog outputs of broadcast related HDTV set top boxes will pass HD video so you should be just fine with any cable or satellite service and also OTA, over the air, HDTV. Analog outputs are still alive and kicking for broadcast HDTV content. At some point though it is expected that those connections will be down re... Hi, Richard, I'm not sure if you agree with the advice/opinion I've been giving with regard to "long runs" of digital cable. In Toronto I have knowledge of a firm which makes custom lengths of an analog "Belkin" component cable with choices of termination for reasonable prices but at this stage no custom lenghts of DVI or HDMI. In anycase my advice has been that long and potentially expensive lengths of hdmi to dvi cables are a waste of money in the long term since hdmi will soon be the norm. If someone must have a long stretch of digital cable it should be the best hdmi he/she can afford with the appropriate dvi to hdmi plug to tide them over. Even less expensive is either to do something that will either shorten the run of cable or stick with component video and coax or opt audio and make sure their display is ISF calibrated. Since I'm still convinced that the only technology that can give the venerable CRT a challenge in the PQ dept is the "still expensive D-Ila or it'... A comment in Ed's last article regarding the analog component outs for set top box makers has been clarified and Ed re-state his intent in the following e-mail: "Yes, most set top boxes DO have, and will continue to have analog outputs - but in the future for SDTV, not for HDTV. It is the strategy of decoder box manufactures to "down-rez" all analog outputs - even component outputs - in order to mitigate the HDTV "analog hole" relative to copy protection. Ed" So, one would think that acquiring a HDTV set today limited entirely to analog inputs would be unwise. _Dale We thank Richard for pointing out the need for clarification. dc... Hi Peter, The best advice from my experience out in the field is make sure the infrastructure wiring to the projector or display remains accessible either by simplicity of having access or putting in large conduit to and from so the cables can easily be changed out. This is the gravest error seen in many home theater installations. I would also add make sure your equipment is easily accessible for service; another grave error by installers since stuff still breaks. As for length, HDMI versus DVI terminations and using adapters your advice is not unreasonable provided you have kept in mind the fact that adapters in nearly all cases will detune the impedance of the connection. This may or may not have an effect, The length of the run and type of cabling is the determining factor. Simply put it either works, hooray, or it won’t with the in between condition of the image popping in and out or macro blocking. There is a common misconception in the electronics worl... More from Ed Milbourn
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About Ed MilbournAfter graduating from Purdue University with degrees in Electrical Engineering and Industrial Education in 1961 and 1963 respectively, Ed Milbourn joined the RCA Home Entertainment Division in 1963. During his thirty-eight year career with RCA (later GE and Thomson multimedia), Mr. Milbourn held the positions of Field Service Engineer, Manager of Technical Training and Manager of Sales Training. In 1987, he joined Thomson's Product Management group as Manager of Advanced Television Systems Planning, with responsibilities including Digital Television and High Definition Television Product Management. Mr. Milbourn retired from Thomson multimedia in December 2001, and is now a Consumer Electronics Industry consultant. |
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