A wireless solution to get rid of the audio and video cables for a display has been a focal point for many years now. While many wireless adapters have come to market the Achilles Heal has always been that none of these solutions could fully duplicate the capability (and more importantly the performance) of a wired HDMI connection. At CES 2008 the WirelessHD group announced they were developing a new wireless standard and technology that could!
At CES 2009 there were press releases about manufacturers getting on board with WirelessHD to provide a wireless solution for displays and source components. This year Panasonic introduced their WirelessHD TC-P54Z1 Plasma display. The highlight of the LG press conference at CEDIA was their new LED line of LCD with their top-of-the-line WirelessHD 55LHX display also introduced earlier in the year. LG provides WirelessHD on two fluorescent displays as well, the 47LH85 and 55LH85. Rocketfish and Gefen recently introduced WirelessHD adapters to the market. The Gefen GTV-WIRELESSHD adapter has an MSRP of $999 and the Rocketfish RF-WHD100 is available at your local Best Buy for $599 (Geffen makes a number of wireless products that are not WirelessHD – watch the specs)
All of the displays come in the form of a dedicated and integrated wireless display product (might have one HDMI input) utilizing a separate control box (the term used in the repair industry). The remote control and A/V switching occurs on the box and it sends the final video and audio to the display pretty much just like the typical A/V receiver. The only ball-and-chain remaining is the AC cord!
During the press conference at CEDIA 2009 the LG rep stated their WirelessHD product was nearly lossless and that raised my eyebrows! WirelessHD had always been presented as a 100% lossless solution in their press releases but the devil is always in the details. So I did some specification research along with wireless technology in general ending with a phone conversation with John Marshall, the chairman of WirelessHD.
For me, a true lossless wireless solution has to fully duplicate the performance response of a wired connection, in this case HDMI. The highest requirement for video comes from the PC, not HDTV or Blu-ray (although that could change with 3D). While scan rate, such as 1080p, and frame rate, such as 60 frames gives us a general reference point the devil is in the details, in this case color detail as explained by fellow author Ed Milbourn in his column issue called Better Broadcast HD. HDTV is 4:2:0, Blu-ray is 4:2:2 and PC is 4:4:4 where the last two digits represent the amount of color detail provided which naturally requires higher bandwidth at 4:4:4. Only 4:4:4 contains the full resolution color response of the original image while the rest are methods of compression to reduce bandwidth or data storage requirements. On top of that PC encodes digital video 0-255 versus the 16-235 of HDTV and Blu-ray, again more data requiring more bandwidth. The highest requirement for audio is the ability to pass the HD audio bitstream or the multi-channel PCM equivalent of Blu-ray.
According to everything I can find, WirelessHD will be able to fully duplicate the video and audio performance of a wired connection even from a PC. John Marshall stated unequivocally that any technology used for WirelessHD has to pass stringent testing to qualify. Currently the technology is limited to the 60 GHz band as provide by SiBeam. This limits the capability to the same room only and it will not pass through walls. The distance between the transmitter and display is limited to 30 feet and per John Marshall this is a conservative rating to ensure success in the home (in a controlled setting they have been able to get 60 feet out of it).
WirelessHD is also committed to fully supporting the interoperability capability of HDMI such as the new CEC protocol that allows you to control all your HDMI products from only one like your HDMI equipped A/V receiver and the remote that came with it.
Four expensive HDTVs and some pricey adapters do not make a lossless wireless HDMI revolution and the most obvious missing player is the A/V receiver! If WirelessHD takes off we may see a future in 5-10 years where displays no longer support A/V switching having nothing more than an HDMI input for service (or optional input) and integrated WirelessHD for use in the home with other WirelessHD products. The power cord will probably still be required though.
This report would not be complete without touching on the fact that the term wireless HD is used by nearly all manufacturers of any wireless video product. The Devil is in the details so look for the term WirelessHD (where wireless and HD is not separated), their logo and a 60 GHz specification.
A great example of this is the recently announced WHDI specification claiming to support top quality uncompressed digital video distribution throughout your house. They also claim to provide the same functionality, cost and quality as a wired connection and state that providing a similar wired experience requires not using compression. On the surface the details sound pretty good and it sure sounds like a WirelessHD competitor but the devil is there to be found. The first hint is a scan rate limitation of 1080p at 30 frames. Knowing how this technology works it may very well be able to duplicate a wired connection up to that point covering home video for equal performance but not your PC. I can give them the benefit of the doubt so far. Regardless of all the terms they use to suggest quality one term never appears; lossless. The devil finally shows up at the bottom of the technical page in the form of compression semantics. No, this product does not take the original signal and apply a compression codec to limit bandwidth requirements like many other products in the field. What it does instead is use a similar type of compression used in audio for MP3 and the like; masking. Masking is a compression scheme based on removing the data the represents a low volume sound in an audio signal that would likely be missed by your ears due to other high volume sounds and therefore masking your ability to hear them; the masked data is thrown out and therefore defined as lossy, period. They have applied the same encoding scheme for video, separating the data of a video image into significant and minor data. The twist here is the transmitter is sending out all of this data and masking is being used as a form of error correction by the receiver. If the signal quality is less than the minimum required for all the data the receiver can throw away the minor video data as necessary and decode only the significant video data providing the perceptual illusion of quality; that would be lossy. They get to waffle on this form of compression because it is being performed on the fly based on reception quality at that moment in time; if you have perfect reception during every moment in time then technically there will be no form of video masking compression applied and the product claims are then valid; there is no compression. Isn’t being a high tech consumer so much fun? But keeping things in perspective, the main application for WHDI technology is multi-room distribution which requires the capability of working through walls, clearly a limitation of WirelessHD.
The purpose here is not to beat up on competing products and technology but to help our readers differentiate between their real capabilities and the marketing hype used to induce your purchase. Many of our readers are likely to be satisfied with the competing technologies and the best recommendation I have is if you decide to purchase one make sure you have a liberal return policy if you are not satisfied. For our performance readers there is currently only one wireless solution that fully duplicates a wired HDMI connection, WirelessHD, and don’t let the marketing hype of the competitors sway you.
How much extra would you pay for a display with WirelessHD? The Rocketfish product for $599 hits an intriguing price point for wireless, no doubt made possible by the volume Best Buy distribution can provide along with down the street brick and mortar availability nation wide.
How much do you care if the wireless connection is limited, such as the terms nearly lossless or visually lossless, versus getting every single bit of data to your screen for the best image possible?
Some useful links
Posted by Richard Fisher, January 15, 2010 8:35 AM
About Richard FisherRichard Fisher is the President of Mastertech Repair Corporation, serving north east Atlanta, Georgia, and has been servicing, calibrating and reviewing audio video products since 1981. Tech Services USA, a division of Mastertech, creates sites, communities and libraries for consumers and professionals to share their technology knowledge and learn from each other. These include The ISF Forum and HD Library. HDTV Magazine exclusively publishes HD Library and Forum for Tech Services USA.
Richard is ISF and HAA certified providing calibration and A/V reproduction engineering services. Richard is a technical consultant and also provides performance ISF and HAA home theater systems and calibration via Custom HT. Mastertech Repair Corporation is a factory authorized service center for Hitachi, Mitsubishi and Toshiba and a member of the National Electronics Servicing Dealers Association, NESDA, and the Georgia Electronics Servicing Dealers Association, GESDA.