WHDI is different from a combination of a codec and WiFi. For starters, WHDI is a CE standard which deals not only with the low levels of communication and video delivery but also with higher layers of CE control, A/V protocols, interoperability of devices, content protection and more. In addition, WHDI's "codec" takes into account the fact that the information is wirelessly transmitted and implements efficient error concealment methods. It also adapts better to the varying channel condition. So, you may think of it as a coder that was designed for wireless delivery. The wireless delivery itself is also different from WiFi both in the PHY level where tools that cannot be used for data are exploited for the video, and in the MAC level, which ensures a low latency and robust delivery while taking care of interference.
So, using a combination of a coder and WiFi is still far from being a solution since it does not ensure interoperability (even if the same coder is used on both sides) and it does not deliver the video robustly and in good quality while maintaining low latency. On the other hand, since most of the underlying tools are similar (OFDM, MIMO, 5GHz, compression toolsets) a combined solution with lower cost and higher functionality can be designed.
To JYoshida in response to Lyn_AL:
Thanks for the article, it was very informative. Two questions:
-Why do you think Amimon's solution will not have compatibility issue. I am thinking it will add to the crowd of codecs (essentially this is a compression scheme).
-Any thought that WiFi LAN proliferation will crowd the WiFi band and interferes with a video solution (in any form) operating in WiFi band?
To Lynn_AL: Actually, I used to think WiFi + H.264 is "the" solution for video networking at home. But no more. The proliferation of so many incompatible codecs used on various Web sites makes it very tough to settle on one codec -- for home networking. What do you think?
WHDI's JSCC Video-Modem approach has been proven in the market to provide the highest quality and robust wireless HD solution with practically no latency. An integrated WHDI and Wi-Fi solution will actually be simpler and much less complex than an integrated Wi-Fi+H.264 encoder solution since WHDI and Wi-Fi have many common building blocks (OFDM, MIMO etc.). Moreover, real-time compression with H.264 degrades quality and adds latency (which is a problem in gaming)
This seems problematic to me; the JSSC approach fundamentally breaks the partitioning of a Wi-Fi solution, which has a separate channel coder (in the PHY) and source coder (above the MAC). You can't just mix and match these pieces that easily. In addition, the JSSC in inherently lossy because it knows some bits carry more information than others; you'd have to put in a special "lossless" mode with equal error protection to carry traditional IP data, which basically puts you back to a standard Wi-Fi radio. Hence, an Amimon licensee would have to have a much more complex piece of silicon that combines a traditional Wi-Fi stack with a JSSC system that bypasses a codec, MAC, and parts of the PHY. I think the Wi-Fi guys will simply tack an H.264 codec on top of the MAC and ship it - why would they do anything else?
It does make sense for combining WHDI with WiFi -- definitely for Amimon, and perhaps for some service operators who want to offer multi-room wireless HD home networking solutions. A bigger question, however, is: Have you ever heard anyone asking for it?
A Book For All Reasons Bernard Cole1 Comment Robert Oshana's recent book "Software Engineering for Embedded Systems (Newnes/Elsevier)," written and edited with Mark Kraeling, is a 'book for all reasons.' At almost 1,200 pages, it ...