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According to a spate of news stories this week, major players in the digital-home-entertainment segment have yet again found a technology that the group thinks can move HDTV video around the home " wirelessly. Without question, wireless video streaming would be a big win across the board. Consumers would love to watch an HDTV stream from any set-top box or DVR in a house on any TV in the house. Doing so with no wires is even better. The major consumer electronic vendors have chased this elusive goal for years. The latest effort called WHDI (Wireless Home Digital Interface) is based on technology from Amimon. The heavyweight supporters include Sharp, Hitachi, Motorola, Samsung, and Sony. And I'm about to tell you why the concept is fatally flawed.
Read about the recent development in "Consumer giants rally around Wi-Fi variant" by Rick Merritt of EE Times. Apparently Amimon is making the license fees to use WHDI technology affordable, and the supporters will help develop a new version of the standard that offers a robust content-protection layer that would protect content from any source to any destination.
Now I'm all for wireless video. In a prior job I wrote about the subject quite a lot and Google will find those links if you are interested. I was definitely guilty of flip flopping a couple of times as to whether I thought a wireless link could ever provide whole-house video distribution. These days I'm back on the side that says we will need a wired backbone. But that's not the point of this post. Moreover, even if the WHDI technology is viable, the timeline claimed by Amimon and its supporters is way to aggressive. Again, however, that's not my beef here.
The problem with the WHDI movement is that the concept is fundamentally flawed. The group is pursuing a technology that transmits uncompressed video around the home. They are taking on a far bigger challenge than they should need to. Amimon claims it can transmit an uncompressed 1080p stream " a 3-Gbps stream " around the home.
Why transmit uncompressed video and what do I see wrong with the situation? I don't think there's any reason to try and transmit an uncompressed stream. On its technology page, Amimon lists two reasons for uncompressed transmission. One involves content-protection technology. The content owners have long been happy with the secure HDMI link that moves uncompressed video a short distance between set-top- box and TV. Presumably WHDI would use similar technology and avoid scrutiny from the content community. In reality, the content owners have also endorsed content-protection over compressed links using DTCP (Digital Transmission Content Protection). There is no content-security-centric reason to move uncompressed streams.
Amimon also claims that uncompressed is the only answer because of the sheer number of different video codecs in use. This argument caries a bit more weight. But codec ICs are quickly evolving to support virtually every possible coding scheme. And there is a short list that will handle most any source. Moreover every TV today includes a decoder IC for ATSC HDTV and that's the primary stream of interest.
The problem with an uncompressed stream is simple. Even if WHDI can move one 1080p stream around a home, what about the second, the third, and the fourth? The situation becomes untenable quickly. Indeed, even a wired network can't support whole-house transmission of multiple 1080p streams. The industry needs to refocus on compressed video transmission " whether the network technology comes from Amimon, the 802.11 group, or some other technology base.
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