Greetings. You may have seen much (deserved) hoopla regarding the new relatively low-priced HD TiVo, that uses CableCARD technology to allow a direct interface between digital cable systems and the TiVo unit.

While it is generally understood that the current generation of these devices (this may well change within a year or two) cannot access two-way cable services such as Pay Per View (PPV) or Video On Demand (VOD), many potential buyers of this TiVo product may not be aware of concerns regarding the use of Switched Digital Video (SDV) on an increasing number of cable systems.

Briefly, SDV technology -- which is being aggressively deployed by Time Warner Cable and also by many other large and small systems -- requires two-way communications with the cable company servers to allow the customer to access all of the available channels. Without this capability, those channels on a cable system being managed via SDV would typically be inaccessible to the associated devices.

Since existing third-party CableCARD host devices of types including the new HD TiVo don't currently support the necessary two-way operations, users of these devices (including the new TiVo) could find themselves unable to watch or record channels of interest (the exact set of which will vary from system to system over time).

While there are continuing statements that the cable companies and TiVo are working on some sort of solution to this problem (keep in mind that CableCARD compatibility is an FCC mandate), no specifics on any possible "fix" or time frame for such a fix have been forthcoming.

There indeed are ways that the problem could be worked around. For example, signaling over the Internet could be used (newer TiVos are Internet compatible). Or, some sort of external device associated with one of the TiVo's various interfaces could be employed to communicate back to the cable system servers.

However, until there are more details available, such workarounds appear to be rather speculative right now. On the other hand, deployment of SDV and the problems it could cause for CableCARD TiVo users are very real and in some cases immediate.

I'm definitely not saying that you absolutely shouldn't buy the new HD TiVo -- it's a very nice box. But be warned that these potentially serious issues do exist at this time.

--Lauren--

Additional Notes (August 23, 2007): There is considerable confusion regarding CableCARDS. My understanding is that both CableCARD 1 and CableCARD 2 specifications actually support bidirectional communications. The more recent CableCARD 2 specs also have led to the first actual implementations of the "M-Card" (which can decode multiple video streams). See, for example, this discussion.

The stumbling blocks to the required two-way communications for supporting SDV natively on TiVo devices apparently have been cable company demands that certain of their (cable company) control software be running on the associated TiVo units themselves (something that TiVo has been unenthusiastic to permit), and that the hardware must also have the necessary bidirectional support functionality internally (and be appropriately enabled).

So, it's quite a mess right now, which is a shame, since the new HD TiVo really is an impressive piece of technology.

--Lauren--

Blog Update (August 25, 2007): Cable Industry Responds Regarding HD TiVo Incompatibilities