More hope for SDV on TiVo Series3 and TiVo HD

I’ve written about Switched Digital Video issues on TiVo before.

Well, it looks like past speculation has been spot on – the proposed solution is a USB 2.0 dongle that would connect to UDCPs (Unidirectional Digital Cable Products) and handle the communication with the cable system for SDV. The National Cable & Telecommunications Association detailed this solution in a comment filed with the FCC on August 24, 2007. (The cover page says *2006*, someone goofed.) There is an early mention on page 5:

(1) “Tuning Resolver:” For those CE manufacturers who believe that all that UDCPs need for success as a “good” product is the ability to receive switched linear cable channels, we are willing to develop and offer a small set-back tuning resolver (described in Part II) which, together with a firmware update in new UDCPs, can deliver two-way switched linear channels to one-way UDCPs.

The pertinent section begins on page 32 under the header “SWITCHED DIGITAL VIDEO MODIFICATIONS”.


Switched Digital Video (“SDV”) is a highly efficient bandwidth management technology employed by cable operators to transmit digital channels to customers on an “as-needed” basis. AT&T’s U-Verse video service utilizes SDV to deliver all of its channels throughout its entire footprint. Cable systems traditionally transmitted all channels simultaneously to all customers, requiring the use of bandwidth for all channels even if few — or no — customers were watching a particular channel. By contrast, when a digital customer tunes to an SDV channel, the channel is only sent to those customers that wish to view it. As a result, when an SDV channel is not being viewed, bandwidth is available for other services.

SDV preserves bandwidth so that it can be used for deployment of innovative new services. The recovered bandwidth can be used to deliver more High Definition, Standard Definition and on-demand channels. Indeed, the recovered bandwidth is essential for cable operators to deal with the digital broadcast transition. The bandwidth can also be used to deliver faster “bonded” channels with dramatically improved “wideband” Internet speeds of 100 Mbps; digital voice service; and more interactive two-way services. SDV promotes broadband deployment and adoption and causes less disruption for consumers because SDV, like on-demand service, uses intelligent network management techniques to expand digital capacity without tearing up the streets to install additional fiber.

It is in everyone’s interest for cable operators to use their networks more efficiently, and SDV technology allows the cable operators to do so. Unfortunately, as designed, one-way UDCPs are not capable of accessing SDV channels: SDV channels require two-way device functionality. In order to address this issue, the cable industry has worked with CE companies such as TiVo to arrive at a solution that can provide two-way SDV channels to one-way digital cable products through an external device attachment to the UDCP.

Under this approach — arrived at through private discussions outside of regulatory compulsion — a small “Tuning Resolver” adapter could be made available to the UDCP consumer. With only firmware modifications to new UDCP products, and a USB 2.0 connection, properly equipped UDCPs could receive programming offered on SDV channels. Many currently deployed UDCPs, including TiVo DVRs, have one or more USB 2.0 connectors and might even be upgradeable with firmware for SDV.

Licensing and testing of this optional feature of a UDCP will be provided under the existing DFAST agreement in a manner similar to that submitted to the FCC by various signators (TiVo, Motorola, Digeo, Solekai, Digital Keystone, and ViXS) for the optional M-CARD interface for UDCPs.68 That is, execution of a DFAST addendum, one-time verification testing, and self-verification thereafter.69

68 Nov. 13, 2006 joint submission in this docket by CableLabs, TiVo, Motorola, Solekai, Digeo, Digital Keystone and ViXs to implement Multi-stream CableCARDs for UDCPs.
69 Some verification testing is required, but it is likely to be minimal. For SDV to operate properly, the host must operate correctly with the cable headend when an end user has tuned away from a switched channel, or when the channel has remained unchanged with no evidence of user involvement or interaction (i.e., the user leaves the TV on and tuned to the switched channel, but then walks away from the TV for some extended period of time). Here, the host should act in sync with the headend to notify the end user of the pending switch (for example, display “are you still watching?”) before the reclamation of the channel.

No word on when such a thing would be available, but it certainly sounds like a lot of work has been done for the NCTA to publicly discuss the implementation of the actual solution. This solution is focuses solely on SDV, which is an immediate concern as more cable networks roll it out, but theoretically this solution could be extended to other bi-directional services such as VOD and PPV in the future, if the cable industry and consumer electronics industry could agree on a communications standard for those services.

I was tipped off to the FCC filing by an article in Broadcast Newsroom.

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  • Christopher D. Heer

    So the real question is…can this be adapted to IPTV? I expect IPTV to come front and center over the next few years, and in fact IPTV will be orderable where I live early next year. Would love to be able to use Tivo.

  • megazone

    The problem is ‘IPTV’ is an almost meaningless term. Broadly it simply means television delivered over an IP network – but IPTV has been used to refer to everything from private networks like AT&T U-Verse to downloading video over the Internet.

    I don’t see where SDV has anything to do with IPTV in general, they’re unrelated really. Unless there was a hybrid system where IP was used to deliver content to the home, then within the home it was redistributed over coax as SDV cable to inter-operate with standard devices – much as how FiOS arrives at the home on fiber, but is then redistributed within the home over coax.

    Depending on the IPTV network and how it works over all, it *may* be possible for TiVo to update their software to connect directly to the IPTV network – at least on the newer units which have sufficient Ethernet performance. Alternatively, an external adapter/tuner could be used – something that takes the IPTV signal and outputs it as QAM for the TiVo to capture via the tuner.