SWITCHED DIGITAL VIDEO

What is SDV?

SDV stands for Switched Digital Video, a scheme where not all TV channels are broadcast out from the cable headend to the homes that it serves all of the time. This is attractive to cable companies, because they can offer more TV channels than their cable plant has the bandwidth to broadcast. For example, you cable company may have 10 different channels in your lineup, but only 5 physical channels to send them from the headend to the houses they service. This requires a cable box that can communicate back upstream to the headend and say “I would like to watch ESPN2HD now” and then headend would take that request, assign it to a frequency and then tell the cable box “ESPN2HD is available on xxx,xxx kHz”




What does this mean for the Series 3 and Tivo HD?

At the current time, the Series 3 and Tivo HD is not able to communicate upstream to the cable headend, so it cannot send the request for channels that are assigned to SDV. Users of the S3 and THD will not be able to watch or record any of these channels. TiVo is working on a work around.


Which channels will be converted to SDV?Traditional methods send every channel to everyone, and if no one on your headend is watching that channel the bandwidth is effectively wasted. SDV allows them to turn off that channel when it's not being watched so that another channel can occupy that bandwidth. If a channel is always being watched it will probably never be converted to SDV. So the less popular a channel is, the more likely it will be converted to an SDV channel. See this Multi-Channel news article.
http://www.multichannel.com/article/CA6454447.html


Is this likely to change anytime soon?

The NCTA and TiVo announced that a dongle will be available in the first half of 2008 that will enable the TiVo to work with SDV channels. It will be a USB device that connects to a USB port on the TiVo and then plugs into the cable TV cable. The TiVo could tell the device “I need this channel”, the device would send that upstream and receive the frequency assignment and tell the TiVo where to find the channel that it requested. There was some talk when the S3 first came out of some unused circuits on the motherboard that could be used for this purpose too, but that seems less likely. Recently, TiVo’s CEO discussed SDV while testifying before Congress and sounded very upbeat about TiVo finding a way to play nicely with SDV, but did not mention the S3 specifically. Check out this article on the Tivo Lovers Blog about for more details:
http://www.tivolovers.com/2007/05/10...-to-washington
Here is TiVo's official info on the adapter.
http://tivosupport2.instancy.com/Lau...1-754C3260112A
CableLabs press release about USB dongle
http://cablelabs.com/news/pr/2007/07...es_112607.html
NCTA and TiVo press release
http://www.prnewswire.com/cgi-bin/st...nktopagebottom
Of if you want to do something about it, report your missing channels to the FCC.
http://www.fcc.gov/cgb/complaints_general.html


What about FIOS?

Right now, because of the fact that FIOS uses fiber optic cable to your house, FIOS has no need to deploy SDV – they have all the bandwidth that they need.

Where is SDV located right now?
SDV deployments are changing very rapidly, but according to a recent article in the WSJ (reg required) and a few reports from members, here are the markets that have at least one SDV channel.

Comcast
Denver
New Jersey
Time Warner Cable SDV in 6 of 23 markets including
Austin, TX
Albany, NY
Charlotte, NC
Greensboro, NC
Rochester, NY
San Antonio, TX
Bright House Networks
Tampa, FL

Cox Communications
Northern Virginia