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SDV FAQ

854K views 2K replies 303 participants last post by  dlfl 
#1 ·

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, your 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, Tivo HD and TiVo Premiere?


With out an additional Tuning Adapter supplied from the provider, the Series 3, Tivo HD and TiVo Premiere 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.

Which channels will be converted to SDV?

Traditional methods send every channel to everyone, and if no one on your head-end 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. That being said, there are some providers who use SDV to deploy a very large number of channels, though.


The solution

The NCTA and TiVo worked together for over a year and finally the first working solution has reached TiVo owners in NJ on Comcast. The device from both Cisco and Motorola are called Tuning Adapters (formerly known as Tuning Resolvers) and connect via USB to the TiVo (9.4 or higher) and feature pass-through coax connections, so a splitter is not needed. So when you attempt to tune a channel delivered using SDV, the TiVo sends a signal via USB to the Tuning Adapter which sends the signal via coax upstream to the providers head-end. This turns the channel on and returns the tuning information back to the TiVo.

In a demo at the Cable Show a few years ago I had a chance to play and was not able to notice any difference in speed when changing channels that were deployed with traditional QAM or SDV.

Depending on the head-end there are two solutions, Motorola and Cisco (formerly Scientific Atlanta). If your operator hands out Cisco set-top boxes, then odds are they'll use a Cisco TA.

The Cisco STA1520


The Motorola MTR700


Some providers are offering these for free, but some charge at first or after a few months.

Here is TiVo's FAQ that address the Tuning Adapter.

Here is Time Warner's FAQ about the Tuning Adapter.

San Antonio TWC customers can pre-order their Tuning Adapter from here.

Here is some of the history of the Tuning Adapter, formerly known as the tuning resolver:
http://www.tivolovers.com/2007/05/10/mr-tivo-goes-to-washington
Here is TiVo's official info on the adapter.
http://tivosupport2.instancy.com/LaunchContent.aspx?CID=CBECF1B9-88DE-4B74-82C1-754C3260112A
CableLabs press release about USB dongle
http://cablelabs.com/news/pr/2007/07_pr_dcr_devices_112607.html
NCTA and TiVo press release
http://www.prnewswire.com/cgi-bin/s...11-26-2007/0004711019&EDATE=#linktopagebottom
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 plans to deploy SDV - they have instead chosen to invest in expanding their QAM RF overlay infrastructure and use IPTV for PPV and VOD.

Where is SDV located right now?

SDV deployments are changing very rapidly and impossible to track, in fact even most of the CSRs don't know if their company uses SDV and even if they do, not which channels.

Tuning adapters are here to stay
TiVo has asked the FCC to modify the rules pertaining to 3rd party CableCARD devices and eliminate Tuning Adapters. The proposed solution was to allow the TiVo to communicate via IP to the operators servers to perform the requests that are currently handled by the TA. This would've require that you have internet service from the same provider, but would eliminate a set-top box from the equation.

TiVo claimed it was necessary to increase reliability and would reduce costs for the operators. The NCTA and its members claimed that the TAs are well accepted and supported and it is not necessary to make any changes.

The FCC determined that it would rather not mandate a specific solution, but instead mandated the SDV channels work for CableCARD users and will be making it easier to report issues so that consumers could help enforce the mandate.
 
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#2 ·
bdraw said:
Unfortunately for Series3 owners, Switched Digital Video (SDV) channels are being deployed on cable systems all over the US. I did a few searches and wasn't able to find one thread that we could reference with a list of confirmed SDV channels. So I'll start it up and edit the first post, if it's useful then it will stick around, otherwise it will fall to the bottom.

Bright House Networks
Tampa FL
  1. Ch 694 Golf/Versus

If this is a lame post and this thread already exists, please post a link and perhaps this will act as a good pointer to the resource.
Pardon me for asking, but could you confirm that this is, in fact, the "complete" Versus and Golf Channel sharing your channel 694 (in which case, how do you choose between the two), as opposed to the Vs/Golf HD channel (which is a single channel that shows some Golf Channel shows and some Versus shows)?

-- Don
 
#3 ·
Honestly I don't know since I can't watch it, but according to BHN's website it's the Versus HD+ (7pm-12pm) everyday but Thursday/Friday when it's (12am-12pm). Then it's the Golf Channel HD+ (12pm-7pm) everday but Thursday/Friday when it's (12pm-12am) .
 
#4 ·
bdraw said:
Honestly I don't know since I can't watch it, but according to BHN's website it's the Versus HD+ (7pm-12pm) everyday but Thursday/Friday when it's (12am-12pm). Then it's the Golf Channel HD+ (12pm-7pm) everday but Thursday/Friday when it's (12pm-12am) .
That's not SDV - it's two networks airing at different times on the same channel.

SDV allows for more than one station to be accessible through a single channel (although just one at a time). The problem as far as TiVo is concerned is, there needs to be a way for the tuner to tell the cable system which of the multiple channels to air at any particular time - something a TiVo cannot do.

Pardon me for going off on a slight tangent, but does anybody out there know more specifics as to how SDV would work? Would each SDV channel have an on-screen menu of some sort, and the viewer would select which station to watch on a particular channel, or would different channel numbers be mapped to the same physical channel somehow?

-- Don
 
#5 ·
Don,
You can't tell it's an SDV channel if you have a standard digital cable box. I know it's SDV cause I called BHN to ask why I wasn't receiving the channel and they told me that the channel doesn't work with CableCARDs since they are one way (in many more words).

The fact that the channel splits it's time between two networks has nothing to do with the fact that it's an SDV channel.
 
#6 ·
Since Ben hasn't been able to keep up with the SDV reports in the OP, I'm going to keep this post updated with reports from the forums:

TWC Cincinnati:
http://www.tivocommunity.com/tivo-vb/showthread.php?p=5460259&&#post5460259
JoeSchueller said:
SDV just went in to effect here in Cincinnati today. They introduced ESPN2HD and placed a lovely asterisk next to it indicating that it was "Not available on one-way cable cards." I'm about to file my FCC comment now.
TW Hawaii:
http://www.tivocommunity.com/tivo-vb/showthread.php?t=364085
HiKent said:
TWC Hawaii moving all HD to SDV
We got a letter-bomb from TWC Hawaii today saying all the HD entertainment channels are moving to SDV on Sept 24. All that's left (HD-wise) are network programming, HBO and Showtime. They also got rid of a couple of dozen SD channels for good measure.

While I love my series 3, I certainly would not have purchased it to get only HBO & Showtime. As for the network programming, here in hawaii most HD programming is broadcast SD -- we don't even get all the networks in HD.

SDV Fear, uncertainty and doom -- replaced with doom.
TW Myrtle Beach:
http://www.tivocommunity.com/tivo-vb/showthread.php?p=5327449&&#post5327449
vstone said:
I think MHD & A&EHD are SDV on TWC in Myrtle Beach, SC (which probably means all of TWC in SC) , but I can't confirm that.
TWC Albany:
http://www.tivocommunity.com/tivo-vb/showthread.php?p=5424033&&#post5424033
miller890 said:
TWC in Albany, NY has started using SDV. Here is the list so far that no longer can be tuned in by the Series-3 with CC's.

746 Showtime West
747 Showtime 2 West
748 Showtime 3 West
749 Showtime Extreme West
750 Showtime Beyond West
754 Showtime Next West
755 Showtime Family Zone West
756 Showtime Women West
COX Fairfax (VA):
http://www.tivocommunity.com/tivo-vb/showthread.php?p=5468367&&#post5468367
precarious said:
Just got off the phone with a well-informed "customer loyalty specialist" from Cox Fairfax who told me which channels will go SDV effective on September 10th and which those of us with S3s using cablecards, will not be able to access as they will no longer receive a dedicated frequency.

157 - Nasa Channel
158 - Jewelry Television
159 - Cable Marketplace II
164 - CSPAN 3
223 - BET on Jazz
227 - Ovation
233 - AML - American Life TV
239 - CMP - Country Music Prime

All the PPV channels

All of the Spanish Language from 400-430
All other "Premium" foreign language channels from 271-276

He said that this could of course change after Sept. 10th, but this was the latest
info he had. All of the other channels he felt would not be affected. He didn't seem
to know very much about the "tuning resolver" talked about as a solution. Hope this helps anyone who is a Cox subscriber in Fairfax using a S3 with cablecards.

I actually started writing a post in notepad a few days ago on this exact topic (including what SDV is for those that aren't sure). One of the mods said that he would sticky it if there was value.

SDV FAQ moved from here into the OP. :D

Here's the full text of the URL for the OP:
http://www.tivolovers.com/2007/05/10/mr-tivo-goes-to-washington
 
#7 ·
searching the Time Warner Raleigh website for "Switched Digital" gives 1 hit. And that hit is a graphic for cable cards saying that cable cards can't get switched digital channels. I haven't tried, but I suspect if I call customer service and ask about these SDV channels, they will have no clue what i'm talking about.
 
#9 ·
bdraw said:
If you have links, please submit them.

GoHokies,
If you don't mind I'll copy your great SDV synopsis into my first post.
Not at all, you beat me to the punch. :D

I'll post up some of the links that I found the info from also.
 
#10 ·
bdraw said:
If you have links, please submit them.

GoHokies,
If you don't mind I'll copy your great SDV synopsis into my first post.
The link to http://www.tivolovers.com/2007/05/10/mr-tivo-goes-to-washington/ doesn't work in your copy of GoHokies post, since you just copied the text (that doesn't copy the actual URL), so you need to edit that URL to make it work.

Thanks for the writeup. :)
 
#11 ·
Good idea to get all of this into one post. However, in your definition of SDV you describe it as the switching ocurring at the cable company head-end. I thought most of the switching has been done at a "neighborhood junction box" of some kind, e.g. the cable company runs fiber to some point in a neighborhood, then coax to houses, and the switching was done at that junction.
 
#13 ·
bdraw said:
Jim,
Exactly, and that junction box is sometimes called a headend, but I see what you mean, maybe someone in the cable industry and clarify.
That's what I thought that it was called, and I hoped that someone would come along and correct some of my mistakes. :D I had the right idea, and the wrong terminology.

Looks like I have a little bit more learning to do :D
 
#15 ·
Go to the scientific Atlanta web site and search for SDV and you'll find several articles talking about SDV and SA's equipment. I assume it's roughly parallel to Motorola's eq.

AIR, the SA docs can be read to say that the control info is routed via TCPIP. If so, an S3 fix might be relatively easy.
 
#17 ·
That Don Guy said:
Pardon me for going off on a slight tangent, but does anybody out there know more specifics as to how SDV would work? Would each SDV channel have an on-screen menu of some sort, and the viewer would select which station to watch on a particular channel, or would different channel numbers be mapped to the same physical channel somehow?

-- Don
Simply each SDV channel will have a channel number like any other channel, and from the users perspective, work like that too. It is just underneath, the box knows instead to tune that channel, it has to ask the headend (or node if you will) for it, which the node controller will place the channel on the node, if not yet selected by another user on the node, and tell the box which channel/subchannel to tune to get it.
 
#19 ·
In some, perhaps many, places, cable plants used to populate the datastream with enough information to tell you that, for example, you tune to channel 707 to get the local HD CBS broadcast. This information is being deleted from the data stream. It could be that they are doing this to make clear QAM tuners look bad. They could also be doing this because of SDV. Any thoughts?
 
#21 ·
From ATSC standard (which is enacted in CFR by reference):

STT - System Time Table
CVCT - Cable Virtual Channel Table
TVCT - Terrestrial Virtual Channel Table
MGT - Master Guide Table

The rules governing the transport of PSIP tables for cable are:
• Requirement 6: The required tables for a cable system are: the STT,either the CVCT or
the TVCT, and the MGT. For any region that makes use of the capability to change the
RRT, that RRT shall be included in the TS if any content_advisory_descriptor in use refers to
that region. An RRT defining the rating system for a given region shall be included in the
TS if any content_advisory_descriptor in use refers to that region, unless that region has
explicit standards that define the rating system and the meaning of the values in the
content_advisory_descriptor.
• Requirement 7: The PSIP tables shall describe all of the digital channels multiplexed in
the Transport Stream. For convenience, the tables may optionally include information
about analog channels as well as other digital channels available in different Transport
Streams.

Comment: Its hard to decipher, but I think it also requires RRT (Rating region Table) for US & possessions. ATSC also used outside US.

From ATSC:

IN CVCT:
virtual channel – A virtual channel is the designation, usually a number, that is recognized by the user ...

Comment: I'm hard pressed to believe that cable companies expect me to remember that 116-1 is WSLS HD. That is not what their channel lineup says. However, I'm going down to the local cable company to ask them what channel is what?

I haven't noticed that cable folk are required to populate tables, but I guess I'm naive - I think its implied.
 
#22 ·
vstone said:
Comment: I'm hard pressed to believe that cable companies expect me to remember that 116-1 is WSLS HD.
That's not what I said. If WSLS-HD OTA had PSIP VCT (which it should), your cable company is required to propogate (and adjust the channel freq/modulation/etc for cable specific info)

I also said I didn't believe there was any requirement for the cable company to add its own PSIP VCT/CVCT info (when it wasn't present originally) One common example where this would come into play is if your system has ADS (digital simulcast) channels.

Basically while you can expect some of your digital channels to have PSIP VCT/CVCT it likely will not cover the range of all the digital channels you can receive.

Maybe I misunderstood what you meant by "populate" and took it to apply to more channels than you intended.

I looked at the transport streams on my system and the OTA digital sourced stuff does have both VCT and CVCT info for the OTA digital sourced channels I checked. The ADS channels have no VCT or CVCT. My head-end used to be misconfigured to not propagate the VCT info correctly. I say my head-end rather than my cable system because the surrounding areas did have proper VCT, just not my head-end. They finally fixed that 6 months ago.
 
#23 ·
It is not that FIOS's IPTV approach has the bandwidth so that it doesn't need SDV. It is simply that IPTV is even more efficient than SDV. The reason why is that SDV channels that are allocated do not fully utilize the bandwidth. You have a segment of a variable encoded movie that is all or nearly black, and with SDV, you still have 6 MHZ sitting there carrying no real data. With IP, during such low data periods, you are transmitting smaller packets and so the bandwidth can be used for other stuff- like your unbox downloads. :D But seriously- it allows a channel to be "Bursty". With SDV you have to allocate enough for the peak Mbps needed during an action scene even though most of the time you are using half that much data.

By the way- that Graphic is originally from Wikipedia's article on switched video, it isn't TivoBlog's.
 
#24 ·
bdraw said:
I've always called it a headend as well. The illustration calls it a distribution hub, which is new to me. Either way there are 500-2000 people all using it.
In reference to the diagram: The switching is not done at the head-end, nor the distribution hub, it is done at the Optical Node, the point where fiber ends and coax begins.
 
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