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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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#252 ·
There isn't anything technically wrong about the article, it just leaves out the crucial fact that including the 2 way bits would have forced them to be OCAP compliant, which means that the cable company would be able to download their own OS onto the box and overwrite the Tivo OS.

The link that needs to be broken is the 2-way=OCAP bundling crap that exists today.
 
#253 ·
GoHokies! said:
There isn't anything technically wrong about the article, it just leaves out the crucial fact that including the 2 way bits would have forced them to be OCAP compliant, which means that the cable company would be able to download their own OS onto the box and overwrite the Tivo OS.

The link that needs to be broken is the 2-way=OCAP bundling crap that exists today.
I didn't know that issue. And that is a crucial issue. What is a Tivo Box with a cable companies OS? Just another paper weight useless box with a crappy interface, lack of features and add banners.

Why is that OCAP thing a requirement of 2-Way? With that there can be no real third party competition, doesn't that alone warrent a fcc complaint or possible legal action that can stand ground. It's not that Tivo is not in compliance its the fact, they need to be one way to have a box that differs from the cable companies.
 
#254 ·
txagfan said:
So, are you also going to complain about the sat. co's having a waiver and not opening up their network? Are you going to complain when the cable co says "ok, you can have ESPN2 HD, but you will NEVER get another new HD channel because we are out of bandwidth?'' Quit your crying, SDV is the future, it is the only way cable has to compete with D*. You are part of a very small minority, like .001% of cable co's customer base. The rest of the customers want more HD channels.
Quit crying? There's a much easier solution to the problem - turn off analog! SDV is not the only way to add HD, it is just the most convenient way to continue to collect STB rental and pimp PPV to me. The sat-co's are subject to competition - thus they have consumer choice. Sat-co's also do not use public right-of-way's and public infrastructure. They are inherently private enterprises. Cable companies are granted monopoly status by gov't franchise authorities, and thus should be held to a higher standard of openness and consumer choice.

I see your point, but I respectfully disagree.
 
#255 ·
LoREvanescence said:
Why is that OCAP thing a requirement of 2-Way? With that there can be no real third party competition, doesn't that alone warrent a fcc complaint or possible legal action that can stand ground. It's not that Tivo is not in compliance its the fact, they need to be one way to have a box that differs from the cable companies.
Because the cable companies do not want to give over control of the boxes. The CEA is lobbying against it and so far as I know the FCC hasn't gotten involved yet. That's where my heartburn with the FCC's half-implementation of the '96 telecom act that was supposed to fix all this crap.
 
#256 ·
Re the often made statement "SDV makes more channels available."

I fail to see the logic here. If the cable company says they have, say, 10 HD capable delivery channels, but they offer 30 HD channels available, then they can only deliver 10 HD channels at a time. If the 10 HD capable delivery channels are already in use, and you want to watch one of the 20 HD channels not being transmitted, you are out of luck.

It makes no difference how many HD channels they say are available, 30, 50, 1000. Eventually the 10 HD capable delivery channels will be in use with the 10 most popular HD channels, and the other 20, 40, or 990 HD channels are unavailable to you.

They still can only deliver only 10 HD channels at a time. SDV does not allow them to increase the number of deliverable HD channels.

Now, if you want to watch unpopular channel 29, at, say, 8:00PM Wed evening, you might be able to get up at 4:00AM Wed morning, tune your STB to channel 29, and leave it there until 8:00PM Wed evening, and channel 29 will still be being delivered. But good luck in being able to tune in unpopular channel 29 at 7:55PM Wed evening! Unpopular channel 29 will be essentially unavailable for prime time viewing!
 
#257 ·
Tip for those in the SDV nightmare.

Get your friends and neighbors to tune their STBs to the most unpopular channels they can imagine. Lock the SDV system into delivering all the unpopular channels. Then let the cable companies start getting the complaints from customers who find that the popular channels are "Not Available".
 
#260 ·
wbertram said:
Re the often made statement "SDV makes more channels available."
Yes, you scenario is correct, but if they size the SDV pool of channels properly as well as the node sizes the chance that a user will want a channel and no slots will be available should be a six-sigma event (well maybe not that rare, but rare).

Also, future systems will be able to re-claim bandwidth by increasing the compression on the lesser watched channels to squeeze in the new request.
 
#261 ·
wbertram said:
Now, if you want to watch unpopular channel 29, at, say, 8:00PM Wed evening, you might be able to get up at 4:00AM Wed morning, tune your STB to channel 29, and leave it there until 8:00PM Wed evening, and channel 29 will still be being delivered.
Any channel with inactivity for a period of time is able to be polled to see if the watcher is still there. "Please hit the enter button if you still want this channel". If no response is received the channel will be reclaimed and the STB will be sent to a safe channel.

oh, and getting up at 4:00 to set a channels seems like an awful lot of work.
 
#262 ·
wbertram said:
Question.

If all the delivery channels are in use, and somebody wants to watch a PPV movie, will the cable company knock off one of the free channels being delivered, and replace that programming with the PPV movie in order to reap the PPV fee?
Current systems usually have PPV and linear channels separate. Future systems will mix and match for greater efficiency.
 
#263 ·
ah30k said:
Yes, you scenario is correct, but if they size the SDV pool of channels properly as well as the node sizes the chance that a user will want a channel and no slots will be available should be a six-sigma event (well maybe not that rare, but rare).

Also, future systems will be able to re-claim bandwidth by increasing the compression on the lesser watched channels to squeeze in the new request.
If they do as you suggest, then the "SDV pool of channels" would have to be essential the same as the advertised number of available channels. So, what has SDV bought them? Nothing!

With regards to the "compression fix". You would be happy watching highly compressed channels? ala the HD Lite used by the satellite companies?
 
#264 ·
wbertram said:
I fail to see the logic here. If the cable company says they have, say, 10 HD capable delivery channels, but they offer 30 HD channels available, then they can only deliver 10 HD channels at a time. If the 10 HD capable delivery channels are already in use, and you want to watch one of the 20 HD channels not being transmitted, you are out of luck.

It makes no difference how many HD channels they say are available, 30, 50, 1000. Eventually the 10 HD capable delivery channels will be in use with the 10 most popular HD channels, and the other 20, 40, or 990 HD channels are unavailable to you.
If the buildout of the fiber is deep enough to have just 10 outlets in a switch group, you'd be the 10th person so could always get what you want.

The number I seem to be seeing is 400-500 subscribers being served by a hub, and I guess 300 or so Mhz of SDV bandwidth (both SD and HD). If all HD, that would be 100-150 channels.
 
#265 ·
ah30k said:
Any channel with inactivity for a period of time is able to be polled to see if the watcher is still there. "Please hit the enter button if you still want this channel". If no response is received the channel will be reclaimed and the STB will be sent to a safe channel.

oh, and getting up at 4:00 to set a channels seems like an awful lot of work.
If I get up to get a beer during a commercial, I might get "polled", and when I come back, I will have lost the channel in the middle of a show? That will make customers very happy!
 
#266 ·
wbertram said:
If they do as you suggest, then the "SDV pool of channels" would have to be essential the same as the advertised number of available channels. So, what has SDV bought them? Nothing!
Statistical analysis shows that if you offer an x channel pool for y offerings with a node size of z you will be able to satisfy all of the users 99.9% of the time. The x can be much less than y. You can choose not to believe it if you want.
wbertram said:
With regards to the "compression fix". You would be happy watching highly compressed channels? ala the HD Lite used by the satellite companies?
Most users would never notice the difference and it would rarely happen anyway. Once again, you can choose to disagree if you want.
 
#267 ·
wbertram said:
If I get up to get a beer during a commercial, I might get "polled", and when I come back, I will have lost the channel in the middle of a show? That will make customers very happy!
The timeout for the response is configurable and will surely be tuned to allow people to take a piss. Again, this message will only pop up if you have done nothing with the STB for a long period of time. So if you are in the corner case of someone who has done 'nothing' with your remote for a long time, and you are still watching a show, and you get up for a beer at just the right time and you take a very long time to get back THEN your worry might be valid.
 
#269 ·
wbertram said:
If I get up to get a beer during a commercial, I might get "polled", and when I come back, I will have lost the channel in the middle of a show? That will make customers very happy!
Kind of like when you are watching something in the middle of the 30-minute "live" buffer, and your TiVo prompts you to change channels to record something, and discards the rest of the buffer if you don't respond in time. :)
 
#270 ·
ah30k said:
Statistical analysis shows that if you offer an x channel pool for y offerings with a node size of z you will be able to satisfy all of the users 99.9% of the time. The x can be much less than y. You can choose not to believe it if you want.
Most users would never notice the difference and it would rarely happen anyway. Once again, you can choose to disagree if you want.
Put some realistic numbers for x, y, and z in the appropriate formulas, and let us see what the probability is that I will not be able to receive a random channel selection when I want to. Try it with the appropriate numbers for, say, TWC in Austin.

Poll the SDV users in Austin and see how often they are getting the "Channel Not Available" screen.
 
#271 ·
wbertram said:
Put some realistic numbers for x, y, and z in the appropriate formulas, and let us see what the probability is that I will not be able to receive a random channel selection when I want to. Try it with the appropriate numbers for, say, TWC in Austin.

Poll the SDV users in Austin and see how often they are getting the "Channel Not Available" screen.
The only time I have seen that screen is when a channel is down due to a service outage. Otherwise, I have never seen that screen.
 
#272 ·
ah30k said:
Statistical analysis shows that if you offer an x channel pool for y offerings with a node size of z you will be able to satisfy all of the users 99.9% of the time. The x can be much less than y. You can choose not to believe it if you want.
Most users would never notice the difference and it would rarely happen anyway. Once again, you can choose to disagree if you want.
This is exactly how the public telephone system works...there are many less channels for completing calls than there are subscribers - depending on telco, and where in the network you are, they concentrate up to 5:1 (one voice channel for 5 subscribers) and it works 99.9% of the time for 100% of subscribers.
 
#273 ·
wbertram said:
Put some realistic numbers for x, y, and z in the appropriate formulas, and let us see what the probability is that I will not be able to receive a random channel selection when I want to. Try it with the appropriate numbers for, say, TWC in Austin.
Sorry, no can do. Not public data.

wbertram said:
Poll the SDV users in Austin and see how often they are getting the "Channel Not Available" screen.
Why are you telling me to go do something. You're welcome to if you wish.
 
#274 ·
ah30k said:
The timeout for the response is configurable and will surely be tuned to allow people to take a piss. Again, this message will only pop up if you have done nothing with the STB for a long period of time. So if you are in the corner case of someone who has done 'nothing' with your remote for a long time, and you are still watching a show, and you get up for a beer at just the right time and you take a very long time to get back THEN your worry might be valid.
And what about my kids who are watching a children's show, and don't understand the message on the screen? "Daddy, Daddy, my show went off and won't come back! sob, sob, sob".
 
#275 ·
ah30k said:
The timeout for the response is configurable and will surely be tuned to allow people to take a piss. Again, this message will only pop up if you have done nothing with the STB for a long period of time. So if you are in the corner case of someone who has done 'nothing' with your remote for a long time, and you are still watching a show, and you get up for a beer at just the right time and you take a very long time to get back THEN your worry might be valid.
What would happen though, if you have a dvr stb forsay, and are not home while it's recording. If it were to get polled while recording event could the station get pulled? Just a interesting thought.
 
#276 ·
wbertram said:
And what about my kids who are watching a children's show, and don't understand the message on the screen? "Daddy, Daddy, my show went off and won't come back! sob, sob, sob".
You are moving into the realm of irrational argumenting now. For those looking to argue against it, nothing will convince you. I already said 1) it should not even be statistically needed 2) it will only go to STBs with long periods of inactivity. If you kids fall into both then tough luck. **** happens.
 
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