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SDV FAQ

Discussion in 'TiVo Series3 HDTV DVRs' started by bdraw, Jul 3, 2007.

  1. Dec 4, 2007 #741 of 2401
    mikeyts

    mikeyts Stream Warrior

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    You're right--CableCARDs are not tuners and could be used to decrypt streams carried on higher frequencies. However, the OpenCable Host Device 2.0 Core Functional Requirements only require the host to be able to tune inband frequencies between 54 and 864 MHz. The range can be greater, but it's optional. It seems improbable that any UDCR equipment on the market is capable of tuning up to 994MHz., but it's possible.
     
  2. Dec 4, 2007 #742 of 2401
    dswallow

    dswallow Save the ModeratŠ¾r TCF Club

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    CableCARDS can decrypt any tuned demodulated signal; the problem is the standard for the host device doesn't require the host device to be able to tune to those higher frequencies.
     
  3. Dec 4, 2007 #743 of 2401
    dr.greghouse

    dr.greghouse New Member

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    Ahh. Thank you for the info and link. 864 MHz looks like the cutoff.
     
  4. Dec 4, 2007 #744 of 2401
    mikeyts

    mikeyts Stream Warrior

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    864 MHz is the offset of the last block of 6 MHz in 870. From 54 MHz through 864 MHz is still 136 6 MHz slots, enough for 272 HD channels at 19 Mbps each, packed two to a stream (of course they won't use it that way, but we can dream :)). Downstream DOCSIS channels can inhabit the low GHz range with standard cable modems, so they can utilize that upper 130 MHz of capacity for data and telephony, moving some or all of that out of the 54 MHz-864 MHz range, making space for more "plug-and-play" video channels.

    Bring on 25/4 Mbps as a standard for cable data service and bring on fat, luscious high def downloads from Amazon Unbox and elsewhere!
     
  5. Dec 5, 2007 #745 of 2401
    djones18

    djones18 New Member

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    Cox yesterday, activated 11 new HD channels in Fairfax County, VA. Here is their headline:
    ----------------------------------------------
    Effective immediately, Cox now offers the following new high-definition channels:

    - CNN HD (708)
    - Versus/Golf HD (711)
    - TBS HD (722)
    - Food Network HD (723)
    - HGTV HD (724)
    - TLC HD (725)
    - Discovery HD (727)
    - History Channel HD (728)
    - The Science Channel HD (729)
    - Animal Planet HD (730)
    - NHL Network HD (731)

    Televisions and other consumer owned devices equipped with a CableCARD may require a digital set top receiver in order to receive all programming options offered by Cox Digital Cable.

    ---------------------------------------------
    Inference is these are all SDV. Can any of you TIVO HD/Series 3 owners in Fairfax County, Virginia confirm you are not receiving these channels?
     
  6. Dec 5, 2007 #746 of 2401
    mikeyts

    mikeyts Stream Warrior

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    I like the way that they say "may require a digital set top receiver", as though there was some chance that a CableCARD device might currently tune SDV channels without one :rolleyes:.
     
  7. Dec 5, 2007 #747 of 2401
    MichaelK

    MichaelK New Member

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    In response to someone's comment that cablelabs if funded by the cable company's ...

    sorry to drift off topic but I cant seem to let this go for some reason (I know I know I have issues-LOL)

    Maybe it WAS open to all at one point but that no longer seems to be the case-

    from cablelabs own website:


    the list of member company's is found here:

    http://www.cablelabs.com/about/companies/

    I am NOT very knowledgable about the subject but I dont see any hollywood players, cable manufactureres (surely moto and SA would be on the list if allowed) and no phone company's (i'd think verizon would surely wont to join so they could have some say in the standards go- no?)

    So how is cablelabs not funded by the cable company's exactly?

    I guess beyond dues from the above players (which I think are assessed as a percent of revenue or perhaps as a surcharge per customer)- there are some testing or licensing fees paid by manufactures to get stuff certified- but seems to me the people making the decisions are clearly only cable company's.

    Or am I missing something?


    Now that I think about it - I think you are confusing cablelabs with the NCTA. The NCTA I believe DOES have hollywood and equipment makers in the mix. And if I recall even a phone compnay or 2 that were allowed in before the NCTA decided to ban telco's.

    I seem to recall that cablelab's (I think it had a differnt name back then?) was initially a part of NCTA but at some point it got spun off and became the monopolistic entity that it is today.
     
  8. Dec 5, 2007 #748 of 2401
    hokiethang

    hokiethang New Member

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    Apr 21, 2004
    Herndon,...
    Just checked, in Herndon, and my TivoHD doesn't even know the channels exist. My guess is they haven't updated the CC Map for them :-(
     
  9. Dec 5, 2007 #749 of 2401
    mikeyts

    mikeyts Stream Warrior

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    If they're being presented as SDV services, as that notice from Cox strongly suggests, they're not gonna update the CableCARD maps for them. Good luck. At least they don't include Sci Fi HD, which is about the only new HD channel I've heard of that being deprived of through the use of SDV will truly piss me off.
     
  10. Dec 6, 2007 #750 of 2401
    mel.simmons

    mel.simmons New Member

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    Del Mar CA
    SDV has become a problem for TiVo owners. However TiVo could become a big problem for SDV.

    SDV is a business strategy of over-selling product, in expectation that not every customer will show up to buy. It's a lot like the airlines overbooking a flight, assuming that many of those with reservations will not actually show up for the flight. The cable company is offering more channels than they can deliver simultaneously, assuming that not all channels will be requested at the same moment. And that will usually, but not always, be true.

    The only statistical study of SDV that I have found on-line (http://www.bigbandnet.com/index.php/tech_whitepaper_statswb.html) claims a large "efficiency" advantage of SDV, that is, the average number of QAM streams used by SDV is significantly less than the number of channels offered on SDV. The author's explanation is that there are a few channels that many people watch, and many channels that are very seldom watched (a Zipf distribution, or a "long tail" effect). However in their plots of the data collected in two experiments, the more important effect is that many set-top boxes were off a lot of the time. Thus, the most frequently watched channel was "off".

    However TiVo does not have an off button. It's always watching a channel, and always filling its 30 minute buffer for our instant gratification when we want to skip back and re-run something from live TV. Actually most TiVo's are now watching two different channels, 24 hours a day, 7 days a week. TiVo does not know if the TV monitor is on or not, or if anyone is in the room or not. Thus a TiVo will create a much higher average demand on an SDV service than an average human viewer. If a large portion of the households on an SDV node have TiVo (or a similar technology), the statistical model of SDV will fail.

    What happens when the statistical gamble of SDV goes bad? Instead of getting the channel they are requesting, viewers get blocked. Sort of like being bumped from an over-sold airline flight. So TiVo might be trying to record some show from an alternative HBO feed, but it won't be able to get the channel when it needs to, and unless some new protocol gives TiVo appropriate feedback, it won't even know that it can't record your show.
     
  11. Dec 6, 2007 #751 of 2401
    classicsat

    classicsat Astute User

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    I'd suspect, TiVo will have a mode that will, when done with a recording, tell the headend to release the channel, if needed.
     
  12. Dec 6, 2007 #752 of 2401
    dswallow

    dswallow Save the ModeratŠ¾r TCF Club

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    Suggestions don't usually record continuously, though certainly there are such times that does happen. But the 30-minute buffer recording will affect how channel demand from SDV occurs since there's really no current "stop recording anything including the buffers" state for TiVo receivers. Standby mode could be used as one way of doing this, but of all the people I know using TiVo, I know no one who goes to the trouble of using standby mode, so statistically I'm not sure that'll help much.

    The receiver does keep track of the last user interaction that occurred, so they may implement some sort of longer term stop-recording-any-buffers mode after sufficient time passes without user input... 6 or 12 hours, for instance. Much like happens now with cable's set-top boxes and how they spin down the hard drive after some extended inactivity.
     
  13. Dec 6, 2007 #753 of 2401
    bicker

    bicker bUU

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    Perhaps one of the conditions associated with the agreement that resulted in the tuning resolver was that TiVo suggestions would be limited to non-SDV sources.
     
  14. Dec 6, 2007 #754 of 2401
    ah30k

    ah30k Active Member

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    People get bumped all of the time. It is a relatively high probability. It should be more analogous to not getting a land-line telephone call through which is very unlikely. Also, if I define a node to be 300 tuners and have 300 channels available, I can use SDV to offer an unlimited number of SDV video streams with 100% probability of success.
     
  15. Dec 6, 2007 #755 of 2401
    mel.simmons

    mel.simmons New Member

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    Yes, your suggestion is one way that SDV technology could be used. However that is not the economic model that motivates the cable companies. The values used in one of the experiments I cited included
    334 set-top boxes in a node,
    100 QAM streams, and
    169 programs
    so the potential for blocking was very real. If the cable companies had to reduce the number of set-top boxes per node to about 100, their costs would go up significantly. They don't like that.
     
  16. Dec 6, 2007 #756 of 2401
    ah30k

    ah30k Active Member

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    On what do you base your suggestion that the potential is very real. Do you have any usage statistics or just a gut feel. I have seen real data suggesting that the tail of watched channels drops very quickly.

    The http://www.motorola.com/mot/doc/6/6578_MotDoc.pdf white paper shows a generic version of the statistics graph. I don't have a more detailed version handy that is able to be posted on the internet.
     
  17. Dec 6, 2007 #757 of 2401
    rdowty

    rdowty New Member

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    Dec 31, 2002
    Springdale, AR
    Does anybody know if Tulsa, OK has or is planning on rolling out SDV anytime soon? I'm just about to jump back onto a TiVo for the first time in about four years now the the HD is around $250.
     
  18. Dec 6, 2007 #758 of 2401
    mikeyts

    mikeyts Stream Warrior

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    I suspect that SDV schemes use a channel "lease" model, where the terminal asks for information for tuning a channel and the system returns something like "Requested channel XXX is in a transport stream on a QAM 256 carrier at frequency YYY as program PPP, guaranteed for for 10,800 seconds". So the terminal starts a timer and 3 hours later, if the tuner hasn't been tuned to something else, stops buffering the channel if it's a non-viewed tuner or if it is viewed, puts up a pop-up asking the user whether he wishes to continue watching, and if he responds, sends a request to renew. If the tuner is still in use recording, it automatically renews. If it doesn't renew, the network automatically rescinds the lease and decrements the channel's use-count, relinquishing the bandwidth for re-use when the count falls to zero.

    Since the "are you still watching?" prompt is a bit awkward, the network should probably always make a lease granted that ends in the middle of primetime extended through the end of primetime.
     
  19. Dec 6, 2007 #759 of 2401
    bicker

    bicker bUU

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    The details of the leasing scheme is explained either earlier in the thread or in linked references earlier in the thread.
     
  20. Dec 6, 2007 #760 of 2401
    mikeyts

    mikeyts Stream Warrior

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    We have discussed the concept of leasing channels somewhere in these forums, though I'm not sure that it was in this thread. Of course, it's all still speculation, since we don't have specifications of any of the SDV systems in use.
     

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