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SDV FAQ

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

  1. Apr 3, 2008 #1301 of 2401
    bxojr

    bxojr New Member

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    It all depends on where you are and what your local cable system is doing with respect to SDV. For what it's worth, I switched to cable and bought a TiVo HD less than a month ago, even after reading about the SDV issues. For me the TiVo HD was perfectly viable, and I'm happy with my decision.

    Why? I decided the risk was acceptable. My local provider (TWC in Raleigh/Durham) has not yet implemented SDV, although they could do so at any time. Even if they do, it's likely to be only for newly added channels (so I won't lose anything I have now), and it's likely to be only for less popular channels. Most of the HD programs we watch are on the major networks, which are not likely to go SDV.

    My advice would be to find out whether and how your local cable company is using SDV, and whether any channels you care about are affected.

    Eventually the tuning resolver will appear, so this is all a transient situation anyway. I've lived this long without Animal Planet in HD, so I figure I can last a few more months if necessary. (I don't subscribe to the pessimistic "don't hold your breath" view about the tuning resolver -- there's too much at stake for both TiVo and the cable companies.)
     
  2. Apr 3, 2008 #1302 of 2401
    rockymountaind

    rockymountaind New Member

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    Sep 10, 2007
    If I understand the issue correctly, it's the TiVo boxes that can't do SDV (because they aren't 2-way); the cards themselves have nothing to do with SDV.
     
  3. Apr 3, 2008 #1303 of 2401
    ajwees41

    ajwees41 Active Member

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    rocky you are correct.
     
  4. Apr 3, 2008 #1304 of 2401
    mikeyts

    mikeyts Stream Warrior

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    Exactly. All the new boxes that the cable companies have acquired since last July (the SA Explorer boxes with "C" on the end their model, like SA8300HDC) have M-Cards in them which they use to decrypt everything. Anyplace where SDV is deployed, CableCARDs are being used to receive them.

    The trick with SDV is not in tuning the channel, but in finding out where it is--what frequency band has its QAM carrier and what program number the channel is assigned within that stream. To find this stuff out, you have to be able to ask the system for the information; TiVos can't do it because they completely lack the ability to talk to the cable system over the coax. The Tuning Resolver will do that talking for them and TiVos will talk to the Tuning Resolver through a USB connection.
     
  5. Apr 3, 2008 #1305 of 2401
    Firekite

    Firekite New Member

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    Mar 11, 2008
    San Antonio, TX
    Ugh. This has been addressed to death. Technically that is correct, yes. However, by "CableCARDS" most people are actually referring to any 3rd party CableCARD device. This being the TiVo forum, that generally means their TiVo. It is true that it's not CableCARDS themselves that are the problem, but rather that no 3rd party device (which is necessarily a CableCARD device, while the proprietary CATV-provided devices may not be) can communicate back to the CATV provider.
     
  6. Apr 3, 2008 #1306 of 2401
    ah30k

    ah30k Active Member

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    Yes, and some around here get very testy when someone corrects a poster who makes this error. Don't know why.

    Anyway, I think the best way to say it is: while all CableCARDs are inherently two-way, the licensing terms associated with becoming an authorized CableCARD device require any CE device wishing to take advantage of two-way services also be OCAP compliant. Many CE companies find these terms onerous and choose not to sign the terms thus become forced into one-way usage.
     
  7. Apr 3, 2008 #1307 of 2401
    bxojr

    bxojr New Member

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    Mar 4, 2005
    Pittsboro, NC
    I have no intention of involving myself in this argument, but speaking for myself, I really do prefer more precise terminology. When I say "CableCARD," I mean the CableCARD. If I want to talk about the CableCARD host device, I say "CableCARD host device." This is the terminology used by the CableCARD spec, the NCTA, the CEA, the FCC, and anyone else who wants to have a clear technical discussion about the issues.

    You're probably right that "most people" are not careful to make this distinction. But I think it's an important distinction, and being careful about it would really help to avoid some awfully pointless arguments on this forum.
     
  8. Apr 4, 2008 #1308 of 2401
    HDTiVo

    HDTiVo Not so Senior Member

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    You can look on my blog back in January and Megazone & Zatz for more info on this. One product is made by Gefen. Perhaps TiVo will someday incorporate such technology, but they have never commented on doing so as far as I know.
     
  9. Apr 4, 2008 #1309 of 2401
    HDTiVo

    HDTiVo Not so Senior Member

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    Nov 27, 2002
    Don´t forget the other trick: requesting/maintaining the channel. ;)
     
  10. Apr 4, 2008 #1310 of 2401
    mikeyts

    mikeyts Stream Warrior

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    That's what I meant when I said "To find this stuff out, you have to be able to ask the system for the information". You find out where the channel is by requesting it. Of course, it might not be anywhere until after you request it and there's a possibility that it won't be able to allocate bandwidth to it.
     
  11. Apr 4, 2008 #1311 of 2401
    lrhorer

    lrhorer Active Member

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    'Too right. 'Excellent post. Of course, Cable hopes they can successfuly pursue both ends of the spectrum, and as such they have a very broad range of demographics to consider. Anything they can inexpensively and reasonably do to keep one segment happy is worthwhile, unless it impacts the spending of another, larger demographic, in which case it's a bad idea. Larger in this case means more dollars, not just more subs. The thing is, no matter how one slices it, third party CableCard users, although dfinitely visisble, respresent a rather small demographic. If they are business wise, then the CATV providers will exert some effort to make TiVo users happy, but not out of proportion to the TiVo user's spend and not in conflict with other user's desires.

    That leaves us in a less than optimal situation.
     
  12. Apr 4, 2008 #1312 of 2401
    lrhorer

    lrhorer Active Member

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    'Or an investor. The sales manager might have some sympathy for the saleman. The investor couldn't care less how much effort the sales staff has to expend.
     
  13. Apr 4, 2008 #1313 of 2401
    lrhorer

    lrhorer Active Member

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    "Awful" is a huge understatement. Listening to fingernails on a chalkboard is less irritating.

    It's pretty simple. SDV requires 2-way communications between the customer's system and the CATV headend. TiVos are not 2-way hosts, so no SDV without some means of help.

    I'm not worried that somehow it will get worked out. When is another matter. I wouldn't worry about SDV incompatibility after the fact. Anything that breaks the dongle woud be extremely likely to break the CATV company's STBs and DVRs, as well.

    Don't hold your breath on the HDMI. Even if HDCP would allow such a thing (very unlikely), you're asking for a really beefy - read that expensive - piece of hardware. Converting a 3Gbps uncompressed digital stream to a 16 or 17 Mbps compressed stream on the fly is a very tall order. Even compressing the analog Composite signal is challenging.

    Well, it woud ahve to be a piece of aditional hardware, not just software, but network based IR controllers are readily available.

    It was alsoa different technological world.

    'so they could manufacture them for less than $10,000 each.
     
  14. Apr 4, 2008 #1314 of 2401
    lrhorer

    lrhorer Active Member

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    I'm not pessimistic they or some devices with comperable functionality will be availble eventually. I'm just not betting on the June 30 deadline.
     
  15. Apr 4, 2008 #1315 of 2401
    mikeyts

    mikeyts Stream Warrior

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    Being something that the cable companies will distribute and maintain, I'd expect Tuning Resolvers to have field upgradable firmware just like their leased tuning STBs. The OpenCable Tuning Resolver Interface Specification anticipates this and specifies how the TR will signal the UDCP (i.e., TiVo) that it's temporarily offline and then available again.
     
  16. Apr 4, 2008 #1316 of 2401
    slude

    slude New Member

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    Feb 9, 2008
    I've seen this explanation offered several times before, but I don't follow the transition from the problem statement to the conclusion regarding available implementations.

    Accepting that first sentence as factual, I take note that my CableCARD device (perhaps oddly so for this forum, although I have a TivoHD my only CableCARD device is a Sony TV so my experience with CableCARD use may be different) has done quite well at finding out the frequency band/QAM carrier/program number information for any given channel in spite of several changes my cable provider has made to those relationships over the two years I've had a CableCARD installed. My Sony TV has no problem finding where Comcast has hidden a channel lately (almost always; it did lose track of the Cartoon Network for a couple days last week and need help) even though it has absolutely no way to ask the cable system for that information.

    From what I've read, communicating this information from the cable provider to any CableCARD device is, in fact, one of the primary functions of the CableCARD. So whether the cable provider is changing the frequency band/QAM carrier/program number information for a channel once a quarter, once a month, once a day, once an hour or every 60 seconds, I don't see the logical basis for concluding "you have to be able to ask the system for the information" in order to be able to tune in a channel being managed via SDV.
     
  17. Apr 4, 2008 #1317 of 2401
    MichaelK

    MichaelK New Member

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    Jan 10, 2002
    NJ

    the point of SDV is the channel is only turned on when someone wants to watch it. So if no one else in your neighborhood is watching SDV channel X- your box needs to notify the cable company that you want it.

    After that the SDV equipment would assign an unused channel and then tell your box where to find it.

    THEN equally important. For the system to work properly when you dont want to watch the channel anymore the SDV system needs to shut the channel down so if someone else wants channel Y or Z there is a place for it.

    So periodically your box and the headend need to speak to each other and see if you still need the channel.

    with 2 way communication (OCAP, propiretary box, or the dongle):
    -your box "hey headend I want to watch channel X"
    -headend "OK I put it on qam slot 99.3 look there"
    -your box would tune to channel 99.3 then some time later:
    -headend "hey are you still watching that channel?"
    -box "yep my owner hasn't changed channels, shut me off, or not touched a button on the remote for 90 minutes so he must be watching"
    -and the headend leaves the channel on.

    without 2 way communication- like any current cablecard receiver availible in retail as they are all currently one way:
    -your box says TO ITSELF "my owner wants channel X let me look for it on the channel list" and no one is currently watching it so it isn't assigned a channel number so the box thinks to itself "gee I just dont see channel X anymore on the list so the channel must not be availible on this system"
    -maybe you get lucky and the channel is still up and the box finds it's on channel 99.3 so it tunes to it. Some time later the cable company polls everyone IT KNOWS is watching the channel "HEY any of you still watching this channel" - Your box might scream it's head off "YES YES I AM" but no one hears it. SO if no one else is watching the channel then the SDV systems at the head end shuts the channel off right in the middle of you watching it.

    So 2-way communication with SDV is absolutely necessary.
     
  18. Apr 4, 2008 #1318 of 2401
    ilh

    ilh New Member

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    Dec 21, 2007
    How does SDV know when you are no longer watching a channel? What if you never turn off the cable box?
     
  19. Apr 4, 2008 #1319 of 2401
    MichaelK

    MichaelK New Member

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    NJ

    I am not certain as I've never owned a cable company cable box. But I assume it's like a tivo with suggestions or a featuer on certain tv's.

    I rarely watch live tv but I think that the tivo does a similar thing for suggestions- If your tivo detects no input via the remote (including volume up or down to the tv) for a set period it assumes you aren't around and asks with a confirmation if it can switch channels on you to record a suggestion- if you aren't there to say no it switches channels and does what it wants.

    I assume cable boxes with SDV behave very similarly. If they you dont change channels for a set period and it doesn't see you change the volume on the tv then it will put a prompt on the screen asking if it's ok to shut down the channel. If you dont say NO it will shut off the SDV channel (probably dumping you to the guide or some barker or ad channel).

    My sharp aquos TV does a similar thing - if it senses no activity for a certain period then it shuts itself down.
     
  20. Apr 5, 2008 #1320 of 2401
    mikeyts

    mikeyts Stream Warrior

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    Apparently in the case of a device using a Tuning Resolver, you will get asked, much like TiVo's "I-want-to-change-channels-in-a-few-minutes-to-make-a-scheduled-recording. Okay?" query. See the OpenCable Tuning Resolver Interface Specification; page 42 shows some suggested User Inactivity Messages, which are to be displayed when a particular message from the tuning resolver is received by a UDCP (Unidirectional Digital Cable Product, like TiVo). There's also some vebiage in there about sending udcp_status_update() messages to the tuning resolver when remote control command or front panel button presses occur.
     

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