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TiVo Crafts ‘Embedded’ Switched Digital Video Tech

Discussion in 'TiVo Coffee House - TiVo Discussion' started by Johncv, Jul 30, 2014.

  1. Johncv

    Johncv Active Member

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  2. wmcbrine

    wmcbrine Ziphead

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    As I understand it, the problem was always cable company resistance, not technical difficulty.
     
  3. Dan203

    Dan203 Super Moderator Staff Member TCF Club

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    Sounds like this uses the internet just like Comcast VOD. Unfortunately most cable companies actively try to deter CableCARD use so I doubt many of them will be rushing to add this functionality to their headend.
     
  4. Dan203

    Dan203 Super Moderator Staff Member TCF Club

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    Exactly!
     
  5. Johncv

    Johncv Active Member

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    From the article: "TiVo’s technical team is already holding discussion with operators about a way to support SDV without a Tuning Adapter."

    I think the "cable companies" are starting to realize that they need to compete with someone or they will be declare a "common carrier" and not just for internet, but for everything.
     
  6. rainwater

    rainwater Active Member

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    I would imagine these "discussions" are with MSOs that already use TiVos. I'm not sure other cable operators are really their priorities for this initially. I hope I am wrong and this will work for the stand alone market but I am not holding my breath.
     
  7. SullyND

    SullyND L:45-21 TCF Club

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    Margret talked about it in the summer release thread.
     
  8. wmcbrine

    wmcbrine Ziphead

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    God, I wish.
     
  9. Aug 3, 2014 #9 of 78
    Bigg

    Bigg Active Member

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    Yeah, you're probably right. TWC goes out of it's way to be extremely hostile to TiVo users, and they are the big SDV user, so unless the Comcast-TWC merger goes through, they're not going to do anything about it.

    If the merger does go through, then it remains to be seen if Comcast "Comcast-izes" the TWC systems and gets rid of SDV, or puts SDV on it's own systems or what. Comcast would be the only MSO that would actually do this, except that they don't use SDV.

    The real answer is MPEG-4. An 860mhz plant can do 200 HDs and 300mbps internet if they use MPEG-4 for all the HDs.
     
  10. aaronwt

    aaronwt UHD Addict

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    That's it? Really? Only 200 HD channels with switch to H.264?
     
  11. moyekj

    moyekj Well-Known Member

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    I think it's a lot more than 200.
    860 Mhz / 6 Mhz per QAM 256 = 143 QAM 256 channels.
    Each QAM can support total bit rate up to 38 Mbps. So let's assuming you are very generous and limit each QAM to 3 HD channels (12.67 Mbps each which is generous for H.264 encodings) then you can fit 143*3 = 429 HD channels. Of course you don't use full bandwidth for TV channels since there will be a lot of bandwidth dedicated to cable modem and other uses, but still back of napkin calculations give you an idea. Realistically, the cable companies would probably try to squeeze in 5 to 6 HD channels per QAM when using H.264 encoding - many already squeeze in 3 or more HD channels per QAM using mpeg2 encoding.
     
  12. tarheelblue32

    tarheelblue32 Active Member

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    The main reason that TWC uses so much SDV is that they are still sending through analog channels in many markets. I still get about 60 analog channels coming through on my TWC system. If the Comcast merger does go through, Comcast will force TWC to phase out analog signals and that will free up a lot of bandwidth.

    Eventually, cable systems will also stop sending through both SD and HD digital signals for the exact same channel, which will also free up some more bandwidth. Any new cable boxes capable of decoding MPEG-4 should also be able to down-convert HD signals to SD signals as needed.
     
  13. Bigg

    Bigg Active Member

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    I don't think that there are more than about 200 HD channels in the first place. But I'll go through the exercise below anyways.

    That's pretty far off base. Let's start with a best-case scenario, Verizon FIOS, which has NO internet, NO phone, and NO VOD, and has an ~860mhz system. The downstream starts at ~50mhz, so that's 810mhz or 135 channels. They have something like 400 SDs and upwards of 200 HDs, and their system is absolutely, completely, jam packed full. Even if they're aggressive with the SDs running 10 per QAM, that's 40 QAMs. It's probably more like 50 QAMs, and I think they may actually have more than 400 SD channels. Now there's 95 QAMs left in a best case scenario. It's probably more like 85, which with a little bit of MPEG-4, and the rest MPEG-2 with some lesser-watched channels tri-muxed works out to close to 200 HDs on FIOS.

    Now let's look at cable. Comcast runs around 130 HD's, mostly tri-muxed or bi-muxed with an SD or two on the QAM, plus around 300-350 SD's, internet, VOD, phone, and home security on an 860mhz system, although they aren't maxed out yet on those systems. On their totally maxed out 650mhz systems, they are running around 90 HDs, probably 250-300 SDs, and all the rest. You add two more QAMs for internet, 50 SD channels using 5 QAMs and around 14 QAMs for the additional HDs, and that's 21 QAMs, or 126mhz above a 650mhz system, or an approximately 770mhz that they are running on the 860mhz systems, leaving around 70-80mhz free.

    So, back to my original post, which promised "200 HDs and 300mbps internet". Let's do the internet first. Comcast is currently running 8 QAMs on 860mhz systems, so they would need 8 more to do 300mbps internet like TWC is doing (16 downstream channels). So starting off with 78mhz free, we now have 30mhz free. Assuming that we do nothing to the SDs, let's move to MPEG-4 with 5 HD's per QAM. That 130 channels currently using say, 50 QAMs/300mhz is now crushed down to, say, 28 QAMs/168mhz, freeing up 22 QAMs/132mhz. In both I'm assuming a few channels don't get as squished as standard, as is the norm for Comcast now for a select few channels like ESPN and HBO. It's also not that clean, since they mix HDs and SDs, but the math still basically works.

    Now, we have 30+132=162mhz or 27 QAM's free. That's 135 MPEG-4 HDs in addition to the 130 already there. So yes, you could probably push it to about 250-270 HDs before you are completely out of room on an 860mhz systems, assuming you are willing to go right to the top of the system.

    If I were Comcast, I would do some additional pruning to free up space. I would preserve what the DTAs get as MPEG-2 SD, but take all other SD channels, and just get rid of the ones that are also broadcast in HD, and convert the remaining ones over to MPEG-4. This would require a little bit of additional hardware, but not much, as very few people subscribe to more than Digital Starter/Expanded Basic but don't have HD. That could potentially free up a little bit of additional space, although not a whole lot, something on the order of magnitude of 30-50mhz.

    Many of their markets, like NYC are all-digital and still require SDV. They have an epic crapload of HD channels and are still using MPEG-2.

    That's going to be a LONG time for the Expanded Basic/Digital Starter channels, but will happen sooner for higher tier SD channels.
     
  14. Bigg

    Bigg Active Member

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    U-Verse has just north of 200 HD "channels", so with the right system management (MPEG-4) and upgrades (860mhz), Comcast should be able to match their HD offering while blowing their internet totally out of the water, and offering as many tuners as people will pay for.
     
  15. tarheelblue32

    tarheelblue32 Active Member

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    I understand that, but in my market where the analog channels are still taking up a ton of space, even very popular HD channels are on SDV, which means if my tuning adapter fails I am pretty screwed. Getting rid of the analog channels should at least allow them to have the 50 or so most commonly viewed HD channels as non-SDV channels. I am not against using SDV for the more niche HD channels that have limited appeal, that actually makes some sense, but having AMC HD or TNT HD or FX HD being SDV is very aggravating.
     
  16. nooneuknow

    nooneuknow TiVo User Since 2007

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    Cox Cable...
    Even with a 1GHz network, my Cox market has all my favorite channels on SDV, while still supporting analog. Cox made the community a promise that analog cable would continue to work, after the OTA digital transition. I think they fear a major backlash if they cut analog service, after the media blitz campaign with that promise...

    Still, once again, they are doubling our internet speeds, as they promise every year "for free". In 6-8 months, the bill will reflect the speed doubling, in the name of "due to increased operational costs, tariffs, and taxes...".

    They get away with murder. I love the "Free HD", that we have to pay extra to get. Yet, they keep analog around... I guess they must have enough "low income" subscribers, who they figure they'll lose if those subscribers can't just connect and get channels 3-69, with some gaps in-between...
     
  17. Dan203

    Dan203 Super Moderator Staff Member TCF Club

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    U-verse is pure IP. They only send a channel to your house when it's requested by one of your boxes. So the number of channels they actually offer is irrelevant. They could potentially offer every channel in existence if they wanted to. However they only have about 25-30Mbps total to use for both TV and internet, so the maximum number of simultaneous streams is limited to just 4 and that's with them using super compressed 5-6Mbps H.264 for the HD channels.

    Typically H.264 only reduces video by about 30-40% compared to MPEG-2, so if we have 100 HD channels now converting to H.264 would only add the capacity for 40-50 more HD channels. To go beyond that they need SDV. SDV is essentially the same thing that U-verse does just at the node level instead of the individual home. If properly managed SDV can add a LOT more channels then a switch to H.264. Plus SDV is compatible with most existing equipment, whereas a switch to H.264 would require a major upgrade at the headend and the replacement of a large number of boxes in the field.
     
  18. moyekj

    moyekj Well-Known Member

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    I don't see SDV going away. Here in Orange County Cox upgraded to 1 GHz quite a long time ago now and still heavily employ SDV. The 860 Mhz-1GHz space they are currently partially using for H.264 channels since the newer set top boxes needed for 1 GHz tuning can decode H.264 anyway. Of course they still have all the analog channels as well, so can reclaim a lot of bandwidth eventually just by doing away with those. Even if they got rid of all analog channels and all H.264 I fully expect SDV to remain. They've already made the investment in SDV (including increasing number of nodes to make SDV more efficient) so doesn't make much sense to get rid of it at this point.
     
  19. ajwees41

    ajwees41 Active Member

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    Cox Omaha already upgraded to 1GHz and just list past year might have been end of 2013 started using sdv So I guess with Cox at least SDV will be everywhere even in 1GHz areas.
     
  20. ajwees41

    ajwees41 Active Member

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