Local Subchannels

Discussion in 'DIRECTV Programming' started by jacksonm30354, Sep 22, 2009.

  1. jacksonm30354

    jacksonm30354 Icon

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    Ok, I know there have been other threads about this and that it is unlikely for Directv to carry subchannels. But after thinking about it I am wondering why they won't/can't.

    A station has X amount of bandwidth. If you have subchannels, they all still add up to X. I know they have some sort of dynamic allocation so the subchannels don't necessarily have a set bandwidth but it still must add up to X.

    Is it an encoding issue? I.E. the TV station would have to have one encoder for MPEG-2 to send to the broadcast tower, and another piece of equipment to encode all the channels to MPEG-4 to send to Directv.

    Directv uses DVB-S2 correct? Can't a DVB-S2 channel have subchannels like ATSC?

    It just seems like it not a capacity issue as a station without subchannels would take X bandwidth and a station with subchannels would also take X bandwidth.

    Sorry in advance for the lack of the proper technical terminology :)
     
  2. Tom Robertson

    Tom Robertson Lifetime Achiever DBSTalk Club

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    Good start on the analysis.

    Yes, OTA channels are fixed in bandwidth and every sub channel steals bandwidth from the main channel.

    But, here is where I think we run into problems.

    I'm pretty sure each subchannel needs it's own chain of equipment to be carried: receiver, encoder, slot on the uplink mux, monitor at the broadcast center, etc. That starts adding up quickly.

    Until each part of the equipment chain can handle multiple sub channels as one feed, correcting the sub channel carrier info on each subchannel, etc. I don't think we'll see subchannels uplinked. (Or the cost of uplink equipment drops dramatically.) :)

    Cheers,
    Tom
     
  3. dishrich

    dishrich Hall Of Fame

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    But you're forgetting another part of the equation - D* takes the "main" prog stream (be it in HD or SD), then converts it from MPEG2 to 4, does some "reshaping" of it, then puts it up on their bird. Even if they are putting up an HD station (eg: WBBM-CBS Chicago) that has NO subchannels, they are NOT putting up that full entire 19.2mhz of bandwidth on their bird.
    The point of all this is - EVERY one of those extra subchannels DOES take up extra bandwidth, which D* obviously has decided NOT to waste on all those litany of subchannels. Even though most are SD only, if they were put up many or all of them, all of that combined IS a lot of extra bandwidth, that could better be used on national HD!
     
  4. Tom Robertson

    Tom Robertson Lifetime Achiever DBSTalk Club

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    Actually it wouldn't affect national HD. The locals are all on local spotbeams, not on the national beams.

    (Now it does affect $$ that could impact national HD...) :)
     
  5. dishrich

    dishrich Hall Of Fame

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    Yes, but it COULD affect additional DMA's that D* could carry on those same beams. They would probably rather be able to add another DMA of locals, & get MORE new subs, instead of carry a bunch of subs in existing DMA's that would probably be negligable at best, of bring in new subs.
     
  6. Shades228

    Shades228 DaBears

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    They could use compression to fix that scenario however as Tom pointed out the costs would not justify those sub channels. There are very few exceptions but most sub channels have lower ratings than even the lowest rating of the main channel.
     
  7. LarryFlowers

    LarryFlowers New Member

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    The thing about this conversation that bothers me is why people aren't raising cain with the stations for cutting back on the quality of the primary channel to support these largely useless sub channels.
     
  8. HoTat2

    HoTat2 Hall Of Fame

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    Yeah I think so too ...

    In order for DirecTV to include a station's local sub-channels on their LiL spotbeam satellite feeds I don't think the equipment can at present statistically multiplex streams which are in turn already statistically multiplexed. DirecTV would have to de-multiplex any multicast OTA local and then treat each sub-channel as a separate single tributary to the MPEG-4 encoder/ stat-multiplexer for the uplink.

    IOW, the uplinking equipment and individual spotbeam transponders aboard the satellite would be burdened with producing and carrying a stat-mux. mix comprised of dozens of HD and SD channels.

    Totally impractical for now I would think ...
     
  9. Shades228

    Shades228 DaBears

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    Most people grew up with cable or the old antenna and are used to bad PQ. People also don't understand it's taking PQ away from them.
     
  10. mattdreed

    mattdreed Cool Member

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    Not sure about other markets, but if most are like the Huntsville/Decatur, AL area, some subchannels are rebroadcasts of syndicated networks anyway (RTN and ThisTV). Plus, they're in SD at that. I'm sure that's not too appealing to D* to carry a network via a "backdoor." I'm sure there's some licensing issues there.

    If you're interested in those, I'd push for D* to carry them as part of their lineup.

    The APT station does have good alternate programming on it's subchannels, but again, only in SD.

    Until my local area can get its main channels right, I'm happy to wait for the subs.
    --MATT
     
  11. jacksonm30354

    jacksonm30354 Icon

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    I guess I haven't noticed that it has affected the quality of the main channel. CH 2 and Ch 11 both have subchannels.

    Come to think about it though, the only local subchannel I would have liked is the WeatherPlus on 11-2, but WeatherPlus is being dropped.

    I have some ideas on how they should redo the whole network/affiliate setup. I'll save that for another thread :)
     
  12. ThomasM

    ThomasM RF Engineer

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    DirecTV CAN and DOES transmit local OTA subchannels. (sort of) We have one in Milwaukee (ML41).

    Here's how it works:

    WMLW-TV (channel 41) is a local low-power ANALOG over the air TV station in Milwaukee. It's STILL analog, in fact. DirecTV has carried it for years, probably because it carries selected sports games when the other channels have different sports broadcasts. It is owned by Weigel Broadcasting which also owns WDJT-TV (the local CBS affiliate).

    Some time back, Weigel began carrying the WMLW programming on one of the digital subchannels (58.2) of it's full-power CBS station, since the signal of low-power WMLW leaves a lot to be desired.

    As soon as this happened, DirecTV switched to this digital subchannel feed. The difference was remarkable with the instant removal of all the irksome ghosting of the picture. Just out of curiosity, I phoned the station and spoke to an engineer who told me that indeed DirecTV had switched to the digital subchannel feed of WMLW.

    So from a TECHNICAL standpoint, it can and is being done. From a COST/BANDWIDTH standpoint, well that's a different story.
     
  13. dishrich

    dishrich Hall Of Fame

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    Nobody was saying it CAN'T be done - again, D* is NOT going to waste bandwidth on multiple copies of SD prog like THIS TV, RTV, PBS Create, PBS World, PBS Kids, local weather's, etc. With your example, all D* did was switch from the (poor quality) analog feed, to the digital sub version of the SAME thing. And at least in your case, they are carrying something that's unique to your area. (of course, I'm SURE they ended up doing this so that Weigel would let D* carry your local CBS HD, so obviously that's a little different situation) D* ALSO did this in the Chicago DMA; carrying WWME-LP (MeTV) but it's my understanding they carry it off WCIU-DT2 now.

    Whether they are pulling it off an analog or subchannel doesn't really matter, as D* is going to compress it down to their "standard" bandwidth they give SD locals.

    And in my market, our local CBS-HD is picked up via our local MNT affiliate, (WCFN-DT2), as the primary DT feed (WCIA-DT) is too far away from our local D* LRF. (FYI - WCFN-DT is NOT in HD, so that's why they have the room for HD on DT2 ; ) WCFN-DT is also carried by D*.
     
  14. JoeTheDragon

    JoeTheDragon Hall Of Fame

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    I think all Chicago locals are fiber feed.
     
  15. Tom Robertson

    Tom Robertson Lifetime Achiever DBSTalk Club

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    While I can't say about Chicago (I suspect you are correct), I can affirm many locations are.

    What I have no inkling of is where in the pipeline does DIRECTV get its fibre feed from the plant. Is it before the statmux which squeezes all the bits from the subchannels to make them fit, or at some point after the squishing is done. (Ie after the main subchannel is compromised.)

    Cheers,
    Tom
     
  16. dishrich

    dishrich Hall Of Fame

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    You might be right - there's a tech w/WCIU on avsforum, that might have mentioned them being on fiber to D*.
     
  17. JoeTheDragon

    JoeTheDragon Hall Of Fame

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    talking about whether how hard will be for TWC / direct tv to have 4-5 regional weather vers of weather scan?
     
  18. hanz_erichson

    hanz_erichson Mentor

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    The Raleigh-Durham market (and I would guess other NC markets) has a subchannel of the local PBS station. It's listed as UNC-TV Kids and is on channel 4-2. It appeared at the same time as PBS HD was added to DIRECTV so my guess is that it was part of the contract negotiations. There are two other subchannels of the same PBS channel that aren't on DIRECTV.
     
  19. JoeTheDragon

    JoeTheDragon Hall Of Fame

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    do they know if wciu HD, me too will come when d-12 goes live?
     
  20. dishrich

    dishrich Hall Of Fame

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    Well first of all, it's probably NOT a D12 issue - since it would be added to the existing Chicago spot, they could have already added it.

    The issue REALLY is - Weigel wants BOTH WCIU-HD AND MeTOO added, & I'm quite sure D* does NOT want MeTOO. So, both are holding out until 1 blinks - & I DON'T think it's going to be D* this time.

    I think someone did ask & he didn't know anything about it - which is to be expected from a tech... ;)
     

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