Freeview: DVB-S vs DVB-T

Forums › Home Theatre (including HTPC and EPG Collector) › Freeview: DVB-S vs DVB-T

steve2222

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#15541 28-Aug-2007 09:02

Why is it that Freeview are proposing to broadcast over two different broadcast environments. Given satellite produces the best reception over all NZ why wouldn’t they have just backed this platform. Instead they effectively perpetuate two cost structures which ultimately impact customers, broadcasters and create additional effort for manufacturers. Is it perhaps that Freeview have no redundancy if the satellite fails? Is it that they cannot do HD on satellite (although I understand Sky plan to). Is it that satellite does not have enough capacity for them? If so, why did they not buy more capacity instead of incurring the cost of rolling out DVB-T and causing customers to maintain two aerial systems (if the use Sky). As I understand it, one advantage of satellite is some DVB-S tuner cards actually allow you to record more than one channel at the same time if they are on the same Mux (you presumably can’t do that on DVB-T). Maybe Freeview’s reason to have a DVB-T platform is they will say customers already have the aerials. But then they are only broadcasting the signal in main cities off the main transmitter only. Also I suspect that a number of people will have UHF aerials that are not in good enough condition to pick up DVB-T reliably. Is it perhaps that DVB-T better allows for regional stations. But is this really worth the cost of running two platforms.

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#84066 28-Aug-2007 09:14

steve2222: one advantage of satellite is some DVB-S tuner cards actually allow you to record more than one channel at the same time if they are on the same Mux (you presumably can’t do that on DVB-T).

I was under the impression that you could. Someone want to clarify?

allstarnz

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#84070 28-Aug-2007 09:43

itey:
steve2222: one advantage of satellite is some DVB-S tuner cards actually allow you to record more than one channel at the same time if they are on the same Mux (you presumably can’t do that on DVB-T).

I was under the impression that you could. Someone want to clarify?

Only i you have multiple tuners on the card. My HVR3000 can only tune into one channel at once (be it watching or recording)

mruane

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#84071 28-Aug-2007 10:07

I think it depends on the software being used. GBPVR for instance can only record one channel from the DVB-S card per tuner on the card. Media Portal's TVE3 engine however can record multiple channels from a single tuner DVB-S card. I have had TV1 and TV2 recording at the same time from a single tuner Nova S Plus card, so it might work the same way with your HVR3000 card. It works by intercepting the complete mux and (I guess) by stripping out the individual transmissions from the digital stream.

I am not sure if that feature works if you save in a format other than .ts (transport stream). When I tried recording both channels and saving to .mpg format it did not work. So, perhaps you need to use the .ts format.

PS Is the HVR3000 a hardware based mpg encoder or is that done in software?

Cheers Mike

sbiddle

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#84073 28-Aug-2007 10:13

steve2222: Why is it that Freeview are proposing to broadcast over two different broadcast environments. Given satellite produces the best reception over all NZ why wouldn’t they have just backed this platform. Instead they effectively perpetuate two cost structures which ultimately impact customers, broadcasters and create additional effort for manufacturers. Is it perhaps that Freeview have no redundancy if the satellite fails? Is it that they cannot do HD on satellite (although I understand Sky plan to). Is it that satellite does not have enough capacity for them? If so, why did they not buy more capacity instead of incurring the cost of rolling out DVB-T and causing customers to maintain two aerial systems (if the use Sky). As I understand it, one advantage of satellite is some DVB-S tuner cards actually allow you to record more than one channel at the same time if they are on the same Mux (you presumably can’t do that on DVB-T). Maybe Freeview’s reason to have a DVB-T platform is they will say customers already have the aerials. But then they are only broadcasting the signal in main cities off the main transmitter only. Also I suspect that a number of people will have UHF aerials that are not in good enough condition to pick up DVB-T reliably. Is it perhaps that DVB-T better allows for regional stations. But is this really worth the cost of running two platforms.

IMHO what they are doing is prefectly logical. The DVB-T broadcasts are the intended platform for viewing TV in metropolitan areas and the DVB-S service is primarily for outside metropolitan areas. DVB-T offers greater bandwidth at a much cheaper cost that satellite space and also offers redundancy incase of a complete satellite failure. Sky fall into exactly the same situation.

The setup costs of a DVB-T system for an end user are also significantly cheaper than DVB-T since many already have UHF aerials that will work fine and we're also likely to see the bulk of TV's sold in the NZ marketplace with built in DVB-T tuners within probably 12 months so no additional hardware will be required in many cases for somebody buying a new flat screen TV.

HD broadcasts are available on the DVB-S service however they use far more bandwidth. The Freeview satellite service is only DVB-S at present however an upgrade to DVB-S2 to support HD has not been ruled out in the future. People keep talking about Sky rolling out HD but the reality is Sky will only be offering a limited percentage of their programming in HD, it's not as though every single Sky channel will suddenly be HD.

allstarnz

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#84077 28-Aug-2007 10:53

yeah that makes sense what Sbiddle says. Terrestrial bandwidth is cheaper, and more abundant. You're not reliant on a third party either, as you are with satellite (Optus)

thanks Mike, will have a look into that later on. Am having enough trouble just getting the card to work reliably at the moment

lchiu7

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#84091 28-Aug-2007 11:59

Looking at what is going on in the US market you can understand some of the rationale of this deployment strategy.

1. Satellite is very common (with HD) but you need a dish. Not always possible when you live in an apartment complex or in places with onerous building regulations

2. Terrestrial digital over UHF means folks don't necessarily have to invest in any additional gear. In fact in the US from what I understand, the majority of folks who received terrestrial UHF HD broadcasts have TV's with ATSC tuners in them so there is no need to buy a box to receive the signal.

3. Even now with cable you don't need to buy a cable box since a TV can receive HD QAM broadcasts over cable which are not encrypted (most of TCL cable is encrypted - I wonder if they will re-transmit and encrypt Freeview?) and for some sets, you can insert what they call a cablecard (which is basically a smartcard) into a slot on the set to decrypt the cable signals.

Having purchased a Freeview DVB-S box and leveraging the existing Sky dish on the roof, when DVB-T comes I doubt I will do anything until the HD situation is clearer. having a PS3 possibly might purchase the PlayTV addon if it can record HD

Larry

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openmedia

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#84092 28-Aug-2007 12:01

It is also about retaining ownership of spectrum. The terrestrial spectrum the TV companies currently use is potentially worth a lot of money.

Also not everyone want or can have a satellite dish. For example some rental agreements don't allow you to install one.

Lastly, in most of the world they tend to produce TV sets with integrated DVB-T tuners rather than DVB-S tuners.

Steve

Generally known online as OpenMedia, now working for Red Hat APAC as a Technology Evangelist and Portfolio Architect. Still playing with MythTV and digital media on the side.

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Fossie

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#84095 28-Aug-2007 12:33

Channels on Dvb-t are usually multiplexed aswell. This is how it was with the mpeg-2 trial. This means you can watch as many channels as there are on the one multiplex.

cyril7

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#84097 28-Aug-2007 13:06

Fossie the transport streams that are used on all DVB-T. S and C platforms is identical, DVB only specifies one type of transport stream, its only the modulation method that changes as appropriate for each propagation media.

As for bandwidth, well the Sky and FreeView DVB-S muxs both have typical post FEC usable bitrates of around 30Mb/s, when Sky moves to HD they will most certainly implement the DVB-S2 standard that would achieve around 40Mb/s from the same bandwidth. Depending on what modulation mode a DVB-T mux is operated in will dictate what bitrate can be achieved, but max bitrates are only around 24Mb/s, so from a bitrate point of view DVB-S is more capable. However satellite capacity comes at a cost and an ongoing rental cost at that, whereas DVB-T bandwidht comes at a fixed price, ie the cost of kit and the cost to buy the channel allocation in the first place, the UHF spectrum that Freeview will be using has come at a pretty small spectrum right cost (none in some cases).

I think the reasoning for going with a hybrid system makes very good sense, for many the cost of a dish over a UHF antenna can make the deal, however the added cost of mpeg4 capable boxs may steal some of that back. I guess the regional add thing has a lot to do with it, from a DVB-T stance, yet the ubiqutious coverage of the DVB-S solution solves the need for hundreds of small translators.

As time goes by I think it reasonable to see Freeview doing some HD via Sat, the DVB-S2 technology that most/all HD Sat boxs support is backwards compatible with the older DVB-S and infact can be overlayed on DVB-S transmissions but gain extra bandwidth for HD transmissions. Going DVB-S mpeg2 from day one made easy and cost effective access to readily available STB's although I presonally think the whole certd box thing is a complete farce, having tried both I would never purchase one of the current certd boxs, as better non certed boxs for half the money are readily available.

FreeView themselves have stated that the move to DVB-S on mpeg2 only at this point was to solve the problem of good quality pics to everyone anywhere at a reasonable price, and enable all NZ's to move to digital TV at real price.

The thing that gets my goat is that FreeView seem a bit pig headed and protecting their patch to spite their face by not letting Sky rebroadcast some Freeview channels. I think Freeview needs to ask themselves are they in the business of flogging STB's or broadcasting material to all who want it. By letting Sky access to the FreeView muxs they instantly add 45% of NZ homes to their viewing, whereas as of today some 20k certd FreeView STBs and another say 30k FTA STBs are all that can see the likes of TVNZ Sports extra, and the up and coming TVNZ6.

Cyril

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#84099 28-Aug-2007 13:22

Hi, what I do not understand is that TVNZ 6+7 will be advert free and be the portal for Government specified content, yet TVNZ can stop 700,000 Sky customers from seeing that content, without buying another decoder. I would like to know the legality of this, as TVNZ is a state broadcaster as well as a profit driven company.

I aim to misbehave.

allstarnz

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#84102 28-Aug-2007 13:58

also using h264 MPEG4 as opposed to ??? MPEG2, you can get bigger bang for your buck. You can broadcast in MPEG4 and get just as good quality for lower bandwidth usage. h264 has much better compression than what MPEG2 uses. i.e more channels on the same amount of pipeline.

Fossie

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#84112 28-Aug-2007 15:17

I wasn't saying that you couldn't. Just responding to

As I understand it,
one advantage of satellite is some DVB-S tuner cards actually allow you
to record more than one channel at the same time if they are on the
same Mux (you presumably can’t do that on DVB-T)

lchiu7

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#84121 28-Aug-2007 16:04

DS9:
Hi, what I do not understand is that TVNZ 6+7 will be advert free and be the portal for Government specified content, yet TVNZ can stop 700,000 Sky customers from seeing that content, without buying another decoder. I would like to know the legality of this, as TVNZ is a state broadcaster as well as a profit driven company.

TVNZ is not stopping 700K Sky subscribers from seeing the content. If it indeed it is true that the content will not be available over Sky, Sky subscribers can always get a Freeview box to view the transmissions, just as non Sky subscribers have to? One advantage they will have is, they won't need to purchase and install a dish.

Staying in Wellington. Check out my AirBnB in the Wellington CBD. https://www.airbnb.co.nz/h/wellycbd PM me and mention GZ to get a 15% discount and no AirBnB charges.

cyril7

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#84125 28-Aug-2007 16:10

TVNZ has denied Sky access to any FreeView channels other than TV1,2,3,4 and MaoriTV, currently these sky provide these via their own streams. Sky claims they have approached FreeView to gain access to forthcoming channels however TVNZ in particular seems to want to play the sell FTA STB game rather than broadcasting to the masses. TVNZ is the problem here, not Sky.

That said, it does not stop Sky from providing a software update that allows subscribers limited access to scan transponders and store a number of FTA streams in a set of adlib EPG locations. The SkyUK boxs allow (or did allow this), as I remember they were limited to only 10 or so EPG locations, but you could add and delete FTA streams that interested you. In this way Sky is not "rebroadcasting" channels (even if only by mapping to the normal EPG), but just allowing their STB to operate in some limited manner as a FTA STB.

Cyril

lchiu7

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#84140 28-Aug-2007 16:38

As I said, TVNZ has not denied Sky subscribers from seeing Freeview content. It just that they cannot see it (without the hack you described) via their Sky boxes. That is a commercial decision I guess (no idea of the motives). But if Sky subscribers want to see the other channels, they can go get a Freeview box like the rest of us!

As an aside I wonder if TCL will be allowed to rebroadcast the new Freeview channels?

Staying in Wellington. Check out my AirBnB in the Wellington CBD. https://www.airbnb.co.nz/h/wellycbd PM me and mention GZ to get a 15% discount and no AirBnB charges.

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