Who *is* doing genuine IPtv?
One could ask El Reg's tame IPtv man, if he can be found... only 2 blogworthy happenings in the IPtv world this year, Alex?
Meanwhile, wasn't Homechoice originally delivered over *ATM* not IP? The ADSL spec is designed to allow ATM traffic over a DSL line. IP sits on top (hence PPPoA). ATM, being a circuit-oriented technology, allows guaranteed bandwidth, which by coincidence is what you need for decent quality "on demand" TV. If the bandwidth can't be guaranteed the ATM circuit won't connect, whereas an IP session will connect and fail miserably later (e.g. once you've paid :().
IP, being packet-oriented, allows operators to sell more bandwidth (sometimes lots more bandwidth) than they can ever actually deliver, and operators have used this magick to "keep costs down". In the broadband market, the industry calls this overselling "contention", and much of the time, historically, this has worked well enough. For the operator. But for the punter, when demand approaches capacity (as it will when subscriber numbers increase, or when new applications take off, applications which won't work when not fed enough data, applications whose traffic can't be "traffic managed" because there simply isn't enough bandwidth), Bad Things *will* happen.
Last time I looked at BTwholesale's service description for their IPQoS, which is of course a "value added" (ie costs extra) option, it only guaranteed up to 2Mbit and if you had a 2Mb QoS session it seriously limits the amount of non-QoS traffic you can have (512kbit?). Is 2Mbit enough for BT Vision "on demand" content? BT don't say, not anywhere I could find, but http://www.radioandtelly.co.uk/btvision.html says you need 4Mbit. Cheers BT.
The broadband DSL networks currently being rolled out in the UK by BTwholesale and LLU operators all conveniently focus on IP not ATM, because (for them) it is cheaper. For the punter? They'll have 12/18 month contracts, and all the hiptrendy IPtv ISPs are going down the same route anyway, so who gives a **** about the punter...
The sad thing here is that without BT's early work into DSL and stuff there wouldn't be a residential broadband market today. Which of today's broadband market names is really doing that kind of fundamental next-generation research? Thank you Mrs Thatcher and the armies of beancounters.