[daniel99]

that puts us out who live in a village that does not yet have Infinity we only get BT Broadband at 2MB

[jamcambs]

Originally Posted by Jono

The linear channels will only be a available to people with Infinity because multicast is only been used on fibre products.

I think you will find that wont be the case. Linear channels will work if you have BTVision on DSL.

[Jono]

Well references to iptv multicast on openreach website all point to fibre only

GEA Multicast

GEA Multicast is a dynamic point to multipoint network layer service that enables*you to deliver IP data streams (typically, but not exclusively, for IPTV traffic) more efficiently to your customers. GEA Multicast is enabled at the NGA head-end/layer 2 switch (L2S) level*through a nominated GEA Cablelink to*your customers*on both FTTC and FTTP.

[onephat]

I thought I remembered reading an old register article where BT had stated they had begun upgrade adsl to support multicast.

[wwwebber]

So, going back to my original question about recording streamed channels....

TalkTalk have announced thier Youview box but it can't apparently record streamed channels.

I piggin well hope that this doesnt apply to BT's Youview offering too.

[shug15]

Originally Posted by wwwebber

Anyone see any news or has it been a damp squid?

I presume you mean a damp squib?

[M_at]

Originally Posted by SimonBlackham

No I am not - BBC1 is a linear channel - a BBC1 programme on iPlayer is VOD.

Linear channels are just streamed VOD with a publication time before which you cannot watch.

That's only one way of offering linear channels. It's a valid mechanism for a channel only on IPTV service but it's typically not the best route for a live TV channel.

The most efficient way is to multicast a bitstream and have the network opt in to reception on your behalf. This means that there is only ever one copy of the material traversing the network.

By locating media servers to "split" streams within the ISPs infrastructure and across the Internet - something that CDNs such as BT, Akamai, LimeLight and others do - you get an element of this efficiency but it's nowhere near as good as multicast.

As for the fact that you can "rewind" live TV even if it's being traditionally broadcast rather than VOD playlisted - this is a buffering trick played by Adobe Flash Media server - it effectively saves a local copy and allows scrubbing from the indicated start of the programme until the live point.

[wwwebber]

Just been looking at the BT offers for those who have thier own Youview box. It seems BT have now launched the BTVision player which appears to allow BT Broadband customers to view BTVision content - similar to the TalkTalk player I guess. Again you won't be able to record stuff but this is VOD after all and not streamed channels so thats no different to existing BTVision functionality.

What is interesting though in that, the up and coming BT Youview box must offer something over and above just a Youview box with BTVision player built in. So this must be the linear chanbels surely ?. I'm hoping these are offered via the EPG, not via the BTVision player and thus will be recordable. FIngers crossed.

[Bryan Spink]

Originally Posted by wwwebber

So, going back to my original question about recording streamed channels....

TalkTalk have announced thier Youview box but it can't apparently record streamed channels.

I piggin well hope that this doesnt apply to BT's Youview offering too.

You can always try connecting a recorder to the YouView box. Unless there is any copyright protection on the streamed channels you should be able to record.

[wwwebber]

Originally Posted by Bryan Spink

You can always try connecting a recorder to the YouView box. Unless there is any copyright protection on the streamed channels you should be able to record.

Possible but not practicle. Thanks anyway.

[SimonBlackham]

Originally Posted by M_at

That's only one way of offering linear channels. It's a valid mechanism for a channel only on IPTV service but it's typically not the best route for a live TV channel.

The most efficient way is to multicast a bitstream and have the network opt in to reception on your behalf. This means that there is only ever one copy of the material traversing the network.

By locating media servers to "split" streams within the ISPs infrastructure and across the Internet - something that CDNs such as BT, Akamai, LimeLight and others do - you get an element of this efficiency but it's nowhere near as good as multicast.

As for the fact that you can "rewind" live TV even if it's being traditionally broadcast rather than VOD playlisted - this is a buffering trick played by Adobe Flash Media server - it effectively saves a local copy and allows scrubbing from the indicated start of the programme until the live point.

Yes we have (had) this on a number of boxes - but it only works if you have started to watch the stream before the start of the programme - ie you cannot 'back record' a programme that had started before you either took the box out of standby or tuned the channel.

The advantage of the YouView scenario (and Tivo??) is that you can wind back live TV to before you started to 'watch' it. If you need to record linear channels for later viewing - then the YouView EPG should make this unnecessary for at least 7 days and if you can record VOD then beyond 7 days.

If YouView allows you to wind back to before your box started to 'buffer' then it is VOD (at that time) and Multicast is no longer relevant.

For watching "Emmerdale" we already - watch live (in HD) if convenient - record on the BTvision Box to chase-play if we start watching before it has finished and/or it has appeared on ITVnetPlayer (the split is about 25%/25%/50% on the three ways).
It would all be a lot more straightforward with YouView - especially if the YouView EPG offers "View from the start" as an option when the programme has already started (or finished) as well as the normal "View"option.

Getting to your point...
To enable rewind before the start of the programme (in the limit) you would have to have the whole weeks EPG worth of programmes stored in each local exchange which is untenable - downloading (locally) popular programmes to the exchange (dynamically - as each programme is demanded the first time) is more tenable but could lead to as much demand as IP VOD at certain times of the day. Downloading each stream at 'Broadcast' time may be the way to do it but with a large number of channels it may become a storage problem - perhaps solid-state drives would be a reliable solution (MTBF could be a problem with Disks unless totally redundant - then costs escalate especially with the total number of exchanges - and with YouView who pays?). The problem still exists with fibre to the door as the local loop is not really the bandwidth throttle even now (although we all?? know that the higher the lowest bandwidth in the delivery chain the better - the reason for BitTorrent being the low upload bandwidth throttling transfer)

PS can we not have an English lexicon so the spellchecker doesn't throw a fit at normal spellings