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How Video On Demand Works (long and technical!)
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Old 08-08-2005, 15:09   #46
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Re: How Video On Demand Works (long and technical!)

just press the "on demand" button on your remote to get access...it seems at the moment that it is just some of the BBC programs you can watch again, but there is a lot of other pay for stuff such as music videos, films, cartoons etc.
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Old 08-08-2005, 15:19   #47
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Re: How Video On Demand Works (long and technical!)

Just press the On Demand button and select what you want from the menus. Or go to channel 106 or 107 and press Red.

If it doesn't work, power your STB off for 30 seconds then try again.
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Old 13-02-2006, 18:04   #48
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Re: How Video On Demand Works (long and technical!)

Have any Tivo users/Pace STB owners (Langley) noticed that after watching VOD, any programmed recordings which involve channel changes rarely work ? You have to switch the channel manually before the recording starts to ensure the recording happens okay.
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Old 14-04-2006, 13:28   #49
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Re: How Video On Demand Works (long and technical!)

So technically, the way VOD works... couldnt ntl implement some sort of PVR functionality remotely using existing boxes with new software with all the recording done at the head end and streamed in the way VOD currently does?

Im guessing it would be cheaper too?
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Old 14-04-2006, 14:22   #50
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Re: How Video On Demand Works (long and technical!)

Some American cable companies a trialling this idea. Forgotten the term for it though. So it is possible
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Old 14-04-2006, 17:00   #51
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Re: How Video On Demand Works (long and technical!)

Cablevision: http://www.multichannel.com/article/...=SUPP&nid=2226

Others have played with it in the past but dropped it due to legal concerns, namely that the content producers will sue them. I believe a lawsuit is in the process against Cablevision.
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Old 20-04-2006, 00:40   #52
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Re: How Video On Demand Works (long and technical!)

In cities where there is both a headend and a Hub where does the VOD come from ? I know my broadband comes from the hub but not sure about the tv.
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Old 20-04-2006, 01:32   #53
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Re: How Video On Demand Works (long and technical!)

Quote:
Originally Posted by uno
In cities where there is both a headend and a Hub where does the VOD come from ? I know my broadband comes from the hub but not sure about the tv.
More than likely both are in the same building, but you can get virtual headends in major citys. All TV and BB traffic goes to a headend where genarally the telephone switch is located also.
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Old 21-04-2006, 13:41   #54
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Re: How Video On Demand Works (long and technical!)

No in my city the headend and hubs are in two seperate parts of the city so do i presume the tv comes from the headend while the internet comes from the hub
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Old 13-06-2006, 21:46   #55
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Re: How Video On Demand Works (long and technical!)

Quote:
Originally Posted by Tristan
With the software required for VOD now being rolled out in Glasgow, it seems Digitalspy's rumours of a January launch on NTL are quite possibly accurate.

With this in mind, there's been some speculation about how VOD works, whether it will have the same facilities as Sky Plus, what sort of picture quality we can expect, etc etc. So I thought I should spend a little time explaining things

At the moment, the Front Row service operates using what's called "Near Video On Demand", or NVOD. What this means is that there are many video streams coming to your house, each showing the same movie with staggered start times. When you order a film, the software selects the appropriate stream and shows it on channel 0. (On NTL Bromley and Telewest, this has always been invisable to the end user. Langley users will remember having to tune to channels in the 200s for Front Row, prior to the CR3 update.) This is also the way Sky Box Office operates, and how the Sky Movies "multistart" function works (there is more digital bandwidth available on satellite than cable, and so it's relatively easy for Sky to use 10 or so different streams).

True Video On Demand works rather differently. Rather than receiving scores of video steams, and selecting the appropriate one, the box takes notice of just one stream. The difference is that this steam is for you, and only you. So you can pause, rewind, fast-forward and stop playback, all without affecting anyone else. How is this possible?

Well the first thing to point out is that, contrary to what some people have suggested, the box is not downloading any video content via the in-built cable modem. I don't even know whether this is possible, and it certainly wouldn't be very efficient. So forget scare stories about web-quality pictures, because it's completely untrue. Your box will be displaying a multiplexed DVB MPEG2 steam, the same as it does at the moment.

VOD works its magic by changing the source of the video. At the moment, all the steams are prepared at NTL's DTV HQ (try saying that when you're drunk) in Langley, from where they're forwarded on to your local "headend", and then on to your house. In this way, every house in the country receives the same video streams. VOD changes this by housing the programming on servers at your local headend, instead of centrally. This means that it becomes possible for your box to send "rewind" commands (for example) to the server, which will then start playing the stream backwards.

The eagle-eyed amongst you will have spotted a problem here however. Say there are 100 Front Row streams at the moment (I don't know the exact number, but it's a ballpark figure). If you replace this by local content at the same quality, you've still only got room for 100 streams. This isn't enough for the 10,000 subscribers who might be connected to a particular headend (I've no idea how accurate this figure is!) to each have their own stream. So how do you do it?

The answer is by using the "localness" of cable. For the greater part of its journey, all data travels around on fibre-optic connections. It's only in the last few hundred metres -- at the local cabinet level -- that this is transfered to coaxial (copper) cable and into your house. If you can then send different data to different street cabinets, then you can re-use the same frequencies on the coax cable in different areas. I beleive this is already done with cable modem connections.

In this respect, it's possible to share the 100 "spaces" you've got between relatively few properties. How many you share it between will be a tradeoff. The lower the figure, the more equipment you need, and the more it costs to set up. The higher the figure, the greater the contention, and the greater the risk that there won't be a stream free when someone wants to use the service.

So that's how it works. But what will it do? Well, the first and most obvious application is to replace the NVOD Front Row system that's currently used. That's a no-brainer. But past that, you're really only limited by server disk space. A survey published last year suggested that VOD will offer a large library of old and not-so-old films, probably as a rival to Sky Movies. There are also things like classic programmes and sports. On the existing (DSL-based) VOD systems operating in the UK, Homechoice and KIT, the BBC have offered a large number of programmes -- so if you missed last week's Eastenders, you can watch it again on VOD. Channel 4 have a similar deal with Homechoice. As the first large-scale VOD deployment in the country, I suspect the On Demand Group will have been trying to make deals left, right and centre. We'll have to wait and see what they come up with though.

People have been wondering whether VOD will be cable's version of Sky Plus. It's true that some of the functionality doubles up, but really they're quite different beasts. For example, the only way you can see last week's Eastenders on Sky Plus is if your box recorded it in the first place. Likewise, pausing and rewinding films etc requires that these things are on your box's hard drive. Sky Plus also requires a new STB, whereas VOD will work on any cable box with a working return path. On the other hand, VOD will not allow subscibers to pause live TV, nor plan for future future viewing (though it's technically possible to do both these things on VOD, setting aside 80GB of disk space per subscriber is a very big ask). Both NTL and Telewest are said to be working on PVR devices, so it will be interesting to see how these work in relation to VOD.

Any questions, please ask. Hope this is of some use,

Tristan

PS: Usual disclaimers apply. I don't work for NTL, Telewest, the On Demand Group, Sky, Homechoice, KIT, or anybody else for that matter. I have no qualifications in the subject. I could be completely, massively wrong.
Is there a simplified english version of that?
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Old 13-06-2006, 21:58   #56
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Re: How Video On Demand Works (long and technical!)

Think of it this way. Have you ever watched a video clip from the BBC website? When you double click on them, your PC communicates with the server at the other end and requests that it start sending your video clip. In this way, it's like downloading the clip. Now, the major difference between streaming and downloading is that with streaming, the player downloads a very small section of the clip, then plays that, while downloading the next section in the background. It carries on like this until the clip is finished. That's basically the priniciple behind web streaming.

VOD uses the same priniciple (you select a programme, click, the STB then streams it in the same way as the video clip above), but you can pause it, rewind and fast forward the video as if you were watching it on tape.

The reason it is taking a long time is that NTL actually require an awful lot of hardware to make it work (mainly servers for the Set Top Boxes to stream from). The user will never see this hardware, so it's easy to think NTL is doing nothing, but the hardware is being installed at each headend (where your TV comes from)., and takes a while to install.

Note: STB = Set Top Box.
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Old 20-07-2007, 09:56   #57
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Re: How Video On Demand Works (long and technical!)

great info folks, keep up the work
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Old 08-09-2007, 21:21   #58
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Re: How Video On Demand Works (long and technical!)

Anyone know if they plan to change whats on tv on demand
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Old 18-09-2007, 17:46   #59
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Re: How Video On Demand Works (long and technical!)

a new section has been added to tv hits, warner...............has about 3 pages of stuff.

war at home, cold case veronicas closet, veronica mars just to name a few.
get smallvile on there and i'll be a happy bunny
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Old 18-09-2007, 18:16   #60
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Re: How Video On Demand Works (long and technical!)

It won't let me rep you.

But very good post anyway, thanks.

BTW What's happened to Bill C?
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