Mute

C&W/NTL/Telewest Box Revival

Here are a few more random recollections based on the last few posts.

Cable and Wireless and ntl built their networks separately from each other, so ended up with very different technology. I recall someone mentioning that Telewest hired the same consultants that Cable and Wireless used and asked them to help them build an identical digital TV network as they were expecting to eventually get taken over by Cable and Wireless.

When ntl acquired the consumer division on Cable and Wireless they ended up with two networks that were quite different, resulting in years of ntl customers on various Internet forums having to identify which of the two networks they were on when discussing issues. ntl did a terrible job of integrating the two networks, they didn't even get around to using the same channel numbering on the two networks, resulting in broadcasters having to advertise two different channel numbers for ntl customers.
The software used on the boxes of the two networks was also very different (resulting in former C+W customers having much better interactive services than those of us on the original ntl network). Eventually the user interface on the software was made to look the same on the two networks, but it was still very different underneath.

I believe that all three networks used boxes from Pace that were very similar, but had some differences, so there were some subtle variations in the model numbers of the boxes. Eventually ntl released a box from Samsung which was the first time the exact same model of box was used on both of their networks, albeit with different software. This first Samsung box was also the first box used on the original ntl network that had a DOCSIS cable modem in it. The ntl Pace boxes all had DAVIC cable modems in them, expect for the last one which actually had a dual standard cable modem that initially used DAVIC but with the intention of activating the DOCSIS modem in a later software update (which they never got round to doing).
Interestingly, Virgin Media would have had to continue operating the DAVIC broadband infrastructure on the network in the original ntl regions up until a couple of years ago in order to keep these older boxes working.

I believe that the engineering menus on all of the boxes are incredibly similar across all of the different models. Even the TiVo boxes have the same style of engineering menu that's accessed in the same way, it's just the V6 boxes that don't

After the disaster that ntl had trying to integrate their two networks it was interesting to see how things went very differently after the merger with Telewest. They seemed to very quickly align the products between the two companies, having mostly the same channel line up, with the same channel numbers and same packages across the whole on the network before they rebranded the company as Virgin Media. They even unified the software architecture on the boxes and video on demand systems fairly quickly.

Not long after the merger they carried out a major upgrade of the head ends (in a project called Next Generation TV) which saw a single super head end feeding the entire network, rather than having separate networks for the three legacy companies, although some technical differences remain.
There was a software update at the time that was needed to make the boxes compatible with the new network. I'm not sure exactly what changed to need this update, but if you're seeing differences in what needs to be fed to a box to get it to work then it might not just be which of the three networks the box came from but also if the box is running software from before or after they switched to the NGTV network.

The rapid changes that have happened to the network in recent years have mostly been due to the older boxes being removed. Whilst I can appreciate the technical nostalgia of getting the boxes to work, especially the ones running software from before the Virgin Media era, they were clearly holding back other technical advancements on the network. I think that all of the digital TV platforms have had problems with having to remain compatible with the oldest and least capable box that is still in use, so it been interesting to see Virgin Media being able to make some big changes (such as channels going HD only and switching SD channels to MPED4) since these older boxes have been removed.

Virgin Media - V6 Recordings Query

The way that recordings work on Virgin Media boxes is different to the way that Sky do it. My understanding is that whilst the Sky boxes record the encrypted signal as broadcast, the Virgin Media boxes decrypt the signal, but then encrypt it again before saving to disk using a different system and an encryption key that's unique to each box (which is why you can't swap drives between boxes, they wouldn't be able to decrypt a recording made on a different box).

As there is no connection between the encryption system used to broadcast the channels and the system used to save recordings then technically there is no requirement to still be subscribed to a channel to play back a recording. For many years this is how it worked and you could continue to watch recordings from channels that you no longer subscribed to.

At some point Sky decided they didn't like this and required Virgin Media to change they system so that it behaved in the same way as the Sky boxes. This is the point where it went wrong as Virgin Media implemented the new system badly.

The way it works now is that there are restrictions placed on the channels from Sky, but not other broadcasters. The Sky channels are flagged so that the boxes know which channels to apply the restrictions to. When you go to play back a recording the box checks to see if the recording came from a channel that Sky own and if it does then it will only let you play the recording if you still subscribe to the channel. Unlike the Sky boxes there is no technical reason for this restriction, it's a contractual requirement imposed by Sky.
If a recording is from a non Sky channel then the check to see if you're still subscribed isn't done, so you should still be able to play back recordings from non Sky channels that you no longer subscribe to.

The problem is that in order for this check to work the channel still needs to be broadcasting on the system. Shortly after introducing this system a channel closed down and lots of people on various forums complained that they couldn't watch recordings from that channel any more. Because it was no longer broadcasting the check to see if it was flagged as a Sky channel couldn't be done, so the box refused to play back the recording.

As a result, when a channel on Virgin Media closes down it isn't completely removed from the system. The broadcast stops, but the channel remains in the channel tables as a hidden channel for awhile so that any recordings can still be watched. After some time (normally a few months, but it can vary) the channel is completely removed and recordings can no longer be played back.

This can cause a lot of problems, not only when people try to watch old recordings from channels that no longer exist, but also when changes are made to which regional version of a channel is broadcast, or where a channel has gone HD only with the SD version closing. Whilst viewers can still receive the channel, if it's not the exact same version (with the same ID) that the recording was made from then the recordings can't be played back.