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HD content comes to BT Vision
Sunday 14 September 2008 09:31:47 by Andrew Ferguson

After a short period of testing BT Vision is now offering HD downloads to all its customers. DigitalSpy has some more of the details, prices start at £2.95 for a 24 hour rental. New releases cost £4.95, with the BT website providing more information on how to access the HD content.

The HD material is a download rather than a stream, so if you want to watch a film you will have to wait for it to be downloaded to the set-top box. The films are believed to be around 8GB in size. An 8GB file on a 2Mbps connection will take around 9 hours to download, it is thought that the rental period does not start until you play the movie, so it seems best thing is to start a download just before going to bed, or when leaving for work so it is ready to view that evening.

Interestingly the films are encoded at 1080i with Dolby 5.1 Surround Sound, so should be significantly better than normal TV. The service will be competing with DVD and Blu-ray rental services, downloads will struggle to compete with popping down the road to the nearest video store in terms of time to have the film in your hands, but then if its a popular film they may not have it in stock, plus there is the cost of getting there, parking etc.

Comments

Posted by zyborg47 over 8 years ago
I was thinking of getting BT vision because of the HD promise, but looking at it now, I think I am better off staying with Lovefim DVd rental, ok they may take a bit longer to get the film here, but they are cheaper.

Sorry Bt, once again you are just over priced.
Posted by comnut over 8 years ago
yep if you realy want HD, a disc is far more reliable... no downloads gone wrong, no 'forgetting the expiry time', just plug it in and get guaranteed HD!

there is Terrestial HD promised for after 2012 though...
Posted by chrysalis over 8 years ago
that is very expensive for what you get.
If it was delivered over a fibre 100mbit connection in just a few minutes it would be different but to pay that price for something coming down at 2mbit is a bit of a joke.
Posted by c_j_ over 8 years ago
If HD matters, how do you get Blu-Ray/HD quality in the same 8GB of data that fits on a dual-layer DVD ("better compression" doesn't count)?

Can BT download you a takeaway to eat whilst watching the movie picked up at Blockbuster?

Ignoring BT Retail for the moment: how much is an 8GB download at the PAYG ISPs, or at the quality ones (AAISP to Zen) which have correspondingly small quotas on their affordable tariffs? Elsewhere, how much of the usual unpublished "fair usage" quota is left after you've downloaded a couple of 8GB movies in a month?
Posted by CARPETBURN over 8 years ago
I havent looked further into this but will that 8Gig be part of the BT broadband monthly cap???
Seems a bit pointless if it is.

@C_J... I imagine the films come in x264 format, which although is a lossy codec produces good results, if video is encoded right with it you can half the original size of say a bluray movie without affecting quality (atleast not easily noticed), if its not X264 based id be interested in what codec and container they are using.
Posted by andrew (Favicon staff member) over 8 years ago
BT vision downloads do not count towards cap, hence why they carry a fee.

As for quality a DVD with a good upscaling player is actually a pretty good picture. Whether they match that quality at a subjective level I don't know.
Posted by ian72 over 8 years ago
@c+j. This isn't bluray quality as bluray is 1080p (however, many people have only 1080i TVs so the result is the same).
Posted by jas88 over 8 years ago
You shouldn't discount better compression, c_j: using a more efficient codec will indeed fit HD content into a bitrate which could only deliver SD (or below) using MPEG2. The 8Gb will be expensive at current PAYG tariffs, and while it may take 9 hours at 2 Mbps - but using the 8 Mbps line I have now, it drops to just over 2 hours; anywhere close to ADSL2 speeds, it'll download in less time than it takes to watch.
Posted by c_j_ over 8 years ago
"using a more efficient codec will indeed fit HD content into a bitrate which could only deliver SD (or below) using MPEG2. "

Cleverer compression may do that IF the content is slow moving or if the content lacks detail. Now, what were the supposed benefits of HDTV? Ultimate detail, and not just in slow moving pictures?

"a DVD with a good upscaling player is actually a pretty good picture"

Indeed. But no codec can fit a quart into a pint pot, unless there's a visible loss of quality along the way.
Posted by andrew (Favicon staff member) over 8 years ago
1080i is a resolution and frame rate descriptor, and says nothing about bit rates.

There are places with 1080 HD Video but 1 to 2Mbps bit rates.

Posted by c_j_ over 8 years ago
Given a resolution and a refresh rate you can work out the raw data rate. To get the effective data rate down below that, you need compression. Sometimes content compresses nicely without loss of detail, sometimes it doesn't. The stuff that's obvious candidates for obvious candidates for good compression (not much detail, not much motion) don't sound like typical HD markets (sports, action movies). BluRay/HDDVD wouldn't have used 50GB if they didn't need it.

Ye canna change the laws of physics, capn. But given a big enough marketing budget you can fool a lot of people at least once.
Posted by c_j_ over 8 years ago
"that's obvious candidates for obvious candidates for good compression"

Another candidate for good compression is repetition is repetition, but only when it's easily spotted algorithmically.

"that's obvious candidates for obvious candidates for good compression"
Posted by comnut over 8 years ago
by definition: http://en.wikipedia.org/wiki/1080i
- more links to documentation within... (EBU docs, etc..)


Posted by comnut over 8 years ago
and if you dont trust wiki, at least try this...
http://hd1080i.blogspot.com/2006/12/1080i-on-1366x768-resolution-problems.html
Posted by CARPETBURN over 8 years ago
The content is obviously delivered using a lossy codec (probably mpeg4 based like x264 or AVC), that is the only way you would be able to deliver something that is HD and maintain the quality... Compared to a bluray disk and a critical eye the content will be poor... Although officially bitrate is not what makes something high def other things apart from just the resolution and frame rate come into play like amount of pixels.... Compress too far using a low bitrate and you lose pixels (thats what all that blockiness is) thus technically its no longer HD. CONT.....
Posted by CARPETBURN over 8 years ago
Even a normal scaling process depending on the res the screen can display can lose upto 5% in quality terms... Theres no doubt 8gigs worth of movie will look good, but it wont match bluray in general picture terms its more likely to look like a good dual layer dvd transfer of a film. The term HD is banded about too freely... If i take a dvd and convert it to xvid and alter the res to that of HD does that suddenly make it HD?? Of course it doesnt.
Posted by c_j_ over 8 years ago
I'm not sure folk fully understand the meaning of lossy here. If a codec wasn't lossy, you could take a 50GB BluRay and recode it with a lossy codec and then decode it, to get a bit for bit identical 50GB image stream. It doesn't work like that. Information is lost, hence the name: "lossy".

There are subtler effects than pixellation, like colour palette reduction: compressiong a smooth colour transition (thousands of colours) becomes a series of discrete steps (dozens of colours). And others too numerous to mention.

HD is not the same as HQ.
Posted by CARPETBURN over 8 years ago
Very well said c_j_ :)
Posted by comnut over 8 years ago
well here is a good demo, at various res, so you can see the sizes to expect..
http://www.nvidia.com/object/nvision08_gpu_v_cpu.html
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