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Topic: SDC Screenfast
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Stephen Furley
Film God
Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002
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posted 11-01-2015 09:17 AM
So far we have been offered six films for download, and have taken five. The first one we rejected as we did not have an adequate Internet connection at the time.
There were some technical issues with the first download, 'Amy', but once those were resolved there were no problems with ingesting, or playing.
The next two films were missing the BBFC certificate, but this seems to have simply been a matter of the distributor not including it. The final two films have downloaded without problems.
A typical download takes about 10-12 hours for us on a ADSL connection which peaks at about 17.5 Mb/s. This connection is dedicated to the cinema, and quite separate to the main network in the building.
It has generally been necessary to upgrade the downloader. Software before each film while it has been in beta; presumably this will settle down somewhat now.
David has responded very quickly to any issues we have had, often long after office hours.
I have seen speculation that downloaded DCPs are more heavily compressed than ones supplied on disk; I don't know if this is the case or not. They may possibly be somewhat smaller but it's difficult to be sure, as there is considerable variation in size between films of similar length, delivered by both methods, I have no complaints about picture quality. David, do you have any knowledge of this?
The main problem we have with the system at the moment is something outside David's control, and that is that most of the films we show are not available that way. We typically show about ten films each month, and about one of those is available as a Screenfast download, so about 90% are not. The only distributors who have delivered films to us by this means so far have been Soda and Altitude. Maybe others will follow now that the system is out of beta. Our last download so far will be screening this week, and the next one will not be until late in December.
Rather more distributors seem to be supporting the MPS Lansat system; I want to have a look at that at another cinema sometime, but for a number of reasons I think it is less likely that we will be getting that.
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David Margolis
Film Handler
Posts: 4
From: London, no state, England
Registered: Oct 2015
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posted 11-03-2015 09:59 AM
Hi Stephen. In terms of compression, there is no difference in what we offer as a download and what we send on hard drive.
The DCI recommendations allow for JPEG2000 compression at a maximum of 250Mbps. Let's make no mistake, this is a ridiculously high data rate. 250Mbps is useful if you have, for instance, 3D High Frame Rate. I’m sure everyone thought that particular version of the Hobbit looked great, right? But think about it. That film was essentially 96fps (two streams of 48fps). That left the encoders with 2.6Mb per frame. Compare that with 24fps 2K 2D, they would have 10.42Mb per frame. So if we are to accept that a single frame of a single eye from the Hobbit 3D HFR looked great (which it did) then we are sort of admitting that we are using nearly 4 times more bandwidth than we need to encode 2K 2D 24fps.
Most encoders, until now, have been quite lazy when it comes to thinking about efficient data rates. The slider goes up to 250 and hard drives are cheap. So, might as well just turn everything up to maximum and leave it.
Nowadays, we're thinking about getting the file size down to make DCPs easier to download. But, because this is cinema, we CAN NOT COMPROMISE QUALITY. The quality control process we go through with distributors is very stringent and they will look at things on a forensic level. We even have software that looks for compression artefacts before we start a human QC. Overall, if you spot compression nowadays in a DCP, it's more than likely to have been introduced before the DCP process, which is sadly out of our control.
Fortunately, manufacturers of the DCP encoding systems we use have woken up to the fact that encoders are trying to encode more efficiently. And they've provided us with a lot of tools that create streamlined "VBR" (Variable Bit Rate) DCPs. VBR is nothing new but the methods by which you decide where to hide the lower bit rates have become more advanced. Software is now better at applying more compression in areas where detail can't be seen and concentrating the higher bit rates to the images that need it most. The result, what used to be a 120gig DCP can now be bought down to between 60 and 80gigs with literally no visible loss in quality. To be honest, we could go smaller. I’ve seen 30gig DCPs that look excellent. But you are then getting dangerously close to introducing visible compression artefacts which would be unacceptable for cinema.
On your other point, distributors using Screenfast during the Beta trials included: Soda, Altitude, NT Live (for Encores), Eureka, The Works, Axiom and various other smaller distribs. The big ones are now looking at it although I'm limited to what I can say for the moment. But the system is growing in popularity and I think we will see more coming on board in 2016. If any projectionists prefer Screenfast delivery, please feel free to ask the distributor. It helps get the message across that cinemas are using the system and want more content delivered this way.
Somebody was also mentioning going over their download allowance. Most ISPs offer unlimited deals nowadays that don’t cost too much. We recommend singing up to one of these and also a business broadband line is better as you will get a lower contention ratio and hopefully faster downloads.
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Amanda Mundin
Expert Film Handler
Posts: 122
From: Belper, Derbyshire, UK
Registered: Sep 2005
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posted 11-04-2015 06:20 AM
Unfortunately Fibre isn't available yet for us, so if we were to use Screenfast it would just jam up our broadband line for those 10-12 or 14-16 hours, if we had a dedicated computer and broadband line for Screenfast it may be more feasible.
We have a LANsat from MPS and a Transit Box from Unique digital which both have dedicated lines, the LANsat seems the best option as it has around 13.5TB of usable storage, can also tune in & record Satellite shows, and has a web interface you can log in to from anywhere and push content to your server, although for some reason they can't get it to push to our Christie IMB-S2, only our backup Doremi currently.
If SDC could do some sort of deal to allow them to send their content to our LANsat this would be the best option for us, as looking at the BT Infinity website it could be 2017 before we have Fibre available, and in all likelihood that could be pushed back further.
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