It's not exactly straight forward...
Special Report
BSkyB goes digital:Multichannel facilities put automation to a test
GERALD M. WALKER
06/30/98
World Broadcast News
Copyright 1998 Intertec Publishing Corporation, a PRIMEDIA Company. All rights reserved.
When BSkyB decided to hitch its wagon to digital technology, the challenge was to design and equip multichannel facilities that were different from any other multichannel satellite service. Sky was planning not simply to pass-through programming. It intended to create content and play-to-air commercials on 54 general channels, as well as present 48 channels of near video-on-demand (N-VOD). Sounds like a job for super automation.
If you are contemplating the purchase of a digital video server, think about what BSkyB has installed at its new all-digital facilities in Osterley and Chilworth England. Sky Chief Engineer David Sparks has 72 Tektronix Profiles and one Quantel ClipBox, plus 57 Sony FlexiCarts operating under the control of a DAL (Drake Automation Ltd) automation system. That's what it takes to operate one of the world's largest and most complex satellite broadcast systems.
The Sky digital service initially will operate from Astra 1D, which Astra-owner SES earlier this year relocated from the orbital location 19.2 degreesE to 28.2 degreesE. This temporary relocation was to accommodate the 14-transponder package for the UK, of which BSkyB has 12 transponders. The plan is to have Astra 2A take over this service when it is finally operational.
The transmission areas involve 48 channels for N-VOD and 54 general channels. Program material includes commercial spots and long form programming. Says Sparks, "The master of every commercial or promotion is stored in a Sony Library Management System (LMS). Those are trickled to the Quantel ClipBox server, which holds about 7500 spots - the LMS holds 60,000 spots."
The spots remain in the ClipBox until they are no longer required, which is usually in about two weeks time. The Profiles are used as small on-air servers and are running in duplex. They hold material for about eight to 16 hours, playing out typically 1600 spots, which are shared among three channels.
"That is for general sport services, news, general entertainment and subscription movie services where there is a different movie every two hours," explains Sparks. "The long form programming for those channels, anything in excess of 15 minutes, is played from a FlexiCart off tape."
A DAL multichannel automation system (D-MAS), already successfully implemented at Osterley for BSkyB analog services, controls the program playout from the Sony FlexiCarts and the interstitial material from the servers. The Osterley site has three general control rooms. Co-located with the multichannel control rooms and also under D-MAS control, are six single channel control rooms using Pro-Bel TX220 mixers.
Sparks adds, "In addition, we have a near video-on-demand service (at Chilworth) where you have the same movie being played every two hours. They are all done off of the Profiles. The N-VOD movies get staged on three RAID Profiles." The ClipBox is running 10:1 compression and the Profiles are running Motion J-PEG at 24Mb/s. The Sky project is also one of the largest systems to use Java software with the Quantel ClipBox. In addition, Sparks notes that high-end promos will be edited on two Quantel Henry systems.
The expanded satellite uplink site at Chilworth is a tapeless N-VOD facility with signals being sent by Fibre Channel links from Osterley. DAL estimates that the two facilities incorporate the greatest number of interconnected Profiles using Fibre Channel and ATM links."Our involvement wit h the project," says Barry Goldsmith, chief executive of Drake Automation, "was initial concept design, working with Chief Engineer Dave Sparks. From that, we developed an engineering approach. We then acted in two roles. One was as systems integrator, installing and testing the equipment in the transmission area. The other role was doing all the automation system -installing and commissioning the whole area. In the engineering design role, it was a partnership, which I think these things have to be in order to be effective."
According to Goldsmith, the systems integration role helps with the implementation of the automation, because they understand the environment, having put in the broadcast hardware. As far as Sky was concerned, they were dealing with one organization, which took on the responsibility for making everything work. Goldsmith adds that because of this "one-stop responsibility," the Sky project developed into a very close partnership and Sparks concurs.
The D-MAS automation system interfaces with the Electronic Program Guide (EPG) provided by NDS, while the Conditional Access (CA) system has been developed by Open TV. "On the transmission side," Sparks points out, "we are running statistical multiplexing on the NDS multiplexers, and we are typically getting 10 channels per transponder."
Unique aspects Both Sparks and Goldsmith agree that the Sky project was unique, compared to other multichannel, direct broadcast satellite services.
Comments Sparks: "If I go look around the world at multichannel broadcasters, whether it be DirecTV, USSB, or whatever, most are really just network providers who are doing a lot of pass through and maybe some N-VOD. What we are doing is to start off with 54 channels and build each channel from the ground up. We play individually every spot, every program from one center. I haven't yet come across anyone else doing that sort of volume in terms of having to handle the media for that number of channels from the ground up. And it all works."
Goldsmith explains: "The unique aspect is that it is a very large multichannel origination system, whereas others may be only pass-through systems. When you see a 50 or 60 channel facility with automation, it sounds impressive, but they are not actually originating material, they are passing through material. The key to Sky was the high level of origination, because they have over 50 FlexiCarts playing out and a large number of Profiles for the interstitial material. Secondly, there is extensive use of Fibre Channel. They are very much in the forefront of actually implementing and using Fibre Channel, whereas others have only been talking about doing so."
Sky has 48 channels of N-VOD being played from the uplink site at Chilworth, but the tape library and all the base material is held in servers at Osterley, 60 to 70 miles away. That material is being played down ATM links to the remote uplink site to be held on servers, and that's the transmission play-out area. So, according to Goldsmith, the system is effective when broadcasters have a centralized tape library, but they cannot keep moving it around. "Now you can have a centralized tape library, build that up, then you can have your play-out transmission area at the uplink site and load the material across ATM links," he adds. In short, high capacity, centralized material is loaded down to remote, automated sites for transmission, and the remote site could be unmanned.
In another N-VOD application, DAL provides for the transmission of low bandwidth video as quarter screen film images so viewers may preview N-VOD programs within the NDS EPG. This feature was made possible because of the unique functionality of the EMC MPEG -2 server, which will be under D-MAS control. The system works in conjunction with the NDS capture station. When combined with the control from the D-MAS, the server internally multiplexes low data rate video into a single transport stream, which is then mixed into a main transport stream.
Lessons learned With all of the advantages that the RAID protected servers and the automation system bring to the Sky facilities in the way of over-all reliability, one of the key lessons learned, observes Goldsmith, is that there is never enough time for training the operators. Experienced operators who are accustomed to hands-on procedures have trouble learning that they are not continuously influencing what's on-air. With multichannel automation, the operator may have 16 or more channels, all playing out with no need for operator influence.
"Then, all of a sudden you have to do something and you have to think very quickly," he remarks, adding, "That puts quite a stress on the operator. In one sense, you are off-loading routine activities, but in another, you are putting a heavy load on people."
The same perspective applies to servers. Says Goldsmith, "Servers need a lot of configuration in setting up and people often don't realize that if you change one parameter, that will change the way the whole system operates. It only seems like one parameter, but these things are tightly coupled, like any computer. If all of a sudden you change something, the machine doesn't recognize the sequence. When you set up servers and establish all of the configurations, you should leave them alone - you have to stop playing with them." WBN
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