Today's sports production teams are challenged more than ever to deliver better quality coverage. Directors are always demanding even greater flexibility, and it all has to happen faster and more efficiently.
Hard disk recording has become standard practice at most live productions because of its obvious advantages. Multiple operators can access content instantly and simultaneously. Replay or edit functions never interrupt any of the continuous record processes, and nothing is ever missed out. The recording and replay of super-slow-motion sequences is now also possible in high definition, which is difficult to achieve using tape. What once began as a disk recorder now is a family of networkable servers that can also exchange HD images in real time. With the integration of automatic back-up and archiving, as well as exchanging content with nonlinear editors of different kinds, all the bricks are now available to build a truly integrated live production environment for sports.
Server networks
When working on a live OB sports production, the main requirement of the server network is to be extremely reliable. Recordings must be secure, robust and, of course, of good quality. In addition, no single point of failure, such as loss of power, or board or disk failure, should cause the loss of recordings or stored material. Modern servers can achieve this by using independent units networked together, each with individual RAID arrays and dual power supplies, and connecting them together with a network.
For large multi-camera sports events, the server network must allow real-time access to all sources by multiple users with different objectives, such as instant slow-motion or super-motion replays, building packages for expert analysis, highlights and closing music montages. Furthermore, each user must be able to perform his or her own task without affecting other users.
A typical setup might be where each independent server consists of a configurable combination of record and playback channels, say up to six in SD and four in HD. The individual servers would then be linked together to allow any operator access to any material, and to provide a modular network that can be expanded to suit the requirements of the production.
For general file exchange, a cost-effective form of networking is TCP/IP over gigabit Ethernet, but as this is a packet-based system, it cannot be relied on for live broadcasting. However, for live playout direct from a networked server, rather than copying to local storage, an alternative is to use SDTI. This uses standard 75V BNC cables and supports data rates up to 540Mb/s in one direction. For two-way communication, a network could be set up to have duplex SDTI connections.
In practice, a typical installation would have around 10 servers connected to accommodate between eight and 10 real-time live movements in SD, or three in HD. The network control protocol must not only be able to deal with video, but also control information and bandwidth management. Bandwidth management ensures that simultaneous demands on the network are prioritized so that, for example, HD live on-air traffic has the highest priority, while archiving has a lower priority.
Indeed, once the live event has ended, the focus of attention turns to the problems of archiving what can amount to hours of material recorded during the event, and how to catalogue and retrieve the material at a later date. In preparation for this, metadata can be added to material at the time of recording, and this is then carried within an MXF wrapper that can be interpreted by any third-party database. Material that is required for archiving could be sent in MXF format, via the SDTI network system to removable drives, during the event.
Sports servers in action
An example of such a network in action was an EVS system installed at the CBS Super Bowl XXXVIII event, where 20 networked servers formed the backbone of the high-definition production. The architecture offered any operator access to all current feeds, previously recorded sources and archive material via removable hard drives. It also supported several network branches that were created to handle the pre-game coverage, the game telecast that included super motion replays and in-game editing, and the half-time and post-game coverage.
In order to optimize workflow and bandwidth allocation, the network was broken out into three areas. For the graphics portion of the pre-game/post-game production, networkable video servers were used on a distinct network, animated graphics were played from HD video servers under control of vision mixers, and additional video servers were used to play the coveted millions of dollars in advertising seen throughout the broadcast. The HD instant access server was optimized for operation under control of third-party devices, and while this can include station/playout automation systems, in this instance, it refers primarily to visions mixers, special effects/graphics systems, and even VTR controllers.
Two HD live production servers were tied to the game production network to allow footage from any isolated camera source to be used for packages to be included in half-time and post-game coverage. This was accomplished while other operators were working on the same sources to produce replays for the game coverage. Super-motion cameras, which were not available in high definition at the time, were linked on a separate SD network. During all of this, several XFile units were used to automatically archive both the HD footage and SD super-motion material onto standard removable IDE hard drives that could be taken away at the end of the production.
The total recording capacity of the networked server system was 60 hours of HD plus 80 hours of SD, and the total backup capacity of the XFile units used was 36 hours of HD plus 72 hours of SD.
One of the most important aspects of the system to CBS Sports was the unification of SD and HD production, so that both telecasts featured exactly the same camera angles, replays and graphics. From the operator's point of view, the HD servers worked exactly like their SD counterparts, so they could seamlessly move back and forth between HD and SD systems; the only difference was the picture quality.
Conclusion
The networked live production concept is doing away with the last remaining reasons to roll any more tape during OB/sports productions. The technology unites the best of both worlds: the speed of operation offered by disk recording meeting the mobility of content by networking and removable media. Such systems can embrace the complete production workflow, from the capture of cameras and feeds, via nonlinear editing, to playout, including archiving.
Networked technology has proven itself during impressive productions such as the UEFA Champions League in Europe and the Super Bowl in the USA, but its flexibility and modular approach means it can be used in configurations of a much smaller scale.
Marcel Groos is the product marketing manager, and Mike Davis is a consultant, for EVS Broadcast Equipment.
