Fully digital production studios (Second installment)

This article, of which we present the second installment, measures the success of four solutions for the fully digital production studio, concentrating on the areas of editing, graphics and reproduction/transmission. The first three solutions are only partially successful but obviously lead to the fourth, based on Clipbox, which meets all the objectives. The technological changes needed to reap the potential benefits of a fully integrated system are illustrated here.

An alternative is to connect the server in a star configuration.

In this way each interface only needs to operate at video speed keeping the server internal no matter what the requirements of a multichannel bandwidth. The connections can use the proven SDI television industry standard, capable of operating up to 270 megabits per second and over 600 feet of coaxial cable. With routing switches available and many TV equipment capable of accepting the signal directly, this seems to be a suitable solution.

Perhaps the most obvious configuration is to use each server channel as a device for recording and video/sound source. In this way, the server channels replace the VTR in an editing regulation panel while providing facilities for file entry and playback. By storing the entire movie on the server, it can be available to all users for editing, graphics, and playback. This puts the server on the production axis and, with proper performance, could succeed in achieving our four goals. However, assuming that an average of four VTRs are used in each of the four panels for editing control, this uses 16 server channels. Increasing one for playback and one for direct input means that 18 channels are needed: much more than any server offered today. Again an escape route consists of compressing the images, thus risking the quality of the signal.

Solutions 2 and 3 point to a deficiency in network and server bandwidth that prevents quality performance.

Figure 4 presents a solution that meets the objectives and depends on the equitable distribution of tasks and the application of recognized technology that works closely to new developments. In Solution 3, much of the channel capacity is used to provide fonts in the panels for editing control. It was recently assumed that dashboards are based on the traditional theme of multiple VTR, each server channel replacing one, so that the movie that was stored on the server can be edited and re-stored ready to resubmit. With more modern methods discs can be used to achieve a much better effect.

Success depends not only on the server and its network but also on the design of its outstations. In the last two years, disk-based editing control panels such as Newsbox and EditBox have been developed for online operation that feature effective real-time random access (the ability to read any frame in any order, at or above video speed) in their storage locations to provide true non-linear editing systems. Although direct comparisons are not valid, these can offer panels for editing control that use up to six VTRs and, due to the speed of access to storages, the editing process involves little or no dubbing. In effect, the editing process produces a set of instructions for new presentations rather than recording a new video. This is very important because it drastically decreases the need to copy video information, saving disk space and copy time and minimizing video transfers throughout the system.

By designing a server capable of giving true random access to its channels, each can replace the disk storage of the panels for editing control. Such a feature is included in the Clipbox specification. This true random access channel is really far from the traditional "linear" concept of channel. When interfaced with a true random access editing system, such as an Edibox, it can be equivalent to many VTR channels: or rather to sources with non-linear access.

It is clear that the operation of the panel for editing control with Clipbox storage requires a very high degree of integration to achieve the necessary frame-by-frame control at video speed. The ability of the SDI, adopted today to carry video and recessed sound, has been extended to also carry as recessed signals the necessary control commands. The entire connection of the server with the outstation is made with only two coaxial channels (input and output).

Using SDI also means that standard routing switches can be used to reconfigure the system in such a way that the panels for editing control can be on-line or off-line to the server.

Since the panel described above would be out of operation if disconnected from the service, it was arranged that four complete panels with their own disk tank are also connected. These are autonomous units that have enough flexibility to work alone or with the server. This has several advantages: they offer security by eliminating total dependence on the continuous operation of the central reservoir and, since not all panels need to operate with the server all the time, they allow a greater number of them to be connected by simply adding an SDI switch.

System Administration: The job of designing an entire production studio should include system administration. The necessary facilities and tapes must be available in the right place at the right time: a task traditionally assigned to planning. The internal management of a video repository with true random access is very complex: it is no less so because the frames of any clip can be scattered. One function of the internal storage management system is to give direct access to all the boxes without requiring any knowledge of where they are located. Another function is to remove contention in such a way that any channel can have access to a frame at any time. It is possible that all channels simultaneously present the same tape and although this is not always an operational requirement, such flexibility greatly simplifies the task of external control, just like the computer. Without taking into account another activity, the entire tape is available to present with the following modality.

In the case of Editbox and Newsbox that work with Clipbox, the Clipbox vault control is integrated into the menus of the control panels. In this way, using the Clipbox tank becomes a simple extension of your normal operation. As with any good management system, the power or complexity of operations is hidden from the operator.

Several designs were described for a fully digital production studio but all but the last one fail to meet all the original goals. The tape-based solution may offer good quality, but is deficient in the speed and flexibility of operation of current disk-based systems. The attraction of open ring connections based on computer networks decreased because they have to work with compressed video. Operating a server on a network with star configurations decreases the bandwidth requirements for network operation, but very soon it runs out of sufficient channels to offer quality work. Only the integrated editing and playback approach can be projected to encompass the entire production studio while meeting the objectives of quality, program availability, flexibility and operation with the new disc technology.

With the prospect of disc-based editing and playback systems it is important to realize all the advantages of working with the new medium. Going blindly after the ideas for networking originally developed in the computer industry and the editing panel designs of the tape era does not give the best results. It is possible to meet the objectives using the new ideas developed within the disk-based era, both for the server repository and for the editing panels, and to elaborate with them an integrated system. This article may seem like an over-advance from current practices, but it presents the clearest possible view of future fully digital production studios.