Network solutions in TV production

By Alexander Peregudov

Review contents:

Network solutions in TV production Network solutions of company Avid for broadcasting and video production Automation of broadcasting: DIP solutions Networking for live television production Solutions of the JC System Integration Company VSN — all in one Network disk arrays of company Maxtronic Network file-based broadcasting with On-Air Central Video server The tvSuite as the output module of system for organization of the off-the-air broadcasting built with application of network technologies Network solutions for program-making on the basis of Pinnacle Liquid systems Network production from Sony Network solutions Vectorbox

Introduction

During its speedy development the information technologies find new scopes. One of such areas is TV production and broadcasting. Means of production of the TV-programs (TV systems) in era of digital tapeless technologies are considered as the certain class of information systems. It means that:

• On inputs and outputs of system the information (non-material) streams of content operate;
• Media data (video and audio clips, graphics, and photos) and metadata are transferred in the form of files or data streams;
• Production operations are the operations with the data, and executive mechanisms — the program components functioning on standard computer platforms;
• Storage of content as sets mediadata and metadata is carried out in file form in the distributed or centralized storages;
• Transport of content on physical media inside system and between systems is completely excluded in reality;
• Workplaces of users of TV system are basically made on PC base with user’s software, and the majority of applied processes is carried out in server part of the system;
• Infrastructure of data transmission basically represents the standard telecommunication equipment;
• Feature of the TV systems lies in especially large volumes of the storing data and requirements on maintenance of real time of the information flows input/output.

One of the most significant results of use of information technologies in TV is the occurrence of network systems for production of the TV-programs. The network solution means the organization of production at which the job is carried out by system users on a set of the workplaces incorporated by a network infrastructure of data transmission.

Some works are carried out on one workplace, others — in parallel on several workplaces. In a complex of news production the number of workplaces of journalists may reach several hundreds. On the other hand, in a complex of the automated air one operator supervises the issue of tens programs.

Operation results on each workplace should be accessible to other participants of production as files or data streams. For short-term and long-term preservation of the data the file storages organized both on workplaces, and as separate units of network system should be provided. The jobs are carried out by resources of network production system which may be included in structure of workplaces or be taken out in separate server components, access to which is possible in a mode of separation from several user workplaces. Server components of the advanced network systems include means of coordination of separate technological sections of the general TV-program production chain.

Network systems in the expansion dynamics

Implementation and it is better to say — approach of IT to TV already has short, but impetuous history during which were both the overestimated expectations, and disappointments. There has nowadays come the period of more thoughtful, cautious approach within the framework of which the introduction of IT-solutions is made step by step as it was made and in other branches.

One of variants is prototyping when in the beginning the small system which subsequently extends and modernized up to full scale is under construction. Most frequently for design of prototype systems the news production is used. Here are the highest requirements to efficiency of work, and character of creative activity of journalists make special requirements to the user interface of workplaces.

The attractive side of prototyping consists in transition from lump-sum costs for purchase and installation of system to its stage-by-stage expansion. Stage-by-stage expansion allows to the specialists of broadcasting organization to correct technical solutions on the basis of operating experience of prototype “island” systems. Correction of technical solutions includes the changes of technological processes, selection of system components and their suppliers. In some cases correction of technical solutions becomes such volumetric, that speech already goes about repeated designing of the system — re-engineering. The given task is actual mostly for any broadcasting organization and may be shared into some individual subtasks:

• Scaling of system by increase of number of channels, number of journalist workplaces, capacity of the general storage for media data;
• Expansion of system at development of production of new type programs, creating of HD program, broadcasting in the Internet;
• Increase of economic efficiency of production due to decrease of operational expenses;
• Increase of reliability of system as a whole or its separate components;
• Introduction of a full cycle of program-making on the basis of IT-solutions.

The basic requirements which should be carried out under any stage of expansion and re-engineering of network production system are as the following.

Open technologies and platforms

Following to standards available in branch is meant, and at use of corporate standards of the supplier — full documenting of solutions. Conformity to the open and documentary standards allows for the owner of system to choose during its expansion the components without binding to the concrete manufacturer.

Extensibility

The system should be open for connection of components of new types which earlier in system were not used.

Scalability

The system should be open for increase of number of components of already available type.

Control of configuration

Dynamic distribution of resources at which job may be appointed to various components.

Safety

The given requirement becomes especially important at involving in working processes of users of various level and motivation.

Restoration after failures

Any system on the basis of IT-solutions is subject to failures owing to the various reasons arising both on hardware, and at software level. As obligatory for the advanced systems there is the prediction function of crisis situations, for example achievement of the top critical border of the used volume of the general mediadata storage.

Expansion of system as a whole may occupy some years, thus keeping of continuity both an internal technical policy of broadcasting organization, and technical solutions and reliability of suppliers and integrators are important also.

Integration of network TV systems

At the beginning of creation of network production system the broadcasting organization should solve the basic question for itself — whether to get the completed full-function system from one manufacturer or to build a complex with the help of the company-integrator on the basis of components from various manufacturers. The first way is represented as the most simple, however global experience of creation of large production systems on the basis of IT-solutions has shown, that as the result the collision with problem of integration is inevitable. For today that problem is the basic task for the broadcasting company which have chosen thorny, but promising way of introduction of IT-solutions in traditional TV-production

The integration means the adjustment of interaction between components inside one network system and between separate systems on principles of compatibility (interoperability). Reference of the TV-complexes to the class of information systems means, that the task of integration should be solved on base of methodology, developed in sphere of information technologies.

Integration on the basis of copying the data

The general network system is designed as set of self-contained workplaces (subsystems), each of which operates independently to a great extent providing necessary functionality for the user of each workplace.

In most cases the independent subsystems are the inexpensive desktop editing systems. They are the major elements of program-making. Under video and audio processing the editing, graphics and special effects are carried out faster and received the increasing functional charging. One of the major features of the independent desktop systems — an opportunity to function for creative personnel not only within the margins of local network of the enterprise, but also in domestic conditions, and also in field condition of shooting.

The first projects of network systems were based on use of independent desktop systems provided with sufficient set of functions, but have provided with the limited communication with external environment. Thus at each station the certain number of mediafiles have been collected, the first part of which was intended for internal use, the second part was imported from adjacent stations, the third part was intended for export. Sharing of the job results is reached by data transmission between workplaces as file copies (fig. 1). The preferable case is transport of mediadata and metadata in uniform file package that improves features of the system regarding to integrity and synchronism of the data.

The given type of integration is realized simply and quickly. But with increase of number of workplaces the problem of synchronization of the data when the user on the workplace number 2 may not be sure that he is used the latest results of processing of initial file on the workplace number 1, sharply becomes aggravated. Interaction of separate systems is carried out through the operator — the user of system in each act of the mediadata exchange. Formation and application of the policy of media assets control on each workstation became a part of the operation processes included in the list of the personnel responsibilities.

Productivity of the general system in such solution does not increase with rise of number of the incorporated subsystems; the amount of errors which are caused by wrong actions of users is grown only. Required storage volume for all system may reach to the total amount of mediadata, multiplied by the number of involved workstations. Maintenance of reliable storage becomes an uneasy task which demands significant rise in price of disk subsystems on workplaces.

Maintenance of uniform media politics on a plenty of independent workstations is solved by inclusion in system of the general shared resource which would answer for safety, integrity and control of access rights.

Integration on the basis of shared data file or uniform server of applications

The data are stored in single copy in uniform shared storage. Administration of the data is carried out within the margins of functionality of the used file server. Any workplace is provided with the opportunity of access to the data in real time. The unity of media politics of network production system is provided with a set of the corporate standards giving the common model of the data (system of metadata) and uniform file package of the content. Development of the given variant of integration normally goes on a way of installation of the uniform server of applications in which the shared functionality of data processing is concentrated (fig. 2).

The files being a subject and a product of teamwork of several users should have the uniform description in the form of metadata. All attributes should be interpreted, created and modified uniformly on all workplaces involved in joint network operation over common projects. The checked up solution is the use of standard file packages according to AAF and MXF specifications.

The first specification provides wide opportunities over fixing editing solutions at the production stage. The second specification is intended for exchange of the programs completed in production both inside one production system, and between separate broadcasting companies. File specifications do not impose any restrictions on formats of compression of mediadata and methods of the description of audio and video line by metadata. The important feature of both specifications is the opportunity of joint keeping of mediadata and metadata, and also separate keeping of metadata and mediadata. In the second case the file includes references to addresses of storage mediadata of URL format.

As specifications of files are approved recently, to present time not all manufacturers provide a support of the specified file formats in their products. However the general requirement to means of operation with mediadata of new generation the compatibility with AAF and MXF is included obligatory.

Integration for uniform technological chain

The supreme stage of development of network TV systems is maintenance of each user with all resources of uniform production system in which the majority of functions is carried out automatically. The isolated systems should be replaced with a combination of the components which are carrying out certain functions and capable to interaction with other components of the system.

Such systems are based on sharply defined sequence of operations, in other words — a chain of escalating of cost of the end product (Value Chain). Components of system are shown on fig. 3. Here as a typical example is the integrated system of production of news by principle News Room. The given type of integration also can be named as system of integration of business-processes of broadcasting company; however the formalization of business-processes is necessary for successful realization of the project. Such works are now begun in many broadcasting companies that create the necessary prerequisites for the future success. Each system user receives in his disposal the integrated software of user part, executed in the most cases by a principle of a portal of information retrieval systems. User’s tools are located on specially designed working table, in the greatest degree providing an overall performance of the user with all resources of the general production system necessary for him.

Component structure of network systems

The given models of integration require to understand what parts form the system, what functions carry out by them in structure of system, what cooperation is between them. During inevitable process of re-engineering the quality of components which were chosen and acquired at various stages of life cycle of system is presented. Unsuccessfully chosen components may require the replacement and connected additional, frequently unpredictable financial expenses which are capable to call into question the success of the whole project.

The consequence is consideration and formulation of requirements to components of system not only from the point of view of functional, cost and other features, but also from the point of view of integration opportunities of components. Integration opportunities of components mean their ability to interaction with other components in network system. Ability to interaction means ability to exchange mediadata and metadata with the adjacent components of system under standard protocols and interfaces. The traditional hardware of video production as the cameras, VTRs, switchboards, mixers has passed a difficult way of standardization of connecting interfaces. The software of video production is only at the initial stage of standardization of interaction, and, first of all, it is necessary to have classification of components by their properties and carried out operations.

The objective approach to construction of network systems

Within the margins of the objective approach the TV system is broken into set of components cooperating between themselves. Each component may be considered as separate system and in turn be exposed to splitting into components. The component has a row of properties (attributes) and may carry out some operations on conversion of the input data to the output data. For performance of operations the component has internal data area.

The group of components with similar attributes and operations is described as object. Objects are provided with encapsulation property in relation to the internal data and procedures. It means, that the internal data area and algorithms of procedure performance are latent (protected) from other objects. It is possible to change the internal data of object only by a call of procedures which are declared in properties of object. Encapsulation provides integrity of object and an opportunity of updating of system by change of properties of components of its objects or, if necessary, by replacement of one object with another.

In classical information systems all objects are realized as program components and function on some computing platform. In TV systems one part of objects is realized as software components, and another part — as hardware components. Introduction of information technologies in TV means, that the increasing part of objects is realized as program components which function, as a rule, on the allocated computing platforms.

For performance of operation chain in TV system the procedures declared in properties of objects are used. Works are carried out inside object, and for their initiation and reception of result of work the objects have message dialog. Messages are shared on messages of data transmission and on messages of the remote call of procedures (operations). Complex compound operations occur as the transactions including a chain of atomic actions, together bringing to the required result. Distribution of operations between objects is one of the problems of designing and realization of network TV systems.

Layered model of TV system

The main assignment of any system is execution phase for the users. Users of systems initiate the beginning of works and results of the executed works are given them in the upshot.

Layer model of TV system reflects hierarchy of the objects in relation to the user. For TV systems on the basis of IT solutions the four-layered model shown on fig.4 is applicable.

Within the margins of model each object concerns to one of the several layers, located one above another. In each layer the set of the objects having similar attributes and operations is functioned. The layer object gives its operations for object of overlying layer and uses the operations of objects of underlying layers.

The general property of objects of layer of representation (Presentation) is that they directly cooperate with the system user. The user may be the person-operator or other system. Through the Presentation layer the system is visible to the user, and underlying layers for the user are latent (encapsulated). Objects of the Presentation layer give to the user the interfaces of control of the system. The messages framing work in the beginning and in termination are introduced in the system and removed from it through interfaces. It is necessary to determine two types of interfaces, the first — for interaction with the operator, the second — for interaction with other systems.

For the user-operator the means of input of commands and means of visual display of results of command executions are necessary. Objects with interfaces for the operator may be realized both as by software and hardware. Program realization is the user software with windows of applications. Hardware realization is control panels, TV cameras and monitors.

Basic advantage of program realization consists in an opportunity of adjustment and configuration of the system control tools for concrete kind of jobs carried out and for concrete user-operator.

The interface of system for interaction with other systems is set as the protocol of interaction.

Objects of a layer of applications (Applications) represent executive mechanisms, or business-logic systems. The business-logic is realized by procedures of data processing which may be connected only to one object of the representation layer, or simultaneously process the inquiries from several overlying objects. In the second case the question is a shared resource which functions on a platform of the Applications server. The same procedure of data processing, for example MPEG-2 encoding, intraframe combination of images, may be realized both by hardware, and software tools. The important advantages of program realization are multitasking and mobility of the Applications server by way of its start on various platforms and under the control of various operational systems.

In a layer of the data (Data) the objects connecting logic and physical representation of the initial and resulting data for processing are located. Communications are made out as database tables, and inquiries from objects of overlying layers of logic model are processed by the server of database. One system may include some servers of databases, for example for access to mediadata, for access to metadata, for linkage of logic names of system users with addresses in the network of the system.

In a layer of storage (Storage) there are the objects providing centralized physical data storage and access to them from the objects of overlying levels. Because of significant volumes of storage in TV systems are used both the file storages, and storages with replaceable media as cartridges and disks. Essentially the common solution is the hierarchical systems of storage on the basis of robotized libraries and file servers for fast access to the data.

Scripts of passage of messages in logic model have a set of realizations as transactions. As an example it is possible to specify the following transactions: Read, Create-Write, Read-Modify-Write. The first script reflects distribution of the data on the user inquiry, the second — the creation of new essence of the data, the third — updating of already existing essence of the data. On the script of realization of transaction the objects of one level may interoperate with objects not only from the adjacent levels, but also with the missing of a level. Last mode is especially characteristic for layer of the data. By search of physical recording the object-application requests the database, and after receipt of the reference directly addresses to objects of the storage layer for access to files.

Open and closed systems

The system refers to as closed if access to it is possible only through interfaces of objects of the representation level. The system refers to as open if access to it is possible through interfaces of objects of levels of applications, data, and storage. The number of levels access opened characterizes a degree of the system openness. Completely open system gives an opportunity of third party control by own objects of any level of logic model (fig. 5).

The thesis of an openness of systems is disputable. If the system is closed, it operates more stably, but hardly cooperates with third party systems. The open system works less stably, but is easier integrated with the changing environment.

For example, from the part of system A the input in storage and registration of new mediafiles in database of system B is required. The standard way through interfaces of the representation level of system B does not satisfy for system A on any features. If system B is closed the problem is not solved. If system B opens access to levels of storage and levels of the data the system A receives potentiality of mediafiles recording and their registration in base of system B.

However the openness of system A is not sufficient condition for the solution of the put problem of the system interaction. An obligatory condition of the solution of the problem is the general protocol of interaction of the object of the applications level of system A with objects of the data and storage level in system B.

The generalized model of integration of network TV systems

On the basis of above mentioned versions of integration and layer model it is possible to offer a generalized layer model of the integrated TV system shown on fig. 6.

The given model consider, that by virtue of the historical development the majority of the TV companies has the distributed structure when media materials, resources of their processing and users are in nodes of some information network. Nodes may be formed owing to the various reasons. One of them is the existence of the separate centralized data storages providing groups of works on gathering of materials (Ingest), program production (Production), issue of programs (PlayOut), archiving of programs and similar materials (Archive). In that case the problem of integration consists in adjustment of an inter-node exchange of media- and metadata on the basis of information technologies.

For maintenance of the system integration the customer should demand from suppliers the presentation of the protocol descriptions according to which each component of system cooperates with the environment. The best solution is that protocols of interaction should correspond to the common standards of the TV industry.

However the given requirements are not always carried out even at design stage of system. At transition to the problem of re-engineering it is necessary the inclusion of new components in structure of system and, accordingly, of new interfaces of access to them. The problem repeats, and thereof practically inevitably there is a problem of adjustment of interaction between components of system which may not directly cooperate. For coordination of protocols in the advanced network TV systems the binding (intermediate) software named Middleware is used. Within the framework of the given approach there are more and more software products intended not for performance of real actions on processing of mediadata, namely for maintenance of interaction of software products of different manufacturers.

Topology of network TV systems

The given models both for one system and for their integrated set in any way do not specify a physical arrangement of components in system. It is possible the choice when the whole system is realized on a platform of one computer or when the system is developed on set of the computers connected by a communication network. The standard topology of network production system of average scale is based on a local area network (LAN) in which nodes the components of system of different assignment are located, as shown in fig. 7.

In process of the development or owing to other reasons the topology of network system may get much more complex configuration. For example, the broadcasting company owning by network production system, territorially located on several sites within the borders of megapolis. At design stages or re-engineering of system it is necessary to choice a solution from two following variants: either to develop local network of the company geographically or to use the means of general purpose data transmission rented from the independent communication provider. Other modern tendency is the removal of some user stations to the Internet and concentration of server components and components of data storage only within the margins of local network of the company. Both said variants, as well as set of others, specify the necessity of careful design and configuration of transport infrastructure of network production system.

Transport platform

Owing to the specificity of TV systems some environments of data transmission are used according with the requirements to characteristics of connection of the source and the receiver of the data. Data transmission for each kind of connection is based on a specific stack of protocols. There are transmission lines of compressed and uncompressed video and audio SDI, SDTI, AES, DVB-ASI, the transmission lines based on a stack of TCP/IP protocols, broadband lines Fiber Channel, ATM. For control of switchboards, mixers, VTRs the interfaces RS-232/422/485 are used. Inquiries to databases are made out in structures of language SQL. The exchange of messages with user workplaces in the Internet in modern style is realized on a stack of protocols XML-SOAP-HTTP that guarantees the passage of the data not only through any network equipment, but also through firewalls of local networks.

Requirements to quality of transmission of files and streams of mediadata are ranged on three degrees of quality of service according to the band of communications channel, initial delay and jitter.

Hard-Real Time

Display of the stream of mediadata at receiving side should have the fixed initial delay, band which is higher than the stream rate value, and the jitter which is not exceeding an interval of one TV frame.

Soft-Real Time

The band of a communication channel is not less than the rate of transmitted stream, and the jitter and an initial delay of transmission are blocked by stream buffering on the receiving side in a range about several seconds.

Non-Real Time

The band of communication channel is much less than the speed of transmitted stream, and the jitter and initial delay have the floating unpredictable values. Thereof the mediadata transferring is possible only in a mode of file transmission with termination time which exact prediction is impossible.

For these reasons the choice of components of data transmission and maintenance of their interaction in view of initial requirements is one of the major design stages of network production system and its subsequent re-engineering. Classification and grouping of components of data transmission is based on abstraction of the transport platform shared on some levels (fig. 8).

In development of network system with increase of workplace quantity and data exchange intensity the overload of network infrastructure owing to achievement of the limit of the network data transmission throughput incorporated at initial designing is in most cases inevitable. It is possible to say, that the first victim of success becomes the transport platform of network production system.

Levels of transport platform are specified in figure according to the known document of incorporated working group SMPTE/EBU “Harmonization of standards for maintenance of exchange of TV programs as digital streams”, issued in 1998. Components of layer model of TV system are based on a transport platform and use it for dialogue among them.

At present time there is the general opinion that as a transport platform of perspective network systems the uniform stack of protocols based on IP is necessary to use. Control of mixers, switchboards, modular systems of signal processing on the basis of the given interface becomes an obligatory condition of inclusion of such devices in structure of network production systems. The occurrence of the first VTR with built-in interface Ethernet models of IMX series with function e-VTR is the very important event. Within the margins of project Nugget completed in the current year by some European broadcasters, the prototype of the professional studio camera with uniform interface Ethernet is designed and tested. The interface provides transmission of video signal from the camera in real time, service communication of the operator and the engineer with the equipment room, transmission of the text on the prompter, control of adjustments of the camera.

Distribution and broadcasting of the TV programs in the near future will pass to the stack of protocols of transmission on base of IP, which encapsulate the streams of any compression mode. Channels of digital broadcasting DVB become as segments of a global information network of delivery of the IP-traffic.

Physical realization of the network may be various. For local production systems the environment of transmission Ethernet is the universal solution. Within the borders of megapolis the interaction between several local networks of the enterprise is under construction with use of universal network MAN (Metropolitan Area Network). Use of the global transport infrastructure of data transmission WAN (Wide Area Network) the prospect of construction of “No Boundary Enterprise” is made quite real.

In such model of integration the spectator somewhat becomes as participant of productions, receiving in the order the specialized terminal as a network adapter for the program reception. The TV system from only production system becomes the network system of production and distribution of the TV programs. The spectator (rather the user) will choose the TV program for viewing not by installation of parameters of the subscriber decoder, but assignment of the route of passage of packets of the required program in local, and then in global information network. Broadcasting models Broadcast will give up the place to models Multicast and Unicast. When number of programs accessible to viewing will be some hundreds the struggle of broadcasters for the spectator will become considerably strained. Instead of simple search of channels the spectator will use the search mechanisms (browsers) based on reversal to metadata files of broadcast content.

All these tendencies demand from each broadcaster the most serious meditations about the prospects and about that technical base which already now should be pawned in the base of TV systems of the near future.