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Nuggets and MXF: Making the Networked Studio a Reality By B. Devlin, H. Heber, J. P. Lacotte, U. Ritter, J. van Rooy, W. Ruppel, and J. P. Viollet
T B. Devlin
U. Ritter
W. Ruppel
J. P. Viollet
Nuggets1 is a European project researching the use of MXF files on IT networks, allowing remote control of cameras in a live production environment. The project partners (Thomson Grass Valley, ZDF, Snell & Wilcox, T-Systems, Enertec, INESC Porto) are creating a local area network/ wide-area network (LAN/WAN)-based workflow that will be demonstrated in 2004. This paper will outline many of the issues discovered in the process of moving from a traditional tape/SDI point-topoint environment to a server/file interchange environment. Details of the proposed network functionality will be given in order to generate audience discussion of the requirements of a file interchangebased workflow.
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he Nuggets project 1 is partly funded by the European Commission’s Integrated Society Technology (IST) program. The two-year project started on April 1, 2002, with the goal of providing an improved real-broadcast production chain using an ITbased studio network environment (in-house and between locations). The network will contain essence, metadata, and control data. It will integrate cameras, viewing, and control devices, interfaces, and storage with guaranteed quality of services and low latency. The goal of the project by April 2004 is to introduce digital network technologies into the program production part of the broadcast chain; develop rich media bidirectional network architecture based on file manipulation, compatible with in-house as well as public network constraints; interchange at high data-rates of filmquality video and data as generic files over several storage area networks (SANs) and local area networks (LANs), connected via wide area network/metropolitan area network (WAN/MAN); and introduce an important cost-reduction on ownership and program production with file transfer through networks. Figure 1 gives an overview of the devices and interconnections in a typical Nuggets network. It shows how workstations for different production processes are clustered around specific SANs, providing extremely high bandwidth and low latency storage. These work areas are then interconnected within a building or site by the LAN. Sites are then interconnected using an external metropolitan area network (MAN) (often involving permanently leased lines). Wide area network (WAN) connections are then made on an ad-hoc basis to the rest of the world via internettype IP links. The Nuggets project works closely with end users, such as the German Broadcaster, ZDF,
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NUGGETS AND MXF: MAKING THE NETWORKED STUDIO A REALITY which is one of its partners. The project is driven by the generation of user requirements, which in turn creates technical issues that must be investigated within these networks. • Realization of a camera system fully integrated in the network (control and content). • Implementation of low-latency compression technology operating at relatively high bit rates. • Study of IP QoS mechanisms, such as traffic control and queuing disciplines that can be used at the local premises to guarantee services. • Evaluation of network elements supporting guaranteed services. • Implementation of a virtual private network, based on multiprotocol label switching/ATM technologies for a WAN/MAN. • Extension of the bandwidth of the system to HDTV and film application, using multiple-quality levels of the video depending on the network and the device performance. To realize the objectives, some fundamental achievements have to be reached: There should be no operational differences between accessing a local and a remote file. The files may contain high-resolution picture-data and have to be sent at a high data rate. The camera system should be integrated in the network. This means that camera control is no longer limited to dedicated devices, but can be invoked from anywhere within the LAN/MAN/ WAN. Parts of these results will be implemented in a full production chain for validation.
Moving from a Tape-Based to a Networked Environment Current production systems follow a sequential process, and hence all operations are carried out one after the other. All production steps rely on new archival material that has to be provided separately for each production process. In the case of ITbased production systems, all data (content and metadata) are handled
Figure 1. Typical Nuggets system. SMPTE
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NUGGETS AND MXF: MAKING THE NETWORKED STUDIO A REALITY by means of file-based processes, and all files can be shared among all workstations within the production network. Different production teams may access and use the same material for their individual projects. With the IT-based production, a method for parallel use of raw material is expected, as well as faster and tailor-made production for different distribution channels. Figure 2 shows all elements required for netFigure 2. Global architecture of a production infrastructure based on IT-network technology. worked production. Storage and editing devices will vary in their capabilities and storage capacity. These will Issues Concerning Live Control of range from simple desktop assemble editing with small Cameras on Networks storage requirements to high-end post-production on a Traditionally, camera control is done entirely isolated SAN-based storage subsystem. from any other system, and every manufacturer uses When moving from IT-based production, improveits own protocol and interconnection scheme. ment is expected in concurrent production work Gradually, the systems have been modified to carry through file sharing, re-purposing of raw and archive private data from other devices as well (e.g., pan and material, easy and fast access to a large amount of tilt heads), but not in a way that seamlessly can inteaudiovisual material, reduced cost of contribution lines grate into a more general structure. by making use of IT-network infrastructures and protoIn a LAN/WAN-based workflow, this structure can no cols, and instant access from any place to any source. longer be maintained. The control loop has to use the A number of technological issues have to be network to enable camera control from anywhere. addressed and must be solved, such as appropriate Once the step to general network environments with implementation of MXF and metadata, and appropriate IT hardware is made, it becomes tempting to explore compressions schemes for low-latency preview. The the possibility of pure software control for the camera. latency problem is due to a number of processes, such Although this is very possible for off-line setup of the as compression, wrapping, unwrapping, link-delay, and cameras, and actually may benefit from the flexibility so forth. and large capabilities for storing scene files, it is not The Nuggets Demonstrator the way to go for live production. Typically, three ways of accessing camera control A program of system specification and the developare seen in practice: ment of new components was implemented to provide 1) During production, fast access to control is necessolutions to the technical constraints. This will lead to a sary. Iris and black controls are used mostly, almost on system demonstrator (Fig. 3), which will prove the a continuous base. Therefore, specialized control usability of the system and show its specific strengths. hardware is used for the operational control panels This demonstrator will serve as a test platform for (OCPs). practical studies and for implementation of this tech2) For more specialized functions, typically used in nology in future production environments. SMPTE
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NUGGETS AND MXF: MAKING THE NETWORKED STUDIO A REALITY Nuggets improves the interoperability and usability of filetransfer-based workflows by implementing MXF as a file format. In addition to many other benefits, MXF is a “wrapper” that allows for the seamless interchange of files regardless of their internal information representation (e.g., of the codec that has been used). It is highly desirable for users, network service providers, and systems integrators to have a commonly agreed file interchange format as it allows for integrating codec agnostic and interoperable systems. In the case of file transfer, the most important network requirement is that a file can be transferred from A to Figure 3. (Left) Interfaces and control points in a Nuggets production environment; B within a given time frame (above right) Nuggets camera control system; (below right) Nuggets monitoring. without any uncorrectable transmission errors. set-up to create a general look of the picture before the For file transfer, non-error-free networks such as event, a more computer-like master control panel best-effort networks, can be used because protocols (MCP) can be used. An MCP also gives the opportunilike Transmission Control Protocol (TCP) are able to ty to monitor and/or adjust the control of multiple camcope with transmission errors. era’s at once from a single access point. In terms of the quality of service (QoS) parameters, 3) Finally, in integrated systems, system configurapacket loss, latency, and average bitrate, only a certion, control, and setup can be done, in principle, from tain throughput (represented by an average bitrate), any computer within the network. with a value depending on the user’s requirements, Network Issues when Using Large Files at needs to be ensured. Packet loss can be corrected by a High Bandwidth higher level protocols such as TCP.
File Transfer versus Live Streaming
Live Streaming
The two basic services under consideration in the Nuggets project are file transfer and live streaming.
Live streaming applies in remotely controlled live productions. Within the project, a network platform has been provided enabling the realtime transfer at high data rates up to 50 Mbits/sec per live channel. For reasons of interoperabiliy, MXF was decided on as a streaming format and the internet protocol (IP) as a transmission protocol. The user requirements for live streaming are very challenging, resulting in a maximum end-to-end delay of 150 ms, no packet loss, and a very low jitter value.
File Transfer File transfer is already a common practice in production environments. Disk-based storage systems require mechanisms to exchange files, both locally via an in-house network or remotely via WANs. Nevertheless, many proprietary file formats now exist—resulting in barriers and missing links.
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Network and Maximum Guaranteed Protocol Stack Delay
Maximum Jitter
Average Packet Loss
Remark
IP/Ethernet/ WDM
5 ms
2 to 4 ms
n/a
Proprietary QoS mechanisms, only for MANs, not WANs
IP/SDH
35 ms
20 ms
