Above: As part of its IT infrastructure, Hollywood’s Pacific Title & Art Studio uses an SGI InfiniteStorage CXFS shared filesystem SAN.
The move to digital operations has freed broadcasters from many of the limitations of working in an analog environment. But, as broadcasters put their new digital infrastructures in place, it is becoming increasingly obvious that they need to integrate an IT-based workflow.
IT-based broadcast infrastructure reduces redundancy and allows greater sharing of media across a facility. This, in turn, streamlines production workflow. A common network also offers greater creative latitude in the use and reuse of graphics, program content and other material.
As broadcasters shed the constraints of the traditional broadcast business, they must consider a series of issues and opportunities inherent in the adoption of an IT-based broadcast infrastructure.
Video-centric and IT-centric workflows
These include selecting an appropriate platform and operating system and deciding on the file types they will support. These decisions affect interoperability within the facility. Regardless of the type of infrastructure being instituted, concerns such as storage and security present themselves. And, of course, the broadcaster must consider the facility's network and how it will enable this new digital, file-based workflow.
Figure 1. With a traditional workflow, the system contains multiple copies of the material and a number of people are required to transport the content within the facility. Click here to see an enlarged diagram.
Platforms, OSs and file formats
Figure 1 shows a representation of a traditional workflow. The key points of this model are the multiple copies of the material that exist in the system and the number of people required simply to move the content around. With a traditional asset management system, multiple copies exist on tape and local video servers, and are distributed by SDI routers and/or “sneakernet.” The final output originates from a copy of the program on a localized playout server, which delivers live SDI content to an encoder for air.
Figure 2 shows the equivalent facility in a tapeless environment. Here, the emphasis is on shared content and multiple accesses to a central, managed resource. Multiple users can access content without making copies, preserving video and audio quality. This type of system also allows for increased automation because file transfers for airing can come from the central server according to the playout schedule. Actual broadcasts may involve involve live compression or pre-prepared offline compression, depending on whether the ultimate target is broadcast, VOD, phones, the Internet, etc.
Figure 2. In a tapeless environment, the emphasis is on sharing content and multiple points of access to central, managed resources. Click here to see an enlarged diagram.
Interoperability is key to building an efficient IT-based infrastructure. So, it's important to select the right server platforms and operating systems for editing and graphics.
Some facilities will choose a single OS such as Windows, Unix, Macintosh, Linux, Irix or BSD. This consistency provides a seamless flow of data and media, though it can limit the choice and use of equipment. Other facilities may rely on several different operating systems working on a common network. Here, the vendors dictate the OS in exchange for the functionality, pricing or feature sets the broadcaster wants. In this case, interfaces are necessary to bridge the gap and facilitate interoperability over the network, regardless of the devices connected to it and the file systems used. (Such file systems include FAT, NTFS, HPFS, SMB, UPFS and ISO9660.)
One platform might support one set of rules for file naming, ownership, access and modification, while a second platform may rely on an entirely different set of rules for the same functionality. The time the facility spends managing communications, privileges and rights between these different platforms could instead be used to improve the quality and quantity of material the facility produces and distributes. This difference in functionality may arise from the vendor's choice of OS or file system, but the customer bears the administration cost.
New file standards
A networked facility achieves the greatest benefit if the design engineer or systems integrator can build the broadcast infrastructure on the file format or standard that offers the greatest flexibility. Often, this will determine the choice of a server or primary storage device.
New file standards such as MXF and AAF are changing the way facilities can use file types internally or across a network. These new standards include both the essence of the original file as well as metadata about the file format, such as sampling rate, image dimensions and similar parameters. With this information, a smart device can determine if and how it can use each file.
The MXF wrapping mechanism interweaves individual video frames and associated audio. The file's header and footer contain a description of what is in the file (the types of essence, the size of the pictures, the sample rate of the audio, etc.) for quick reference.
Vendors are still improving the MXF and AAF standards through testing, reporting and collaboration. Testing tools, available for Internet download, allow broadcasters to implement a common and consistent level of interoperability among their broadcast systems. One example is the tool provided by the MXF Test Centre of the IRT, the Germany-based Broadcast Technology Institute, which has made its MXF test tool available for download at www.irt.de/.
Data networks and storage systems
Vendors including Snell & Wilcox are also providing free, online access to their code base to speed improvements to the MXF standard (www.snellwilcox.com/mxf/). As broadcasters increase interoperability through these standards, they streamline their operations and achieve more cost-effective production and playout.
Storage costs have dropped, but the overall cost of implementing and administering these solutions has increased. The total cost of ownership, however, depends on leveraging operational benefits.
The local area network (LAN) is the simplest storage solution for IT-based asset management. You can connect a direct, attached storage system to a LAN to provide fast transfer speeds, immediate access and in-house control over the entire network. For a facility where media transfer and sharing is a strictly internal affair, a LAN provides sufficient access.
Broadcasters who need to share media across facilities would fare better by using metropolitan area networks (MANs) or wide area networks (WANs). Such networks have greater reach than a LAN but have less reliable data transfer speeds and are more dependent on outside sources for maintenance. In applications such as live broadcasting, these drawbacks can jeopardize the quality not only of video transfer, but also of the on-air product.
Table 1. NAS and SAN networked storage solutions each have their own unique advantages and disadvantages. Click here to see an enlarged diagram.
Newer and smarter storage options include network attached storage (NAS) and storage area networks (SANs). Table 1 compares these two storage architectures.
It's impossible to say which system is better, faster or cheaper because the ultimate choice will depend on a number of factors, including:
- Number of simultaneous accesses needed to the storage
- Bandwidth required for each access
- Type of file (large video vs. small audio files)
- Nature of the access — streaming or random access
- Total volume of storage required
- Requirements for online backup and purging
It is possible to build a system that uses the best of both technologies to hit certain price and performance criteria. For example, one broadcaster from the Athens Olympics used a SAN system with a few hundred hours of content for live ingest with online editing of the live content. Behind this was a large (1000-hour) NAS system that had less strenuous real-time requirements, but was optimized for large volumes of near-line storage at reasonable cost.
Security is a loaded term today. A security threat may be as simple as human error resulting in the loss of data, or it may be as great and overwhelming as a flood, earthquake or other natural disaster. It could also take the form of a malicious threat from an employee, computer virus or external attack.
A careful evaluation of the broadcast facility's vulnerabilities is critical in choosing an appropriate security solution. Centralized IT storage, while efficient, also requires a number of protection technologies and education of its users to achieve successful, continuous operation. In the end, the main goal of ensuring system security is to establish a reliable and cost-effective solution for upholding an acceptable broadcast standard.
IT now and to come
IT-based digital broadcast infrastructures open many doors for broadcasters. And with these opportunities comes the challenge of choosing among an ever-increasing selection of products and solutions. Deploying new transmission, storage and management tools in a file-based environment enables the broadcaster to lower the costs of using an inter-vendor solution. Open-source, IT-based standards such as MXF and AAF are helping broadcasters to optimize operations to suit their changing needs.
Bruce Devlin is vice president of technology at Snell & Wilcox.
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