File-based delivery
Dec 1, 2008 12:00 PM, By Brad Gilmer
Thanks to technical advances and falling prices for bandwidth, file-based content delivery is more common.
Many fiber-optic cables have been installed over the last 15 years, making file-based content delivery a reality.
Five years ago, file-based content delivery was making inroads with broadcasters, but it was still a somewhat unusual way to deliver video. Now, file-based content delivery is the norm. Thanks to the deployment of key enabling technologies, less expensive networks and a rise in file-based content delivery to the consumer, file-based delivery is coming of age.
For decades, content was delivered to the broadcaster by one of two methods. Network programming was delivered on a network satellite, and syndicated programming and commercials were delivered by overnight courier. The network programming feed made sense because there was a single source distributing the same content to many stations. The overnight courier was an efficient way to do point-to-point delivery, where many different commercials were being sent from many originating points to many different broadcasters. While satellite transponder and shipping costs were not insignificant, they were, and in many cases they still are, the most cost-effective way to distribute content.
Almost as soon as the Internet came into being, broadcasters and content distributors began looking into ways to deliver content over this new medium. But financial and technical hurdles stood in the way. When it was developed, the Internet excelled at moving text from one place to another. Because even a small video clip is many times larger than the average text file, the cost of bandwidth was one of the major stumbling blocks to moving video over IP. Second, there was the last mile problem. You might be able to get high-speed connectivity between two cities, but it may be impossible to get a high-speed link over the last mile from a telephone company central office to the broadcast facility.
Today, bandwidth costs are falling, and while it may still be a determining factor in whether a particular project is able to move forward, in many cases, affordable connectivity for video distribution is available. Let us look at some key enabling technologies that have made file-based content delivery practical.
Digital video
It almost goes without saying that digital video technology is the keystone of file-based content delivery. From where we sit today, digital video is a given. But it was not clear at the time that the industry would be successful in creating a single ubiquitous digital video standard. Without its development, file-based content delivery would be impossible.
Video and audio compression
Without the development and deployment of interoperable, efficient video and audio compression, file-based content delivery would be just a dream. Compression ratios of 10:1, then 100:1 and now beyond have allowed broadcasters to lower their transmission costs with an acceptable impact on quality. The industry has been extremely well served by the development of compression and would not be where it is today without it.
Extensible Markup Language
A comparatively new invention is Extensible Markup Language (XML). XML has allowed broadcasters and content distributors to include metadata about the files they are sending. The industry has recognized what a critical role metadata plays in the content distribution chain. The adoption of XML allows us to use many of the software tools developed in the computer industry for the construction and manipulation of metadata.
Material eXchange Format
The Material eXchange Format (MXF) is a wrapper that allows a content delivery service to wrap together video, audio, closed captioning and metadata in a single container. The container can be streamed from the content delivery service to the broadcaster and played directly, or it can be saved as a file. The power of MXF is in its object model — the way metadata is arranged in the wrapper. A receiving application can decode the metadata in the MXF header and quickly determine if the content meets delivery specifications without detailed analysis of the contents of the file. Furthermore, the items in the file and the way they are referenced in the metadata have been standardized to increase interoperability.
Error correction
Error correction has been around for many years. In fact, error correction has been available for files sent across the Internet since the Internet's inception. However, the industry is now discovering standardized ways of implementing error correction that allow interoperability among different implementations.
Peer-to-peer networking
Peer-to-peer (P2P) networking has been used on the consumer side of the Internet for quite some time. P2P gets around a number of issues with broadcasting over the Internet. It can be difficult to send the same file to hundreds or thousands of sources simultaneously, because traditionally, the sender must establish a one-to-one conversation with each receiver.
Clearly, a traditional broadcaster would be overwhelmed if it had to electronically talk to each receiver. P2P allows portions of a file to be sourced from any number of senders, so the load of sending the file can be distributed beyond a single source. Several professional implementations of P2P have been created, and the implementation of this technology on the broadcast side is increasing.
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