Options For Handling Embedded Audio

Most TV stations and other media enterprises today move audio in the form of digital signals embedded in the main video routing system. For these facilities, eliminating audio routing and distribution equipment along with patch panels, cabling and support gear has reduced complexity and saved money. However, embedded audio also presents challenges, one of which prompts a system design question: Should audio shuffling be performed by dedicated equipment, or by advanced processing capabilities added to the video router’s I/O?  

First some background. Embedded audio has become dominant because of its benefits, but it does have a downside: It is inflexible. Once an audio signal has been embedded in the video, its pattern — say left channel on 1, right channel on 2 — is essentially fixed. To be used within the system, audio from an outside source, whether it is footage of breaking news or a production truck’s coverage of a high school football game, must conform to the same pattern. If it doesn’t, it must first be reconfigured, or shuffled.

Shuffling may mean only adding a second language track, or making a left-right swap to maintain a consistent channel assignment pattern. But in extreme cases, it can require complete rearrangement of channel positions. One way to accomplish this is for a trained operator using dedicated equipment — a standalone audio shuffler — to unscramble and reconfigure the signals at the point of ingest into the system. Audio shufflers are available from many suppliers, but because their use requires manual operation, it can be cumbersome in a facility where quick changes to live feeds are common. Likewise, if multiple audio shufflers are needed, the investment expense becomes a factor.

Traditionally, video routing switchers did not perform signal processing functions like audio shuffling. Today, however, improvements in field-programmable gate-arrays (FPGAs) have made it possible for signal processing to be incorporated into a video router’s circuitry without operational reliability being compromised. Adding this new capability to the I/O card, however, makes it several times more expensive than one that just moves SDI signals. Because routers are typically configured in blocks of 12 or more ports, the additional feature will add at least $10,000 to $20,000 to the overall cost of the router. In contrast, an audio shuffler costs about $2,000.  

Now we come to the crux of the matter: In assessing the most cost-effective and efficient system for a given facility, the decision-point rests on a traffic analysis of the content processed. In other words, how often does the content being used require audio shuffling?

A TV station that relies principally on server-based content played to air may reconfigure the audio signal on 12 pieces of content a day. As long as no more than two at a time are needed, the station can probably get by with two dedicated audio shufflers at a cost of about $4,000 — until traffic increases.

In contrast, a large facility, like a cable news network continually receiving hundreds of signals, cannot afford the inefficiency of manually shuffling individual pieces of content. It needs speed and automation. For that kind of facility, the expense of a centralized, router-based shuffling system is worth it.

Fortunately, a decision on how much advanced I/O functionality to buy today is not carved in stone. Advanced video routers like those in the Utah-400 series can be upgraded to perform audio signal processing by means of a simple plugin. Similarly, a hybrid approach is possible. The minimum audio-enabled section might be added to the video router now, with its control system’s pathfinding facilities and tie-line management used to route the shuffled signals to any destinations that need them.

In summary, taking cost-effective advantage of the operational and cost benefits of embedded audio requires careful assessment of need and evaluation of the available technology, as well as solid planning and system design.

Scott Bosen is director of marketing for Utah Scientific. He can be reached at sbosen@utahscientific.com.