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From SDI to IP: The Evolution of Distribution

July 2, 2019

The transition to internet protocol (IP) networks has been underway in the broadcast industry for some time. However, only recently have standards been defined that allow true interoperability and efficiency that make the switch from SDI (serial digital interface) to IP a feasible option for migration. As such, distribution is now rapidly evolving from the traditional digital interface to IP-based systems.

Before we get into the benefits of IP, let’s briefly go over SDI. 

What is SDI?

SDI—or serial digital interface—was first standardized by SMPTE in 1989, marking a revolutionary transition from analog to digital video infrastructure. At its core, the system is used for the transmission of uncompressed, unencrypted digital video signals for professional broadcasting. Widely adopted among industry professionals, an SDI router was designed to:

  • Deliver serial digital input signals in a point-to-point, one-way structure.
  • Provide consistent delay and performance, regardless of the number of active signals being routed and switched.

Since its inception, SDI has developed a suite of encompassing standards that support the creation of higher resolutions, color gamuts, and frame rates to meet the needs of the industry and advancing consumer technology.

However, the need for increased bandwidth for the transmission of ultra high definition (UHD) content and better connectivity, combined with the growing over-the-top (OTT) market, simply outweigh the capabilities of what SDI can offer. Due to this, there’s been a shift to internet protocol (IP)-based networks for all-IP studio operations. 

The Move to Internet Protocol-Based Infrastructure

IP networks utilize internet technology ecosystems that offer more agility and flexibility for broadcasters. In the long run, this means decreased costs, improved bandwidth consumption at higher bit rates, and improved overall efficiency. Additionally, IP switches are bidirectional and can manage multiple input and output ports, unlike SDI.

A few other benefits of migrating to an IP-based system include:

  • Cloud-based computing requiring less physical storage
  • One common data center
  • Higher quality streams of live content
  • Future-proofing for scalability and bandwidth

The transition doesn’t come without skepticism, though. The newness of all-IP requires extensive changes in infrastructure that make the decision a costly one for many local and regional broadcasters. There is also a concern of security for housing valuable content in the “cloud.”

Despite these concerns, SMPTE ST 2110 for Professional Media Over Managed IP Networks has gained widespread acceptance within the industry.

SMPTE ST 2110 for Interoperability

SMPTE ST 2110 consists of a suite of standards that detail the “carriage, synchronization, and description of separate elementary essence streams over IP for real-time production, playout, and other professional media applications.” Additionally, ST 2110 is video-format-agnostic, so it can support UHD such as 4K, 8K, and other emerging formats.

Note: For a full list of the included standards and enhanced details about the SMPTE ST 2110 family, visit the SMPTE ST 2110 FAQ page.

The most important thing to note about ST 2110 is its ability to separately route and break apart audio, video, and ancillary data to work on different streams independently, then bring them back together again at the endpoint. Not only does this enable truly flexible workflows when you consider the ethernet’s asynchronous nature, but it also simplifies the process of adding metadata, captions, time codes and more.

What are your thoughts on the transition to all-IP? Share in the comments!

For in-depth details on the technical aspects of IP-based networks, enhanced scalability, and evolving distribution as a whole, take a look at the July Motion Imaging Journal by SMPTE.



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