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Transitioning Media Production Facilities from SDI to IP

June 28, 2022

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This era’s explosion of content creation means that infrastructure needs to grow to support the studios, control rooms, editing and graphics suites that these productions require. When the expansion requirements have outgrown existing infrastructure, there are important decisions to make about how the facility will evolve to support the enormous expansion in file-based infrastructure and secure content flow. In the June issue of the SMPTE Motion Imaging Journal, director of engineering and technology for ABC News Mike Strein addresses key considerations in his tutorial, “Transitioning an Existing SDI Facility to IP.”

One of the most obvious scenarios is the need to expand or replace an SDI video router. Audio/video routers have traditionally been based on the constraints of the physical switch matrix at their heart which limits the input/output size, typically to 1152x1152 baseband HD-SDI I/O. Off-the-shelf IP switches for large A/V routing matrices deliver much larger scale with a reduction in power requirements. However, their operating systems were tailored to IP traffic instead of the realtime, lossless, minimal latency transmission and the control interfaces required for media production. So, installing an IP A/V router into a predominantly SDI facility requires the use of gateways as IP-to-SDI and SDI-to-IP conversion devices, with ports that can be configured to allow egress and ingress to the IP core of the router on the same cable.

Managing the A/V pathways in an IP environment is very different from managing the signals in an SDI matrix. The IP-based media router must also provide:

  • The ability to add A/V products (often called media nodes) with native SMPTE ST 2110 standards connectivity for media over IP.
  • A software-defined network (SDN), an entirely new function for the broadcast controller to handle the end-to-end flow management, bandwidth control, and proper connections for all I/O.
  • Support and sourcing for Precision Time Protocol (PTP) to provide reference signals for timing. This system can ideally serve as a reference for other signals as well, such as the Network Time Protocol (NTP).
  • Connections to dual IP streams – both internally and externally – to provide redundancy.
  • The same control panel capabilities found in existing SDI systems, so that the migration from SDI to IP is hidden, a key to promoting operator acceptance.

Many media production facilities will have significant areas of their facilities dedicated to audio. In fact, audio product manufacturers, user groups and standards bodies such as the Audio Engineering Society (AES) were early adopters of IP techniques in audio production. Today, many products are available with interfaces through gateways that allow existing islands of digital audio production within the facility to move to SMPTE 2110 for carriage on the IP-based A/V routing system. Media facilities that do live production are also likely to have an extensive intercom system as well as a large telephony system. Just as in audio production, gateway products can be deployed for both sources to gain access across the IP-based A/V router.

IP-based A/V routing provides enormous scale, but with that comes management complexity. In addition to the management of the I/O and names, it also adds the management of the IP address space which may include not only the multicast addresses for the A/V sources, but also the IP addresses for the management interfaces. Organizations such as the Advanced Media Workflow Association (AMWA) have developed a suite of specifications called Networked Media Open Specifications (NMOS) to help. AMWA is also working to create specifications for domain name self-discovery (DNS) and multicast DNS self-discovery in what will eventually be an IP address management system (IPAM) that encompasses the entirety of the media modes resident on the IP-based A/V router.

Traditionally, analog and SDI facilities where the A/V devices had no physical connection to the outside world were not concerned about security. However, almost all media delivery is electronic file-based now, and connectivity occurs in the production media environment with realtime content ingressing and egressing the IP-based A/V router. Both expose the facility to outside entities and security issues. Techniques such as zero-trust networks, issuance and management of certificates, and the development of media-centric firewalls are security methods that will become part of media infrastructures going forward.

Future media production facilities will likely leverage the flexible infrastructure that the public and private cloud can provide. And at some point in the continued evolution of the media production facility, designers may look from a monolithic topology to a spine/leaf topology. This architecture provides higher bandwidth uplink ports that allow greater expansion capability with gradual implementation of bandwidth increases that enable growth to 4K and beyond.

Because the IP industry so dwarfs the media production industry, Strein says that the media industry can take advantage of the IP research and development potential to work on a scale that traditional media manufacturers cannot approach. A future growth scenario, he says, is to look to the IP switch industry to support the routing infrastructure of the media production facility, with the broadcast control management systems coming from the more “media-centric” manufacturers.

For all the details of Strein’s tutorial, read the complete article in this month’s SMPTE Motion Imaging Journal.

Keywords: SMPTE, Media over IP, ST 2110, Media Production, Advanced Media Workflow Association, AMWA, Audio Engineering Society, AES, domain name self-discovery, DNS, IP address management system, IPAM, network time protocol, NTP, Networked Media Open Specifications, NMOS, precision time protocol, PTP, software-defined network, SDN,

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