Tech Focus: Networked Audio, Part 2 — SMPTE Readies a Refresh for ST 2110
The familiar standards suite is transitioning to IP
This year marks the 45th anniversary of the original SMPTE timecode standard. Like much of the rest of infrastructure for broadcast and other media, it is undergoing a transition to IP, even as its current iteration is part of virtually every broadcast, live production, and recording today.
That underscores the robustness of SMPTE’s work on the ST 2110 suite of standards, established to guide uncompressed digital audio, video, and control over IP networks within broadcast production and distribution facilities, where quality and flexibility are more important than bandwidth efficiency.
Now five years old, ST 2110-10, the first of the six initial standards and focused on system architecture and synchronization (system timing), is undergoing review for potential revisions and updates, along with stablemates ST 2110-20 (uncompressed active video), ST 2110-21 (traffic shaping and delivery timing for video); and ST 2110-40 (ancillary data).
Click here for Tech Focus: Networked Audio, Part 1 — Standards Help the Technology Grow Up.
The two standards that directly affect audio, ST 2110-30 (audio transport, based on AES67) and ST 2110-31 (transport of AES3-formatted audio, the most recently published standard of the group), were introduced in 2018 and will be due for review in 2023.
In addition, two new standards are currently in the balloting process, including SMPTE ST 2110-41 (fast metadata), which concerns general metadata that is carried, like video and audio, in a single separate RTP stream.
“It is relevant to audio in SMPTE ST 2110,” explains Frank Kunkle, marketing manager, SMPTE, “because the request for it originated from a desire to have a constrained way of signaling audio metadata as a single RTP stream over IP networks, similar to the AES-X242 effort in AES, and the application will support technologies like [for example] immersive audio. While SMPTE ST 2110-41 would allow all kinds of metadata to be transported, it will certainly support audio metadata similar to what has been done in SMPTE ST 2109 for AES3 audio.”
A second forthcoming standard, RP 2110-24, will address legacy standard-definition content within the ST 2110 ecosystem. (Given the coronavirus pandemic, SMPTE has made the documentation of the “core” standards of ST 2110 — -10, -20, -21, -30, and -40 — available without a subscription.)
“The review period is an opportunity for the [subcommittee] to look at the experience and decide if it requires any fixes or updates,” says Thomas Bause Mason, director, standards development, SMPTE, adding that the two new standards are between six months and a year from being ready.
Along with such standards as AES67, the ST 2110 standards form a foundation for the accelerating migration from earlier interfaces, such as SDI (which SMPTE also helped standardize) to an IP environment.
“We’re seeing more and more deployment of IP as the basis for infrastructure,” Bause Mason says of the ST standards’ impact on the industry. “At first, it was OB vans that spearheaded the transition to IP. Now we see entire facilities being built on it by broadcasters like NBC and the CBC.”
However, he sees a place for proprietary protocols, such as Dante for audio, in smaller settings, such as edit bays. And, although Networked Media Open Specifications (NMOS) have been developed, by the Advanced Media Workflow Association (AMWA) to provide a control and management layer in addition to the transport layer provided by SMPTE ST 2110, he suggests that they are still undergoing development and that ST 2059, which addresses synchronization of video equipment over an IP network, is awaiting wider implementation.
“But it will get there,” he predicts. “IP is a much more efficient environment for broadcast to work in.”