At NAB Show New York, SMPTE’s PTP Bootcamp Explores the Role and Challenges of Precision Timing in AV-Over-IP Systems
Precision Time Protocol (PTP) is a crucial component of SMPTE ST 2110 transport. When a device’s local clock loses synchronization with the common reference clock, severe audio and video problems can occur, including intermittent audio during a live production. Therefore, engineers and designers working with media infrastructure that require time to be distributed using PTP need to understand how PTP works, and how to identify and troubleshoot timing problems.
PTP is also used well beyond ST 2110, including in Dante, AES67, Q-SYS/Q-LAN, RAVENNA, and other audio/video technologies. That broader relevance is the focus of “SMPTE Bootcamp: Precision Timing for ST 2110,” taking place Wednesday, October 21, at the Javits Center during NAB Show New York. Intended for engineers and designers working with technologies that use PTP, the training will run from 9:30 a.m. to 12:30 p.m. and 1:30 to 4:30 p.m., with full- and half-day registration available.
The training will build participants’ understanding of PTP from the ground up, moving from fundamentals such as PTP messaging and clock synchronization to grandmaster behavior, boundary clocks, and network infrastructure. Presenters will also discuss how specific products support PTP in real-world systems.
Why Timing Matters
Transmitters and receivers use PTP to synchronize their local clocks to a common reference clock. A grandmaster is the ultimate reference for a PTP domain, while some networks use boundary clocks to distribute that reference. With their clocks synchronized to the same reference, receivers can relate the transmitter’s media timestamps to their own local time and determine when to play out the audio or video.
Receiving the media, however, does not by itself confirm that devices’ local clocks are synchronized to the common reference clock. Engineers therefore need to distinguish between problems with the media and problems with timing.
Redundancy introduces more complexity. Devices may transmit duplicate media streams over separate physical networks so that one remains available if the other fails. Receivers may receive timing information from different grandmasters over those distinct paths, making it important to verify that both provide equivalent time references.
These practical complications are why engineers need to understand more than basic PTP principles. They also need to know how timing behaves as network configurations become more complex.
Inside the PTP Bootcamp
AIMS members Telestream, Meinberg, Arista, Lawo, Bridge Technologies, and NETGEAR are among the companies participating in the training. Telestream will open the event with PTP fundamentals, combining introductory material with more advanced topics such as PTP message types, delay and clock offset calculations, grandmaster selection and failover, and boundary clocks.
Leigh Whitcomb, broadcast technologist at Meinberg, will build on those fundamentals with a discussion of SMPTE ST 2059 and best practices, including an update on the standard. Arista will then address PTP network infrastructure, including boundary clocks and how to verify that PTP is working properly. The morning will conclude with a “Stories from the Field” panel discussion.
In the afternoon, John Salt of Audinate will address PTP in the context of Dante, including video. He will discuss Dante’s use of PTP version 1, support for PTP version 2 in some devices, and the PTP capabilities available through the Dante Controller. Presentations from Leader, Meinberg, Bridge Technologies, and NETGEAR will follow, focusing on specific products and their PTP capabilities.
Andreas Hildebrand, RAVENNA/AoIP technology evangelist at Lawo, will close the day with a discussion of timing in devices that use ST 2022-7 for seamless protection switching. He will also explore asynchronous timing.
The Collaboration Behind Interoperability
The PTP Bootcamp brings together participants from across the industry, including manufacturers of grandmaster clocks, network infrastructure experts, integrators, and television production organizations. Many participating companies are competitors, but PTP matters to them all. Bringing their perspectives into the same room gives attendees a broader view of how timing works across different products and systems.
That collaboration is especially important in an interoperable environment. PTP is defined by the IEEE 1588 standard, while ST 2110 and AES67 are open standards that enable compatible devices from different manufacturers to work together. Engineers therefore need to understand how these technologies interact across products and systems, not simply how an individual device operates. Education from organizations such as SMPTE, along with the willingness of companies across the industry to share their knowledge and experience, helps build that understanding.
Putting PTP in Perspective
Because many Ethernet- and IP-based media systems depend on PTP for synchronization, a timing problem can have consequences throughout the network. Engineers who understand how PTP works and where its challenges lie are better equipped to design, deploy, and troubleshoot systems that depend on it. That understanding also includes recognizing if PTP is an enabler or too much of a constraint for the overall needs of the system. Whether PTP is required depends on the audio/video technology being used.
Technologies such as NDI, SRT, and RIST do not depend on PTP, while IPMX transmitters and receivers can operate with or without it. Understanding PTP’s constraints and requirements helps engineers and designers choose the appropriate timing approach for a particular application.
PTP becomes easier to understand when engineers can ask questions and learn from others who have faced the same challenges. Events such as the PTP Bootcamp provide that opportunity. They connect engineers with colleagues who can help them design systems and troubleshoot timing problems.
