Daisy-Yuanwen Sun
Principle Technical Product Manager
Blog

Broadcast Industry Revolution - Migration to IP Infrastructure

August 9, 2019 by Yuanwen (Daisy) Sun

The broadcast industry has embraced IP technology and is transitioning from tradition serial digital input (SDI) to IP/Ethernet infrastructure for live production and professional television to meet the increasing amount of content distribution, flexibility for modern media processing, as well as a single communication infrastructure for both media transport and synchronization. 

Ethernet is an inherently asynchronous medium and best effort. It needs to provide stringent time synchronization and guaranteed delivery to support professional broadcast applications. Audio/video bridging (AVB) defined by the IEEE was developed several years back to help with time synchronization. This is an Ethernet layer-2 solution. With the uptake of all-IP studio gaining more and more momentum, the Society of Motion Picture and Television Engineers (SMPTE) ratified a new set of SMPTE 2110 standards in 2018 to support video over IP transport. 

Time Synchronization for Professional Broadcast Applications

SMPTE ST-2059-2 defines the SMPTE PTP Profile for time and frequency synchronization in a professional broadcast environment. The IEEE Std 1588-2008 defines a set of required/ permitted/ prohibited options, and the ranges and defaults of configurable attributes. It is intended to be used with SMPTE ST-2059-1 which defines a point in time, the SMPTE Epoch for alignment of real-time signals among all devices. The time synchronization accuracy shall be within 1 microsecond and a slave shall be synchronized within 5 seconds.

The SMPTE profile requires Management message to convey Synchronization Metadata (SM) required for synchronization and time labeling of audio/video signals. A Management node sends management message to Ordinary Clocks, Boundary Clocks and/or Transparent Clocks which may either configure or monitor these clocks from a centralized location.

Critical Points for Testing

As the profile defines required and permitted options of mixed unicast and multicast communication modes for various PTP messages, different implementations may take different approaches and interoperability testing is required to ensure proper operation among Master, BC/TC-enabled switch, and endpoint devices acting as slave.

A Boundary Clock (or a Transparent Clock) is typically installed to decrease the degradation of time synchronization as it traverses the packet network. It is important to test the scale and performance of a Boundary Clock used in live production centers, which need to support many devices. It is also important to test BC/TC-enabled switches along with other control and data traffic.

Validate SMPTE Media Profile Using IxNetwork

With the IxNetwork 9.00 release, customers can now validate SMPTE profile support for BC/TC-enabled switches, as well as Master Clocks designed for the broadcast industry.

By emulating one or more Masters at one side and hundreds or thousands of slaves over one or many downstream ports, IxNetwork can validate Boundary Clock functionality and performance with fully loaded slaves. The enhanced offset triggered logging capability can capture erroneous conditions over long-duration runs and record sub-second changes including offset, patch delay, and T1~T4 to help troubleshoot and pin-point issue quickly.

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IxNetwork 1588v2 (PTP) SMPTE Profile

Check out the IxNetwork 1588 SMPTE Profile demo