Skip to main content

Troubleshooting ST 2110 IP Challenges With Lawo SMART

Lawo
Nik Kumar, senior engineer at Diversified – Media & Entertainment. (Image credit: Lawo)

KENILWORTH, N.J.—Access to a robust set of test and monitoring tools is becoming indispensable when designing and building SMPTE 2110 IP systems for TV stations and other M&E customers. Lawo’s smartSCOPE and smartDASH helped us immensely with our testing and commissioning that facilitated the successful launch of a big project. Additionally, smartANC Shuffler allows us to manage ancillary data streams in a way that was not directly possible in an SDI environment.

Diversified recently completed a systems integration project for a major market TV station in the U.S. The station was built in a brand-new facility using state-of-the-art ST 2110 technology and went on air with full-time production several months ago.

THIRD-PARTY INTEGRATION

At the core of the system are Lawo’s VSM broadcast/router control and V__matrix C100 processing blades, some of which are used as IP gateways and multiviewers. Numerous third-party IP devices were also leveraged to provide a best-of-breed system to the customer: ST 2110-based cameras, production switchers, graphics systems, editing IO, satellite IRDs, general-purpose encapsulators and de-encapsulators, etc. 

The master control switcher was fully virtualized using VSM and the master control air chains for the various station channels were all designed and built utilizing IP. 

With the integration of different third-party systems and the implementation of complex workflows, there was a need for a robust troubleshooting and monitoring system. smartSCOPE offers a good range of measurement and analysis tools, including basic features such as video and audio monitoring tiles, along with more complex IP measurement tools such as packet telemetry, packet pacing, service timing sync, etc. 

Various RTP stream characteristics within the packet telemetry toolset can be monitored. For instance, users can view the min, max, and mean interpacket arrival times of ST2110-20/30/40 streams along with RTP packet losses and packet jitters. One tool I particularly like is “Service Timing Sync,” which can be used to determine the essence RTP stream offset with respect to PTP, along with the relative offsets between video, audio, and ancillary RTP streams. 

Packet Pacing is another excellent tool to model VRX buffer behavior and overflows for incoming streams from a narrow- or wide-based sender. It helped me diagnose an issue with the receivers on a production switcher, which are hard-set as narrow receivers. When slightly bursty narrow-based traffic from a particular vendor was sent to these receivers, video inputs began to tear due to consistent packet overflows. The production switcher vendor duly wrote a firmware patch to deepen the receive buffers and no video tearing has been observed since. Additionally, the Packet Pacing tool offers TRoffset readings of the time offset between the actual start of the first packet of a video frame vs. derived time with respect to the ST2059-01 Epoch. 

FLEXIBLE WORKFLOW FOR 2110

smartDASH is also an effective graphical tool for network-level troubleshooting. It uses real- time streaming telemetry data gathered from the network switches in an easy-to-understand graphical fashion. While I habitually perform network-level troubleshooting at the switch CLI layer, smartDASH is a powerful tool for broadcast engineers unfamiliar with CLI.

One of the challenges we faced during the design phase of the master control air chain was architecting a workflow that would give us the flexibility to mix and match different ST2110-40 ancillary data streams with the outgoing final-air ST2110-20 video and ST 2110-30 audio streams. The smartANC shuffler provides an elegant solution: we can decouple upstream ancillary data streams (closed captioning, AFD, SCTE104, etc.) from different sources and marry them with the outgoing video and audio output streams. 

This type of flexibility is generally not offered in an SDI system where ancillary data is carried in the VANC and HANC spaces of the SDI video payload. 

For more information visit https://lawo.com.

Nik Kumar is a senior engineer at Diversified – Media & Entertainment. He can be reached at nkumar@diversifiedus.com or at 703-552-6900.