NMOS is the open standard for multiple vendors co-operating on a broadcaster network, particularly ST 2110, to announce new devices and configure them. Acting as both a database but also a way of easily describing settings to be shared between systems. Often new ST 2110 systems are specified to be NMOS IS-04 and IS-05 capable.
NMOS IS-04 is the name of the specification which defines discovery and registration of devices while IS-05 describes the control of said devices. It’s very hard to run a SMPTE ST 2110 system without these or a proprietary protocol which exchanges the same information. It’s not practical to manage any of these tasks at anything more than the smallest scale.
John Mailhot from Imagine Communications delivers a concise summary of these technologies which may be new to you. He explains that an SDP will be generated and John reviews how you would read them. John explains that the stack is open source with the aim of promoting interoperability.
John takes the time needed to look at IS-04 and IS-05 in terms of practically implementing it at the end of this short talk.
PTP is the beating heart behind video- and audio-over-IP installations. As critical as black and burst reference, it pays to get it right. But PTP is a system, not a monolithic signal distributed around the facility. Unlike genlock, it’s a two-way conversation over networked infrastructure and whilst that brings great benefits, it changes how we deal with it. The system should be monitored, both at the ST 2059 layer and network layer. But before we even get to that point, implementation requires care particularly as the industry is still in the early phases of developing tools and best practices for project deployments.
Leigh Whitcomb from Imagine Communications has stepped up to bring us his experiences and best practices as part of the Broadcast Engineering and IT Conference at NAB. This talk assumes an existing level of knowledge of PTP. If you would like to start at the beginning, then please look at this talk from Meinberg and this from Tektronix.
Leigh starts by explaining that, typically, the best architecture is to have a red and a blue network. A grand master would then be on both networks and both would be set to lock to GPS. He explains how do deal with prioritisation and preventing other devices from becoming grand masters. He also explains some of the basic PTP parameter values such as setting the Announcement time outs. Other good design practices he discusses are where to use Boundary Clocks, avoiding PTP Domain numbers of 0 and 127 plus using QoS and DSCP.
As part of the commissioning piece, Leigh goes through some frequently-seen problems such as locking up slowly due to an incorrect Delay Request setting or the Grand Master announce rate being the same as the timeout. To understand when your system isn’t working properly, Leigh makes the point that it’s vital to understand in detail how you expect the system to behave. Use checklists to ensure all parameters and configuration have been applied correctly but also to verify the PTP packets themselves leaving the GM. Leigh then highlights checklists for other parts of the network such as the switches and Media Nodes.
There are a number of tools available for faultfinding and checking compliance. As part of commissioning, the first port of call is the device’s GUI and API which will obviously give most of the parameters needed but often will go further and help with fault finding. WireShark can help verifying the fields in the packets, the timing and message rates. Whilst Meinberg’s Track Hound is a free program which allows you to verify the PTP protocol and Grand Masters. The EBU List project also covers PTP/ST 2059. Helpfully, Leigh talks through how to use Wireshark to verify fields and message rates.
In terms of Testing, Leigh suggests running a packet capture (PCap) for 48 hours after commissioning to verify any issues. He then highlights the need for redundancy testing. This is where understanding how you intend the network to work is important as redundancy testing should also be combined with network testing where you deliberately pull down part of your network and see the GMs change as intended. This changeover will be managed by the Best Master Clock Algorithm (BMCA). When troubleshooting, you should use your monitoring system to help you visualise what’s happening. A good system should enable you to see the devices on the network and their status. Many companies would want to test how successfully the system recovers from a full failure as this will represent the maximum traffic load on the PTP system.
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Major technology transitions can be hard to keep up with, and when you have a project requiring you decide which one to go with, it can seem unmanageable. This panel put together by SMPTE New York looks gives the view from System Integrators on how to make this work and cover their experience with a wide range of new technologies.
SMPTE ST 2110 is an entire paradigm shift
John Turner kicked off explaining the reasoning for using SDI over SMPTE ST 2110 in some circumstances. For that project, his client had a fixed space so wouldn’t see the benefits of 2110 in terms of expansion. Their workflow already worked well in SDI and at the time, the costs of 2110 would have been higher. Overall, the project went with SDI, was successful and they are a happy customer. Karl Paulsen agreed that new technology shouldn’t be ‘for the sake of it’ and added that whilst individual products with a new technology may be stable, that’s not certain to be the case when interoperating within a whole system. As such, this puts the implementation time up meaning the incumbent technologies do tend to get chosen when time is at a premium.
Turning to 5G, Karl answered the question “what are the transformational technologies”. For some applications, for instance back of the camera RF in a stadium, 5G is a major leap compared to microwave packs, but early on in a technology’s life, like we are with 5G, it’s a matter of working out where it does and where it doesn’t work well. In time, it will probably adapt to some of those other use cases that it wasn’t suited for initially. John Turner highlighted the elements that ATSC 3.0 transforms in a big way. From an RF perspective, its modulation is much stronger and more flexible, that it’s able to drive new business models.
John Mailhot’s view on transformational challenge is ‘the people’. He puts forward the idea that the technical constraints of router size and max cable length, to name two examples, embedded themselves into the routines, assumptions and architectures that people embody in their work. With SMPTE ST-2110, most of these constraints are removed. This means you are a lot freer to work out the workflows the business wants. The challenge here is to have the imagination and fortitude to forge the right workflow without getting paralysed by choice.
“SMPTE ST 2110 is an entire paradigm shift”, John Humphrey
After responding to the moderator’s question on how much turmoil these transitions are causing, Mark Schubin summarises the situation by saying we need to work out which of the technologies is like a fridge (replacing previous technologies), a microwave (used as well as a conventional oven) and an induction cooker (requires change in cookware, little adoption). John Humphrey adds that ST 2110 is a technology which viewers don’t notice since the visual quality is the same. HDR, is the opposite so they need different approaches.
During the last 45 minutes, the panel took questions from the audience covering how to hire talent, the perspective of younger people on technology, programming specifically made for smartphones, ATSC 3.0 implementation, reliability of home internet, PTP and more.
As you walk around any exhibitions there seems to be a myriad of ‘benefits’ of IP working, many of which don’t resonate for particular use cases. Only the most extraordinary businesses need all of the benefits, so in this talk, Imagine Communication’s John Mailhot discusses how IP helps sports venues.
John sets the scene by separating out the function of OB trucks and the ‘inside production’ facilities which have a whole host of non-TV production to do including driving scoreboards, displays inside the venue, replays and importantly has to deal with over 250 events a year, not all of which will have an OB truck.
We see that the scale that IP can work at is a great benefit as many signals can fit down one fibre and 2022-7 seamless switching can easily provide full redundancy for every fibre and SFP. This is a level of redundancy which is simply not seen in SDI systems. With stadia being very large, necessitating cable runs of over 500m, the fact that IP needs fewer cables overall is a great benefit.
John shows an example of an Arista switch only 7U in height which provides 144x 100G ports meaning it could support over 4000 inputs and 4000 outputs. Such density is unprecedented and for OB trucks can be a dealbreaker. For sports venues, this can also be a big motivator but also allow more flexibility in distributing the solution rather than relying on a massive central interconnect with a 1100×1100 SDI router in a central CTA.
TV is nothing without audio and the benefits to audio in 2110 are non trivial since with the audio being split off from the video, we are no longer limited to dealing with just 16 channels per video and de-embedding from a video frame any time we want to touch it.
Timing is an interesting benefit. I say this because, whilst PTP can end up being quite complex compared to black and burst, it has some big benefits. First off, it can live in the same cables as your data where as black and burst requires a whole separate cable infrastructure. PTP also allows you to timestamp all essences which helps with lip-sync throughout your workflow.
John leads us through some examples of how this works for different areas finishing by summing up the relevant benefits such as scalability, multi-format, space efficient, and timing amongst others.
CTO, Networking & Infrastructure,
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