On-Demand Webinar: 21 Minutes
Starting with an overview of the different approaches to uncompressed video over IP, Paul Robinson, then CTO of Tektronix, explains how PTP works and how it is applied in practice. Finishing with a Q&A, these topics are all still relevant in a post SMPTE 2110 world. ST 2110 was built on some of the technologies discussed separately in this talk from 2016 and much can be gained from this understanding.
Search Results for: PTP
Videos: Standards – What are they and how are they changing?
Standards in media go back to the early days of cinema standardising the sprocket holes in rolls of film with the intent of making it easier for the US Army to distribute training films. This standardisation work marked the beginning of SMPTE, though the acronym lacked a T at the time since television hadn’t yet been invented. There is a famous XKCD comic that mocks standards or at least standards that promise to replace all that went before. This underlines why it’s more important what standards don’t say than what they do. Giving the market room to evolve, advance and innovate is a vital aspect of good standards.
The broadcast industry is emerging from a time of great stability thanks to a number of standards that have been around for ages. SDI is a decades-old technology that is ubiquitous in the industry. Likewise, H.264 has become the only codec to use unless you have a specific use case for HEVC, AV1, VP9 etc. thanks to its almost universal presence in devices. Black and burst is now being replaced by PTP in IP installations. This is novel, despite PTP’s upcoming twentieth birthday, because it doesn’t matter if PTP is four decades old, its launch in the broadcast sector is recent, support will be low.
This panel from SMPTE Hollywood features two members of SMPTE deeply involved with standardisation within the industry: Bruce Devlin, Standards Vice President and Thomas Bause Mason Director of Standards Development. . They are joined by IP specialist JiNan Glasgow George and moderator Maureen O’Rourke from Disney.
In a sometimes frank discussion, we hear about the attempt by standards bodies to try and keep up with the shift form hardware to software within the whole industry, the use of patents within standards, how standards bodies are financed and the cost of standards, software versus hardware patents, standardisation of AI models, ensuring standards are realistic & useful with plugfests, the difference between standards bodies such as ANSI, ISO, SMPTE etc.,
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Thomas Bause Mason Director of Standards Development, SMPTE |
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Bruce Devlin Standards Vice-President, SMPTE |
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JiNan Glasgow George Patent Attorney, Neo IP |
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Maureen O’Rourke Technical Lead Quality Control Officer, The Walt Disney Company |
Video: IPMX Makes Networks Easy
IPMX is bringing a standards-based, software deployable connectivity solution to ProAV. It stands itself in contrast to hardware-based IP technologies such as Zeevee and SDVoE which both aim to create de facto standards by building large alliances of companies based on their chips. IPMX’s aim is to open up the market to a free-to-access technology that can be implemented in hardware and software alike. In this way vendors have more freedom in implementation with the hope of wider interoperability, depending on IPMX adoption. These are amongst some of the business reasons behind IPMX which are covered in this talk Matrox’s David Chiappini.
In today’s video, Matrox’s Jean Lapierre looks at the technical side of IPMX to answer some of the questions from those who have been following its progress. AIMS, the Alliance for IP Media Solutions, are upfront about the fact that IPMX is a work in progress with important parts of the project dealing with carriage of HDCP and USB still being worked on. However, much has already been agreed so it makes sense to start thinking about how this would work in real life when deployed. For a primer on the technical details of IPMX, check out this video from Andreas Hildebrand.
Jean starts by outlining the aims of the talk; to answer questions such as whether IPMX requires a new network, expensive switches and PTP. IPMX, he continues, is a collection of standards and specifications which enable transport of HD, 4K or 8K video in either an uncompressed form or lightly compressed, visually lossless form with a latency of <1ms. Because you can choose to enable compression, IPMX is compatible with 1GB, CAT5e networks as well as multi-gigabit infrastructure. Moreover, there’s nothing to stop mixing compressed and uncompressed signals on the same network. In fact, the technology is apt for carrying many streams as all media (also known as ‘essences’ to include metadata) is sent separately which can lead to hundreds of separate streams on the network. The benefit of splitting everything up is that in the past if you wanted to read subtitles, you would have to decode a 3Gbps signal to access a data stream better measured in bytes per second. Receiving just the data you need allows servers or hardware chips to minimise costs.
Jean explains how multicast is used to deliver streams to multiple receivers and how receivers can subscribe to multiple streams. A lot of the time, video streams are used separately such as from a computer to a projector meaning exact timing isn’t needed. Even coming into a vision mixer/board doesn’t always need to be synchronised because for many situations, having a frame synchroniser on all inputs works well. There are, however, times when frame-accurate sync is important and for those times, PTP can be used. PTP stands for the Precise Time Protocol and if you’re unfamiliar, you can find out more here.
The upshot of using PTP with IPMX is that you can unlock perfect synchronisation for applications like video walls; any time you need to mix signals really. IMPX relaxes some of the rules of PTP that SMPTE’s ST 2059 employs to reduce the load on the grandmaster clocks. PTP is a very accurate timing mechanism but it’s fundamentally different from black and burst because it’s a two-way technology that relies on an ongoing dialogue between the devices and the clock. This is why Jean says that for anything more than a small network, you are likely to need a switch that is PTP aware and can answer the queries which would normally go to the single, central switch. In summary then, Jean explains that for many IPMX implementations you don’t need a new network, a PTP grandmaster or PTP aware switches. But for those wanting to mix signals with perfect sync or those who have a large network, new investment would reap benefits.
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Jean Lapierre Senior Director, Advanced Technolgies Matrox |
Video: ST 2110 Over WAN — The Conclusion of Act 1
Is SMPTE ST 2110 suitable for inter-site connectivity over the WAN? ST 2110 is putting the early adopter phase behind it with more and more installations and OB vans bringing 2110 into daily use yet most sites works independently. The market is already seeing a strong need to continue to derive cost and efficiency savings from the infrastructure in the larger broadcasters who have multiple facilities spread around one country or even in many. To do this, though there are a number of challenges still to be overcome and moving a large number of essence flows long distances and between PTP time domains is one of them.
Nevion’s Andy Rayner is chair of the VSF Activity Group looking into transporting SMPTE ST 2110 over WAN and is here to give an update on the achievements of the past two years. He underlines that the aim of the ST 2110 over WAN activity group is to detail how to securely share media and control between facilities. The key scenarios being considered are 1) special events/remote production/REMIs. 2) Facility sharing within a company. 3) Sharing facilities between companies. He also notes that there is a significant cross over in this work and that happening in the Ground-Cloud-Cloud-Ground (GCCG) activity group which is also co-chairs.
The group has produced drafts of two documents under TR-09. The first, TR-09-01 discusses the data plane and has been largely discussed previously. It defines data protection methods as the standard 2022-7 which uses multiple, identical, flows to deal with packet loss and also a constrained version of FEC standard ST 2022-5 which provides a low-latency FEC for the protection of individual data streams.
GRE trunking over RTP was previously announced as the recommended way to move traffic between sites, though Andy notes that no one aspect of the document is mandatory. The benefits of using a trunk are that all traffic is routed down the same path which helps keep the propagation delay for each essence identical, bitrate is kept high for efficient application of FEC, the workflow and IT requirements are simpler and finally, the trunk has now been specified so that it can transparently carry ethernet headers between locations.
Andy also introduces TR-09-02 which talks about sharing of control. The control plane in any facility is not specified and doesn’t have to be NMOS. However NMOS specifications such IS-04 and IS-05 are the basis chosen for control sharing. Andy describes the control as providing a constrained NMOS interface between autonomous locations and discusses how it makes available resources and metadata to the other location and how that location then has the choice of whether or not to consume the advertised media and control. This allows facilities to pick and choose what is shared.
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Andy Rayner Chief Technologist, Nevion, Chair, WAN IP Activity Group, VSF |
