Often overlooked, but very important for IP streams such as SMPTE ST 2110, is SDP – Session Description Protocol.
SDP describes the stream by transferring a small text file from the sender to the receiver which defines what the media is (audio, video etc.) the IP address of the sender and other data.
Sithideth Viengkhou from Embrionix takes us through some of the details, shows some examples and explains and why it’s so useful.
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Sithideth Viengkhou R&D Project Manager, Embrionix |
Delivering an all-IP truck is no mean feat. tpc explains what they learnt, what went well and how they succeeded in delivering a truck which takes no longer to fire up than a traditional SDI truck.
A common question among people considering a move to IP is ‘do I need to?’ and ‘how can I get ready?’. Here at The Broadcast Knowledge we always say ‘find a small project, get it working, learn what goes wrong and then plan the one you really wanted to do.’ The Swiss broadcasting service provider ‘Technology and Production Centre’, known as ‘tpc’, has done just that.
tpc is currently working on the Metechno project – a large, all-IP news, sports and technology centre for Swiss radio and television. In order to acquire necessary experience with the SMPTE ST 2110 standard, tpc designed the UHD1 OB van ahead of time which has been used in TV production for 6 months now. In this video, Andreas Lattmann shares the vision of the Metechno Project and, critically, his experiences related to the design and use of the truck.
The UHD1 is a 24-camera OB van with all IP core based on Arista switches with non-blocking architecture. It is the equivalent of an 184-square UHD SDI system however, it can be expanded by adding additional line cards to network switches. The truck is format agnostic, supporting both HD and UHD formats in HDR and SDR. IP gateways are incorporated for SDI equipment.
The SMPTE ST 2110 specification separates video and audio into discrete essence streams which boosts efficiency and flexibility, but we hear in this talk that more attention to latency (lip-sync) is required compared to SDI systems. Andreas talks about the flexibility this truck provides with up-/down-conversion, colour-correction for any video plus how IP has enabled full flexibility in what can be routed to the multiviewer screens.
Andreas spends some time discussing redundancy and how IP enables full redundancy – an improvement over many SDI infrastructures and how SMPTE’s ST 2022-7 standard makes this possible.
The main GUI is based on a Lawo VSM control system which aims to deliver a familiar experience for operators who used to work in the SDI domain. Network training has been provided for all operators because troubleshooting has changed significantly with the introduction of essences over IP. This is not least because NMOS IS-04 and 05 standards were not mature enough during the design of the truck, so all IP connections had to be managed manually. With more than 50 thousand IP addresses in this system, AMWA’s NMOS IS-04 which manages discovery and registration and IS-05 which manages the setup and take-down of connections would have helped significantly in the lean management of the truck.
Lattmann emphasizes the importance of using open standards like SMPTE ST 2110 instead of proprietary solutions. That allows you to choose the best components and not rely on a single manufacturer.
The learning’s the Andreas presents us involve difficulties with PTP, IP training, the benefits of flexibility. From a video point of view, Andreas presents his experiences with HDR->SDR workflows, focussing in HDR and UHD.
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Andreas Lattmann CTO, Head of Planning & Projects tpc Switzerland AG |
RIST solves a problem by transforming unmanaged networks into reliable paths for video contribution. This comes amidst increasing interest in using the public internet to contribute video and audio. This is partly because it is cheaper than dedicated data circuits, partly that the internet is increasingly accessible from many locations making it convenient, but also when feeding cloud-based streaming platforms, the internet is, by definition, part of the signal path.
Packet loss and packet delay are common on the internet and there are only two ways to compensate for them: One is to use Forward Error Correction (FEC) which will permanently increase your bandwidth by up to 25% so that your receiver can calculate which packets were missing and re-insert them. Or your receiver can ask for the packets to be sent again.
RIST joins a number of other protocols to use the re-request method of adding resilience to streams which has the benefit of only increasing the bandwidth needed when re-requests are needed.
In this talk, Ciro Noronha from Cobalt Digital, explains that RIST is an attempt to create an interoperable protocol for reliable live streaming – which works with any RTP stream. Protocols like SRT and Zixi are, to one extent or another, proprietary – although it should be noted that SRT is an open source protocol and hence should have a base-level of interoperability. RIST takes interoperability one stage further and is seeking to create a specification, the first of which is TR-06-1 also known as ‘Simple Profile’.
We then see the basics of how the protocol works and how it uses RTCP for singling. Further more RIST’s support for bonding is explored and the impact of packet reordering on stream performance.
The talk finishes with a look to what’s to come, in particular encryption, which is an important area that SRT currently offers over and above reliable transport.
Watch now!
To dig into SRT, check out this talk from Chris Michaels
For more on RIST, have a look at Kieran Kunhya’s talk and Rick Ackerman’s introduction to RIST.
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Ciro Noronha Director of Technology, Compression Systems, Cobalt Digital |
OB vans have been notable early adopters of Video over IP, both in the form of SMPTE ST 2110 and ST 2022-6. The reasons are simple, all new vans are ‘green field’ sites, weight and space are at a premium and many need more weekly flexibility than SDI has been giving them.
In this case study, Hartmut Opfermann discusses design considerations for all IP large OB trucks dedicated for sports, music and entertainment production and explores the decisions that have been made for ORF’s new FU22 OB tuck including the drivers behind switching to IP technology and SMPTE ST 2110 for media transport.
Interesting to note is the proportion of SDI Vs IP in new IP installations. BBC Cardiff, for instance, has a minimum quota for IP-enabled endpoints but isn’t assuming it can reach 100%. There are few IP installations which are 100% IP.
In ORF’s truck we also see that, although the truck is fully based on IP technology, SDI-IP gateways have been provided to keep compatibility with existing baseband infrastructure. Keeping all internal processing in the IP domain simplifies cabling, reduces cable weight but, importantly, enables the use of flexible FPGA based processing platforms – functionality thus depends on software and can be changed on fly.
The broadcast control system provides a single point of control over complex infrastructure of the truck and provides a seamless experience for operators who used to work in the SDI domain. However, configuration and troubleshooting of IP systems requires a very different skillset, so training had to be provided to ORF engineering team.
Some other points discussed in this video are audio channel management, failover of PTP and B&B synchronisation and IP address management using the JT-NM’s TR 1001-1, which has been covered here on The Broadcast Knowledge before.
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Hartmut Opfermann Head of Division Broadcast IT, BFE Studio und Medien Systeme GmbH |
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