Let’s face it, SMPTE ST 2110 isn’t trivial to get up and running at scale. It carries audio as AES67, though with some restrictions which can cause problems for full interoperability with non-2110 AES67 systems. But once all of this is up and running, you’re still lacking discoverability, control and management. These aspects are covered by AMWA’s NMOS IS-04, IS-05 and IS0-08 projects.
Andreas Hildrebrand, Evangelist at ALX NetworX, takes the stand at the AES exhibition to explain how this can all work together. He starts reiterating one of the main benefits of the move to 2110 over 2022-6, namely that audio devices don’t need to receive and de-embed audio. With a dependency on PTP, SMPTE ST 2110-30 an -31 define carriage of AES67 and AES3.
We take a look at IS-04 and IS-05 which define registration, discovery and configuration. Using an address received from DHCP, usually, new devices on the network will put in an entry into an IS-04 registry which can be queried by an API to find out what senders and listeners are available in a system. IS-05 can then use this information to create connections between devices. IS-05, Andreas explains, is able to issue a create connection request to endpoints asking them to connect. It’s up to the endpoints themselves to initiate the request as appropriate.
Once a connection has been made, there remains the problem of dealing with audio mapping. Andreas uses the example of a single stream containing multiple channels. Where a device only needs to use one or two of these, IS-08 can be used to tell the receiver which audio it should be decoding. This is ideal when delivering audio to a speaker. Andreas then walks us through worked examples.
Is SMPTE ST 2110 suitable for inter-site connectivity over the WAN? ST 2110 is moving past the early adopter phase with more and more installations and OB vans bringing 2110 into daily use but today, each site works independently. What if we could maintain a 2110 environment between sites. 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 work in progress which started 18 months ago. The presentation looks at how to move media between locations which has been the primary focus to date. It then discusses how control over which media are shared will be handled as this is a new aspect to the work. Andy starts by outlining the protection offered in the scheme which supports both 2022-7 and FEC then explains that though FEC is valuable for single links where 2022-7 isn’t viable, only some of the possible ST 2022-5 FEC configurations are supported, in part, to keep latency low.
The headline to carrying 2110 over the WAN is that it will be done over a trunk. GRE is a widely used Cisco trunking technology. Trunking, also known as tunnelling, is a technique of carrying ‘private’ traffic over a network such that a device sending into the trunk doesn’t see any of the infrastructures between the entrance and the exit. It allows, for instance, IPv6 traffic to be carried over IPv4 equipment where the v4 equipment has no idea about the v6 data since it’s been wrapped in a v4 envelope. Similarly, the ipv6 equipment has no idea that the ipv6 data is being wrapped and carried by routers which don’t understand ipv6 since the wrapping and unwrapping of the data is done transparently at the handoff.
In the context of SMPTE ST 2110, a trunk allows one port to be used to create a single connection to the destination, yet carry many individual media streams within. This has the big benefit of simplifying the inter-site connectivity at the IT level, but importantly also means that the single connection is quite high bandwidth. When FEC is applied to a connection, the latency introduced increases as the bit rate reduces. Since ST 2110 carries audio and metadata separately, an FEC-protected stream would have variable latency depending on the type of the of traffic. Bundling them in to one large data stream allows FEC to be applied once and all traffic then suffers the same latency increase. The third reason is to ensure all essences take the same network path. If each connection was separate, it would be possible for some to be routed on a physically different route and therefore be subject to a different latency.
Entering the last part of the talk, Andy switches gears to talk about how site A can control streams in site B. The answer is that it doesn’t ‘control’, rather there is the concept of requesting streams. Site A will declare what is available and site B can state what it would like to connect to and when. In response, site A can accept and promise to have those sources available to the WAN interface at the right time. When the time is right, they are released over the WAN. This protects the WAN connectivity from being filled with media which isn’t actually being used. These exchanges are mediated and carried out with NMOS IS-04 an IS-05.
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 the 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.
IPMX promises a ‘plug and play’ out-of-the-box experience, but with uncompressed SMPTE ST 2110 video and audio underneath. Given many tier 1 broadcasters have invested months or years implementing ST 2110. So how can IPMX deliver on its promise to the Pro-AV market?
Andrew Starks from Macnica presents this talk explaining how NMOS will fit into IPMX. Key to enabling a minimal config environment is the added mandatory specifications and standards within IPMX. For instance, while you can build an ST 2110 system without NMOS, that’s not an option for IPMX. The focus is on consistency and interoperability. Optional parts of IPMX cover HDCP carriage, USB, RS232 and IPV6. Many of the things often used within Pro-AV but may not be appropriate for low-cost, small use-cases.
Andrew gives an overview of IS-04 and IS-05 which allow for discovery and control of devices. He then looks at EDID and USB carriage and finishes by discussing why AMWA is choosing to use open specifications rather than creating standards.
Director of Product Management,
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