Adoption of SMPTE’s 2110 suite if standards for transport of professional media is increasing with broadcasters increasingly choosing it for use within their broadcast facility. Andy Rayner takes the stage at SMPTE 2019 to discuss the work being undertaken to manage using ST 2110 between facilities. In order to do this, he looks at how to manage the data out of the facility, the potential use of JPEG-XS, timing and control.
Long established practices of using path protection and FEC are already catered for with ST 2022-7 for seamless path protection and ST 2022-5. New to 2110 is the ability to send the separate essences bundled together in a virtual trunk. This has the benefit of avoiding streams being split up during transport and hence potentially suffering different delays. It also helps with FEC efficiency and allows transport of other types of traffic.
Timing is key for ST 2110 which is why it natively uses Precision Timing Protocol, PTP which has been formalised for use in broadcast under ST 2059. Andy highlights the problem of reconciling timing at the far end but also the ‘missed opportunity’ that the timing will usually get regenerated therefore the time of media ingest is lost. This may change over the next year.
The creation of ST 2110-22 includes, for the first time, compressed media into ST 2110. Andy mentions that JPEG XS can be used – and is already being deployed. Control is the next topic with Andy focussing on the secure sharing of NMOS IS-04 & 05 between facilities covering registration, control and the security needed.
The talk ends with questions on FEC Latency, RIST and potential downsides of GRE trunking.
RIST solves a problem by transforming unmanaged networks into reliable paths for video contribution in an interoperable way. RIST not only improves reliability through re-requesting missing packets, but also comes with a range of features and tools, not least of which is tunnelling. Cobalt Digital’s EVP of engineering, Ciro Noronha explains how the protocol works and what’s next on the roadmap.
Ciro starts with a look at the RIST Simple Profile covering the ARQ negative acknowledgement (NACK) mechanism, link bonding and seamless switching. He then moves on to examine the missing features such as content encryption, authentication, simpler firewall configurations, in-band control, high bitrates, NULL packet extraction. These features define RIST’s Main Profile.
Tunnelling and Multiplexing is a technique to combine Simple Profile flows into a bi-directional tunnel, providing simpler network and encryption configuration. Using a GRE (RFC 8086) tunnel, RIST provides a full, protocol agnostic tunnel and a UDP-only reduced overheard mode which only requires 0.6% data overhead to implement. Ciro explains a number of setups, including one where the connection is initiated by the receiver – something that the Simple Profile doesn’t allow.
Authentication and Encryption are covered next. DTLS us the UDP implementation of TLS which is the security mechanism used on secure websites. This provides security to the tunnel so everything which travels through is covered. Ciro explains the pre-shared key (PSK) mechanism in the Main Profile.
The talk finishes by covering NULL Packet removal, also known as ‘bandwidth optimisation’, header extension which extends RTP’s sequence number to allow for more in-flight packets and questions from the audience.
Is SMPTE ST 2110 suitable for inter-site connectivity over the WAN? As ST 2110 continues to mature and the first facilities are going live bringing 2110 into daily use, 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 presents the work the VSF is doing to recommend transport of ST 2110 over WAN outlining where they have got to and what has been recommended to date.
The talk starts with SMPTE 2022-7 seamless protection which is recommended for dealing with path breaks. For compensating for transmission errors, FEC is recommended and Andy explains the parameters needed.
Key to the inter-site transport is trunking whereby the individual essences are mixed down to one flow. This has a number of advantages: Reducing the number of flows makes life simpler for service providers, all essences will now share the same signal path from site to site and it FEC protection can be more efficiently applied.
The trunks are made using GRE – Generic Routing Encapsulation – which is a pre-existing IT standard for grouping lots of traffic into a single tunnel whilst preserving the data inside. This then appears at the other end of the trunk with the same IP information as if nothing had happened. Andy looks at the extra encapsulation headers needed to make this work and goes on to discuss payload lengths as we need to keep them short so as not to result in fragmented packets.
Timing, as ever, is important meaning that the recommendation is to align all essences before sending them in to the trunk, though Andy looks at alternatives. Also of key concern is compression as there will be times when uncompressed video is simply too high a bandwidth to be carried on the WAN. JPEG 2000 and, now, JPEG XS are available for this task.
Andy covers timing, discovery, control, security and conversion to and from 2022-6 before finishing the talk by taking questions.
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