PTP is an underlying technology enabling the whole SMPTE 2110 uncompressed ecosystem to work. Using PTP, the Precision Time Protocol, the time a frame of video, audio etc. was captured is recorded and so when decoded can be synchronised with other media recorded around that same time. Though parts of 2110 can function without it, when it comes to bringing media together which need synchronisation, vision mixing for instance, PTP is the way to go.
PTP is actually a standard for time distribution which, like its forerunner NTP, was developed by the IEEE and is a cross-industry standard. Now on version IEEE-1588-2019, it defines not only how to send time onto a network, but also how a receiver can work out what the time actually is. Afterall, if you had a letter in the post telling you the time, you’d know that time – and date for that matter – was old. PTP defines a way of working out how long the letter took to arrive so that you can know the date and time based on the letter and you new-found knowledge of the delivery time.
Knowing the time of day is all very well, but to truly synchronise media, SMPTE ST 2059 is used to interpret PTP for professional media. Video and audio are made from repeating data structures. 2059 relates these repeating data structures back to a common time in the past so that at any time in the future, you can calculate the phase of the signal.
Karl Khun from Tektronix starts by laying out the problems to be solved, such as managing jitter and the precision needed. This leads in into a look at how timestamps are used to make a note of when, separately, video and audio were captured. The network needed to implement PTP, particularly for redundancy and the ability of GPS allowing buildings to be co-timed without being connected.
Troubleshooting PTP will be tricky for many, but learning the IT side of this is only part of the solution. Karl looks at some best practices and tips on faultfinding PPT errors which leads on to a discussion of PTP domains and profiles. An important aspect of PTP is that it is bi-directional. Not only that but it’s much more than a distribution of a signal like the previous black and burst infrastructure. It is a system which needs to be managed and deserves to be monitored. Karl shows how graphs can help show the stability of the network and how RTP/CC errors can show network packet losses/corruptions.
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.
The MPEG-5: Essential Video Codec (EVC) promises to do what no MPEG standard has done before, deliver great improvements in compression and give assurances over patents. With a novel standardisation process, EVC provides a royalty-free base layer plus licensing details are provided upfront.
SMPTE 2019 saw Jonatan Samuelson take us through the details. Founder of Divideon and an editor of the evolving standard. Jonatan starts by explaining the codec landscape in terms of the new and recent codecs coming online showing how EVC differs including from it’s sister codec, VVC in parallel with which EVC is being developed.
Jonatan explains how the patents are being dealt with, comparing to HEVC, he shows that there is a much more simplified range of patent holders. But importantly, the codec has very granular tools to turn on and off separate tools so that you can exclude any that you don’t wish to use for licensing reasons. This is the first time this level of control has been possible. Along with the royalty-free base layer, this codec hopes to provide companies the control they need in order to safely use the codec with predictable costs and without legal challenges.
Target applications for EVC are realtime encoding, video conferencing but also newer ’emerging’ video formats such as 8K with HDR & WCG. To do this, Jonatan explains the different blocks that create the codec itself ahead of walking us through the results.
Networking is increasingly important throughout the broadcast chain. This webcast picks out the fundamentals that underpin SMPTE ST 2110 and that help deliver video streaming services. We’ll piece them together and explain how they work, leaving you with more confidence in talking about and working with technologies such as multicast video and HTTP Live Streaming (HLS).