Video: Keeping Time with PTP

The audio world has been using PTP for years, but now there is renewed interest thanks to its inclusion in SMPTE ST 2110. Replacing the black and burst timing signal (and for those that used it, TLS), PTP changes the way we distribute time. B&B was a waterfall distribution, PTP is a bi-directional conversation which, as a system, needs to be monitored and should be actively maintained.

Michael Waidson from Telestream (who now own Tektronix) brings us the foundational basics of PTP as well as tips and tricks to troubleshoot your PTP system. He starts by explaining. the types of messages which are exchanged between the clock and the device as well as why all these different messages are necessary. We see that we can set the frequency at which the announce, sync and follow-up messages. The sync and follow-up messages actually contain the time. When a device receives one of these messages, it needs to respond with a ‘delay request’ in order to work out how much of a delay there is between it and the grand master clock. This will result in it receiving a delay response. On top of these basic messages, there is a periodic management message which can contain further information such as daylight savings time or drop-frame information.

Michael moves on to looking at troubleshooting highlighting the four main numbers to check: The domain value, grandmaster ID, message rates and the communication mode. PTP is a global standard used in many industries. To make PTP most useful to the broadcast industry, SMPTE ST 2059 defines values to use for message repetition (4 per second for announce messages, 8 for sync, delay request and delay response). ST 2059 also defines how devices can determine the phase of any broadcast signal for any given time which is the fundamental link needed to ensure all devices keep synchronicity.

Another good tip from Michael is if you see the grandmaster MAC changing between the grandmasters on the system, this indicates it’s no receiving any announce messages so is initiating the Best Master Clock Algorithm (BMCA) and trying the next grandmaster. Some PTP monitoring equipment including from Meinberg and from Telestream can show the phase lag of the PTP timing as well as the delay between the primary and secondary grandmaster – the lower the better.

A talk on PTP can’t avoid mentioning boundary clocks and transparent switches. Boundary clocks take on much of the two-way traffic in PTP protecting the grandmasters from having to speak directly to all the, potentially, thousands of devices. Transparent switches, simply update the time announcements with the delay for the message to move through the switch. Whilst this is useful in keeping the timing accurate, it provides no protection for the grandmasters. He finishes video ends with a look at how to check ptp messages on the switch.

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Speakers

Michael Waidson Michael Waidson
Application Engineer
Telestream (formerly Tektronix)

Video: TV Sport Innovation – Staying Ahead of the Game

Sports has always led innovation in many areas of broadcast, but during COVID not only did they have to adapt nearly every workflow and redeploy staff, but they then had to brace to deliver 100 games in 40 days. Gordon Roxburgh sums it up: “I’ve been at Sky twenty years, and I think [these have] been the most challenging six months…we’ve faced.”

In this session from the DTG’s Future Vision 2020 conference, Carl Hibbert from Futuresource Consulting talks to Sky, Arsenal TV and Facebook to find how their businesses have adapted. Melissa Lawton from Facebook explains how their live streaming, both for user-generated footage and produced sport have adapted to the changing needs. When COVID hit, Facebook lost some very valuable content. Their response was to double down on fan engagement, with challenges to fans to create content and also staging events which were produced and commentated as real sports events, but all shots were people at home exercising but being brought into the narrative of an Iron Man competition. Facebook have also invested in their user-facing tools and dashboards to help expose and monitor contribution via live streaming.

Gordon Roxburgh from Sky explains the seachange he’s seen in production. “The first thing was to keep channels on air…and keep staff safe.” They moved rapidly from a fully staffed office to just three or four people on-site and a presenter. In order to mix, they created a Virtual Production suite which allowed people to create content in the cloud.

For content, Gordon says that watch-alongs proved very popular where key sports personalities talk through what they were thinking during key sporting moments. This was just one of the many content ideas that keep programming going until “Project restart” commenced where the whole sports ecosystem asked itself ‘How can we deliver 100 games in 40 days?’ Once they knew the season would start, Gordon says, this opened up a 3-week build period during which BT Media and Broadcast, NEP, NEP Connect and multiple internal departments collaborated to produce rapid turnarounds.

“As an industry, we came together.” The working practices developed at Sky were shared with other major broadcasters who also shared their best practice – always putting staff first. Sky even went to the extent of building a technical space in a large studio floor to keep people apart and co-opted a set of training rooms to become a self-contained graphics unit. These ideas kept graphics operators together but not mixing with the rest of the production.

The view from Arsenal TV is explained by John Dollin. They worked quickly very early on and were able to be back in the office from February. Whilst Arsenal TV doesn’t have the rights to stream live, they produce their programmes live for transmission later. This used to be done in a crowded room but was soon transferred to a virtual mixer in the cloud with remote editors. John highlights the challenge of involving freelancers into the system and providing them with appropriate supervision. More importantly, he feels that their current ability to maintain the pre-covid production quality is due to the continued dedication of certain personnel who are putting in long hours which is not a sustainable situation to be in.

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Speakers

Gordon Roxburgh Gordon Roxburgh
Technical Manager,
Sky Sports
Melissa Lawton Melissa Lawton
Live Sports Production Strategy,
Facebook
John Dollin John Dollin
Senior Product & Engineering Manager,
Arsenal Footballl Club
Carl Hibbert Carl Hibbert
Head of Consumer Media & Technology,
Futuresource Consulting

Video: Delivering Quality Video Over IP with RIST

RIST continues to gain traction as a way to deliver video reliably over the internet. Reliable Internet Stream Transport continues to find uses both as part of the on-air signal chain and to enable broadcast workflows by ensuring that any packet loss is mitigated before a decoder gets around to decoding the stream.

In this video, AWS Elemental’s David Griggs explains why AWS use RIST and how RIST works. Introduced by LearnIPvideo.com’s Will Simpson who is also the co-chair of the RIST Activity Group at the VSF. Wes starts off by explaining the difference between consumer and business use-cases for video streaming against broadcast workflows. Two of the pertinent differences being one-directional video and needing a fixed delay. David explains that one motivator of broadcasters looking to the internet is the need to replace C-Band satellite links.

RIST’s original goals were to deliver video reliably over the internet but to ensure interoperability between vendors which has been missing to date in the purest sense of the word. Along with this, RIST also aimed to have a low, deterministic latency which is vital to make most broadcast workflows practical. RIST was also designed to be agnostic to the carrier type being internet, satellite or cellular.

Wes outlines how important it is to compensate for packet loss showing that even for what might seem low packet loss situations, you’ll still observe a glitch on the audio or video every twenty minutes. But RIST is more than just a way of ensuring your video/audio arrives without gaps, it. can also support other control signals such as PTZ for cameras, intercom feeds, ad insertion such as SCTE 35, subtitling and timecode. This is one strength which makes RIST ideal for broadcast over using, say RTMP for delivering a live stream.

Wes covers the main and simple profile which are also explained in more detail in this video from SMPTE and this article. One way in which RIST is different from other technologies is GRE tunnelling which allows the carriage of any data type alongside RIST and also allows bundling of RIST streams down a single connecting. This provides a great amount of flexibility to support new workflows as they arise.

David closes the video by explaining why RIST is important to AWS. It allows for a single protocol to support media transfers to, from and within the AWS network. Also important, David explains, is RIST’s standards-based approach. RIST is created out of many standards and RFC with very little bespoke technology. Moreover, the RIST specification is being formally created by the VSF and many VSF specifications have gone on to be standardised by bodies such as SMPTE, ST 2110 being a good example. AWS offer RIST simple profile within MediaConnect with plans to implement the main profile in the near future.

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Speakers

David Griggs David Griggs
Senior Product Manager, Media Services,
AWS Elemental
Wes Simpson Wes Simpson
RIST AG Co-Chair,
President & Founder, LearnIPvideo.com

Video: IP Media Networks for Live Production

Building and controlling a network for SMPTE ST 2110 go hand in hand when it comes to planning an installation. As ST 2110 delivers all media essences separately, networks can easily end up carrying tens of thousands of flows emphasising the need for efficient network design and having a full understanding of the paths your media are using.

This video is co-presented by Nevion and Arista and starts by observing that the traditional difference between a LAN and WAN is being eroded leading as WANs get faster and better, we find that we can now deliver multi-location broadcast facilities which act similarly to if everything was co-located. Moreover, introduces Martin Walbum Media Function virtualisation which is enabled by network-connected equipment allowing for shared processing and shared control. For instance, it’s now possible to house all equipment in a datacentre and allow this to be used remotely maximising the utilisation of the equipment allowing a broadcaster to maximise the value of its purchases and minimise costs.

Arista’s Gerard Phillips takes a look at SDI systems to understand how we expect IP systems to behave and what we expect them to do. The system needs to deliver high throughput, instantaneous switching with low latency and no tolerance for failure. In order to do this, not only do we need to get the right software but to deliver the resilience we need, the network needs the correct architecture. Gerard takes us through the different options starting with a typical, flat, layer 2 networks and working up to leaf and spine along with a treatment of red, blue and purple networks.

Gerard recently did a deep dive on network design for live production for the IET. Take a look for much more detail on how to architect a network for uncompressed media.

Martin then looks at the need for orchestration. Broadcasters expect to deliver systems with, preferably, no downtime. As such, we’ve seen that network elements are typically duplicated as is the traffic which is delivered over two paths and SMPTE ST 2022-7. If you want to take something out of use for planned maintenance, it’s best to do that in a planned, ordered, way meaning you migrate flows away from it until it’s no longer in-circuit. Software-Defined Networks (SDNs), do exactly that. Martin walks us through the pros and cons of managing your network with IGMP and SDN. Gerard’s previous talk also looks at this in detail.

The video finishes with a look at which Arista switches can be used for media and a look at how Arista and Nevion implemented an ST 2110 network at Swiss broadcaster, tpc. This case study is presented in longer form in this video from the IP Showcase.

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Speakers

Gerard Phillips Gerard Phillips
Systems Engineer,
Arista
Martin Walbum Martin Walbum
Senior Vice President of Solution Strategy,
Nevion