Video: IP Fundamentals For Broadcast Seminar IV

“When networking gets real”, perhaps, could have been the title of this last of 4 talks about IP for broadcast. This session wraps up a number of topics from the classic ‘TCP Vs. UDP’ discussion to IPv6 and examines the switches and networks that make up a network as well as the architecture options. Not only that, but we also look at VPNs and firewalls finishing by discussing some aspects of network security. When viewed with the previous three talks, this discusses many of the nuances from the topics already covered bringing in the relevance of ‘real world’ situations.

Wayne Pecena, President of SBE, starts by discussing subnets and collision domains. The issue with any NIC (Network Interface Controller) is that it’s not to know when someone else is talking on the wire (i.e. when another NIC is sending a message by changing the voltage of the wire). It’s important that NICs detect when other NICs are sending messages and seek to avoid sending while this is happening. If this does’t work out well, then two messages on the same wire are seen as a ‘collision’. It’s no surprise that collisions are to be avoided which is the starting point of Wayne’s discussion.

Moving from Layer 2 to Layer 4, Wayne pits TCP against UDP looking at the pros and cons of each protocol. Whilst this is no secret, as part of the previous talks this is just what’s needed to round the topic off ahead of talking about network architecture.

“Building and Securing a Segmented IP Network Infrastructure” is the title of the next talk which starts to deal with real-world problems when an engineer gets back from a training session and starts to actually specify a network herself. How should the routers and switches be interconnected to deliver the functionality required by the business and, as we shall see, which routers/switches are actually needed? Wayne discusses some of the considerations of purchasing switches (layer 2) and routers (layer 3 & 2) including the differing terms used by HP and Cisco before talking about how to assign IP addresses, also called an IP space. Wayne takes us through IP addressing plans, examples of what they would look like in excel along with a lot of the real-world thinking behind it.

Security is next on the list, not just in terms of ‘cybersecurity’ in the general sense but in terms of best practice, firewalls and VPNs. Wayne takes a good segment of time out to discus the different aspects of firewalls – how they work, ACLs (Access-control Lists), and port security amongst other topics before doing the same for VPNs (Virtual Private Networks) before making the point that a VPN and a firewall are not the same. A VPN allows you to extend a network out from a building to be in another – the typical example being from your work’s address into your home. Whilst a VPN is secured so that only certain people can extend the network, a firewall more generally acts to prevent anything coming into a network.

As an addendum to this talk, Wayne explains IPV4 depletion and how IPv6 addressing works. In practice, for broadcasters deploying within their company in the year 2020, IPv6 is unlikely to be a topic needed. However, for people who are distributing to homes and working closer with CDNs and ISPs, there is a chance that this information is more relevant on a day-to-day basis. Whilst IP address depletion is a real thing, since every company has a 10.x.x.x address space to play with, most companies use internal equipment with an IPv4 address plan.
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Wayne Pecena Wayne Pecena
Director of Engineering, KAMU TV/FM at Texas A&M University
President, Society of Broadcast Engineers AKA SBE

Video: RIST – an evolutionary video transport protocol

Delivering low-latency live-video over the public internet, or any network which sees packet loss is ever a challenge, but recently there have been a number of protocols which have been created to allow this to work.

The problem to be fixed is that packets get lost and when you have a video decoder trying to output 50 images every second, there really isn’t time to deal with missing packets. Protocols such as SRT, Zixi and, now, RIST allow a mechanism which adds a small buffer and a mechanism to request missing data.

This isn’t a problem, in general, for live streaming to consumers on devices or computers such as Netflix or iPlayer because they use HLS or similar protocols based on TCP, but for low-latency streams this is not practical.

In this talk Kieran Kunhya explains more about these basics, the challenges to be overcome and the ways of dealing with them.

He covers:

  • UDP & TCP.
  • RIST and other similar protocols
  • Retransmissions
  • Negative Acknowledgements
  • Implementations of RIST
  • Future plans for RIST
  • A live demo

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Kieran Kunhya Kieran Kunhya
Open Broadcast Systems

Video: Uncompressed IP Video Basics

To the uninitiated, it’s not obvious how to send video over IP, what things are important to think about and how close it is to an analogue/SDI signal. Fortunately, Ed Calverly has this excellent tutorial on the basics needed to understand uncompressed video across the board.

This presentation from the IBC 2018 IP Showcase examines the need for timing, a reminder of what ‘blanking’ is and how this is treated in the over-IP world. Discussion of blanking wouldn’t be complete without a discussion of ancillary data (VANC, HANC, DPI, Embedded audio etc.) Whilst blanking was essential in analogue video and is filled with data in SDI, there is a benefit in breaking the signal up into its component parts: video, audio and ancillary data – not least removing upto 30% of dead space; blanking takes bitrate!

Now that Ed’s established the key points of the video which need to be transported, how and where they exist, it’s time to look at how to actually get the data on the network. To do this Ed presents a very accessible explanation of IP discussing how we can split up any message into packets and how we add headers to the packets to ensure they go to the right place. This leads on to a discussion of UDP and TCP, both ways of launching traffic onto a network but with their own pros and cons.

This builds into an examination of subnets, routing and multicast. Whilst these sound fairly academic – and to be clear they can be – they are also essential to a well-founded understanding of the topic and are useful day-to-day when working with SMPTE ST 2110 and SMPTE ST 2022-6 systems. Both of these terms are also explained by Ed along with and comparison of SDI timing (usually black and burst, or tri-Level sync) and PTP timing which is used for IP systems. For more detail on PTP, have a look at this talk, or this one also from the IP Showcase

Wrapping up by talking about the important topic of packet timing called ‘traffic shaping’, we see how important it is to ensure that each packet is equally spaced to avoid problems with buffers on receiving equipment or even within the network itself.

Ed’s presentation style and animated slides work excellently together to make this talk very understandable to people coming in fresh to IP systems and, many of us should be willing to admit, a great reminder of the key basics for those who are already on the path. The slides are downloadable and annotated with extra information so they stand on their own as a reference. The only thing missing from the downloaded slides is Ed’s final video demonstrating traffic shaping in the form of planes land at Heathrow.

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Ed Calverly
Ed Calverly
Professional Trainer for the Broadcast Industry,

Video: Next Generation Sports Broadcast Workflows that Expand the Value of Live Production

In this webinar, learn what challenges there are in today’s production and how EVS has teamed up with Aspera at major international sporting events to build Cloud-based production workflows that connect live content with production teams, accredited teams and final viewers. Also discussed is how next generation sports broadcasting workflows are transforming the digital media supply chain.


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