Video

Video: SRT Protocol Overview

Posted on by Russell Trafford-Jones

SRT’s ability to make lossy networks seem like perfect video circuits is increasingly well known, testified to by the SRT Alliance having just surpassed 400 member companies. But this isn’t your average ‘overview’, it dispenses with the technology introductions and goes straight into the detail so is ideal for people who already know the basics and want some deeper knowledge plus a look at the new features to come.

For those wanting an introduction, this article What is SRT? is a good starter which also links to two other intro videos. But today we’re going to join Haivision’s Maxim Sharabayko to look below the surface of SRT.

Maxim starts by introducing the open-source Git repository and the open-source integrations available before heading into the feature matrix. This shows what is and isn’t in SRT. We see that on top of ARQ, it has FEC, encryption, stream multiplexing and, soon, connection bonding. Addressing the major feature areas one by one, we start with connectivity.

SRT has two modes to establish a connection which Maixm shows on handshake diagrams. We can see that establishment need only take 2x round trips so is quick to establish. This allows Maxim to show how firewall traversal is accomplished, though NAT traversal is not yet implemented.

Next on the list of topics is access control whereby we need to ensure that only authorised users can gain access. This is achieved using the Stream ID field within SRT control packets which can contain up to 512 characters meaning it can be used to transfer usernames, passwords (in the form of keys) and requests. Maxim then explains the AES PSK encryption function and discusses the potential implementation of TLS and DTLS.

Content delivery is next under the magnifying glass starting with the structure of SRT packets and the difference between the two types: Data and Control, the former being restricted to only containing payload or FEC data. Maxim covers the positive acknowledgement which is contained with SRT with the range of received packets being acknowledged every 10ms and, where 64 packets come in less than 10ms, a low-overhead acknowledgement being sent for each group of 64 data packets. But of course, it’s the NAK packets which are the most important part of the protocol. Maxim explains they are able to send back one sequence number or a range of lost packets and talks about when they are sent. We see how this then fits into the Timestamp Based Packet Delivery (TSBPD) mechanism which itself is a feature of SRT which delivers packets to the receiver with the same timing as they arrived at the sender. The last thing we look at in the section is a worked example of Too-Late Packet Drop which explains when and why packets are dropped.

ARQ isn’t the only recovery mechanism in SRT, it also provides FEC and, soon, channel bonding. FEC’s can be useful but do have downsides which should be understood. There is a permanent bandwidth overhead, even when the circuit is working well, and a further latency is needed in order to generate the necessary recovery packets. Bonding allows you to stream the same stream over more than one circuit and use data from circuit B to fill in any gaps in circuit A, this technique is used in SMPTE ST 2022-7. Connection bonding, though, can also be used with multiple connections at once and having dynamic balancing across them. Maxim sums up the pros and cons of the different techniques in the table below.

Pros and cons of different packet recovery techniques. Source: Haivision

The talk finishes with a look at stream multiplexing, congestion control and ways in which you can use the SRT statistics which are constantly updated to manage your connectivity.

Watch now!
Speakers

Maxim Sharabayko Maxim Sharabayko
Senior Software Developer,
Havision

Video: RIST: What is the Future?

Posted on by Russell Trafford-Jones

Many see RIST as a new kid on the block, but they’ve worked quickly since their formation 3 years ago, having produced two specifications and now working on the third. RIST makes sending video over the internet reliable as it corrects for missing data. The protocol which, aims at multi-vendor interoperability, continues to gather interest with the RIST Forum now having over 80 companies.

“What does RIST do today” and “what’s next?” are the two questions Rick Ackermans, Chair of the RIST activity group at the VSF, is here to answer. Firstly, then, Rick looks at the documents already published, TR-06-1 and TR-06-2. Also known as the simple profile TR-06-01 has already received an update to allow for continuous measurement of the round trip time (RTT) of the link. Rick makes it clear that these are living specifications and the VSF won’t shy away from updating them when it helps keep the protocol relevant and responsive to the industry. TR-06-2 is the main profile which was released last year.

The simple and main profiles are summarised in this article and by Rick in the video. The simple profile provides a sender or receiver which can speak plain RTP and also run with high-performance packet recovery and seamless switching.

Main Profile brings in encryption and a powerful tool, GRE. As we wrote about last week, the idea of a tunnel is to hide complexity from the network infrastructure. Tunnelling allows for bidirectional data flow under one connection which is transparent to the network carrying the tunnel and to the endpoints. This enables a lot of flexibility. Not only does it allow for the connection to be set up in either direction, to suit whichever is easiest for firewall reasons, but it also allows generic data to be sent meaning you could send PTZ camera control data along with the video and audio.

But the highlight of this presentation is looking to the future and hearing about the advanced profile which is still in progress. Planned, though not promised, are features such as auto-configuration where a receiver works out many of the parameters of the link itself and dynamic reconfiguration where the sender and receiver respond to changing conditions of the link/network. Also in the works is a hybrid operation mode for satellites allowing and an internet connection to be used in addition to the satellite feed to receive and deliver re-requests.

Watch now!
Speakers

Rick Ackermans Rick Ackermans
Rist Activity Group Chair
Director of RF & Transmissions Engineering, CBS
Wes Simpson Wes Simpson
Co-Chair, RIST Activity Group,
Owner, LearnIPVideo.com

Video: What is esports? A crash course in modern esports broadcast

Posted on by Russell Trafford-Jones

With an estimated global revenue of over USD1.1 billion1 and a global audience of almost half a billion people2, esports is a big industry and all accounts report it as growing. Although it sounds different, when you look behind the scenes, there’s actually lot of equipment and production that a broadcaster would recognise, as we showed in this behind the scenes footage that we featured in a previous article

Press play below as a taster before the main video to be a fly on the wall for five minutes as the tension mounts at this esports event final.

https://www.youtube.com/watch?v=A486rxl7HYc&t=14m17s

In this today’s talk from the Royal Television Society, Thames Valley, we’re introduced to esports from the bottom up: What it is, who does it and which companies are involved. I think esports is special in its ability to capture the interest of the broadcast industry, but exactly what it is and how it’s structured…few actually know. That’s all changing here, with Steven “Claw” Jalicy from ESL.

Steven explains that ESL is the largest company that runs tournaments and competitions outside of the games publishers. He explains that, unlike sports such as tennis, athletics and football which don’t have ‘owners’, all esports games have publishers who are able to control the way that gaming happens and have the ability to run tournaments themselves or, in effect, franchise this out around the world.

 
Steven takes us through the broadcast chain. Usually held in a stadium, OB kit and temporary set ups are nothing new to to the broadcast sports community. The first thing which is a change however, is ‘in-game’. There’s a lot more to covering esports than tennis in as much as for a tennis match you can turn up with some cameras and ball tracking kit and televise the games. Whilst doing it well is by no means trivial, with esports there are many more levels due to the fact that we have human players who are playing computer characters; to experience both the real and the in-game drama you need camera angles both in the real world and within the game. These in-game camera operators are call observers and just like real-life camera operators, their task is to capture all the action of the game. Sometimes this is done by following the players, sometimes by a birds-eye-view camera, depending on the game and, as ever, the publisher.

Naturally when you have a peak viewership of over a million people, streaming and live content distribution is really important. ESPN and, more recently, Eurosport have been airing esports so it’s important to realise that linear distribution is very much part of the mix for esports, it’s not an on-line only thing, though most of the numbers shared are the verified streaming numbers.

Steven talks about some of the challenges ESL faces in delivering the highest quality streams with so many tournaments happening and then moving to remote operation.

ESL prefers to build their own hardware for several reasons that Steven explains which include having the result fully-customisable and simplifying replacements. Similarly, ffmpeg and other open-source encoding is favoured for similar reasons.

The discussion finishes off with an extensive Q&A session including the ‘sanctity’ of the players’ equipment, the threshold for choosing to use vendor equipment (EVS vs Mediakind), transport over the internet and much more.

Watch now!
1Statista revenue report
2Statista eSports audience report
Speakers

Steven Jalicy Steven “Claw” Jalicy
Global Head of Streaming,
ESL Gaming

Video: Reopening Film and TV Production in NYC

Posted on by Russell Trafford-Jones


Restarting productions and stepping up MCR staffing could be the difference between life and death if you get it wrong. What are the right precautions to take, what’s proportionate and can you get your staff and freelancers to follow the rules?

This SMPTE panel looks at the recommendations and rules generated by the bustling TV, film and advertising industry in New York. The cornerstone of the session is an overview of the guidelines called The Safe Way Forward which is a collaborative document being put together with negotiation with the unions to ensure there’s a widely agreed and understood rules to run safe productions with.

The Safe Way Forward is based on regular testing and zoning productions. Talent and crew which work closely with them such as sound, make-up, etc. are considered zone A. Often there are times when close contact and/or PPE are not practical so anyone who works in zone A is tested 3 times a week or more to catch any infection quickly. Other crew are considered in zone B and cannot come on set or in designated zone A locations. Zone B staff are tested once a week or more. Zone C is considered anyone else and/or outside of the studio.

The panel agrees that testing is a really important part of the safe working strategy using the example of the Miami Marlins who had 16 members of their team infected. Regular, thorough testing would have caught this earlier and helped reduce the impact of the initial infectious person.

Matt Miller makes the counterpoint that from the perspective of commercials production, testing just doesn’t cut it when your whole shoot is only a day and a half long. For the Association of Independent Commercial Producers, creating a safe environment is the focus of their guidelines which is already on its 5th edition. There are no ‘either/or’s, it’s about PPE and social distancing and</em frequent hand washing etc. Matt says it’s been very effective in maintaining this safety.

Short-term jobs are a source of concern for the panel when it comes to extras who may book themselves in for several different jobs over a week. How do we stop them from spreading the virus from production to production? The idea of a testing passport is under discussions, but this problem has not yet been resolved. It’s certainly possible that scripts will be altered to reduce extras, particularly if they have to be paid to come in ahead of their work to take a test.

Efficiencies are also a topic of discussion. Certainly one benefit of working at home is the ability to remotely collaborate without commuting/travelling and, depending on the type of work can be very effective. On the set, the panel anticipates an increased desire for monitoring. People in Zone B who are used to being on set will want to be able to see what’s happening which will drive increased demand on the network and electrical distribution. But with this more distributed monitoring, there may be more effective ways for people to work. Time will tell how much this will have an effect and where the balance is. Never will the DIT role be more important.

Watch now!
Speakers

Dejan Georgevich Dejan Georgevich
National vice President,
IATSE
Andy Shipsides Andy Shipsides
Presient – North America,
ARRI Rental
Peter Abel Peter Abel
CEO & Co-Founder,
Abel CineTech
Alan Suna Alan Suna
CEO,
Silvercup Studios
Matt Miller Matt Miller
Presient & CEO,
AICP
Mary Rae Thewlis Mary Rae Thewlis
National Vice President,
DGA
Joseph Reidy Joseph Reidy
1st vice Chair, Easter AD/UPM Council
Co-chair, 1st AD Committee, DGA