Video: Decentralised Production Tips and Best Practices

Live sports production has seen a massive change during COVID. We looked at how this changed at the MCR recently on The Broadcast Knowledge hearing how Sky Sports had radically changed along with Arsenal TV. This time we look to see how life in the truck has changed. The headline being that most people are staying at home, so how to you keep people at home and mix a multi-camera event?

Ken Kerschbaumer from Sports Video Group talks to VidOvation Jim Jachetta
and James Japhet from Hawk-Eye to understand the role they’ve been playing in bringing live sports to screen where the REMI/Outside Broadcast has been pared down to the minimum and most staff are at home. The conversation starts with the backdrop of The Players Championship, part of the PGA Tour which was produced by 28 operators in the UK who mixes 120+ camera angles and the audio to produce 25 live streams including graphics for broadcasters around the world.

Lip-sync and genlock aren’t optional when it comes to live sports. Jim explains that his equipment can do up to fifty cameras with genlock synchronisation over bonded cellular and this is how The Players worked with a bonded cellular on each camera. Jim discusses how audio, also has to be frame-accurate as they had many, many mics always open going back to the sound mixer at home.

James from Hawk-Eye explained that part of their decision to leave equipment on-site was due to lip-sync concerns. Their system worked differently to VidOvation, allowing people to ‘remote desktop’, using a Hawk-Eye-specifc low-latency technology dedicated to video transport. This also works well for events where there isn’t enough connectivity to support streaming of 10, 20 or 50+ feeds to different locations from the location.

The production has to change to take account of two factors: the chance a camera’s connectivity might go down and latency. It’s important to plan shots ahead of time to account for these factors, outlining what the backup plan is, say going to a wide shot on camera 3, if camera 1 can’t be used. When working with bonded cellular, latency is an unavoidable factor and can be as high as 3 seconds. In this scenario, Jim explains it’s important to explain to the camera operators what you’re looking for in a shot and let them work more autonomously than you might traditionally do.

Latency is also very noticeable for the camera shaders who usually rack cameras with milliseconds of latency. CCU’s are not used to waiting a long time for responses, so a lot of faked messages need to be sent to keep the CCU and controller happy. The shader operator needs to then get used to the latency, which won’t be as high as the video latency and take things a little slower in order to get the job done.

Not travelling everywhere has been received fairly well by freelancers who can now book in more jobs and don’t need to suffer reduced pay for travel days. There are still people travelling to site, Jim says, but usually, people who can drive and then will sit in the control room with shields. For the PGA Tour, the savings are racking up. Whilst there are a lot of other costs/losses at the moment for so many industries, it’s clear that the reduced travel and hosting will continue to be beneficial after restrictions are lifted.

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Speakers

Jim Jachetta Jim Jachetta
EVP & CTO: Wireless Video & Cellular Uplinks
VidOvation
James Japhet James Japhet
Managing Director
Hawk-Eye North America
Ken Kerschbaumer Ken Kerschbaumer
Editorial Director,
Sports Video Group

Video: What is HESP Ultra-Low-Latency Streaming?

Is it possible to improve on CMAF’s offer of an ultra-low-latency, scalable protocol with good viewer experience? This is what HESP, the High-Efficiency Streaming Protocol, promises. With almost instant channel change times and sub-second latency, it’s worth taking a look at those protocol created by THEOPlayer to understand where it might work in your workflows.

Presented by Pieter-Jan Speelmans and Johan Vounckx from THEO, we hear some more detail surrounding HESP’s inception. Quality, latency and bitrate are often referred to as a triangle where if you improve one or even two, the remaining factor will get worse to compensate. HESP plays in the triangle connecting ‘viewer experience’, ‘low latency’ and ‘scalability’. If you compare WebRTC with CMAF, you see that WebRTC prioritises low-latency streaming but suffers in terms of scalability. CMAF, being 2-5 seconds higher latency, has much better scalability but the channel zapping times are high which affects viewer experience as well as overall latency. HESP, contests Pieter-Jan, actually improves all three. It’s able to do this because it’s not extending existing protocols which weren’t designed to meet all these requirements, rather it’s bringing in new techniques which shift the whole equation.

THEOPlayer has created the HESP Alliance which is devoted to standardising the HESP technology through the IETF or other avenue, promoting adoption through marketing and the creation of tools, certification and management of intellectual property. The talk outlines the decoder royalties which can be payable by subscriber, per subscriber per hour, or per device.

Source: THEOPlayer

Looking at the technical details, we find out that you can actually start playing an HESP stream without downloading the manifest. While HESP does have manifest files, they change very infrequently. If a new one is changed at short notice, the server can ask players to download one by embedding a message in the stream. The channel zapping speed is achieved using two streams, an initialisation stream and a continuation stream. The initialisation stream just I and P frames allowing you to start playing immediately. The continuation stream is intended to be the low-bitrate stream used after the establishment of the stream.

HESP uses two modes: Maximal Gain and Maximal Compatability. Maximal gain aims to have the lowest latency, lowest bandwidth and lowest zapping times. It has long segments with 1 frame chunks containing one I or P frame. The Maximal Compatability mode, however, allows you to reuse Low-Latency DASH and LLHLS streams and uses 6-second segments with 200msec chunks including B frames.

THEOPlayer claim 7x less delivery delay, 20x lower zapping times and a 20% bandwidth saving over CMAF with broad compatibility with many TVs, android, iOS, Web, streaming devices.

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Speakers

Pieter-Jan Speelmans Pieter-Jan Speelmans
CTO & Founder,
THEOPlayer
Johan Vounckx Johan Vounckx
Vice President, Innovation,
THEOPlayer

Video:Measuring Video Quality with VMAF – Why You Should Care

VMAF, from Netflix, has become a popular tool for evaluating video quality since its launch as an Open Source project in 2017. Coming out of research from the University of Southern California and The University of Texas at Austin, it’s seen as one of the leading ways to automate video assessment.

Netflix’s Christos Bampis gives us a brief overview of VMAF’s origins and its aims. VMAF came about because other metrics such as MS-SSIM and, in particular, PSNR aren’t close enough indicators of quality. Indeed, Christos shows that when it comes to animated content (i.e. anime and cartoons) subjective scores can be very high, but if we look at the PSNR score it can be the same as the PSNR of score another live-action video clip which humans rate a lot lower, subjectively. Moreover, in less extreme examples, Christos explains. PSNR is often 5% or so away from the actual subjective score in either direction.

To a simple approximation, VMAF is a method of bringing out the spatial and temporal information from a video frame in a way which emphasises the types of things humans are attuned to such as contrast masking. Christos shows an example of a picture where artefacts in the trees are much harder to see than similar artefacts on a colour gradient such as a sky or still water. These extraction methods take account of situations like this and are then fed into a trained model which matches the results of the model with the numbers that humans would have given it. The idea being that when trained on many examples, it can correctly predict a human’s score given a set of data extracted from a picture. Christos shows examples of how well VMAF out-performs PSNR in gauging video quality.

 

Challenges are in focus in the second half of the talk. What are the things which still need working on to improve VMAF? Christos zooms in on two: design dimensionality and noise. By design dimensionality, he means how can VMAF be extended to be more general, delivering a number which has a consistent meaning in different scenarios? As the VMAF model has been trained on AVC, how can we deal with different artefacts which are seen with different codecs? Do we need a new model for HDR content instead of SDR and how should viewing conditions, whether ambient light or resolution and size of the display device, be brought into the metric? The second challenge Christos highlights is noise as he reveals VMAF tends to give lower scores than it should to noisy sources. Codecs like AV1 have film-grain synthesis tools and these need to be evaluated, so behaving correctly in the presence of video noise is important.

The talk finishes with Christos outlining that VMAF’s applicability to the industry is only increasing with new codecs coming out such as LCEVC, VCC, AV1 and more – such diversity in the codec ecosystem wasn’t an obvious prediction in 2014 when the initial research work was started. Christos underlines the fact that VMAF is a continually evolving metric which is Open Source and open to contributions. The Q&A covers failure cases, super-resolution and how to interpret close-call results which are only 1% different.

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Download the presentation
Speaker

Christos Bampis Christos Bampis
Senior Software Engineer,
Netflix

Video: Case Study: Dropbox HQ ST 2110

Dropbox is embedded in many production workflows – official and otherwise – so it’s a beautiful symmetry that they’re using Broadcast’s latest technology, SMPTE ST 2110, within their own headquarters. Dropbox have AV throughout their building and a desire to create professional video from anywhere. This desire was a driving factor in an IP-based production facility as, to allow mobile production platforms to move from room to room with only a single cable needed to connect to the wall and into the production infrastructure.

David Carroll’s integration company delivered this project and joins Wes Simpson to discuss this case-study with colleague Kevin Gross. David explains that they delivered fibre to seventy locations throughout the building making most places into potential production locations.

Being an IT company at heart, the ST 2110 network was built to perform in the traditional way, but with connections into the corporate network which many broadcasters wouldn’t allow. ST 2110 works best with two separate networks, often called Red and Blue, both delivering the same video. This uses ST 2022-7 to seamlessly failover if one network loses a packet or even if it stops working all together. This is the technique used with dropbox, although there these networks are connected together so are not one hundred per cent isolated. This link, however, has the benefit of allowing PTP traffic between the two networks.

PTP topology typically sees two grandmasters in the facility. It makes sense to connect one to the red network, the other to the blue. In order to have proper redundancy, though, there should really be a path from both grandmasters to both networks. This is usually done with a specially-configured ‘PTP only’ link between the two. In this case, there are other reasons for a wider link between networks which also serves as the PTP link. Another element of PTP topology is acknowledging the need for two PTP domains. A PTP domain allows two PTP systems to operate on the same network but without interfering with one another. Dante requires PTP version 1 whereas 2110, and most other things, require v2. Although this is in the process of improving, the typical way to solve this now is to run the two separately and block v1 from areas of the network in which it’s not needed.

PTP disruptions can also happen with multicast packet loss. If packets are lost at the wrong time, a grandmaster election can happen. Finally, on PTP, they also saw the benefits of using boundary clock switches to isolate the grandmasters. These grandmasters have to send out the time eight times a second. Each end-device then replies to ascertain the propagation delay. Dealing with every single device can overwhelm grandmasters, so boundary clock switches can be very helpful. On a four-core Arista, David and Kevin found that one core would be used dealing with the PTP requests.

A more extensive write-up of the project can be found here from David Carroll

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Speakers

Kevin Gross Kevin Gross
Media Network Consultant
AVA Networks
David Carroll David Carroll
President,
David Carroll Associates, Inc.
Wes Simpson Wes Simpson
Owner, LearnIPVideo.com