How does NDI fit into the recent refocussing of interest in working remotely, operating broadcast workflows remotely and moving workflows into the cloud? Whilst SRT and RIST have ignited imaginations over how to reliably ingest content into the cloud, an MPEG AVC/HEVC workflow doesn’t make sense due to the latencies. NDI is a technology with light compression with latencies low enough to make cloud workflows feel almost immediate.
Vizrt’s Ted Spruill and Jorge Dighero join moderator Russell Trafford-Jones to explore how the challenges the pandemic have thrown up and the practical ways in which NDI can meet many of the needs of cloud workflows. We saw in the talk Where can SMPTE ST 2110 and NDI co-exist? how NDI is a tool to get things done, just like ST 2110 and that both have their place in a broadcast facility. This video takes that as read looks at the practical abilities of NDI both in and out of the cloud.
Taking the of a demo and then extensive Q&A, this talk covers latency, running NDI in the cloud, networking considerations such as layer 2 and layer 3 networks, ease of discovery and routing, contribution into the cloud, use of SRT and RIST, comparison with JPEG XS, speed of deployment and much more!.
How can large sports events keep an increasingly sophisticated audience entertained and fully engaged? The technology of sports coverage has pushed broadcasting forwards for many years and there’s no change. More than ever there is a convergence of technologies both at the event and delivering to the customers which is explored in this video.
First up is Michael Cole, a veteran of live sports coverage, now working for the PGA European Tour and Ryder Cup Europe. As the event organisers – who host 42 golfing events throughout the year – they are responsible for not just the coverage of the golf, but also a whole host of supporting services. Michael explains that they have to deliver live stats and scores to on-air, on-line and on-course screens, produce a whole TV service for the event-goers, deliver an event app and, of course run a TV compound.
One important aspect of golfing coverage is the sheer distances that video needs to cover. Formerly that was done primarily with microwave links and whilst RF still plays an important part of coverage with wireless cameras, the long distances are now done by fibre. However as this takes time to deploy each time and is hard to conceal in otherwise impeccably presented courses, 5G is seeing a lot of interest to validate its ability to cut rigging time and costs along with making the place look tidier in front of the spectators.
Michael also talks about the role of remote production. Many would see this an obvious way to go, but remote production has taken many years to slowly be adopted. Each broadcaster has different needs so getting the right level of technology available to meet everyone’s needs is still a work in progress. For the golfing events with tens of trucks, and cameras, Michael confirms that remote production and cloud is a clear way forward at the right time.
Next to talk is Remo Ziegler from VizRT who talks about how VizRT serves the live sports community. Looking more at the delivery aspect, they allow branding to be delivered to multiple platforms with different aspect ratios whilst maintaining a consistent look. Whilst branding is something that, when done well, isn’t noticed by viewers, more obvious examples are real-time, photo-realistic rendering for in-studio, 3D graphics. Remo talks next about ‘Augmented Reality’, AR, which can be utilised by placing moving 3D objects into a video making them move and look part of the picture as a way of annotating the footage to help explain what’s happening and to tell a story. This can be done in real time with camera tracking technology which takes into account the telemetry from the camera such as angle of tilt and zoom level to render the objects realistically.
The talk finishes with Chris explaining how viewing habits are changing. Whilst we all have a sense that the younger generation watch less live TV, Chris has the stats showing the change from people 66 years+ for whom ‘traditional content’ comprises 82% of their viewing down to 16-18 year olds who only watch 28%, the majority of the remainder being made up from SCOD and ‘YouTube etc.’.
Chris talks about the newer cameras which have improved coverage both by improving the technical ability of ‘lower tier’ productions but also for top-tier content, adding cameras in locations that would otherwise not have been possible. He then shows there is an increase in HDR-capable cameras being purchased which, even when not being used to broadcast HDR, are valued for their ability to capture the best image possible. Finally, Chris rounds back on Remote Production, explaining the motivations of the broadcasters such as reduced cost, improved work-life balance and more environmentally friendly coverage.
The video finishes with questions from the webinar audience.
Video compression is used everywhere we look. So often is it not practical to use uncompressed video, that everything in the consumer space video is delivered compressed so it pays to understand how this works, particularly if part of your job involves using video formats such as AVC, also known as H.264 or HEVC, AKA H.265.
Gisle Sælensminde from Vizrt takes us on this journey of creating compressed video. He starts by explaining why we need uncompressed video and then talks about containers such as MPEG-2 Transport Streams, mp4, MOV and others. He explains that the container’s job is partly to hold metadata such as the framerate, resolution and timestamps among a long list of other things.
Gisle takes some time to look at the past timeline of codecs in order to understand where we’re going from what went before. As many use the same principles, Gisle looks at the different type of frames inside most compressed formats – I, P and B frames which are used in set patterns known as GOPs – Group(s) of Pictures. A GOP defines how long is between I frames. In the talk we learn that I frames are required for a decoder to be able to tune in part way through a feed and still start seeing some pictures. This is because it’s the I frame which holds a whole picture rather than the other types o frame which don’t.
Colours are important, so Gisle looks at the way that colours are represented. Many people know about defining colours by looking at the values of Red, Green and Blue, but fewer about YUV. This is all covered in the talk so we know about conversion between the two types.
Almost synonymous with codecs such as HEVC and AVC are Macroblocks. This is the name given to the parts of the raster which have been spit up into squares, each of which will be analysed independently. We’ll look at who these macro blocks are used, but Gisle also spends some time looking to the future as both HEVC, VP9 and now AV1 use variable-size macro block analysis.
A process which happens throughout broadcast is chroma subsampling. This topic, whereby we keep more of the luminance channel than colours, is explored ahead of looking at DCTs – Discrete Cosine Transforms – which are foundational to most video codecs. We see that by analysing these macro blocks with DCTs. we can express the image in a different way and even cut down on some of the detail we get from DCTs in order to reduce the bitrate.
Before some very useful demos looking at the result of varying quantisation across a picture, the difference signal between the source and encoded picture plus deblocking technology to hide some of the artefacts which can arise from DCT-based codecs when they are pushed for bandwidth.
Gisle finishes this talk at Media City Bergen by taking a number of questions from the floor.
HTTP/2 is an evolution of what most people know as HTTP with the aim of increasing the speed of websites by streamlining the request and delivery of resources. Apple have mandated the use of HTTP/2 for their LL-HLS protocol. Within a typical web page there can easily be 100 requests to the web server so it’s easy to see how increased efficiency could be a benefit. For low latency streaming such as LL-HLS, there are many requests each second so again, even small gains in efficiency can add up.
Rolf W Rasmussen from VizRT explains in this talk the benefits of HTTP/2 taking us through the differences from HTTP. He starts simply by looking at HTTP/1.1 with the messages sent between the client and the server and shows how the requests and responses are sent. Rolf then looks at how the messages are sent at each of the layers of the OSI model. By doing this we discover that the messages are sent in binary.
Binary sending and header compression are ways in which the data to be sent is minimised. We see though that the HTTP/2 is a connection which multiplexes different streams on the same connection. Maintaining the same connection for multiple data streams again reduces the amount of negotiation needed. Multiplexing helps increase the efficient use of that connection. Unlike before, we now see that small requests are cheap whereas there has traditionally been a lot of work to reduce the number of small requests in HTTP/1.1.
Server Push is another key improvement where the server itself can push data into the open connection without a corresponding request. This was originally a requirement of the LL-HLS protocol but has been made optional since. For web pages, there are times when if a page needs resource A, the server knows that it will require resource B later. It’s in these situations that server push is used. Clearly for online streaming, it’s known when the client will need certain chunks or playlist files hence the potential use of server push.
Rolf concludes with questions from the flow and looking at some practical examples of debugging with curl, using proxies and Wireshark as well as dealing with encryption.
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