fundamentals

Video: 5G Technology

Posted on by Russell Trafford-Jones

5G seems to offer so much, but there is a lot of nuance under the headlines. Which of the features will telcos actually provide? When will the spectrum become available? How will we cope with the new levels of complexity? Whilst for many 5G will simply ‘work’, when broadcasters look to use it for delivering programming, they need to look a few levels deeper.

In this wide-ranging video from the SMPTE Toronto Section, four speakers take us through the technologies at play and they ways they can be implemented to cut through the hype and help us understand what could actually be achieved, in time, using 5G technology.

Michael J Martin is first up who covers topics such as spectrum use, modulation, types of cells, beam forming and security. Regarding spectrum, Michael explains that 5G uses three frequency bands, the sub 1GHz spectrum that’s been in use for many years, a 3Ghz range and a millimetre range at 26Ghz.

“It’s going to be at least a decade until we get 5G as wonderful as 4G is today.”

Michael J Martin
Note that some countries already use other frequencies such as 1.8GHz which will also be available.The important issue is that the 26Ghz spectrum will typically not be available for over a year, so 5G roll-out starts in some of the existing bands or in the 3.4Ghz spectrum. A recurring theme in digital RF is the use of OFDM which has long been used by DVB and has been adopted by ATSC 3.0 as their modulation, too. OFDM allows different levels of robustness so you can optimise reach and bandwidth.

Michael highlights a problem faced in upgrading infrastructure to 5G, the amount of towers/sites and engineer availability. It’s simply going to take a long time to upgrade them all even in a small, dense environment. This will deal with the upgrade of existing large sites, but 5G provides also for smaller cells, (micro, pico and femto cells). These small cells are very important in delivering the millimetre wavelength part of the spectrum.

Network Slicing
Source: Michael J. Martin, MICAN Communications

We look at MIMO and beam forming next. MIMO is an important technology as it, effectively, collects reflected versions of the transmitted signals and processes them to create stronger reception. 5G uses MIMO in combination with beam forming where the transmitter itself electronically manipulates the transmitter array to focus the transmission and localise it to a specific receiver/number of receivers.

Lastly, Michael talks about Network Slicing which is possibly one of the most anticipated features of 5G by the broadcast community. The idea being that the broadcaster can reserve its own slice of spectrum so when sharing an environment with 30,000 other receivers, they will still have the bandwidth they need.

Our next speaker is Craig Snow from Huawei outlines how secondary networks can be created for companies for private use which, interestingly, partly uses separate frequencies from public network. Network slicing can be used to separate your enterprise 5G network into separate networks fro production, IT support etc. Craig then looks at the whole broadcast chain and shows where 5G can be used and we quickly see that there are many uses in live production as well as in distribution. This can also mean that remote production becomes more practical for some use cases.

Craig moves on to look at physical transmitter options showing a range of sub 1Kg transmitters, many of which have in-built Wi-Fi, and then shows how external microwave backhaul might look for a number of your buildings in a local area connecting back to a central tower.

Next is Sayan Sivanathan who works for Bell Mobility and goes in to more detail regarding the wider range of use cases for 5G. Starting by comparing it to 4G, highlighting the increased data rates, improved spectrum efficiency and connection density of devices, he paints a rosy picture of the future. All of these factors support use cases such as remote control and telemetry from automated vehicles (whether in industrial or public settings.)  Sayan then looks at the deployment status in the US, Europe and Korea. He shows the timeline for spectrum auction in Canada, talks through photos of  5G transmitters in the real world.

Global Mobile Data Traffic (Exabytes per month)
Source: Ericsson Mobility Report, Nov 2019

Finishing off today’s session is Tony Jones from MediaKind who focuses in on which 5G features are going to be useful for Media and Entertainment. One is ‘better video on mobile’. Tony picks up on a topic mentioned by Michael at the beginning of the video: processing at the edge. Edge processing, meaning having compute power at the closest point of the network to your end user allows you to deliver customised manifest and deal with rights management with minimal latency.

Tony explains how MediaKind worked with Intel and Ericsson to deliver 5G remote production for the 2018 US Open. 5G is often seen as a great way to make covering golf cheaper, more aesthetically pleasing and also quicker to rig.

The session ends with a Q&A

Watch now!
Speakers

Michael J Martin Michael J Martin
MICAN Communications
Blog: vividcomm.com
Tony Jones Tony Jones
Principal Technologist
MediaKind Global
Craig Snow Craig Snow
Enterprise Accounts Director,
Huawei
Sayan Sivanathan Sayan Sivanathan
Senior Manager – IoT, Smart Cities & 5G Business Development
Bell Mobility

Video: Broadcast Fundamentals: High Dynamic Range

Posted on by Russell Trafford-Jones

Update: Unfortunately CVP choose to take down this video within 12 hours of this article going live. But there’s good news if you’re interested in HDR. Firstly, you can find the outline and some of the basics of the talk explained below. Secondly, at The Broadcast Knowledge there are plenty of talks discussing HDR! Here’s hoping CVP bring the video back.

Why is High Dynamic Range is like getting a giraffe on a tube train? HDR continues its ascent. Super Bowl LIV was filmed in HDR this year, Sky in the UK has launched HDR and many of the big streaming services support it including Disney+, Prime and Netflix. So as it slowly takes its place, we look at what it is and how it’s achieved in the camera and in production.

Neil Thompson, an Sony Independent Certified Expert, takes a seat in the CVP Common Room to lead us through HDR from the start and explain how giraffes are part of the equation. Dynamic Range makes up two thirds of HDR, so he starts by explaining what it is with an analogy to audio. When you turn up the speakers so they start to distort, that’s the top of your range. The bottom is silence – or rather what you can hear over the quiet hiss that all audio systems have. Similarly in cameras, you can have bright pixels which are a different brightness to the next which represents the top of your range, and the dithering blacks which are the bottom of your range. In video, if you go too bright, all pixels become white even if the subject’s brightness varies which the equivalent of the audio distortion.

With the basic explanation out of the way, Neil moves on to describing the amount or size of dynamic range (DR) which can be done either in stops, contrast ratio or signal to noise ratio. He compares ‘stops’ to a bucket of water with some sludge at the bottom where the range is between the top of sludge and the rim of the bucket. One stop, he explains, is a halving of the range. With the bucket analogy, if you can go half way down the bucket and still hit clear water, you have 1 stop of dynamic range. If you can then go a quarter down with clean water, you have 2 stops. By the time you get to 1/32nd you have 5 stops. If going to 1/64 of the height of the bucket means you end up in the sludge, your system has 5 stops of dynamic range. Reducing the sludge so there’s clear water at 1/64th the height, which in cameras means reducing the noise in the blacks, is one way of increasing the dynamic range of your acquisition.

Update: Unfortunately CVP choose to take down this video within 12 hours of this article going live. But there’s good news if you’re interested in HDR. Firstly, you can find the outline and some of the basics of the talk explained below. Secondly, at The Broadcast Knowledge there are plenty of talks discussing HDR! Here’s hoping CVP bring the video back.

If you would like to know how lenses fit into the equation of gathering light, check out this talk from Cannon’s Larry Thorpe.

Neil looks next at the range of light that we see in real life from sunlight to looking at the stars at night. Our eye has 14 stops of range, though with our iris, we can see the equivalent of 24 stops. Similarly, cameras use an iris to regulate the light incoming which helps move the restricted dynamic range of the camera into the right range of brightness for our shot.

Of course, once you have gathered the light, you need to display it again. Displays’ ability to produce light is measured in ‘nits’, which is the amount of light per metre squared. Knowing how many nits a displays helps you understand the brightness it can show with 1000 nits, currently, being a typical HDR display. Of course, dynamic range is as much about the blacks as the brightness. OLED screens are fantastic at having low blacks, though their brightness can be quite low. LEDs, conversely, Neil explains, can go very bright but the blacks do suffer. You have to also take into account the location of a display device to understand what range it needs. In a dim gallery you can spend longer caring about the blacks, but many places are so bright, the top end is much more important than the blacks.

With the acquisition side explained, Neil moves on to transmission of HDR and it’s like getting a giraffe on a tube train. Neil relates the already familiar ‘log profiles’. There are two HDR curves, known as transfer functions, PQ from Dolby and HLG (Hybrig Log Gamma). Neil looks at which profiles are best for each part of the production workflow and then explains how PQ differs from HLG in terms of expressing brightness levels. In HLG, the brightest part of the signal tells the display device to output as brightly as it can. A PQ signal, however, reserves the brightest signal for 10,000 nits – far higher than displays available today. This means that we need to do some work to deal with the situation where your display isn’t as bright as the one used to master the signal. Neil discusses how we do that with metadata.

Finishing off the talk, Neil takes questions from the audience, but also walks through a long list of questions he brought along including discussing ‘how bright is too bright?’, what to look for in an engineering monitor, lighting for HDR and costs.

Watch now!
Speakers

Neil Thompson Neil Thompson
Freelance Engineer & Trainer

Video: Canon Lenses – A Tale of Three Formats

Posted on by Russell Trafford-Jones

Lenses are seen by some a black art, by some as a mass of complex physics equations and others who see them as their creative window onto the stories that need to be told. Whilst there is an art behind using lenses, and it’s true making them is complex, understanding how to choose lenses doesn’t require PhD academia.

SMPTE Fellow Larry Thorpe from Canon is here to make the complex accessible as he kicks off talking about lens specifications. He discusses the 2/3-inch image format comparing it with super 35 and full frame. He outlines the specs that are most discussed when purchasing and choosing lenses and shows the balancing act that all lenses are, wanting to maximise sharpness whilst minimising chromatic aberration. On the subject of sharpness, Larry moves on to discussing the way the camera’s ability to sample the video interacts with the lenses ability to capture optical resolution.

Larry considers a normal 1920×1080 HD raster with reference to the physical size of a TV 2/3inch sensor. That works out to be approximately 100 line pairs per millimetre. Packing that into 1mm is tricky if you wish to also maintain quality of the lines. The ability to transfer this resolution is captured by the MTF – the Modulation Transfer Function. This documents the contrast you would see then certain frequencies are viewed through the lens. Larry shows that for a typical lens, this 100 line pairs would have 70% of the original contrast. The higher the frequency, the lower the contrast until it just becomes a flat grey. Larry then looks at a 4K lens showing that it’s needs are 200 line pairs per mm and looking at the MTF, we see that we’re only reaching 50% contrast

Aberrations are important to understand as every lens suffers from them. Larry walks through the 5 classical aberrations, focus and chromatic. To the beginner, chromatic aberrations are, perhaps, the most obvious where colours are seen on the edge of objects, often purple. This is also known as colour fringing. Larry talks about how aperture size can minimise the effect and keeping your image above the 50% contrast limit in the MTF will keep chromatic aberration from being obvious. As a reality check, we then see the limits that have been calculated as limits beyond which it’s simply not possible to improve. Using these graphs we see why 4K lenses offer less opportunity to stop down than HD lenses.

Sharpness zones are zones in lenses optimised for different levels of sharpness. Within the centre, unsurprisingly is the highest sharpness as that’s where most action is. There is then a middle and an outer zone which are progressively less sharp. The reason for this is to recognise that it’s not possible to make the whole image sharp to the same degree. By doing this we are able to create a flatter central zone but with a manage decrease at the corners.

Larry moves on to cover HDR an mentions a recent programme on Fox which was shot in 1080p HDR making the point that HDR is not a ‘4K technology’. He also makes the point that HDR is about the low-lights as well as the specular highlights, so a lens’s ability to be low-noise in the blacks is important an whilst this is not often a problem for SDR, with HDR we are now seeing this coming up more often. For dramas and similar genres, it’s actually very important to be able to shoot whole scenes in low light and Larry shows that the large number of glass elements in lenses is responsible for the low light performance being suboptimal. With up to 50% of light not making it through the lens, this light can be reflected internally and travels around the lens splashing the blacks. Larry explains that coating elements can correct a lot of this and careful choice of the internal surface of the lens mechanisms is also important in minimising such reflections.

Telephoto lenses are lenses which have variable zoom. Larry shows how Canon developed a lens so fully frame a 6 foot athlete from 400 metres away so that they were fully framed on a 2/3″ sensor, but still with a wide angle lens of 60 degrees. With such a long zoom, internal stabilisation is imperative which is done by a very quick active feedback sensor.

So far, Larry has talked about the TV’s standardised 2/3″ image sensor. He now moves on to cover motion format sizes. He shows that for Super 35, you only need 78 line pairs per millimetre which has the knock-on effect of allowing sharper pictures. Next Larry talks about the different versions of ‘full frame’ formats emphasising the creative benefits of larger formats. One is giving a larger field of view which Larry both demonstrates and explains, another is greater sharpness and by having a camera which can choose how much of the sensor you actually use, you can put all sorts of different lenses on. Depth of field is a well known benefit of larger frame formats. The depth of field is much lower which, creatively, is often much desired, though it should be noted that for entertainment shows in TV, that’s much less desirable whilst in films, this is an intrinsic part of the ‘grammar.

As the talk comes to a conclusion, Larry discusses debayering whereby a single sensor has to record red, green and blue. He explains the process and the disadvantages versus separate sensors in larger cameras. As part of this conversion, he shows how oversampling can improve sharpness and avoid aliasing. the talk finishes with an overview of solid storage options

Watch now!
Speakers

Larry Thorpe Larry Thorpe
National Marketing Executive,
Canon USA Inc.

Video: ATSC 3.0 Seminar Part III

Posted on by Russell Trafford-Jones

ATSC 3.0 is the US-developed set of transmission standards which is fully embracing IP technology both over the air and for internet-delivered content. This talk follows on from the previous two talks which looked at the physical and transmission layers. Here we’re seeing how IP throughout has benefits in terms of broadening choice and seamlessly moving from on-demand to live channels.

Richard Chernock is back as our Explainer in Chief for this session. He starts by explaining the driver for the all-IP adoption which focusses on the internet being the source of much media and data. The traditional ATSC 1.0 MPEG Transport Stream island worked well for digital broadcasting but has proven tricky to integrate, though not without some success if you consider HbbTV. Realistically, though, ATSC see that as a stepping stone to the inevitable use of IP everywhere and if we look at DVB-I from DVB Project, we see that the other side of the Atlantic also sees the advantages.

But seamlessly mixing together a broadcaster’s on-demand services with their linear channels is only benefit. Richard highlights multilingual markets where the two main languages can be transmitted (for the US, usually English and Spanish) but other languages can be made available via the internet. This is a win in both directions. With the lower popularity, the internet delivery costs are not overburdening and for the same reason they wouldn’t warrant being included on the main Tx.

Richard introduces ISO BMFF and MPEG DASH which are the foundational technologies for delivering video and audio over ATSC 3.0 and, to Richard’s point, any internet streaming services.

We get an overview of the protocol stack to see where they fit together. Richard explains both MPEG DASH and the ROUTE protocol which allows delivery of data using IP on uni-directional links based on FLUTE.

The use of MPEG DASH allows advertising to become more targeted for the broadcaster. Cable companies, Richard points out, have long been able to swap out an advert in a local area for another and increase their revenue. In recent years companies like Sky in the UK (now part of Comcast) have developed technologies like Adsmart which, even with MPEG TS satellite transmissions can receive internet-delivered targeted ads and play them over the top of the transmitted ads – even when the programme is replayed off disk. Any adopter of ATSC 3.0 can achieve the same which could be part of a business case to make the move.

Another part of the business case is that ATSC not only supports 4K, unlike ATSC 1.0, but also ‘better pixels’. ‘Better pixels’ has long been the way to remind people that TV isn’t just about resolution. ‘Better pixels’ includes ‘next generation audio’ (NGA), HDR, Wide Colour Gamut (WCG) and even higher frame rates. The choice of HEVC Main 10 Profile should allow all of these technologies to be used. Richard makes the point that if you balance the additional bitrate requirement against the likely impact to the viewers, UHD doesn’t make sense compared to, say, enabling HDR.

Richard moves his focus to audio next unpacking the term NGA talking about surround sound and object oriented sound. He notes that renderers are very advanced now and can analyse a room to deliver a surround sound experience without having to place speakers in the exact spot you would normally need. Options are important for sound, not just one 5.1 surround sound track is very important in terms of personalisation which isn’t just choosing language but also covers commentary, audio description etc. Richard says that audio could be delivered in a separate pipe (PLP – discussed previously) such that even after the
video has cut out due to bad reception, the audio continues.

The talk finishes looking at accessibility such as picture-in-picture signing, SMPTE Timed Text captions (IMSC1), security and the ATSC 3.0 standards stack.

Watch now!
Speaker

Richard Chernock Richard Chernock
Former CSO,
Triveni Digital