Video: Next Generation TV Audio

Often not discussed, audio is essential to television and film so as the pixels get better, so should the sound. All aspects of audio are moving forward with more processing power at the receiver, better compression at the sender and a seismic shift in how audio is handled, even in the consumer domain. It’s fair to say that Dolby have been busy.

Larry Schindel from Linear Acoustic is here thanks to the SBE to bring us up to date on what’s normally called ‘Next Generation Audio’ (NGA). He starts from the basics looking at how audio has been traditionally delivered by channels. Stereo sound is delivered as two channels, one for each speaker. The sound engineer choosing how the audio is split between them. With the move to 5.1 and beyond, this continued with the delivery of 6, 8 or even more channels of audio. The trouble is this was always fixed at the time it went through the sound suite. Mixing sound into channels makes assumptions on the layout of your speakers. Sometimes it’s not possible to put your speakers in the ideal position and your sound suffers.

Dolby Atmos has heralded a mainstream move to object-based audio where sounds are delivered with information about their position in the soundfield as opposed to the traditional channel approach. Object-based audio leaves the downmixing to the receiver which can be set to take into account its unique room and speaker layout. It represents a change in thinking about audio, a move from thinking about the outputs to the inputs. Larry introduces Dolby Atmos and details the ways it can be delivered and highlights that it can work in a channel or object mode.

Larry then looks at where you can get media with Dolby Atmos. Cinemas are an obvious starting point, but there is a long list of streaming and pay-TV services which use it, too. Larry talks about the upcoming high-profile events which will be covered in Dolby Atmos showing that delivering this enhanced experience is something being taken seriously by broadcasters across the board.

For consumers, they still have the problem of getting the audio in the right place in their awkward, often small, rooms. Larry looks at some of the options for getting great audio in the home which include speakers which bounce sound off the ceiling and soundbars.

One of the key technologies for delivering Dolby Atmos is Dolby AC-4, the improved audio codec taking compression a step further from AC-3. We see that data rates have tumbled, for example, 5.1 surround on AC-3 would be 448Kbps, but can now be done in 144kbps with AC-4. Naturally, it supports channel and object modes and Larry explains how it can deliver a base mix with other audio elements over the top for the decoder to place allowing better customisation. This can include other languages or audio description/video description service. Importantly AC-4, like Dolby E, can be sent so that it doesn’t overlap video frames allowing it to accompany routed audio. Without this awareness of video, any time a video switch was made, the audio would become corrupted and there would be a click.

Dolby Atmos and AC-4 stand on their own and are widely applicable to much of the broadcast chain. Larry finishes this presentation mentioning that Dolby AC-4 will be the audio of choice for ATSC 3.0. We’ve covered ATSC 3.0 extensively here at The Broadcast Knowledge so if you want more detail than there is in this section of the presentation, do dig in further.

Watch now!

Speaker

Larry Schindel Larry Schindel
Senior Product Manager,
Linear Acoustic

Video: How speakers and sound systems work: Fundamentals, plus Broadcast and Cinema Implementations

Many of us know how speakers work, but when it comes to phased arrays or object audio we’re losing our footing. Wherever you are in the spectrum, this dive into speakers and sound systems will be beneficial.

Ken Hunold from Dolby Laboratories starts this talk with a short history of sound in both film and TV unveiling the surprising facts that film reverted from stereo back to mono around the 1950s and TV stayed mono right up until the 80s. We follow this history up to now with the latest immersive sound systems and multi-channel sound in broadcasting.

Whilst the basics of speakers are fairly widely known, Ken with looking at how that’s set up and the different shapes and versions of basic speakers and their enclosures then looking at column speakers and line arrays.

Multichannel home audio continues to offer many options for speaker positioning and speaker type including bouncing audio off the ceilings, so Ken explores these options and compares them including the relatively recent sound bars.

Cinema sound has always been critical to the effect of cinema and foundational to the motivation for people to come together and watch films away from their TVs. There have long been many speakers in cinemas and Ken charts how this has changed as immersive audio has arrived and enabled an illusion of infinite speakers with sound all around.

In the live entertainment space, sound, again, is different where the scale is often much bigger and the acoustics so much different. Ken talks about the challenges of delivering sound to so many people, keeping the sound even throughout the auditorium and dealing with delay of the relatively slow-moving sound waves. The talk wraps up with questions and answers.

Watch now!

Speakers

Ken Hunold Ken Hunold
Sr. Broadcast Services Manager, Customer Engineering
Dolby Laboratories, Inc.

Video: Content Production Technology on Hybrid Log-Gamma


‘Better Pixels’ is the continuing refrain from the large number of people who are dissatisfied with simply increasing resolution to 4K or even 8K. Why can’t we have a higher frame-rate instead? Why not give us a wider colour gamut (WCG)? And why not give us a higher dynamic range (HDR)? Often, they would prefer any of these 3 options over higher resolution.

Watch this video explain more, now.

Dynamic Range is the word given to describe how much of a difference there is between the smallest possible signal and the strongest possible signal. In audio, what’s the quietest things that can be heard verses the loudest thing that can be heard (without distortion). In video, what’s the difference between black and white – after all, can your TV fully simulate the brightness and power of our sun? No, what about your car’s headlights? Probably not. Can your TV go as bright as your phone flashlight – well, now that’s realistic.

So let’s say your TV can go from a very dark black to being as bright as a medium-power flashlight, what about the video that you send your TV? When there’s a white frame, do you want your TV blasting as bright as it can? HDR allows producers to control the brightness of your display device so that something that is genuinely very bright, like star, a bright light, an explosion can be represented very brightly, whereas something which is simply white, can have the right colour, but also be medium brightness. With video which is Standard Dynamic Range (SDR), there isn’t this level of control.

For films, HDR is extremely useful, but for sports too – who’s not seen a football game where the sun leaves half the pitch in shadow and half in bright sunlight? With SDR, there’s no choice but to have one half either very dark or very bright (mostly white) so you can’t actually see the game there. HDR enabled the production crew to let HDR TVs show detail in both areas of the pitch.

HLG, which stands for Hybrid Log-Gamma is the name of a way of delivering HDR video. It’s been pioneered, famously, by Japan’s NHK with the UK’s BBC and has been standardised as ARIB STV-B67. In this talk, NHK’s Yuji Nagata helps us navigate working with multiple formats; HDR HLG -> SDR, plus converting from HLG to Dolby’s HDR format called PQ.

The reality of broadcasting is that anyone who is producing a programme in HDR will have to create an SDR version at some point. The question is how to do that and when. For live, some broadcasters may need to fully automate this. In this talk, we look at a semi-automated way of doing this.

HDR is usually delivered in a Wide Colour Gamut signal such as the ITU’s BT.2020. Converting between this colour space and the more common BT.709 colour space which is part of the HD video standards, is also needed on top of the dynamic range conversion. So listen to Yugi Nagata’s talk to find out NHK’s approach to this.

NHK has pushed very hard for many years to make 8K broadcasts feasible and has in recent times focussed on tooling up in time for the the 2020 Olympics. This talk was given at the SMPTE 2017 technical conference, but is all the more relevant now as NHK up the number of 8K broadcasts approaching the opening ceremony. This work on HDR and WCG is part of making sure that the 8K format really delivers an impressive and immersive experience for those that are lucky enough to experience it. This work on the video goes hand in hand with their tireless work with audio which can deliver 22.2 multichannel surround.

Watch now!

Speaker

Yuji Nagata Yuji Nagata
Broadcast Engineer,
NHK

Webinar: Next Generation Audio & DVB

Webinar Date: 18th March 2019
Time: 14:00 GMT / 15:00 CET

Object oriented audio is a relatively new audio technique which doesn’t simply send audio as one track or two, but it sends individual audio objects – simplistically we can think of these as audio samples – which also come with some position information.

With non-object-orientated audio, there is very little a speaker system can do to adjust the audio to match. It was either created for 8 speakers, 6, or 2 etc. So if you have a system that only has 4 speakers or they are in unusual places, it’s a compromise to it sound right.

Object oriented audio sends the position information for some of the audio which means that the decoder can work out how much of the sound to put in each speaker to best represent that sound for whatever room and speaker set-up it has.

AC-4 from Dolby is one technology which allows objects to be sent with the audio. It still supports conventional 5.1 style sound but can also contain up to 7 audio objects. AC-4 is one NGA technology adopted by DVB for DASH.

In this webinar, Simon Tuff from the BBC discusses what the Audio Video Coding (AVC) experts of DVB have been working on to introduce Next Generation Audio (NGA) to the DVB specifications over recent years. With the latest version of TS 101 154, DVB’s guidelines for the use of video and audio coding in broadcast and broadband applications, being published by ETSI, it seems like a great time to unpack the audio part of the tool box and share the capabilities of NGA via a webinar.

No registration needed. Click here to watch on the day.

Speaker

Simon Tuff Simon Tuff
Principal Technologist
BBC