BROADCAST FOCUS
Audio: The Next Generation
In an object-based world, television sound will not only be more immersive it could also become personalised and interactive, as Will Strauss discovers.
W
hile I am sure that I am preaching to the choir when I say this, great pictures are
nothing without great sound. And never has that been more apparent than with the current move in the direction of Ultra High Definition. With picture resolution quadrupling
in size, viewers will benefit from greater image detail than they have ever had before while producers will potentially be offered further creative choices (plus the odd logistical headache). But unless the quality of the audio experience matches it, they might as well not bother. “It is very challenging to unpick the visual experience from the audio,” details Tony Churnside, media technologist at BBC Research and Development (R&D). “One thing depends on the other. If you make the sound worse, it has a negative impact on people’s perception of the picture. In terms of the audience experience the two things should be tied up.” So, in this next audio step change, what will sound, well, sound like? In an effort to be more immersive, will it be an extension of the familiar channel-based approach that requires complicated speaker configurations in 5.1, 7.2, or even 22.2 that make the listener’s living room look like the bridge of the Starship Enterprise? With TV now increasingly being consumed across multiple platforms and devices, this seems unlikely. “Realistically not all of the audience
can, or wants to experience TV sound that way,” says Churnside. “It’s no longer right to see this as one-size- fits-all. Now, we are looking at the development of a system agnostic environment or format that is object based.”
How does that work then? Well, rather than broadcasting the stereo
18 May 2014
loudspeaker signals and their pre- mixed combination of dialogue, narration, sound effects, music, and background atmospheres, each of those sounds is sent as a separate audio object with associated metadata. Te viewing device or system at the other end then reassembles the objects into an output that can be slightly different for each listener by locally changing the metadata.
BUILDING BLOCKS
It works in a similar way to responsive website design, where a set of associated style parameters control how the content should look depending on the size, shape, and type of browser it is being viewed on. Churnside has a better analogy though: “When you buy a Lego set it comes with a load of bricks and instructions for how you can assemble those bricks,” he explains. “Sometimes those instructions can provide for the creation for more than one thing. Tat is what we’re doing with TV or radio programmes.” Whether you prefer the responsive design comparison, or the Lego one, the key is that this agnostic approach means the listener gets the best possible audio experience for the situation they are in whether that is sat at home in front of a big plasma TV or watching on the move via their tablet computer. BBC R&D carried out a test to this effect last year. A radio drama, Pinocchio, was able to be rendered in stereo for Radio 4 listeners but in surround sound for those listening online: and it was done so via a single production process. Object-based audio can go
further than simply adapting to the end-user device. Using what is termed ‘perceptive media’, where
the programme knows something about its audience, content can be tailored to, say, a geographical location. A TV drama, for example, could have different, automated, dialogue feeds depending on the city that it is being viewed in. It can afford elements of personalisation and interactivity too. Because an object can
be any bit of audio in a programme, the listeners could be given the choice to reduce or increase the levels of the commentary or the crowd noise during coverage of a football match, or even choose which set of supporters they hear. A BBC R&D test with BBC Radio
5 Live at Wembley Stadium last year, where the audio was streamed as a set of objects, allowed listeners to effectively ‘change where they sat in the ground’, an experience that Churnside’s research suggested gave the audience an experience that was ‘more like being there’. It’s certainly an exciting
development, but is it realistic, affordable and practical? “We’re not there yet, other industries
are moving in this direction,” says Churnside, citing the emergence of
TV sound could take a building block approach to create a more personalised experience for the viewer
Dolby Atmos in the feature film market, but “there are challenges to be solved in design,
production, and distribution, particularly what sits on your set- top-box at home”. Tere is already support for object-based audio though. At this year’s NAB Dolby demonstrated a prototype of its object-based multichannel-
mixing approach, while DTS,
Fraunhofer, Fairlight, Calrec, and more all unveiled or discussed developments in this field. Te EBU is also looking at incorporating object-based representations into the burgeoning BWAV format. Clearly, further research is required
before we can fully understand the impact that object-based sound would have on production, post production, and broadcast and what benefit it would provide for the audience. But if BBC R&D has anything to do with it, it will be mere child’s play. “We don’t want to double the cost
of production, the aim is to be able to create the audio bricks once,” says Churnside. “You don’t have to buy a new Lego set if you want to build a new thing. You just re-use the existing bricks to do it. Tat is what we’re trying to emulate.”
For regular updates on the broadcast audio industry sign up for Audio Media’s Broadcast Audio Newsletter at
www.audiomedia.com/newslettersignup
www.audiomedia.com
Sign up for your digital AM at
www.audiomedia.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48