Object Based Audio In Broadcast – The Next Challenge

The world of broadcast audio is on the verge of a major revolution, says Peter Poers, Managing Director, Jünger Audio. Numerous "3D Immersive" formats are under development and will soon find their way into mainstream broadcast production and distribution.

As well as Immersive Audio there is Object Based Audio (OBA), which allows the end user to personalise their listening experience by selecting from a number of audio sources and controlling the level – and maybe even the position of an 'object' – in the mix.

In OBA, an "object" is essentially an audio stream with accompanying descriptive metadata. The metadata carries information about where the engineer placed the object in the mix and at what level, and is used to re-create, or render, the audio experience for the end user. Objects may be static and placed at a fixed point in the mix (for example dialog) or dynamic where they are panned across the 3D soundscape (maybe a plane flying overhead). Think of a sporting event where the options could include home or away commentary, crowd sounds, the referee or match official's voice or pitch side microphones at team ball games. At motor racing events, examples could be commentary, drivers voice or pit crew communication.

One of the major challenges for the production side of the industry will be to start OBA production. This means completely rethinking how we perform the final mix because, with OBA, it will be performed at home by the viewer rather than by a mixer in a post-production facility. We have to bear in mind that as soon as post houses mix objects (different language commentaries, for example) into the audio bed, they are gone and are no longer available for delivery to the viewer at home. Therefore, to give viewers personalized audio, you need to change your production workflow and deliver separate 'unmixed' channels so that the final mix can be finished in the home receiver and decoder.

What does this all mean for the broadcaster? A complete re-build of existing facilities and a total re-think about the audio processing equipment required for outside broadcast vehicles? Well, if we get it right, it should entail relatively minimal changes to overall workflow and hardware, but inevitably some additions to production and distribution equipment. In the case of OBA, the metadata appropriate for the final codec needs to be created and added to the audio for insertion into a conventional SDI stream, and the engineer needs to be able to monitor this complex mix (and all the potential downmix variations) to ensure that the distribution chain is fed with all available objects correctly. Loudness levels should also be considered in respect of existing standards and there should be provision for local insertion of content at any point in the chain.

At Jünger Audio we are already preparing for this challenge by developing quality creation and control tools for OBA. Auto Program Feed Mixing and Auto Commentary Mixing for immediate creation of channel based legacy delivery formats are two of the procedures we can offer to make the introduction of OBA production easier. Our technology will enable broadcasters to start OBA formats with confidence and minimal workflow changes, whilst ensuring that end users benefit from the enhanced listening experience with predictable and reliable results.

www.jungeraudio.com

This article is also available to read in the June edition of Broadcast Film & Video.

(JP/LM)