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MONITORING Authoring and Monitoring for the emerging 3D Immersive Broadcast Audio formats by Anthony Wilkins T he world of broadcast audio is on the verge of a major revolution. Numerous “3D Immersive” formats are under development and will find their way into the mainstream of broadcast production and distribution in the near future. Unlike the world of relatively constrained channel based coding as we are accustomed to (most commonly Left / Right for Stereo and Left / Centre / Right / Surround Left / Surround Right + LFE or Low Frequency Effects for surround), these new codecs will support more channels and/or object based audio coding. For the end consumer, there will be two major benefits from this new approach, a greater sense of involvement or immersion, and a degree of personalisation. Greater involvement will come from an increased channel count typically by the addition of overhead “height” channels. Several proponents including the MPEG-H Alliance (Fraunhofer IIS, Technicolor and Qualcomm), Dolby and DTS have successfully demonstrated broadcast compatible systems based on 5.1.4 or 7.1.4 layouts where 4 overhead speakers have augmented the traditional 6 or 8 floor level speakers. This creates a “3D” sound image where the viewer or listener is immersed in audio in all dimensions. Object based audio will give the end user the option to personalise their experience by selecting from a number of audio sources and controlling the level and maybe even the position in the mix. In object based audio, 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 3 dimensional soundscape (maybe a plane flying overhead). Depending on restrictions and limitations decided at the point of content creation (and signaled in the descriptive metadata), the end user could select which audio source(s) they want to hear from an on-screen list and perhaps vary the level at which they are reproduced. 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. Does this mean multiple speakers need to be installed to avail of these new benefits? Not necessarily, although of course the best experience will result from a full installation of discrete speakers at both floor level and overhead, however where this is not practical (most likely the majority of typical domestic situations), the final “renderer” will re-create the mix as accurately as possible based on the actual number and location of speakers the end user has. An increasing number of Soundbars that are designed to sit underneath a display are already available to create a surround experience without consuming valuable space. Better still, a wall mounted Soundframe completely surrounds the display and can give an incredibly realistic reproduction from the height channels. 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 56 | KITPLUS - THE TV-BAY MAGAZINE: ISSUE 107 NOVEMBER 2015