Immersive Audio: the Pieces Are Coming Togeer

Immersiveness is turning out to be the catch phrase of the century's second decade. The term reflects new audio formats that provide additional channels both on the sides of and above listeners, offering a richer sense of audio cues and, with object-based audio, the potential for increased personalization of sound.

In sports, the evidence of immersiveness is everywhere, from VR goggles for looking at content available only through a venue's WiFi to massive 360-degree halo video displays, such as the one currently being fabricated for the Mercedes-Benz Stadium, home of the Atlanta Falcons and Atlanta United FC.

Jeffrey Riedmiller, VP, Sound Group, Dolby Labs

Immersiveness will be broadcast audio's latest inflection point, after stereo in the 1990s and 5.1 surround a decade ago. Earlier this year, the ATSC's 3.0 standards project announced both Dolby AC-4 and MPEG-H as candidate standards for ATSC 3.0; more recently, the North American Broadcasters Association (NABA) board approved the Dolby AC-4 system as its recommendation for the next-generation audio standard for NABA's membership (in the U.S., Canada, and Mexico), the sonic counterpart to the 4K/UHD that will be its video format.

AC-4 can support up to 11 channels of audio, including two to four on a new axis: height. It also supports object-based audio, which represents sound as a set of individual assets along with metadata describing their relationships and associations. This radical new approach to sound not only means that audio elements can be placed in a 3D space but also offers the potential for allowing home viewers to rearrange the relationships of those elements, adding personalization to audio's new frontier.

Nuts and Bolts

But the details for making that work are still in progress. Take, for instance, monitoring the audio for an 11-channel production. It would be almost impossible to set up 11 discrete audio channels in the space usually reserved for audio on remote-production trucks, which have just about completed a years-long industry-wide upgrade to accommodate the six channels of 5.1 surround sound.

There's no space in the truck [for the monitoring array] that you would need beyond 5.1, observes Chris Fichera, VP, Group One, whose product offerings include Blue Sky speakers and Calrec and DiGiCo audio consoles. But we have seen it starting to show up in [broadcast] flypacks.

He adds that Blue Sky is working on developing modular 7.1.4 (the typical five-channel LCR and stereo rear arrays plus two stereo side and two overhead channels, plus an LFE channel) monitoring arrays that could be scaled up or down, depending on the size and needs of the mixing environment. The expectation is that this will eventually evolve into a scalable product line, based on Blue Sky's MediaDesk line, allowing someone with multichannel monitoring needs - videogaming as well as conventional sports - to buy a basic system and expand it as demand in broadcast and other vertical markets increases.

The real challenge will not necessarily be in the number of speakers in a system, says Fichera, but in managing them. Blue Sky's AMC speaker-control system will be able to be scaled to adapt to larger speaker arrays. Speaker management has been an area of development in recent years for a number of manufacturers, including JBL and Genelec, two other brands often found in remote and plant broadcast facilities. With the number of speakers needed for immersive broadcast audio, he says, you'll need systems that can handle room optimization and other processes automatically.

Capture

Microphones have been following a similar track on the sound-capture side of the equation. Longtime entrants in the multichannel transducer sweepstakes, like Holophone and Soundfield, are being augmented by new products, such as Sennheiser's Ambeo VR microphone and Schoeps's ORTF-3D plug-and-play array.

Sennheiser's Ambeo VR microphone is designed to stand up to outdoor applications and has a widely used interface.

Brian Glasscock, user experience researcher at Sennheiser's Strategic Innovation division, describes the Ambeo multichannel capture system, which will be available for sale in the U.S. this month, as having been designed with input from members of Sennheiser's Creators Program, which includes several national television networks that broadcast sports programming. He says he can not reveal which ones they are, citing NDAs, but notes that they contributed to Ambeo's design by emphasizing the need for a robust microphone that can stand up to outdoor applications and has a widely used interface to accommodate broadcast workflows. In this case, that meant fitting the Ambeo's four mic elements with XLR-type outputs jacks.

Users looking for immersive sound, for VR and next-generation broadcast applications, wanted both of those criteria met, he explains. A number of spherical-capture microphones are delicate or even flimsy. That won't work for broadcast and especially not for sports.

Glasscock stresses that immersive audio capture will have to work in concert with conventional audio techniques and tools. The shotgun microphone isn't going to go away, because the need to capture specific sounds isn't going to go away, he says, adding, VR and other immersive applications will mark a major shift in broadcast sports. We're in the equivalent of early days of film with this. We're trying to figure out the techniques and tools we're going to need for storytelling in the immersive age.

Partnering

Although Dolby has developed the Atmos and AC-4 format, it will rely on a number of development partners for AC-4 implementation. Harmonic's Harmonic Electra X2 AC-4 encoder, for example, was used as part of the first live ATSC 3.0 broadcast of a major profession

LINK:	http://www.sportsvideo.org/2016/11/10/immersive-audio-the-pieces-are-c...
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