Since 2013, my first NAB Show stop has been at Avid Connect. This year I was extremely intrigued to see how the event would differ from previous years, since Jeff Rosica had taken the helm of the company following the still-fresh ouster of the previous CEO — who originated the event — along with the Avid Customer Association. It didn’t take long to find out.

Avid Connect has always tended to be product-heavy from start to finish, but this one simply did not feel that way. There was plenty of discussion of Media Composer, Pro Tools and the Media Central Platform — Avid’s business is to make and sell products after all — but the overall event, and the breakout sessions in particular, were far more interesting and educational than prior years, covering a wide range of topics that were not specific to the company and its products.

TECH TRENDS

One session that was surprisingly engrossing, “Technology Trends Musicians Can Utilize for Tracking Royalties.” It covered, among other topics, the pros and cons of streaming.

Panelist Jordan “DJ Swivel” Young made the case that, for those who have a dedicated fan base, streaming can actually be a greater source of revenue than CD or song purchases because the artist gets paid every time the song is played, not just when a purchase is made.

A different technological solution to the issue was presented by Benji Rogers, CEO of Dot Blockchain Media, who claims that current audio file formats are antiquated — WAV is 27 years old; MP3 is 24; and FLAC is 17 — and are part of the problem because they don’t contain persistent metadata.

Rogers proposes a new format and wrapper with blockchain as part of the fundamental framework so that ownership can be tracked from inception through all iterations, sampling and reuse.

Whether or not you’re an artist trying to get paid, the ability to encode persistent, unmodifiable metadata will soon become an essential element of every single piece of media as the ability to replace original audio and video content with completely believable digital substitutes becomes even more mainstream than it already is.

There were several sessions on immersive content and VR, both key elements of Next Gen Audio, and these sessions were far more informative than any I attended at NAB.

The panel of “Creating Spectacular Experiences With Dolby Atmos” included re-recording engineers Doug Hemphill, Ron Bartlett, and Tim Hoogenakker. During the discussion on mixing immersive content, Hemphill pointed out that as sound density increases, imaging and intelligibility decrease, so films with busier soundscapes are more difficult to mix and it becomes harder to make individual sounds stand out. In fact, he sometimes pulls back the density of the sound mix when there are really intense visuals to give people’s brains a break.

When asked what it was like to be able to place sound in so many locations, Bartlett said that they went a little overboard with the overhead speakers at first, but realized that this actually made the film sound more mono and less immersive, so more judicious use of the overheads is now employed.

[Read: 2018 Audio Prognostication—What Lies Ahead?]

Everyone felt that the soundscape in Atmos is more akin to listening in the natural world than standard surround mixes, though every so often the choices made in the surround mix are the right ones compared to the Atmos mix.

While they do verify downmixes as they mix, Hoogenakker said that he specifically checks television downmixes on a soundbar since more people than ever are listening on them at home.

Something that helps keep costs down while speeding up workflow is being able to work in 7.1.4 in smaller rooms to prepare audio for the Atmos mix room. Hemphill brought us all back to reality by reminding us that even though the ability to create amazing immersive soundscapes is now in everyone’s grasp, dialog remains king. Always.

CHALLENGES OF AUDIO IN VR

In the first session on audio for VR, “Techniques for Mixing Audio in VR Content,” the panelists covered aspects of VR production I had not even contemplated. Benedict Green of Ecco VR stressed the importance of preproduction and the fact that, when shooting content, the crew, recording equipment, cables and anything else that might take people out of the experience must be concealed, which is a tad difficult when shooting live actors while trying to capture and playback audio.

Avid Connect has always tended to be product-heavy from start to finish, but this one simply did not feel that way.

Green and Varuna Nair of Facebook both noted that ambisonics is the preferred format for VR audio and there are different tools for working with different order ambisonics.

They also discussed some of the challenges of working with audio for VR, including never being able to use a boom mic on set; and the difficulty of using ambisonics microphones because they cannot move without changing the soundfield. Managing loudness, and keeping audio from clipping is a huge challenge, as can working with nonaudio people who may reorder or mangle the ambisonics tracks. According to Nair, when thinking about VR, audio engineers should “think of it as another tool in the toolbox.”

In the session “Creating a Compelling Immersive Mix for VR Content,” Scott Gershin made the case that realism is not always the best approach, since the purpose of sound is to help tell the story in whatever way necessary.

Like Green and Nair, he also mentioned things I had not really considered. For instance, if you move a sound in the soundscape, people will pay attention to it, so don’t move it if you don’t want it noticed. Gershin does not move backgrounds, but he does group and move all sounds for given characters together to the same place in the soundscape because that is where the character exists at that moment.

Since we don’t really hear things behind us he feels that a 270-degree soundfield is wide enough. As for where this is all heading, Gershin thinks that VR will be commonplace in five years and boring in 10, but augmented reality is really where we’re heading anyway.

Jay Yeary is a television engineer who specializes in audio. He is a member of AES, SBE, SMPTE and TAB. He can be contacted through TV Technology magazine or attransientaudiolabs.com.

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SAN ANTONIO, TEXAS—With immersive audio knocking on the door of broadcast television, it seems like a good time to investigate some ways to create content for the format. According to some in the industry, a look at the future of immersive audio requires us to charge up the flux capacitor, hop in the DeLorean, and travel back to 1975.

At the 2015 NAB Show, Pro Sound Effects demonstrated an Ambisonics sound effects library of London ambiences. Initially I was skeptical about the utility of these sounds, but, after previewing them and realizing the amount of control available, I walked away intrigued by the prospect of creating and using sound effects that were immersive all the way from capture to consumer.

Testing was done with the SurroundZone 2 software provided with the sound effects library to decode the B-format audio and recreate the captured sound field.

Considered by some to be a dead format, Ambisonics has resurfaced as a possible immersive format, especially since it was created to capture and reproduce 3D audio from the outset. While it’s important to look at how Ambisonics works as an immersive format, we also need to see how it holds up when listening is non-immersive. Though the London sounds previewed at the NAB Show are not yet available, a library of New York City Ambisonic sounds was released and used as test material for this column, along with some B-format recordings I made several years ago.

While we will look specifically at Ambisonics technology in this column, there are other methods of capturing multichannel sound.

COINCIDENT PAIRS
All microphones designed for capturing sound fields and ambiences are composed of some array of capsules, either spaced at a calculated distance or based on some form of coincident pair, where two microphones are placed nearly touching, facing the sound source, with their capsules angled 90 degrees (typically) to each other. X/Y, Mid-Side (M-S), and Blumlein Stereo are coincident pairs, and it, in fact, was Alan Blumlein, the famed English electronics engineer who developed this technique in the 1930s.

The benefit of coincident pairs is that timing and phase errors are eliminated because the source sound arrives at both capsules at the same time with equal amplitude if the source is directly in front and slightly early/late with differing amplitude if the sound is to either side. The elimination of timing and phase errors also means that the sound captured with coincident pairs does an excellent job of folding down to a single channel.

SoundField microphones, designed specifically for Ambisonics, are based on the coincident pair technique, with four capsules close together as opposed to two, in order to provide height to supplement front/back and side to side. Microphones from other manufacturers are available with different coincident pair implementations, essentially some expansion of M-S, including the Schoeps Double M-S and the Sanken WMS-5.

Researchers are experimenting with other microphones and placement options for capturing 3D sound fields, but all recordings tested here were made with the SoundField ST450 microphone system.

SoundField microphones capture raw audio (A-Format) from the four capsules (Lb, Lf, Rf, Rb) in their array, which then go into a processor that converts them to B-format signals for recording. B-format matrixes the raw audio into a more or less 360-degree sound field by recombining channel content to create one omnidirectional channel and three bidirectional channels.

The omni channel, W, combines audio from the four capsules (Lb+Lf+Rf+Rb) and acts as a sound pressure channel. Of the bidirectional channels, X supplies front/rear imaging (–Lb+Lf+Rf–Rb); Y provides side-to-side imaging (Lb+Lf-Rf-Rb); and Z gives us up and down imaging for the all-important height dimension (–Lb+Lf–Rf+Rb).

TESTING SOFTWARE
Hardware processors or software can be used to decode the B-format audio and recreate the captured sound field. My testing was all done with the SurroundZone 2 software provided with the sound effects library. Since B-format recordings consist of four channels of audio (BWF), it seems natural to place them on a four channel-wide track, but they actually need to be placed on a 5.1 track in order to get a 5.1 output (the software currently supports up to 7.1).

Once the decoding software is inserted onto the multichannel track, you have the ability to steer the decoded channels around in the mix as well as change microphone orientation, tilt, width and other parameters. The amount of control you have as the mixer is actually quite substantial, which gives you the ability to create some very dramatic shifts in the image. The most dramatic of all for mixers may be that, despite the fact we are working with a captured 3D sound field, it collapses perfectly to stereo and mono.

There are certainly some issues with the SoundField system if the goal is to use it for truly immersive projects. First of all is the fact that the decoding hardware and software only support 7.1 and there are no current provisions for audio object placement. For post work there is already plenty of overhead involved in creating immersive audio mixes with not many workstations equipped to handle the workflow out of the box.

Even though three dimensions of audio are captured in the B-format recording, I was unable to locate any currently available tools that give us the ability to recreate those dimensions in an immersive production environment.

If there was ever a technology begging to be used for immersive audio, this is it. In a 1990 AES paper on Ambisonics, author Roger Furness stated that, “The original sound field, whether it was a live sound or one created at the mixing console, has an infinite number of possible sound directions.” That sounds more like the immersive technology coming with ATSC 3.0 than one already 40 years old.

More testing and development of Ambisonics are certainly in order, especially when incorporating the technology into immersive workflows, but downmix compatibility is already there. Expanded decoding tools are needed and despite the fact 3D audio can be captured with other microphone configurations, many of those setups are not portable, making them useful only in controlled indoor settings and unsuitable for live events, which are increasingly important as broadcasters seek to differentiate themselves from OTT services.

Jay Yeary is a broadcast engineer and consultant specializing in audio. He is an AES Fellow and a member of SBE and SMPTE. He can be contacted through TV Technology magazine or attransientaudiolabs.com.