3D Special Report: Audio Hardware Is Up to the Challenge

Three-dimensional pictures have come and gone enough over the past eight decades to qualify as the visual equivalent of a Ralph Nader presidential bid. An Academy Award-winning short in 1936 preceded the spate of 1950s flicks like Bwana Devil and House of Wax, which were ancient history by the time the soft-core The Stewardesses in the 1970s and the 3D sequels to Jaws and The Amityville Horror in the ’80s flamed out quickly.

So it’s surprising the traction 3D is getting this time around. With major consumer-TV manufacturers like Samsung and LG already making 3D sets available and broadcast trucks gearing up for sports in 3D, the infrastructure buildout suggests that 3D will be more than a fad this time around.

So where does this leave audio? On one level, with 5.1 sound deeply entrenched in sports broadcasting, 3D can be seen as picture simply catching up to audio’s multichannel present. But others expect that mixing for a 3D picture — especially the live one that sports presents — will require a rethinking of the sound mix and the technology used to accomplish it.

Latency Lasts Longer
The technology for multichannel audio has been fairly standardized for years now, but 3D is already having its effect on design. Kevin Emmott, marketing manager for Calrec, notes that, on his company’s Bluefin2-enabled Apollo console, delay times have been increased to a total of 78 minutes, enough to allow for 1,728 mono legs of delay, each up to 2.73 seconds, which can be inserted into the signal path. This additional latency is necessary to accommodate the additional processing time required by 3D video.

Another consideration is the need for handling signals on the mix surface. “Even though we’re used to working in 5.1 now, you have to be able to think about how to manipulate the signal for 3D, since the visual presentation invites greater creativity,” says Emmott. “That means that manipulating the 5.1 image needs to be quick and simple, and the console requires more processing power for audio.”

Miranda SVP Chuck Meyer agrees that increased delay capability will be a key to audio’s supporting 3D video. But, he says, the routers also need to become more aware of where and when each signal’s delay applications will take place in the much denser environment of 3D.

For instance, he explains, the “pathfinding” router-control technique will become more important as 3D signals move in embedded formats, automatically figuring not only signal routing but also when and at what values to apply delay to the audio to match the video’s processing latency.

“Also, you have to consider the increased total channel count that comes with 3D,” Meyer emphasizes. “And you’ve got increased delay capability in both the router and the [mixing] console, so that can complicate it, too. With level B audio, you can have up to 32 channels of audio embedded with the video,” which will ultimately get reduced to eight channels of Dolby-encoded sound re-embedded with the video.

“Embedded video has really become the dominant format for connectivity,” he adds, “so hybrid routing is key to enabling 3D video production where audio production is equally critical.”

Setting the Stage for 7.1
The radical changes wrought by the transitions from mono to stereo and stereo to 5.1 have already created the hardware infrastructure necessary for audio to adequately support 3D video, says Tim Carroll, president of upmix- and distribution-systems supplier Linear Acoustic. The challenges, he believes, will lie with how mixers use them and, less predictably, whether 3D can stimulate consumers’ demand for expanding their home-theater setups — many of which can already decode 7.1 audio — to include 7.1 speaker configurations.

“The necessary [signal-processing–compensation] delay is already built into our products and a lot of other products, and adding more delay isn’t nearly as radical as it was going from stereo to 5.1, from no delay to some delay,” says Carroll. “The infrastructure is there. It’s a matter of what the mixers do with it and if people want to invest in what it takes to hear it.”

Mark Seigle, VP for business development at DTS, which licenses automated down/upmix algorithms to hardware partner DaySequerra, believes that the rapid penetration over the past two years of the Blu-ray disc format, which includes 7.1 surround capability in its specification, has laid the groundwork for consumer acceptance of that audio format. “[The DaySequerra DTS Neural Surround] systems are already 7.1-ready, and, if you combine that with how it’s rolling out with consumers, thanks to the growing popularity of Blu-ray, it’s really creating a good environment for 3D sound.”

He notes that the hardware and software tools are in place for sports-broadcast mixers and that his company’s Mono2Stereo upmix product can be used to take mono sources and synthesize stereo elements for the additional two side channels that 7.1 brings. “The real question that remains is, how are mixers going to take the extra camera positions and angles and mix to them?” Seigle says. “The tools to do that successfully are available. How will they be applied?”

We’ll find out soon as the training wheels for 3D sound come off this year.