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SMPTE: Immersive sound destined to be a novelty without standards

As immersive audio platforms are rolled out to cinemas worldwide there are warnings that without a standard means of mixing them and playing them back the innovation could be stifled at birth.

As immersive audio platforms are rolled out to cinemas worldwide there are warnings that without a standard means of mixing them and playing them back the innovation could be stifled at birth.

Brian A Vessa, chair of the SMPTE 25CSS Standards Committee that is charged with devising a standard for incorporation into the Digital Cinema Package (DCP), believes that without agreement “immersive sound is destined to be a novelty rather than realising its true potential of being the next big thing in cinema sound.”

By the end of 2014 there will be 1050 screens worldwide outfitted with immersive sound systems, split between Dolby Atmos (650) and Barco Auro 11.1 (500). While this is considered to be a healthy rate of adoption to date, “it’s still less than 1% of the market, so it’s not exactly a tangible size for studios to continue the cost, time and effort in making both workflow passes,” argues Brian Claypool, Barco’s Business Development Director.

“Exhibitors want to play content and not worry about what content is available,” he argued. “An open standard will keep the freedom of choice for theatres to choose the system which makes best economic sense for them.”

Barco Auro 11.1 is an extension of the 25-year old channel-based surround format with added layers for height and overhead. Dolby Atmos, used to mix 100 other titles, including Gravity for which it won an Oscar in sound editing, flies the sound as objects around up to 64 speakers in the auditorium using unique metadata applicable to each audio object.

The need for standards is indeed high. Currently, each immersive audio system requires a special mix and a special audio track in a DCP. Both formats are proprietary and not interoperable. If a theatre elects to go with a particular system, they can only play content that is mixed and delivered for that system, they cannot play all immersive content.

“These issues are actually hindering the wide adoption of immersive sound by studios and exhibitors,” said Vessa. “Studios are unwilling to pay the extra costs of mixing and multiple distribution inventory, and exhibitors are reticent to commit to installing a system that is proprietary or is not guaranteed to be able to play immersive content down the line. Exhibitors also have to be concerned with addressing each immersive sound movie as a special case.”

He added that manufacturers of servers and processors “must build dedicated devices for each system” if they want to compete in this market. “Different pieces of equipment are not guaranteed to talk to each other since there is no standard for doing so,” he said. “The Digital Cinema architecture is being amended via the standards work, which will be necessary for equipment to interoperate.”

He argued that standards would also allow any manufacturer of these devices to build to the standard and therefore more equipment will become available, which will make for higher quality, lower cost and enhanced market share. This will also help exhibitors.”

SMPTE plans to have a standard for Object-Based Audio Essence metadata and bitstream complete within a year. In order to play back in multiple venues, this immersive audio data will need to be decoded and rendered by multiple immersive sound systems, so Barco and Dolby will need to implement this functionality into their systems. According to SMPTE, this could take a number of months.

There are other pieces that also need to be addressed in order to ensure interoperability, such as data transfer, synchronisation and playback calibration. These are parallel efforts that SMPTE is tackling that should finish in a similar time frame.

The odds are that within two years there will be a distribution standard called ‘PLF Audio’ or ‘Immersive Audio’ incorporated into the DCP that exhibitors will be able to automatically render into their Atmos or Auro certified theatre on reception.