Multi Dimensional Audio (MDA) is an audio distribution format capable of carrying every known and yet-to-be-defined cinema audio format. It can carry channel-based audio, object-based audio, and any combination thereof. It was developed by SRS Labs, now owned by DTS. DTS says they will make the format available for industry use on a license-free basis.
The value of an open distribution format that supports both channel-based sound and object-based sound is enormous. It allows competitive makes of mastering systems to generate formatted sound tracks that can be understood by competitive downstream playback equipment. If the installed sound system does not have all of the channels of the mastered audio, it will have the opportunity to render the sound track in the best manner possible to the available speaker system. Similarly, if sound objects are included in the mix – which are sound tracks of limited duration accompanied by timing and panning instructions for the rendering engine – the playback rendering engine will do the best it can to recreate the mix on the available speaker system.
This may sound ideal, but it is not without flaws. If the speaker system that the rendering engine is tuned to is not the same as that used in the mixing room, then the sound heard by the audience may no longer be director-approved. That’s a big departure for mainstream cinema, although in the days of Lt/Rt soundtracks on film, many operators had a screen or two hidden away having sound systems that reproduced a lesser, un-approved version of the format. The value of an audio distribution format that can be read by MDA-compliant systems, regardless of speaker arrangement, is that exhibitors once again would be able to tailor their investments in sound systems with the knowledge that all distributions could still be played in their auditoriums.
For DTS, the promotion of MDA is a smart move. As an open distribution format, it solves a big problem created by Dolby Atmos. Cinema operators probably do not understand the path that Dolby is on. Atmos is its means to take over next-generation home audio distribution and keep competitor DTS out. It will achieve this by giving or discounting Atmos systems to exhibitors, establishing a sizeable footprint, and enticing directors to produce Atmos mixes. Dolby locks its Atmos mixes such that downstream versions of the mix, in Blu-ray or in downloaded media, are not available for remix to a competing format. This will force studios to use a consumer format licensed only by Dolby, even if the consumer version of the mix is reduced to fewer tracks than the cinema version.
MDA has a long road to travel, however, before achieving widespread use. It has to be redefined in a manner that can be including in the digital cinema distribution package. The details of how the format is played back using existing media blocks, and how audio is rendered, must be worked out. Most important of all, there must be movies mixed in the format. There is no incentive for Dolby to make MDA successful, making the task of convincing directors and sound mixers to create mixes that are compliant with MDA a most important one.
At CinemaCon, Wilfried van Baelen, inventor of Auro 3D, personally pulled out his laptop computer and demonstrated to your author the ability to generate an MDA mix using the Auro 3D plugin for the Pro Tools sound mixing platform. It was quite impressive, and exactly the start that MDA needs. For Auro to move down the MDA path in cinema, however, is a big departure from its current proprietary distributions (that are compatible with 5.1 and 7.1 audio tracks). It is not known as to the degree that Barco is onboard with this. And there are those many pieces that must be in place to make an Auro/MDA distribution format a success. Let’s hope they take the leap.
