‘Immersive’ or ‘3D sound’ in cinema – Dolby Atmos, Barco Auro 11.1, DTS MDA and their like – is becoming increasingly ubiquitous, with evermore theatres installing Atmos (or equivalent) rigs and no less than five Oscars won by films utilising the technology at the 2014 Academy Awards. So, with sound for cinema arguably moving into the ‘age of Atmos’, what does this mean for audio in post-production?
Fresh from providing a “full range of mastering and distribution services” for the summer super hero blockbuster X-Men: Days of Future Past – a mammoth task that involved creating no less than 137 (!) unique digital cinema packages (DCPs) for distribution to cinemas around the globe – the ladies and gentlemen of Soho-based Deluxe Digital Cinema invited PSNEurope to their fully Atmos-equipped theatre room (pictured) for behind-the-scenes look at Dolby Atmos in the post environment.
Deluxe’s speciality is the creation and distribution of said DCPs for both US (English) and worldwide foreign-language release. A DCP is a set of files of files that make up a cinema presentation, traditionally comprising three distinct sources: video (hi-res image files, each a scan of a single frame of film), subtitles (both 2D and ‘dynamic’ 3D animated text) and audio (one 24-bit, 48kHz PCM standard channel-based audio).
However, with an Atmos movie, there is a fourth element: an immersive audio MXF (an open-source container format for video and audio) containing the ‘beds’ and objects.
Beds contain the audio that is not location-specific, such as atmospherics, while objects are given specific locations within the 3D soundscape. Deluxe says the Atmos system “generates the optimal soundtrack for the theatre […] and reproduces the objects on one or more of the channels closest to the location specified in the MXF”.
On the subject of how much including a Dolby Atmos track in the DCP increases the file size (the Atmos sync track is on a separate channel to those used by the standard 5.1 or 7.1 audio), Andy Scade, director of digital cinema at Deluxe, assures us it’s negligible – which must be welcome news when the facility is increasingly moving away from sending physical hard drives to theatres towards “new electronic delivery options” like network and satellite delivery.
We’re also told that each element of each DCP is encrypted, and recipient cinemas require a ‘key delivery message’ (KDM) to unencrypt each part of the media (image, audio and subtitle). For films with a Dolby Atmos track, an extra KDM is needed.
According to Scade, Deluxe currently packages some 200 feature films a week – and the number of DCPs that include an Atmos audio component will only continue to increase as immersive sound technologies continue their relentless march into cinemas around the world.
PSNEurope reported on the rise of Dolby Atmos and immersive audio, and its positive knock-on effect for cinema speaker manufacturers, in May’s issue. Commenting, Guy Hawley, senior director of cinema sales and services, EMEA, at Dolby Laboratories, tells us: “Since its début in April 2012, Dolby Atmos has been embraced by all the major Hollywood studios and award-winning sound mixers. The post-production community has responded really well – today, more than 40 digital cinema mastering and duplication facilities, and more than 55 sound mixing facilities, are equipped to support Dolby Atmos.
“With more than 120 films from 12 different countries released or scheduled to be released in Dolby Atmos, we can only expect this momentum to continue.”