• Skip to main content
  • Skip to secondary menu
  • Skip to primary sidebar
  • Skip to footer

mkpeReport

top analysis covering digital cinema, 3-D, HFR, and laser illumination

  • Reports
  • About
  • mkpe.com
  • cinepedia.com

Backwards Compatibility in Sound

May 2014 by Michael Karagosian

Backwards compatibility in audio delivery can be somewhat contrary to the desire to preserve artistic intent. In order for backwards compatibility to exist, all of the sound must be available to not only the primary sound system, but also the secondary system. It is easy to say that a new SMPTE object-based format will be backwards compatible, but it requires careful thinking and strong guidelines to make this work in a manner that does not produce unintended results.

In the history of cinema, only a few formats have set out to actually accomplish backwards compatibility. Dolby Stereo, the matrixed format in which two channels of sound carry four channels of sound, could be played as a stereo track or a four channel track, without any loss of audio information. Not until recent years has this capability been again pursued. In Auro 11.1, also discussed in an earlier report, all of the sound targeted for an 11.1 system can also be heard as a 5.1 track. Dolby Atmos offers backup capability, which could be applied in a backwards compatible manner, although that is not Dolby’s intent. Atmos carries a full 5.1 or 7.1 mix in addition to the channels and objects that comprise the Atmos mix. The 5.1 or 7.1 mix is selected automatically by the Dolby processor should a problem occur.

To be backwards compatible in a manner that remains within the realm of artistic intent requires agreement as to which formats one is to be backwards compatible with. If sound artists are to have their say, then we can’t simply talk about being able to play the audio distribution on a system of arbitrary design. In this regard, there is agreement in the industry for the 5.1 and 7.1 formats, but above that plane of speakers, there is no agreement for speaker layouts. Both Atmos and Auro utilize different speaker layouts. This poses a problem in the general utility of a SMPTE OBA distribution, for if the format is to be successful, it must play on all defined speaker layouts.

How backwards compatibility is realized has not yet been a discussion in SMPTE or anywhere, for that matter. DTS claims an MDA mix can play on any speaker system, MDA has not been put to the test. No movies have been mixed in MDA, and it is the opinions of sound designers and sound mixers that matter more than demonstrations at trade shows. There is the example of Dolby Atmos that is completely contrary to the DTS position. Dolby surely is capable of designing a rendering engine that can fold down an Atmos mix to a 5.1 speaker system. But instead of taking that route, Dolby chose to include a discrete and separate 5.1 (or 7.1) mix in the Atmos distribution.

When choosing to carry a discrete and separate 5.1 or 7.1 mix alongside the Atmos mix, Dolby took the safe route. It was probably too difficult to get mixing engineers to agree to algorithmic mix downs. One would expect that mixers prefer to be in control of all aspects of their mixes, and not allow anything to chance. For example, a sound mixer may prefer that a sound pan over the audience’s heads in Atmos is better positioned in the rear of the room in a 7.1 mix – not the kind of mixing decision one can count on an algorithm for.

Of course, there are ways to guide an algorithmic mix in the rendering engine, such as the inclusion of mix coefficients for a particular speaker layout. But the inclusion of infinite ways of controlling infinite speaker layouts is obviously not practical.

A parallel discussion to that of backwards compatibility is the eventual elimination of the main audio track file in the DCP. If SMPTE OBA is successful, and audio rendering engines are eventually installed in all cinemas, the 16-channel main audio track file will become redundant. This may sound trite, but the digital cinema package, by definition, must include both an image track file and a main audio track file. If we are to one-day eliminate the main audio track file, it would be worth our time to plan that path today. Besides the long term impact, it will also have affect how we think about backwards compatibility.

The point made is that for all of the smoke blown about one object-based format versus another, core issues that will impact the future logistics of the industry, such as the eventual replacement of the 16-channel main audio track file and how backwards compatibility is accomplished, have not yet been seen on an agenda.

Filed Under: Sound Tagged With: Auro3D, Dolby Atmos, Immersive Sound, MDA

Primary Sidebar

Search

Topics

  • 3-D
  • Accessibility
  • Alt Content & Advertising
  • Anti-Piracy
  • Color
  • Communications
  • Deployment Entities
  • Distributors
  • Exhibitors
  • Fulfillment
  • High Dynamic Range
  • Higher Frame Rates
  • Installations
  • Patents
  • Projectors
  • Servers and IMBs
  • Sound
  • Technical Bodies
  • Theatre Management Systems
  • Trade Organizations and Shows

Full Archives

a publication of
MKPE Consulting LLC

Footer

Important Stuff

  • About
  • Privacy Policy

Archives

  • Category & Monthly Archives
Archives date back to 2008.

MKPE

mkpeReport is a publication of MKPE, a world-class consultancy building business at the crossroads of cinema and technology.
Learn more about MKPE.

copyright © 2008 - 2023 mkpe consulting llc

We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. By clicking “Accept”, you consent to the use of all cookies.
Cookie settingsACCEPT
Manage consent

Privacy Overview

This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience.
Necessary
Always Enabled
Necessary cookies are absolutely essential for the website to function properly. These cookies ensure basic functionalities and security features of the website, anonymously.
CookieDurationDescription
cookielawinfo-checbox-analytics11 monthsThis cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Analytics".
cookielawinfo-checbox-functional11 monthsThe cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional".
cookielawinfo-checbox-others11 monthsThis cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other.
cookielawinfo-checkbox-necessary11 monthsThis cookie is set by GDPR Cookie Consent plugin. The cookies is used to store the user consent for the cookies in the category "Necessary".
cookielawinfo-checkbox-performance11 monthsThis cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Performance".
viewed_cookie_policy11 monthsThe cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. It does not store any personal data.
Functional
Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features.
Performance
Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors.
Analytics
Analytical cookies are used to understand how visitors interact with the website. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc.
Advertisement
Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. These cookies track visitors across websites and collect information to provide customized ads.
Others
Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet.
SAVE & ACCEPT
Powered by CookieYes Logo