Downmix
Definition
The process of reducing a multichannel audio mix to fewer channels — typically from surround or immersive formats to stereo. Downmixing applies specific gain coefficients to combine channels while attempting to preserve the spatial balance and overall loudness of the original mix.
In Simple Terms
Converting a surround or Atmos mix down to stereo (or from 7.1 to 5.1, etc.). The software follows mathematical rules to fold the extra channels into fewer ones. A good mix translates well to downmix; a bad one falls apart — elements disappear or the balance shifts dramatically.
In Practice
A Dolby Atmos music mix is automatically downmixed to stereo by the Atmos Renderer for listeners on standard headphones or stereo speakers. The mixing engineer checks this downmix regularly during the Atmos session to ensure nothing critical is lost.
Dolby Atmos Context
The Dolby Atmos Renderer generates downmixes automatically, but the result depends entirely on how the mix was built. Objects panned hard to height channels may become inaudible in a stereo downmix if their downmix coefficients reduce them too far.