Upmixing

Upmixing is the process of deriving a greater number of audio channels from a source that has fewer, such as creating a surround mix from mono or stereo material.^[1] Algorithms analyze the original signal to distribute and place its content across additional channels, producing a wider and more enveloping presentation.

It is commonly used to adapt legacy or stereo content for surround and immersive formats, or to add spaciousness where multichannel stems are not available. Skillful upmixing preserves the balance and intent of the original while avoiding artifacts, since aggressive processing can blur the localization the source relied on.^[2]