Channel-Based Audio
Definition
An approach to audio production and delivery in which each sound is mixed into a fixed set of discrete channels, each mapped to one loudspeaker position in a defined layout such as stereo (2.0), 5.1 or 7.1. The mix is bound to that layout, and playback on a different one requires a downmix or an upmix.
In Simple Terms
Channel-based audio sends each sound to a channel, a feed that goes to one fixed speaker. Stereo has 2 channels, left and right. 5.1 surround has 6: front left, center, front right, two surrounds at the sides and back, and one for deep bass called LFE. The mix is made for that exact speaker layout.
Common Confusion
A mix is made for one speaker layout. A 5.1 mix has 6 channels, but a stereo system has only 2. A downmix, a conversion to fewer channels, blends the center and surround channels into left and right. The LFE is usually left out, unless a subwoofer can play it, as in a 2.1 system. Now the dialogue, the music and the rain share two speakers, so how you perceive the balance can change.
Dolby Atmos Context
Dolby Atmos keeps a channel-based layer, the bed, and adds objects on top of it.
Sources & Verification
- OP-60. Multi-Channel Sound Track Down-Mix and Up-Mix, Issue 3Free TV Australia, 2014
- ITU-R BS.775-4. Multichannel stereophonic sound system with and without accompanying pictureInternational Telecommunication Union, 2022
Last verified: 2026-10-26