O3A Decoder - UHJ Stereo

O3A Decoder - UHJ Stereo

Host Support

Host TypeSupport


Output2UHJ Stereo


This plugin takes a third order ambisonics (O3A) mix and converts it into UHJ stereo. This form of stereo uses phase to encode a small amount of ambisonic surround sound information, which can be recovered later, for instance in special A/V receivers.

UHJ stereo was introduced in 1985 for use with first order ambisonics. It contains no height information, only takes audio from three of the sixteen channels that make up O3A and those channels cannot be recovered entirely. However, it does allow an impressive amount of spatial detail to be "hidden" in the stream while still being good to listen to in stereo.

UHJ stereo is sometimes used for artistic reasons, as stereo formed this way has particular sound qualities. For instance, UHJ produces a "phasey" stereo image when sounds are behind, which can be desirable.

For simple stereo decoding you might also wish to try the basic O3A Decoder - Stereo plugin from the O3A Core plugin library. The O3A Virtual Microphone from the same library also produces stereo.

This plugin uses a gain boost of +4.315dB relative to the common UHJ decoding equations, for consistency with other Blue Ripple Sound studio decoders.

The plugin is available in the O3A Decoding plugin library.