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System Overview
Envelop for Live (E4L) is an open source audio production framework for spatial audio composition and performance. Envelop for Live combines Ableton Live as a front end and music production environment with a Max/MSP application as a standalone spatial effects processor and renderer. Envelop for Live is designed to be a highly modular, flexible platform for artists to compose and perform spatial audio, and for developers to create new kinds of audio effects for the Ambisonics domain.
Ambisonics was originally developed for 3D sound recording and reproduction on speakers evenly distributed over a virtual sphere. It is a set of techniques for reconstructing a completely immersive sound field that emulates the way we hear naturally. Our brain identifies the directionality and location of audio by detecting the subtle differences between sound waves as they arrive at each ear. Ambisonics models these psychoacoustic principles digitally to create the perception of sound directionality. Sound field reconstruction techniques that started in the 1970’s have evolved to a high-fidelity format called Higher-Order Ambisonics (HOA) that can virtually position sound in 3D space. Here is a great technical introduction to HOA.
*Notes on nomenclature: Ambisonics has not fallen to set of standards and is referred to as multi-dimensional, 360 audio, 3D audio among others marketing terms. Other related terms are spherical surround sound, directional- and coordinate-based sound, spatial audio, sound field, etc.
“Binaural” recording and playback refers to a method of using a set of filters (called HRTFs) that simulates a spatial scene when content is played back using headphones. Because Ambisonics content can easily be transcoded into a stereo binaural signal, Envelop for Live can be used with headphones in a preview mode if an Ambisonic-capable array is not at hand. Since using Envelop for Live in binaural mode is the easiest way to get started, the first part of this guide is written for the binaural use case.
Ableton Live is a digital audio workstation (DAW) created by in 1999 by Robert Henke and Gerhard Behles. With its innovative “session view” that allowed musicians to perform and remix their works live, Ableton Live quickly became one of the most popular pieces of music software for electronic musicians. Its “Max for Live” product, built in collaboration with Cycling ‘74, allows developers to create new effects for the Live platform. Envelop for Live takes full advantage of Live’s capabilities, and expands Live’s limitations of its stereo bus to support an Ambisonic rendering environment.
The Envelop for Live system consists of a set of Max For Live devices that communicate via OSC and standard audio channels to a spatial processing server. The Envelop for Live server can run either on the same computer and connect its audio channels internally via the Jack program, or on a completely separate computer and connect using hardware audio interfaces. OSC messages are dispatched to the server via a "client" standalone Max patch, which allows a global view of the spatial audio “scene” as well as network control of the processing server.
Envelop is a nonprofit organization that amplifies the unifying power of music through immersive listening spaces, events, and open-source spatial audio software.