ReWire

ReWire
Name	ReWire
Developer	Propellerhead Software, Steinberg Media Technologies
Released	1998
Latest release	2000s (protocol updates)
Operating system	Mac OS, Microsoft Windows
License	Proprietary

ReWire is a software protocol for real-time audio and MIDI streaming between compatible applications on the same computer. It was introduced to enable synchronization and data exchange between digital audio workstations and virtual instruments, allowing applications such as sequencers, samplers, and synthesizers to interoperate without manual audio routing. The protocol achieved widespread adoption among audio software developers and music producers, influencing the design of later inter-application audio systems and integration features in products from established companies.

Overview

ReWire functions as a host-slave audio and MIDI transport protocol that permits multi-application session management and sample-accurate synchronization. It was developed to connect products from companies like Propellerhead Software and Steinberg Media Technologies while supporting integration with applications such as Ableton Live, FL Studio, Cubase, Logic Pro, and Pro Tools. The protocol provides channelized audio buses, MIDI routing, timeline synchronization, and transport control between connected applications, enabling workflows that combine virtual instruments from Native Instruments, samplers from NI Kontakt, and effect racks from Waves Audio within a single synchronized environment.

History

ReWire originated in the late 1990s as a collaboration between music software firms seeking better interoperability between host applications and plug-in style sound sources and sequencers. Early adoption was driven by companies including Propellerhead Software—notably for integration with their Reason workstation—and Steinberg Media Technologies to facilitate communication with Cubase. Throughout the 2000s ReWire became supported by a broad range of vendors such as Image-Line, Apple Inc., Avid Technology, Sony Creative Software, and boutique developers that produced virtual instruments and sound design tools. Over time, alternative approaches like Audio Units, VST, ASIO, and operating-system level audio routing features offered overlapping functionality, affecting ReWire’s prominence in newer releases from several manufacturers.

Architecture and Protocol

The ReWire protocol is built on a master-slave model where a single ReWire host controls one or more client applications. The architecture defines transport commands (play, stop, locate), tempo and position synchronization, and channelized audio streams—typically supporting dozens of mono or stereo channels. Timing is achieved via sample-accurate callbacks that align playback position across applications, similar in purpose to synchronization mechanisms used by MIDI clock in hardware setups. The protocol exposes virtual audio buses that appear to the host as input channels and to the client as output channels, facilitating routing between applications without intermediate virtual audio devices like Soundflower or Jack Audio. For MIDI, ReWire transmits note and controller messages alongside position information to maintain compositional consistency between sequencers from vendors such as MOTU and softsynths from Korg.

Implementations and Compatibility

ReWire was implemented on Mac OS and Microsoft Windows and shipped in host and device SDKs that enabled integration into products from Ableton, Image-Line, Propellerhead Software, Steinberg, and others. Notable products offering ReWire hosts included Cubase, Logic Pro, Pro Tools, Ableton Live, and FL Studio; clients included Reason, Reaktor, and various standalone synths and samplers from companies such as Native Instruments and Spectrasonics. Compatibility layers in creative software suites allowed cross-vendor setups combining elements from Steinberg VST hosts, Apple Logic, and Avid environments. Over successive OS updates and application generations, some vendors deprecated ReWire in favor of native plugin formats like VST3 and Audio Units while legacy support remained in many professional studios that relied on established toolchains.

Use Cases and Applications

Typical use cases included hosting a virtual rack from one application inside the timeline of another, streaming multitrack audio from a softsynth into a DAW, synchronizing tempo changes between pattern-based sequencers and linear editors, and recording live performances across multiple software instruments. Producers combined modular toolchains involving Reason, Kontakt, and Ableton Live for sound design, arranging, and live looping. Film and game audio professionals used ReWire to align granular synthesis tools alongside multitrack mixers from companies like Avid Technology in post-production workflows. Educational institutions and media labs employed ReWire-enabled setups to teach composition with hybrid environments mixing applications from Steinberg, Propellerhead, and Image-Line.

Reception and Criticism

ReWire received praise for enabling unprecedented cross-application workflows during a period when plugin standards were less universal. Reviewers and users lauded its sample-accurate sync and multichannel routing, with positive mentions in publications and forums discussing tools from Sound on Sound, MusicRadar, and specialist communities centered on Reason Forums and Gearslutz. Criticism focused on the complexity of setup, potential for increased CPU and memory overhead, and limited cross-platform feature parity as operating systems evolved. Some developers argued that ReWire’s host-slave model constrained innovative routing possibilities compared with more flexible plugin APIs championed by Steinberg and Apple.

Security and Privacy Considerations

As an inter-application audio bridge, ReWire operates within the local user session and does not define networked transport, reducing exposure to remote attack vectors common in Internet-facing protocols. Nevertheless, integration between privileged host applications such as Pro Tools and third-party clients raised concerns about process stability, privilege escalation through buggy SDK implementations, and unintended leaking of audio or MIDI data between projects. Best practices advised by vendors like Propellerhead Software and Steinberg included running updated application versions, sandboxing where supported by Mac OS and Microsoft Windows, and auditing third-party ReWire clients from vendors such as Native Instruments and Spectrasonics for secure behavior.

Category:Audio software protocols