OSC

Open Sound Control (OSC) is an open, network-based protocol for real-time communication among multimedia devices, software, and installations. It was developed in the 1990s by the Center for New Music and Audio Technologies (CNMAT) at the University of California, Berkeley, led by Adrian Freed, to provide a flexible alternative to MIDI for expressive control over networks and devices.

OSC messages are typically transported over UDP, though other transports can be used. A message consists of an address pattern, such as /synth/osc1/frequency, followed by a comma and a typetag string that describes the data types of the accompanying arguments. Type tags include i for 32-bit integers, f for 32-bit floats, s for strings, b for binary blobs, and others. Additional data types and special tags handle boolean values, timetags, and nulls. Messages can be grouped into bundles, which may contain multiple OSC messages and nested bundles. Bundles include a timetag, expressed in an NTP-based format, to enable scheduled delivery across devices.

OSC is widely used in music and multimedia contexts for control of synthesizers, effects, and software instruments, as well as interactive installations and art projects. It offers rich addressing and data types beyond MIDI, supports precise timing, and is designed to be cross-platform and extensible. It is not a formal standard, but it has become a de facto standard in many audio and media workflows.

Implementations and libraries are available in many languages and environments, including liblo, oscpack, python-osc, node-osc, and bindings in Max/MSP, Pure Data, SuperCollider, Processing, and various hardware controllers.