Editing Open Sound Control (section)

== Design ==
OSC messages consist of an address pattern (such as <code>/oscillator/4/frequency</code>), a type tag string (such as <code>,fi</code> for a [[float32]] argument followed by an [[int32]] argument), and the arguments themselves (which may include a time tag).<ref name=":1" /> Address patterns form a [[Namespace|hierarchical name space]], reminiscent of a [[Unix]] [[filesystem]] path, or a [[Uniform Resource Locator|URL]], and refer to "[[Method (computer programming)|Methods]]" inside the server, which are invoked with the attached [[Parameter (computer programming)|arguments]]. Type tag strings are a compact string representation of the argument types. Arguments are represented in [[Binary number|binary]] form with four-[[byte]] alignment. The core types supported are

* 32-bit [[two's complement]] signed integers
* 32-bit [[IEEE 754-2008|IEEE floating point]] numbers
* [[null-terminated string|Null-terminated]] arrays of eight-bit encoded data (C-style [[string (computer science)|string]]s)
* arbitrary sized [[Binary large object|blob]] (e.g. audio data, or a video frame)

An example message is included in the spec (with null padding bytes represented by ␀): <code>/oscillator/4/frequency␀,f␀␀</code>, Followed by the 4-byte float32 representation of 440.0: 0x43dc0000.<ref>{{Cite web |last=Wright |first=Matt |date=March 29, 2002 |title=Examples Supporting the OpenSoundControl 1.0 Spec |url=https://opensoundcontrol.stanford.edu/spec-1_0-examples.html#argument |access-date=2023-01-01 |website=opensoundcontrol.stanford.edu |edition=}}</ref>

Messages may be combined into bundles, which themselves may be combined into bundles, etc.  Each bundle contains a timestamp, which determines whether the server should respond immediately or at some point in the future.<ref name=":1" />

Applications commonly employ extensions to this core set. More recently some of these extensions such as a compact Boolean type were integrated into the required core types of OSC 1.1.

The advantages of OSC over [[MIDI]] are primarily internet connectivity; [[data type]] resolution; and the comparative ease of specifying a symbolic path, as opposed to specifying all connections as seven-bit numbers with seven-bit or fourteen-bit data types.<ref name=":1">{{cite web |last=Wright |first=Matt |date=March 26, 2002 |title=The Open Sound Control 1.0 Specification |url=https://opensoundcontrol.stanford.edu/spec-1_0.html |access-date=22 December 2019 |website=opensoundcontrol.org |edition=}}</ref>  This human-readability has the disadvantage of being inefficient to transmit and more difficult to parse by embedded firmware, however.<ref name=":0" />

The spec does not define any particular OSC Methods or OSC Containers.  All messages are implementation-defined and vary from server to server.