LV2

LV2 is an open and extensible standard for audio plugins and their hosts. Designed as a successor to LADSPA, LV2 aims to provide a stable, flexible framework for real-time audio processing while enabling bodies of optional features through extensions. It defines how plugins (the processors) and hosts (the players) communicate, load, and run in a consistent way across platforms.

In LV2, plugins are distributed as shared libraries and discovered by hosts through a standard descriptor interface. A plugin declares its ports and capabilities via a LV2 descriptor, exposing a set of ports that can be audio, control, or event ports. During operation, a host instantiates the plugin, connects ports to buffers or other plugins, and calls a run routine to process blocks of samples in real time. The design emphasizes sample-accurate audio processing, deterministic scheduling, and safe interaction with the host’s GUI and automation.

LV2 is built around an extension mechanism. The core specification covers the basic plugin-host model, while numerous optional extensions add features such as user interfaces (LV2UI), structured data transport (Atom), time and transport information, MIDI handling, and state saving. Extensions are identified by URIs, allowing hosts and plugins to negotiate capabilities at load time without requiring all participants to implement every feature.

The LV2 ecosystem is widely adopted in the Linux audio community and is supported by many hosts, including Ardour, Qtractor, and other digital audio workstations, as well as a broad array of LV2-enabled plugins. Its design emphasizes portability, openness, and community-driven development, making LV2 a common choice for modular audio processing.