LV2UI

LV2UI is an extension of the LV2 audio plugin standard that defines how user interfaces for LV2 plugins are integrated and communicate with the host. Its primary purpose is to allow plugin UIs to run in a separate process from the host, enabling isolation, more flexible GUI toolkits, and easier stability and security management. While LV2 provides the core plugin and port model, LV2UI focuses on the user interface lifecycle and communication between the UI and the plugin.

The core idea of LV2UI is to decouple the plugin’s UI from the host or the plugin’s own processing code. In this model, the host may spawn an external UI (often as a separate executable) that connects to the plugin’s ports and receives state updates or sends user actions back to the plugin. This separation allows UI toolkits and frameworks that may not be suitable inside the host process to run safely, and it supports multiple UIs for a single plugin if needed. The host manages the UI lifecycle, while the UI uses a defined message protocol to exchange parameter changes, automation, and other control data with the plugin.

LV2UI is supported by a range of LV2-capable hosts and plugins, particularly on Linux and other desktop platforms, with varying levels of integration. It is optional within the LV2 ecosystem and may be used to provide rich, responsive interfaces for complex audio tools. Developers implement LV2UI by adhering to the LV2UI protocol and using the appropriate helper libraries, while hosts implement UI spawning, routing, and message handling.

See also: LV2, LV2 Core Specification, LV2UI protocol, external UIs.