Learn Metadata

Getting Started

Welcome to RNBO


RNBO Basics

Key Differences

Why We Made RNBO

Coding Resources


Audio IO

Messages to rnbo~

Using Parameters


Messages and Ports

Polyphony and Voice Control

Audio Files in RNBO

Using Buffers

Using the FFT

Export Targets

Export Targets Overview

Max External Target
Raspberry Pi Target
The Web Export Target
The C++ Source Code Target

Code Export

Working with JavaScript
Working with C++

Special Topics

Sample Accurate Patching
Scala and Custom Tuning

RNBO and Max for Live

RNBO Raspberry Pi OSCQuery Runner


Export Description

Raspberry Pi GPIO

Updating the RNBO Package


Add custom metadata to parameters, inlets, and outlets. Use that metadata however you like to support your own workflows.

RNBO supports the addition of metadata to param and param~ objects, inlets and outlets, as well as inport and outport objects. In all cases, use the @meta attribute to add arbitrary information that will be associated with the object on export. This metadata can be included either as a JSON string, or using a simplified key-value syntax. Metadata will be available as part of the export description for source code targets. The Raspberry Pi target will also make metadata available through the OSCQuery HTTP interface.

Including Metadata

The simplest way to add metadata to a parameter is with a JSON string.


This has no effect in the RNBO editor in Max, but will be included in the parameter description after export.


It's also possible to enter parameter metadata into the Metadata attribute using the inspector.


Finally, the @meta attribute also supports a simple key-value syntax. In this usage, string values must be wrapped in single quotes.


Retrieving Metadata

The source code targets will include metadata in their parameter descriptions. After C++ export, the description.json file will include metadata in its JSON.


The web export artifact is itself a JSON file, containing source code in JavaScript and WASM, as well as the description of the exported patch. Any parameter metadata can be found in that file as well.


Metadata and Audio Plugin Export

The RNBO Plugin export, which uses JUCE to build VSTs and Audio Units, can recognize some @meta values as well. Use these special metadata keys to configure the behavior of your plugin export. If you're working with the JUCE template code, then your application will support this same behavior by default. For more information about using these keys with Audio Plugin export, see The Meta Attribute.

Metadata and Raspberry Pi

The RNBO Runner on the Raspberry Pi can report parameter metadata through its OSCQuery HTTP interface. If there is a Raspberry Pi on your local network, with the IP address, then you can make an HTTP GET request to to retrieve information about the parameter freq. The response will contain parameter metadata, if any.