Runtime for the [Pure Data] (Pd) audio programming language, implemented as an extensible audio library allowing full control over signal processing, message passing, and graph manipulation.
Implemented in Rust with intent to target embedded (i.e. no_std) platforms.
Adapted from [ZenGarden], which was written in C++.
The following four types provide the main interface to PureZen:
ContextGraphObjectMessageThe first three have to do with how the signal graph is organized. The latter represents discrete messages which are sent into, processed by, and out of the graph.
A Context represents a unique and independent instance of Pure Data.
Think of it as Pure Data's console window. A context is defined by its
block size, sample rate, and the number of input and output channels.
Contexts are entirely independent and messages and objects cannot be exchanged
between them.
A graph is a collection of objects and the connections between them.
A Graph is an Object, and thus a Graph can contain other Graphs
(such as abstraction or subgraphs).
Message represents any Pd message, be it a bang or a list of assorted float,
symbols, or bangs. Each Message is timestamped and contains at least one
element, and may otherwise contain any number and any combination of
primitives. PureZen messages are always lists of typed elementary types.
Graph attachment is an important concept in PureZen.
Whenever any change in the signal graph takes place in Pd, the audio thread must wait until the reconfiguration is finished. For minor changes such as removing a connection this can be very fast and avoid underruning the audio buffer.
For larger changes, such as adding an object requiring significant initialization, or many changes at once, such as adding a complex abstraction, audio underruns are almost guaranteed.
PureZen solves this problem by allowing an new object or graph to be created on another thread, and then attached to a context at a convenient time. As the graph has already been instantiated, the attachement process is a relatively quick one and can thus be accomplished without causing any audio dropouts.
Graph attachement generally involves registering global senders and receivers and ensuring that existing objects are aware of the new ones. Similarly, a graph can be unattached from a context, leaving it in memory yet inert.
Copyright © 2009-2019 Tony Arcieri, Martin Roth.
PureZen is licensed under the [LGPL 3.0], which means: