Crate synthizer

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Bindings to Synthizer. For documentation of the library itself, see the book. This documentation covers aspects specific to the Rust bindings which map to the C bindings in a relatively straightforward manner


Synthizer Handles are reference-counted pointers which work like Arc. All the objects in this library that correspond to Synthizer objects (e.g. BufferGenerator but not CustomStreamDef) impl Clone and internally contain a handle. So, e.g:

use synthizer as syz;
let ctx = syz::Context::new()?;
// Refers to the same context.
let ctx2 = ctx.clone();


To initialize the library, use either initialize or the LibraryConfig type. These will give you a InitializationGuard which must be kept alive for the duration of the program. After the InitializationGuard goes out of scope, Synthizer functions all error.


Properties are modeled as a property() method which returns an intermediate object that has methods on it. For example, obj.playback_position().set(5.0). Object properties aren’t type checked but error if using an object of the wrong type at runtime. An internal trait, ToSyzHandle, is implemented for all library types.

Common Functionality

All Synthizer objects implement a set of common methods on their struct. When the Synthizer manual refers to things like syz_pause, this can be found as .pause() on all applicable objects.


Synthizer supports userdata, which can be used to tie application entities to Synthizer objects via Arc<Any>. This is set by e.g. Handle::set_userdata. Note that unlike Synthizer itself, the Rust bindings have to put userdata behind a std::sync::RwLock to offer thread safety,.

Casting Objects

Synthizer itself is modeled as a hierarchy of “classes”. For example Source is a “base class” of all sources. This is handled in Rust via adding a cast_to method to all Synthizer types, which can be used to attempt to cast to other object types when possible. For example Source3D to Source, but also Handle to Source3D.

Where this cast is infallible, From impls are provided.

Custom Streams

Custom streams are possible via CustomStreamDef and register_stream_protocol. See the documentation on those types for more info. In general, it is possible to convert anything implementing std::io::Read and std::io::Seek to a custom stream by implementing CloseStream for that type or a wrapper struct thereof.

Optional Features

Synthizer has the following optional features:

  • asset_lru: Enable support for asset_lru via AssetLruDecoder, which implements the asset_lru decoding traits.




  • Suggested default Q for filter design functions. If you don’t have a better idea what value of Q to use, this is what you want.


  • A trait which custom streams must implement in order to support closing.
  • A Stream, but one which also implements Seek.
  • Marker trait for types which implement non-seekable streams.


  • Query the underlying Synthizer version, returning a (major, minor, patch) tuple. This isn’t the version of the crate, but of the bound library.
  • Initialize Synthizer, returning a InitializationGuard which must be kept alive for the duration of your program.
  • register a custom protocol.

Type Definitions

  • Re-exported Synthizer syz_EchoTapConfig type. Using this instead of a dedicated struct prevents needing to clone your taps on the way to Synthizer.