Crate jack

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Rust bindings for JACK, a real-time audio and midi library.


JACK provides a high priority server to manipulate audio and midi across applications. The rust jack crate does not provide server creation functionality, so a server has to be set up with the jackd commandline tool, qjackctl the gui tool, or another method.


Typically, applications connect clients to the server. For the rust jack crate, a connection can be made with client::Client::new, which returns a client::Client.

The Client can query the server for information, register ports, and manage connections for ports.

To commence processing audio/midi and other information in real-time, rust jack provides the Client::activate_async, which consumes the Client, an object that implements NotificationHandler and an object that implements ProcessHandler and returns a AsyncClient. AsyncClient processes the data in real-time with the provided handlers.


A Client may obtain port information through the Client::port_by_id and Client::port_by_name methods. These ports can be used to manage connections or to obtain port metadata, though their port data (audio buffers and midi buffers) cannot be accessed safely.

Ports can be registered with the Client::register_port method. This requires a PortSpec. The jack crate comes with common specs such as AudioIn, AudioOut, MidiIn, and MidiOut.

To access the data of registered ports, use their specialized methods within a ProcessHandler callback. For example, Port<AudioIn>::as_mut_slice returns a audio buffer that can be written to.


pub use jack_sys;


A JACK client that is processing data asynchronously, in real-time.

AudioIn implements the PortSpec trait which, defines an endpoint for JACK. In this case, it is a readable 32 bit floating point buffer for audio.

AudioOut implements the PortSpec trait, which defines an endpoint for JACK. In this case, it is a mutable 32 bit floating point buffer for audio.

The maximum string length for port names.

Option flags for opening a JACK client.

Status flags for JACK clients.

Wrap a closure that can handle the process callback. This is called every time data from ports is available from JACK.

Internal cycle timing information.

MidiIn implements the PortSpec trait, which defines an endpoint for JACK. In this case, it defines midi input.

Iterate through Midi Messages within a Port<MidiIn>.

MidiOut implements the PortSpec trait, which defines an endpoint for JACK. In this case, it defines a midi output.

Write midi events to an output midi port.

The maximum string length for port names.

The maximum string length for jack type names.

An endpoint to interact with JACK data streams, for audio, midi, etc…

Flags for specifying port options.

ProcessScope provides information on the client and frame time information within a process callback.

Contains 8bit raw midi information along with a timestamp relative to the process cycle.

A lock-free ringbuffer. The key attribute of a ringbuffer is that it can be safely accessed by two threads simultaneously, one reading from the buffer and the other writing to it - without using any synchronization or mutual exclusion primitives. For this to work correctly, there can only be a single reader and a single writer thread. Their identities cannot be interchanged.

Read end of the ring buffer. Can only be used from one thread (can be different from the write thread).

Write end of the ring buffer. Can only be used from one thread (can be a different from the read thread).

A structure for querying and manipulating the JACK transport.

Transport Bar Beat Tick data.

A structure representing the transport position.

A helper struct encapsulating both TransportState and TransportPosition.

PortSpec for a port that holds has no readable or writeable data from JACK on the created client. It can be used to connect ports or to obtain metadata.


Specify an option, either to continue processing, or to stop.

An error that can occur in JACK.

An error validating a TransportBBT

A representation of transport state.


Specifies callbacks for JACK.

Defines the configuration for a certain port to JACK, ie 32 bit floating audio input, 8 bit raw midi output, etc…

Specifies real-time processing.


Return JACK’s current system time in microseconds, using the JACK clock source.

Type Definitions

Type used to represent sample frame counts.

A client to interact with a JACK server.

Ports have unique ids. A port registration callback is the only place you ever need to know their value.

Type used to represent the value of free running monotonic clock with units of microseconds.