JackTrip Mixers for SuperCollider

Copyright (c) 2020-2021 JackTrip Labs, Inc.

Licensed under the Apache License 2.0. Please see LICENSE for more information.

This repository contains source code used to run SuperCollider on JackTrip Virtual Studios.

For local development and testing, clone this repository into your SuperCollider Extensions directory, or any other location that is loaded by your sclang interpreter.

Mixers

Mixers are used to process audio for all JackTrip and Jamulus clients. The mixers directory contains one subdirectory for each type of mixer. Mixers always take the maximum number of clients as an argument to new. For example, to create a simple mixer that supports up to 10 clients, use SimpleMix(10).

An assumption is currently made that every client will have two audio input channels and two audio output channels. You must run SuperCollider with enough channels (and for some mixers, busses) to accomodate the maximum number of clients. For example, 10 clients requires 20 input channels and 20 output channels. You can configure your server to support this by modifying your startup.scd file:

Server.default.options.numInputBusChannels_(20).numOutputBusChannels_(20);

Be very careful not to create mixers with maxClients greater than your number of input and output channels. This will cause it to wrap-around, leading to unnatural results.

BaseMix

All mixers extend the BaseMix class, which contains several common methods:

• connect: establishes a connection to your audio server. By default, this will be your local server, but you can also connect to remote servers by setting serverIp.

• wait: this will block until the mixer has started processing audio.

• after: this can be used to provide a function that is executed after the mixer has started processing audio.

By convention, mixers should also implement a start method which starts processing audio.

For example, to start a simple mixer on your local SuperCollider server for two clients, run:

~maxClients = 1;

~mixer = SimpleMixer(~maxClients).withJamulus_(false);

Routine {
    ~mixer.connect.start.wait;
}.run;

To start a simple mixer on a remote audio server with IP address 10.20.1.10:

Routine {
    SimpleMixer(2).serverIp_("10.20.1.10").connect.start;
}.run

Note that you can use serverIp to connect to and run mixers on remote virtual studios.

Using SynthDefs

It is often useful to share the code for synthdefs. The links and functions directories contain some common code that may be useful.

Additionally, we have established a convention that makes it easier for mixers to load and send synthdefs. The synthdefs directory has one file per definition. Each file includes a function named ~synthDef.

The BaseMix class implements a useSynthDef (and useSynthDefs plural) method. It takes a string that is the name of a synthdef; it should match the name of a file in the synthdefs directory. This implements a simple cache that avoids having to resend the definitions repeatedly. To disable it, set useSynthCache_(false).