Overview

A Virtual Loopback is a mechanism for two or more applications to communicate with each other over MIDI.

Suggested Uses

If you want to have loopback endpoints which are always available for routing between applications, have a single name like existing MIDI 1.0 loopback drivers, but do not want them to be controlled by the applications themselves, this is the right kind of endpoint to set up.

Configuration

As with all configuration file changes, you must use the MIDI Settings app. Direct modification of the configuration file is not supported.

Here’s an example configuration section for the Virtual Basic Loopback MIDI 1.0 endpoints.

"endpointTransportPluginSettings":
{
    "{8BEBE745-291B-4860-A82A-C9726E402E49}":
    {
        "_comment": "Basic MIDI 1.0 Loopback MIDI",

        "create":
        {
            "{0C1B3439-593F-4B7A-8950-4698D97B0897}":
            {
                "_comment" : "the above GUID is the unique association Id for this loopback",
                "endpoint":
                {
                    "name": "Perm Loopback 1",
                    "description": "This is a loopback I created in the configuration file",
                    "uniqueIdentifier": "3263827"
                }
            },
            "{B21B4973-3F85-48A0-8BA3-B35F44683D36}":
            {
                "_comment" : "the above GUID is the unique association Id for this loopback",
                "endpoint":
                {
                    "name": "Perm Loopback 2",
                    "description": "This is a loopback I created in the configuration file",
                    "uniqueIdentifier": "5150-1984"
                }
            }
        }
    }
}

Each loopback endpoint is identified by a GUID for the association id. This was created to ensure there’s a persistent identifier the app can use to add/remove the endpoint. The association GUID must be a valid unique GUID and shall not be an empty (all zeroes) GUID.

Implementation

Internally, the Virtual Loopback is implemented as one endpoint which is wired out-to-in. So anything sent out to the loopback Destination/Output port arrives on the Source/Input of the same loopback endpoint. There’s no practical limit to the number of loopback pairs you can define.