Using JackTrip in the HUB Mode
In this class we will use JackTrip for audio over network connections but there were some successful tests with the Zita-njbridge. JackTrip can be used for peer-to-peer connections and for server-client setups. For the latter, JackTrip was extended with the so called HUB Mode for the SPRAWL System and the EOC in 2019-20.
For connecting to a server or hosting your own instance, the machine needs to be connected to a router directly via Ethernet. WiFi will not result in a robust connection and leads to significant dropouts. JackTrip needs the following ports for communication. If a machine is behind a firewall, these need to be added as an exception:
establish connection (server only)
The Nils Branch
Due to the increasing interest, caused by the pandemic, and the endless list
of feature requests, the Jacktrip project has been growing rapidly in since early 2020
and the repository has many branches.
In this class we are using the
nils branch, which implements some unique features we need for the
flexible routing system. Please check the instructions for compiling and installing a specific branch: Compiling JackTrip
Before starting JackTrip on the server or the clients, a JACK server needs to be booted on the system. Read the chapter Using JACK Audio from the Computer Music Basics class for getting started with JACK. A purely remote server, as used in this class, does not have or need an audio interface and can thus be booted with the dummy client:
$ jackd -d dummy [additional parameters]
To this point, the version of JackTrip used with the SPRAWL system requires all participants
to run their JACK server at the same sample rate and buffer size.
Recent changes to JackTrip
dev branch allow the mixing of different buffer sizes
but have not been tested with this setup.
The overall system's buffer size is defined by the weakest link, respectively the
client with the worst connection.
Although tests between two sites have shown to work with down to $16$ samples,
a buffer size of $128$ or $256$ samples usually works for a group.
Experience has shown that about a tenth of all participants has an insufficient
internet connection for participating without significant dropouts.
As with most command line programs, JackTrip gives you a list of all available
parameters with the help flag:
$ jacktrip -h
A single instance is launched on the SPRAWL Server with the following
$ jacktrip -S -p 5 -D --udprt
The following arguments are needed for starting a JackTrip client instance and connecting to the SPRAWL server (the server.address can be found in the private data area):
$ jacktrip -C server.address -n 2 -K AP_