Jam music online with JackTrip
Updated: Feb 25
Introduction
Earlier in 2020 online jams just exploded. With musicians in isolation, bands had to resort to online tools to be able to play together and even record. We had a look at online tools for jamming in this article, but at that stage JackTrip wasn't the focus. It has evolved quite a lot since then and that is what we want to cover in this article specifically.
So JackTrip is a bit different than Jamulus in the sense that it was based in a peer-to-peer architecture with no codec - audio is 48kHz 16-bit 2-channel PCM whereas Jamulus and others use lossy codecs like the OPUS.
Having said that, you can use JackTrip in a client-server configuration. More on this below.
Getting Started with JackTrip
The best way to understand all the small parts that make JackTrip and online jams possible is to check out this article here. The elements that generate latency are described there, as well as the pros and cons of peer-to-peer and client-server (or hub and spoke).
To simplify things, I want to focus on the client-server application as it is simpler to configure and covers the use cases I am aiming for. If you are seriously tech-minded and want to go down the peer-to-peer path, check out this article that shows how to connect two computers in that mode (and the process needs to be repeated for every other computer connected to the JackTrip network in this mode). Warning: this involves port forwarding and use of the command line.
If that is not for you, let's then discuss the steps for client-server.
Equipment
Of course you will need a computer running Mac or Windows, and a fast internet connection. Given the use of lossless audio, bandwidth requirements are higher than Jamulus. This article here suggests 2.0 Mbps download and upload so of course slow ADSL or dial-up won’t cut it. You need fast broadband, NBN if in Australia, cable, fibre or equivalent. Note that the specific client-server configuration we will discuss here has means to test if you are eligible or not, so watch this space - more on that below.
Extremely important: get your computer close to your router and connect via Ethernet. Do not use WiFi as this will make the latency even worse and cause additional audio issues.
Apart from that, you need an audio interface, your instrument and/or a microphone.
If you don’t have an interface my recommendation is the Focusrite Scarlett Solo:
The server path
First step is to download and install Jack and JackTrip. Instructions for Mac OS X are here, whereas the windows instructions are here. As you will notice, these instructions allow you to install and test Jack and JackTrip, but not much else. So that is where the quest for a server begins. And that is where I found a shortcut for those who want to play music as soon as possible instead of having to install servers by themselves. Sometimes convenience is king.
Enter Musicians Together Apart, a service that provides the servers for JackTrip in various locations of the world, and are even able to deploy servers if not immediately available. Yes there is a fee involved, but you can try for 14 days and get some serious tech support in case things don't work. More importantly, you can head on to their website and test the coverage in your area. Click on test your coverage and pick your region or city. You will then be able to check eligibility by measuring download speed, upload speed, ping time and jitter.
Connecting everything together
Now that you have a server, you should also receive the IP for that server, and a web page that allows you to control the server mode, the buffer size and the server ring buffer size.
The server mode is easier to understand, basically one mode doesn't loop back your audio to you - you will need direct monitoring on your audio interface to listen to yourself. the loopback mode allows you to hear yourself, so it is recommended that in that case you turn your direct monitoring off.
Buffer Sizes
The buffer size is called Frames/Period inside Jack. In this case it is important that they all match - server and all clients - or you won't be able to connect.
So you have to configure server first by heading to the web page provided when you hired the server. Then each user will have to configure theirs inside the 'setup' area of Jack before attempting a connection.
Now it's important to note that Jack does not have an audio interface configuration of its own and so it follows your system setup (windows or MacOS) and only for 2 channels. So the inputs and outputs selected by the system will be used. For example, let's say you have a Focusrite with 4 channels in and out and that is selected as the interface in your system settings. Jack will 'see' the first two channels of that interface, both for input and output.
A typical use case would be to have a guitar connected on channel 1, a microphone on channel 2 and they will both be routed into the session with other musicians. The 2-channel output would be connected to headphones where you can then listen to the session and jam.
The server ring buffer size is additional protection around the network side of JackTrip, and can be different on server and clients. The recommendation is to start with the lowest number (8) and then increase musicians first and then server if you hear crackling or glitches in the audio.
Both buffer size and server ring buffer size will affect latency. So the trick here is to find a trade off where both audio quality and latency are still acceptable.