JammerNetz is an Open Source system for "networked music performance" (NMP), also known as "jamming over the internet". It consists of a lightweight server software, and a little UI client software that can use your audio devices and stream multiple uncompressed high-quality audio channels to other participants as a common mixdown.
The design choice is that if you have a modern DSL or fibre connection, there is no need to degrade your music experience using CODECs mostly designed for speech transmission as used in some other internet jam solutions. We are happily using JammerNetz since months for our weekly sessions with synths, voice, and electric guitar.
Of course be aware that the main influence on the quality has your internet provider and your choice where you are running the server. If you have high quality fibre and a good and fast ASIO-capable audio interface, you can expect 50ms total latency, which we think is awesome. Of course, if some participants are bound for cable internet and are trying to play together across all of Germany, even running the server in a suitable AWS instance in Frankfurt close to the internet's main hub will not get you much better than 70-80 ms total audio latency (including AD and DA conversion in your interface, not round trip time), which we feel stll is worth the effort!
JammerNetz is quite feature rich, the following are the main items:
- It allows you to host a jam session on a server, allowing a configurable number of clients to participate.
- It allows for channel configuration to send mono or stereo channels, and also a "send-only" channel type for using microphones without hearing your own voice. This makes for great communication during the session.
- Send multiple audio channels per client to the server, e.g. your synthesist can send the keyboards and his voice separately.
- Does automatic hard-disk recording of your session to local disk on each client in a lossless compressed FLAC file. After the session, everybody has a record to revisit.
- Does automatic MIDI recording in case it detects any incoming MIDI notes, thereby logging all keys played into a MIDI file for later revisit ("what did I play? Sounds great!")
- Features a built-in instrument tuner display showing you the detected note and cents for each channel, so it is easy and quick to get everybody on the same A.
- BlowFish encryption based on a shared secret that is compiled into the software, so you are not sending data unsecured through the internet.
It should be noted that due to the design of the system, we have a few limitations or restrictions that other systems might not have. We believe that we have made sensible trade-offs, but your milage may vary:
- Only ASIO drivers are currently supported by the JammerNetz Client. As we are aiming for lowest-possible latency, you should really use an audio device with ASIO drivers on Windows.
- All clients need to run on the same sample rate (48000 is set in the source, but you might want to switch to 44100), else mixing the signals together isn't straightforward.
- Even the buffer size used by the device must be identical. The file BuffersConfig.h has the constants and is currently set at 128 samples.
As of today, the system is still in a build-and-run-yourself state. You will need some experience in compiling a C++ application and starting an AWS instance and deploying the Linux build of the server there to run it. Depending on the interest in this system, we might be able to provide more help.
We use JUCE, a cross-platform library with support for all major platforms, but we have tested the system at the moment only on Windows 10 using MS Visual Studio 2017, and the server on an up-to-date Ubuntu Linux 18.04 LTS. Other platforms might work as well, but might require some fiddling and fixing.
We use CMake 3.14 and Visual Studio 2017 for C++. Make sure to have both of these installed. Newer Visual Studios might work as well, you can select them as generators in CMake.
Optionally, if you want to produce a Windows-style installer for your band members: We always recommend the InnoSetup tool, really one of these golden tools that despite its age shines on and on. Download it and install it, it will automatically be picked up and used by the build process.
Clone with submodules from github
git clone --recurse-submodules -j8 https://github.com/christofmuc/JammerNetz
The recursive clone with submodules is required to retrieve the following additional modules already into the right spot inside the source tree:
- We use the magnificent JUCE library to immensly reduce the amount of work we have to do.
- the nice JUCE module ff_meters from ffAudio to display the level meters for each channel.
- Q, a highly interesting modern C++ DSP library we use for the instrument tuning/pitch detection. Go check it out, it's really cool!
- Infra, a little helper library required by Q.
- Flatbuffers, a C++ serialization library we use for parts of the network protocol.
- juce-cmake to allow us to use JUCE and CMake together.
As we don't want to send any unecrpyted audio data through the internet, we use a simple BlowFish encryption scheme to make sure that only authorized people join the jam session. For now, we have simply compiled a shared secret into server and client, more elaborate schemes might follow.
Using CMake and building JammerNetz client and server is a multi-step build, which we have simplified by providing a little batch script. Simply open a command line in the downloaded root directory <JammerNetzDir> and run
buildWindows.bat
Have a look inside that file in case you're interested in the required build commands. The build will take a few minutes, and produce both Debug and Release versions of Client and Server software, as well as a client installer in case you have InnoSetup installeed before kicking off. The installer executable is created as <JammerNetzDir>\Builds\Client\jammernetz_setup.exe
Most likely, you're not going to run your server on a Windows machine but prefer a Linux cloud machine located at some strategic position in the Internet.
Thanks to Docker, it has never been easier to do cross-platform development on Windows. If you don't have it, get yourself Docker Desktop and experience the power!
After installing Docker Desktop, we're ready to do a cross-platform build for Linux.
First, what we are going to do is to create a docker image for the build machine we are going to use. For that, open a command line, cd into the directory <JammerNetzDir>\Server\docker\buildmachine and run the command
buildBuildmachine.bat
You can build the Linux version from a Windows command line by just running the provided batch file inside the buildmachine directory. You need to specify the JammerNetz top level directory in the funky Docker volume syntax with forward slashes and a double slash for the drive letter. E.g. the Windows directory D:\Development\JammerNetz needs to be specfied as //d/Development/JammerNetz:
makeLinux.bat //d/Development/JammerNetz
This is so the Linux virtual machine will mount the source directory from the host, and directly place it's build output on the host, so the virtual machine is immediately removed again after the build is finished.
You will find the output of the Build machine in the directory <JammerNetzDir>\Server\Builds\LinuxMakefile\build. The server executable is just called "JammerNetzServer" and is ready to run on a matching Linux machine.
You can also enable the cross-platform build in the Release export configuration of the Projucer. Just remove the "rem" from the line
rem $(ProjectDir)..\..\docker\buildmachine\makeLinux.bat //d/Development/JammerNetz-OS
and save the Exporter again from within Projucer.
Now, when you compile a release version of the Windows server, after the Windows build is done it will automatically run the Linux build. Neat!
If you are working on Linux, make sure to have all development prerequisites installed! On a fresh Debian 9 machine, that would e.g. require the following installs:
sudo apt-get -y install g++ libasound2-dev libcurl4-openssl-dev libfreetype6-dev libjack-dev libx11-dev mesa-common-dev webkit2gtk-4.0
With those installs and the the recursive git clone from above, cd into the cloned directory and run cmake with the following commands:
cmake -S . -B builds -G "Unix Makefiles"
cd third_party/flatbuffers
cmake -S . -B LinuxBuilds -G "Unix Makefiles"
cmake --build LinuxBuilds/
cd ../..
cmake --build builds
This should have created a server binary as builds/Server/JammerNetzServer and a client binary as builds/Client/JammerNetzClient.
To regenerate the shared secret, create a file named RandomNumbers.bin in the <JammerNetzDir>\common subdirectory. For example, you can use an external source like (https://www.random.org/bytes/) to generate 72 random bytes, or use a more trustworthy key source as you choose.
We had used the great Jamulus system before developing our own system, and JammerNetz certainly has been inspired by this great piece of software. We also made some substantial design and architecture changes over Jamulus, justifying a new development instead of contributing to the Jamulus codebase. Most importantly, while Jamulus is using Qt as a cross-platform library, JammerNetz uses JUCE, massively reducing the lines of code required.
Note that as of today Jamulus is in a much more plug'n'play state than JammerNetz, so if you want to quickly try out the concept of a live internet jam session, we strongly recommend you go over and check out Jamulus - they even host a few test servers so you can get up and running in minutes!
As some substantial work has gone into the development of this, I decided to offer a dual license - AGPL, see the LICENSE.md file for the details, for everybody interested in how this works and willing to spend some time her- or himself on this, and a commercial MIT license available from me on request. Thus I can help the OpenSource community without blocking possible commercial applications.
All pull requests and issues welcome, I will try to get back to you as soon as I can. Due to the dual licensing please be aware that I will need to request transfer of copyright on accepting a PR.
Christof is a lifelong software developer having worked in various industries, and can't stop his programming hobby anyway.