Waveform 9 turns the Rasp Pi into a recording studio

Sound Machine

© Lead Image © Alexander Gorlov, 123RF.com

© Lead Image © Alexander Gorlov, 123RF.com

Article from Issue 220/2019

The Rasp Pi has enough performance to serve as a small digital audio workstation. Waveform 9 provides the necessary software.

Tracktion.com has been selling suites for music production – Digital Audio Workstations (DAWs) – for many years. Waveform 8 was the first Tracktion DAW that supported the ARM processor used with the Raspberry Pi. Since Spring 2018, the new Waveform 9 for the Rasp Pi (Figure 1) has proven that the experiment is a success.

Figure 1: Waveform 9 is a DAW that runs on the Rasp Pi.

Collecting Berries

To download and activate Waveform 9, visit the Marketplace section of Tracktion's website [1], for which you need an account. You'll need to purchase a license for $109 – around EUR93.50.

The virtual instruments and effects are only available for Linux on the x86 platform. However, the Rasp Pi variant contains all internal instruments and effects. You can install the Debian package for Waveform with dpkg -i on Ubuntu MATE for the Rasp Pi (see box entitled "Setup").


The CPU, graphics chip, and RAM of the Rasp Pi support operation of the Waveform interface without delays. The real-time sound engines from JUCE and JACK, however, have requirements that are not met by the BCM sound chip built into the Rasp Pi. Even with very conservative settings for latencies of more than 30 milliseconds, you cannot expect normal operation.

The crude BCM codec is not genuinely suitable for recordings anyway, because input produces a huge amount of background noise on the analog side. The solution lies in a USB sound interface, which is available in a form suitable for music applications starting at around EUR30.

In our lab, we used a UCA222 audio interface by the proven but inexpensive vendor Behringer. The computer detects the device as a USB codec and configures it accordingly. Alsamixer controls the stereo output as a PCM channel, but there's a physical volume control on the unit itself and reasonably acceptable output for the headphones, plus RCA connectors for stereo input and output.

We started the device with QjackCtl and set it for 10 milliseconds latency. This setting means that, even if musicians accompany previously recorded material in sync, recordings can still be made properly. If you use the Rasp Pi as a musical instrument, low latency is even more important. Our configuration allowed us to use the Waveform built-in synthesizers and effects live.

Download purchased packages as needed, choosing the desired platform. The license is valid for all platforms. In other words, if other people in the band absolutely want to stay with Windows, or if you want to edit sessions recorded on the Rasp Pi at home on your Linux PC in the rehearsal room, you simply take the projects with you on a USB stick and continue the work elsewhere.

The website is elaborate and spectacularly designed, but somewhat confusing: It does not reveal at first glance where and how you can access the sample packages.

Some samples are already available for download in the installed and registered Waveform 9 on first launch. However, the download list is not well programmed: After you click on Download, the software searches in the background for an application registered for ZIP files using the XDG tool (which is not maintained on many systems). If your system does not have an application registered for ZIP files, nothing happens. You will not even see an error message; you can only see that something is wrong by popping up a terminal.

In KDE, Plasma Ark is registered for ZIP and opens with a click on the download for the sample packages. Afterwards, however, nothing seems to happen. The reason for this is that the 2GB package – not unusual for such collections – has to be stored in a temporary directory first. While this is happening, Ark waits without any activity and only displays the content after about 10 minutes. From there, you can drag it into a directory below ~/Tracktion/.

The downloads and installations of some other additional packages are a little less of an adventure; these packages include the drum loop collections, which you download individually in your web browser.

However, really serious problems did not occur during the many installation steps. Depending on your Internet connection, you will probably have successfully completed the installation and registration for the entire Waveform package and several gigabytes of templates within about one to two hours.

Since forcibly opening the downloads with a ZIP program adds memory, and KDE Plasma or Gnome are not necessarily the ideal desktop environments for the Rasp Pi, it is a good idea to download the packages on a Linux PC.

Unlike Bitwig's DEB packages or Ardour's installer, Tracktion's DEB packages don't drop the software into /opt/, but into /usr/. Waveform itself goes by the name of Waveform9 in /usr/bin/, which makes it possible to keep Waveform8 if necessary. However, the newer version warns against opening newly edited projects again with the older one.

Beautiful, but Moody

Like its predecessors, Waveform 9 integrates very well with Linux: It automatically sets up the audio connections to JACK and the MIDI devices of the ALSA Sequencer, as did Waveform 8. What's new is a prompt to send diagnostic and usage data to the manufacturer, which only appears at first launch. Under Settings | Maintenance, you can give or withdraw your consent later on.

Another new feature is the list of downloads for samples and updates. Waveform 9.0.3 on the Rasp Pi tells you that version 9.1.1 is already available. This does exist – but only for the PC. A download attempt therefore terminates without an explanation.

Waveform 8 still had a small but annoying problem when managing windows: Opened plugins and other subwindows disappeared somewhere outside their own box behind the main window. In the new Waveform the windows stay nailed to the foreground.

At startup, the software automatically detects installed plugins in all directories you have set up in Settings | Plugins. It finds the venerable LADSPA plugins and native Linux VSTs (LxVSTs). The more modern LV2 format is still not supported. You can use LV2 and Windows VST if needed via LxVST from Felipe Coelho's universal Carla plugin host. However, the additional load caused by the emulation for Windows VST puts a burden on the limited RAM of the Rasp Pi.

In our lab, we discovered two problems that affect Waveform 9 on a Rasp Pi 3 (RPi3). If you create a project with ALSA as the audio driver, the program crashes if you change to JACK and try to open it for editing. In general, however, it is advisable to run audio software on Linux with JACK and stick to it. To fix the problem, reset Waveform by deleting the configuration in ~/.config/Tracktion/Waveform if necessary. After that, you'll need to reconfirm the license and the software setup.

What was genuinely annoying was that the software had serious problems recording MIDI notes (see the "Wave Editing" box). Drawing notes in tracks with the pen tool does not work at all; recordings from a connected keyboard are ignored by the application for the time being. However, you will find them in the track after restarting the application. See the box entitled "MIDI Despite Everything" for more on what still works with MIDI and Waveform on the Rasp Pi.

MIDI Despite Everything

What actually works for MIDI with Waveform 9 on the Rasp Pi? First of all, you can edit existing notes in tracks normally, including the new controller functions for individual notes. Transposing, quantizing, and arranging do not cause any problems, but you cannot insert new notes, not even with copy and paste. It is therefore advisable to proceed very carefully when deleting.

What you can do is edit compositions with score-enabled editors such as Rosegarden [3] or MuseScore [4], type in the notes, then export the MIDI files, and import them back into Waveform. Both Rosegarden and MuseScore are available as free software for the Rasp Pi.

Another tool that is lean enough for the Rasp Pi and has proven itself in our lab is Seq24 [5] (Figure 2). Although the software does not have a score editor, it offers far more convenience than the built-in Waveform editor. Seq24 also features an innovative pattern concept that is reminiscent of a greatly simplified version of the popular matrix sequencers from Bitwig and Ableton.

Figure 2: The Seq24 loop-based sequencer has a plain interface that generates hardly any additional load.

Seq24 can also play an interesting role in another application without a fully functional MIDI editor, and Waveform is the perfect candidate: use of the DAW in live mode. This technique is sometimes known as "controllerism." Controllerists operate software live using MIDI or OSC controllers and a keyboard. Waveform is very much suitable for this kind of music making.

Wave Editing

Waveform 9 is a sequencer, rather than a recorder. Even more so than with Tracktion, creating and arranging loops is the focus. It is possible to use Waveform to record tracks in the traditional way, but effective recording requires you to do some editing and polishing with effects.

Special tools for the mouse, such as those offered for editing by Ardour [2] or Audacity, are not available in Waveform 9. You can instead use the small arrows in the upper frame of tracks while holding down the mouse button. Press S to split the track at the cursor position.

After you have split a recording, it is usually necessary to remove sounds of breathing, quips, and the like from the beginning and end of the recording. Simply select the track, move the play cursor to the desired position, and press S. Select and then delete the parts that have been split off in this way. Caution: After editing, both parts are automatically selected and both react to actions such as remove and shorten/extend.

For precise editing, it is not absolutely necessary to switch off the snap to beat function. Waveform supports adaptive snapping, which means that the grid for the snapping function is finer at higher magnification. If an edited section doesn't snap into place, use the mouse wheel on the bottom scrollbar to zoom in, and the snap-in edges of the section will almost always snap into place.

More Is Better

Although Rasp Pi users are denied the big standalone instruments from Collective and BioTek, Waveform still offers new sound generators and many smaller, new plugin tools in its internal pool. Multi Sampler is still quite simply designed, but it already has a number of features that go far beyond what was possible with Tracktion's old standard sampler (Figure 3).

Figure 3: By defining zones as rectangles that you move and overlap, Multi Sampler lets you build your own instruments that react very subtly to notes and velocities played with MIDI instruments.

A click on the Multi Sampler built into the audio clip toolbox at the bottom right will load the selected audio clip as a recording and automatically try to identify individual sound events. You can then readjust the elements if necessary and automatically turn them into a sample bank.

A click on Create MIDI Clip in the bottom-right corner of the Multi Sampler window creates a MIDI clip that plays the original recording as samples. For monophonic drum loops, this works almost perfectly and gives the arranger a quick way to turn samples into easily manipulable MIDI compositions.

For MIDI compositions, Waveform 9 offers new automatic help, which lets you create a special track with chord patterns, for example, that is automatically followed by the pattern generator for MIDI clips. If the available, chords are not enough, you can easily set up your own chords (Figure 4).

Figure 4: Waveform 9 lets you create your own custom chords.

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