Getting started

First launch

1. On first launch Marbble scans your VST3 plug-ins. Each bundle is loaded in a separate process, so a plug-in that crashes can’t take Marbble down. The result is cached; rescan from Settings › Plug-ins or the Library.
2. The Project Chooser opens (unless Settings › General › At Launch says otherwise). Pick a template, give the project a name and a location, and click Create. The project is saved to its folder straight away, so recordings land in the right place.
3. Open Settings › Audio (Marbble › Settings…, Ctrl+,) and choose your driver and devices (below).

Choosing a driver and devices

Settings › Audio holds the device settings. The driver, devices, sample rate, buffer size, Processing Threads, Monitoring and Recording Delay take effect when you click Apply Changes; Done, switching tabs or closing the window drops changes you haven’t applied. The delay compensation options on the same tab apply at once.

• Driver. On Linux the choices are PipeWire (recommended), PulseAudio, JACK (listed as “JACK (no server running)” when there is no JACK server) and ALSA (direct hardware). On Windows and macOS the system’s default driver is used (WASAPI, Core Audio). Changing the driver resets both devices to System Default.
• Output Device and Input Device. They can be different devices. Choose None (playback only) as the input if you only play back.
• Sample Rate. Only the rates both devices support are offered.
• I/O Buffer Size. 32 to 2048 samples; the time per buffer is shown next to it. Smaller is more responsive, larger is safer against crackles.
• Processing Threads. How many threads play tracks at once, the audio thread included. Automatic (the default) brings in more threads when a project needs them and leaves a light project on the audio thread alone. 1 keeps everything on the audio thread, the way to rule threads out if you suspect them. The output is the same sample for sample whatever you choose. Apply Changes takes effect at once, without restarting audio. Bounces and other renders always play on one thread. On macOS and Windows, Automatic stays on one thread for now, as the extra threads can only get real-time priority on Linux so far.
• Reset Audio Engine closes and reopens the devices, for example after replugging an interface.

The status line at the bottom of the window shows the devices, the sample rate and the buffer size, or “Audio stopped” with the reason. Click it to open Settings › Audio.

The input level check (Linux)

PipeWire and PulseAudio have their own volume control for each recording device, and it is often below 100%. That lowers everything you record before Marbble sees it, and at 0% or muted you record silence. With PipeWire or PulseAudio, Settings › Audio checks this level (using wpctl) and warns when the input is muted or turned down, with a Set to 100% button. Marbble also shows a notice at launch when the level is low. Set your recording level with the gain knob on your interface instead.

The check is not available with JACK, with direct hw: ALSA devices, or on Windows and macOS.

Monitoring

• A track’s I button (Input Monitoring) plays its input through Marbble and its plug-ins.
• Settings › Audio › Monitoring: “Hear record-enabled tracks without pressing I” (off by default) makes armed audio tracks monitor automatically. Leave it off if your interface or pedal monitors directly, or you will hear a delayed second copy.