Visualizer+

A phase-locked audio oscilloscope for the Noctalia bar. It captures the monitor of your default audio output — "what you hear" — through a small native PipeWire helper, locks the waveform to the same phase every frame so the wave stands still instead of scrolling, and draws it next to RMS and peak level meters.

Plugin

Field	Value
ID	al3x/visualizerp
Entries	Bar widget: scope; service: capture

Requirements

The capture helper is built from source on first run, so a C toolchain and the PipeWire development files must be installed (declared in plugin.toml):

• cc and make (any C compiler toolchain)
• pkg-config
• libpipewire-0.3 development headers (Debian/Ubuntu: libpipewire-0.3-dev, Fedora: pipewire-devel, Arch: pipewire, Void: pipewire-devel)
• PipeWire running (any desktop using it already qualifies)

Usage

Add the Visualizer+ widget to the bar (Settings → Bar). One capture process serves every widget instance, so running several costs no extra PipeWire streams.

The widget shows a phase-locked oscilloscope trace with two level meters (RMS on top, peak below). Hover it for a tooltip with the capture target, the locked pitch, and the RMS/peak levels. On silence the trace sits flat on the center line and the meters read zero.

Middle-click the widget to open its settings.

Settings

Capture settings apply when the capture starts (audio restart or plugin reload); render settings apply immediately.

Setting	Type	Default	Description
target	string	""	Sink to monitor. Empty uses the default output.
fps	int	60	Waveform refresh rate.
cols	int	128	Horizontal resolution.
sensitivity	double	1.0	Amplitude gain.
smoothing	double	0.2	Trace smoothing, 0 (raw) to 0.99 (heavy).
gate	double	0.0025	Silence threshold; 0 means auto (0.0025 × sensitivity).
width	int	188	Waveform width in pixels.
height	int	30	Waveform height in pixels.
color	color	primary	Waveform line color.
color2	color	on_surface_variant	Lower envelope color (band view).
line_width	int	1	Line width in pixels.
fill_opacity	double	0.0	Fill under the trace, 0–0.6.
draw_band	bool	false	Min/max band instead of a single line.
show_meter_labels	bool	false	RMS/PK text next to the meters.
rms_color	color	secondary	RMS meter bar color.
peak_color	color	tertiary	Peak meter bar color.
meter_radius	int	0	Meter corner radius in pixels.
meter_width	int	57	Meter bar full-scale width in pixels.
meter_height	int	9	Meter bar height in pixels.
meter_gap	int	4	Gap between trace and meters in pixels.

Notes

• On first run (and after updates that do not carry a binary) the service runs make inside the plugin's own native/ directory to build bin/pwscope, and writes only that one file. If the build fails, the widget shows an error glyph and the tooltip explains what to install.
• The helper connects to a sink's monitor port — the system audio output you hear, not the microphone — via PipeWire's stream.capture.sink and stream.monitor properties. Nothing is recorded or stored.
• No network access. One long-lived child process (pwscope), respawned by a small shell loop if it exits.
• Target resolution order: the target setting → PipeWire metadata default.audio.sink → the first Audio/Sink node.
• Resource usage: ~6 % of one core at 60 fps / 128 columns, ~7 MB RSS; YIN pitch detection dominates the cost.