Real-time audio visualization toolkit for Java / Swing
A lightweight, low-latency Java / Swing spectroscope. Visualizes audio files and live audio (JavaSound/Jack) with a spectrogram, spectrometer, RMS meter as well as caret/seek playback. Built with minimal allocations for continuous real-time rendering for the JudahZone project.
- Live audio capture – JACK or JavaSound (fallback) input with rolling RMS and spectrogram displays.
- File mode – load audio files, precompute FFT transforms, inspect spectrum with a draggable caret/seek control.
- Spectrometer – adjustable frequency response (20 Hz – 14 kHz), sensitivity and tilt controls, logarithmic frequency axis.
- Zoomable time-domain view – pan/zoom large recordings with mouse wheel and drag.
- Shared playback UI – single
BoomBoxcontrol delegates to low-levelPlayAudioplayer for file playback/seeking. - Standalone runnable – works outside JudahZone with zero configuration (JavaSound mode).
- Zero-copy RT path – allocation-free audio callbacks suitable for continuous visualization.
- Java 21 or newer (tested on OpenJDK 21).
- Maven 3.8+ (build tool).
- **Memory to store uncompressed audio + spectra if importing large files.
Recommended: clone the parent aggregator (builds all modules in one step):
git clone https://github.com/jeffmasty/meta-zone.git
cd meta-zone
Build zone-scope:
mvn -pl zone-scope -am clean package
Alternative: build all modules:
mvn clean package
Note: If you cd into zone-scope and run mvn package directly, Maven expects the parent pom.xml at the relative path defined in the module's pom.xml. Building from the aggregator root is simpler.
After building, launch the the shaded (fat) JAR:
java -jar ../zone-scope/target/zone-scope-0.3-SNAPSHOT-shaded.jar
Or, with all projects libraries in place, the slim jar:
java -jar ../zone-scope/target/zone-scope-0.3-SNAPSHOT.jar
The app opens a Swing window with JavaSound input controls, live spectrogram, RMS meter, spectrometer and audio player.
Real-time path (zero-allocation):
- Audio callbacks (
process(float[] left, float[] right)) snapshot data into a ring buffer (Recording). - When enough samples accumulate (configurable buffer size), the
Analysis<T>base class submits an off-thread FFT job to an executor. - Subclass
Transformerperforms windowed FFT (Hamming window via TarsosDSP) and computes modulus + RMS metrics. - Results (
Transformobjects containing amplitudes and RMS) are delivered to the UI via aConsumer<T>callback. - UI components (
Spectrogram,Spectrometer,RMSMeter) repaint using the latestTransformdata.
Spectrometer:
- X-axis: log-scale frequency (min 20 Hz, max Nyquist/2), consistent with human perception.
- Y-axis: amplitude/power mapped to dB, normalized to color intensity or bar height.
- Sensitivity and tilt controls adjust the visible dynamic range and frequency response.
JudahScope– main view/controller, mode switching (live/stopped/file), wiring between components.Spectrometer– adjustable real-time frequency spectrum display (55 Hz – 14 kHz).TimeDomain– handles zoom, caret, mouse interaction and delegates to visualization components.Spectrogram– rolling spectrogram (frequency vs. time heatmap).RMSMeter– peak/RMS level meter with decay.BoomBox– playback UI wrapper (play/pause/seek) that delegates low-levelPlayAudioplayer.Analysis<T>– base class for "copy & analyze" offline effects; standardizes snapshot/FFT workflow.Transformer– Analysis implementation that produces FFTTransformobjects (amplitudes + RMS).
Managed by the parent pom.xml:
zone-core– shared utilities (RT logger, constants, memory pools).zone-fx– analysis base classes.zone-gui– GUI helpers and widgets.zone-javax– JavaSound input/output helpers (JavaxIn,JavaxOut).
When building inside meta-zone, all versions/repos are inherited from the parent.
- File playback works out-of-the-box via JavaSound; no JACK required.
- For full JudahZone integration (MIDI routing, FluidSynth, etc.), see the main JudahZone README.
- JACK support requires a running JACK server (
jackdorjackd2) and native JACK libraries in embedded mode. - The stand-alone app uses JavaSound (higher latency).
- FFT / tuner: TarsosDSP by Joren Six.
- Spectrometer/Spectograph ideas: adapted from Tarsos.
- JACK bindings: JNAJack (via
zone-jnajackmodule).
- Main project: JudahZone
- Aggregator: meta-zone
- JavaSound module: zone-javax
- Analysis Plugin(+DSP): zone-fx
- TarsosDSP: https://github.com/JorenSix/TarsosDSP
- JACK Audio: https://jackaudio.org/
Enjoy visualizing your audio! 🎵📊