🟢 Real-time FFT · 🔵 WASAPI loopback · 🟣 19 modes · 🟠 13 themes · 🔴 dBFS accurate · 🟡 xUnit tested

🎚️ Spectrum — Real-Time Audio Spectrum Analyzer & Music Visualizer for Windows

A .NET Framework Windows Forms visualizer for real-time system-audio analysis, with 83 logarithmic bands and 19 live visualization modes.

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83 logarithmic bands · 19 visualization modes · 13 colour themes · 60 FPS rendering target

A C# .NET Framework 4.8 Windows Forms application that captures your system’s audio output in real time and renders it as an animated frequency spectrum using 83 vertical bars. Audio capture is handled by BASS and BassWASAPI via Windows WASAPI loopback, and an FFT-based band analyzer measures each bar in dBFS — so it works as both a real-time audio visualizer for music and a readable C# FFT spectrum analyzer implementation you can study, with a deterministic xUnit test suite.

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⚡ At a Glance

🎚️ Frequency Analysis	🎬 Visualization	🎨 Customization	⚡ Presentation
83 bands	19 modes	13 themes	60 FPS target
20 Hz – 20 kHz	Runtime switching	5 effects + None	25 ms analysis timer

🧭 Navigation

✨ Features · 🎛️ Modes · 📸 Screenshots · 🪄 Styles · 🎨 Themes · ⚙️ Configuration · 🏗️ Build · 🧪 Tests · 📐 Measurement · ❓ FAQ

⌨️ Keyboard Controls

Shortcut	Action
Ctrl + M	Cycle visualization modes
Ctrl + T	Cycle colour themes
Ctrl + R	Open Fixed/Random rotation settings
F12	Toggle always-on-top

🚀 Quick Start

1. Open Spectrum.sln in Visual Studio 2022 with .NET desktop development tools
2. Restore NuGet packages and build the Release configuration (see Build below)
3. Run Spectrum.exe from Spectrum\bin\Release\

[!TIP] Spectrum automatically captures the Windows default audio output through WASAPI loopback, so normal use does not require selecting an input device.

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✨ Features

[!NOTE] Spectrum combines measurement accuracy, responsive presentation, runtime customization, and automatic device recovery in a single Windows Forms application.

• 83-bar frequency spectrum with a fixed logarithmic 20 Hz – 20 kHz viewport, labelled frequency axis and a 0 to -72 dBFS level axis on both sides
• Calibrated spectrum grid at every 6 dB, with logarithmic frequency guides at 20, 30, 40, 60, 100, 200, 300, 400, 600, 1k, 2k, 3k, 4k, 6k, 10k and 20k Hz; crowded frequency labels are omitted without moving their guides
• Measured band levels — each bar is the integrated power of its frequency band in dBFS (see Measurement)
• 19 visualization modes selectable at runtime, with an initial value from App.config
• Optional styles with a safe None default: Pulse, Glow, Trail, Scanline, and Precision are enabled only where their renderer is meaningful
• 13 colour themes selectable at runtime, including Studio, Platinum Light, and High Contrast instrument palettes
• Live mode, style, and theme selectors in the title bar; changes apply immediately without restarting
• Alphabetical mode discovery uses case-insensitive current-culture names with a deterministic ordinal tie-break; existing mode identifiers and saved selections are preserved
• Original vector mode icons distinguish spectrum, stereo, waveform, matrix, threshold, and history views without bitmap stretching
• 1200 x 480 default client window, manually resizable without mode-driven size changes, with individually accessible window controls, visible keyboard focus, and descriptive mode tooltips
• Heat-map colour gradient with theme-readable peak markers using the theme’s primary text colour
• Independent falling peak markers with configurable hold/decay, thin horizontal lines and a reserved gap above Spectrum, Bricks and LED bars, including full-scale and segmented-cell boundaries; expiring trails release clearance smoothly instead of causing jumps
• Asymmetric ballistics — fast attack, slower release per mode
• Frame-rate independent animation — ballistics use elapsed time; the one-shot analysis timer requests a 25 ms delay and restarts after processing, so actual analysis cadence also depends on processing and scheduling. The display targets 60 FPS; achieved control-paint cadence depends on timer scheduling and workload
• Silence detection — bars fade out gracefully when no audio is playing
• Auto device recovery — restores capture automatically when the default audio device changes
• Scaling layout — bars and labels are laid out from the window’s client size (the process does not declare per-monitor DPI awareness, so Windows scales it on high-DPI monitors)
• Keyboard shortcuts — Ctrl+M cycles visualization modes; Ctrl+T cycles colour themes
• Fixed or Random rotation — choose Fixed to keep selections stable, or Random to change mode, compatible style, and theme together at a configurable 1–240 minute interval (default 5 minutes); preferences are saved per user
• Rotation settings shortcut — press Ctrl+R to open Fixed/Random and interval settings
• F12 toggle — toggle always-on-top
• Single-instance — uses a named mutex to prevent multiple instances

Spectrum is an analyzer, not a player or audio processor. Its selectors, visual styles, and rotation settings change the display, not the captured audio. It has no playback, pause, stop, mute, master-volume, equalizer, or audio-effect controls, and no user-facing input/output device selector. Control playback and volume in the source application or Windows; Spectrum follows the default render endpoint.

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🎛️ Visualization Modes

Advanced Spectral Balance · Band Matrix · Bricks · Contour · Dynamics History · LED · Level Change · Octave Spectrum · Octave Waterfall · Oscilloscope

Peak Trace · Radial Spectrum · Spectral Balance · Spectral History · Spectrum · Stereo Levels · Stereo Spectrum · Threshold Monitor · Waterfall

Choose a visualization mode from the Mode selector in the title bar to change it immediately. The supported modes are:

Mode	Best For
Advanced Spectral Balance	Seven FFT-measured bands (20 Hz–20 kHz) in dBFS relative to a full-scale sine
Band Matrix	Compact single-frame 83-band matrix with frequency and level labels
Bricks (configured startup mode)	Retro block aesthetic; 80s/Synthwave music
Contour	Connected line across the measured frequency bands
Dynamics History	Actual front-channel RMS and sample-peak history; unavailable audio intervals remain gaps
LED	Segmented frequency-band display; not a calibrated VU/PPM meter
Level Change	Per-band frame-to-frame displayed-level change; not a power-domain spectral-flux or beat measurement
Octave Spectrum	Ten grouped octave-range meters; approximate powers reconstructed from displayed band values
Octave Waterfall	Scrolling grouped-octave display history
Oscilloscope	Actual front-left PCM waveform with a labeled auto-ranging amplitude scale
Peak Trace	Current spectrum with a short frequency-history trace
Radial Spectrum	Frequency bands arranged around a circle
Spectral Balance	Estimated bass/mid/high shares derived from displayed frequency-band power
Spectral History	Perspective stack of genuinely captured display spectra; spacing denotes received frames, not uniform sample time
Spectrum (fallback)	Continuous real-time frequency-band analysis
Stereo Levels	Independent front-L/R RMS and sample peaks in amplitude-relative dBFS
Stereo Spectrum	Independent front-left and front-right frequency spectra
Threshold Monitor	Current band levels classified around a visible monitoring threshold
Waterfall	Scrolling history of received frequency display frames, not a uniformly sample-timed spectrogram

Retired selections remain compatible through migration: Dots → LED, Wave → Contour, Lollipop/Center/Ambient Particles → Spectrum, Mirror → Bricks, Note Map → Contour, Orbit History/Frequency Ribbon → Peak Trace, and Level Change Map/Transient Map/Spectral Flux → Level Change. These are aliases, not additional selectable modes.

📸 Visualization Mode Screenshots

🎬 Real screenshots of every mode, captured from the running application (1200 × 480 window, WASAPI loopback of live system audio, ClassicSmooth theme, Precision style).

📊 Spectrum

Classic 83-band real-time frequency spectrum.

🧱 Bricks

Retro block-style LED bricks.

💡 LED

Segmented LED frequency meter.

🔢 Band Matrix

Compact 83-band matrix with labels.

〰️ Contour

Connected frequency contour line.

📈 Peak Trace

Spectrum plus short frequency-history trace.

🎡 Radial Spectrum

Frequency bands arranged in a circle.

🎧 Stereo Spectrum

Independent left/right spectra.

🔊 Stereo Levels

Front L/R RMS and sample peaks.

🌊 Oscilloscope

Front-left PCM waveform.

🎼 Octave Spectrum

Ten grouped octave meters.

🏞️ Octave Waterfall

Scrolling grouped-octave history.

🌈 Waterfall

Scrolling spectrogram-style history.

🏔️ Spectral History

Perspective stack of captured spectra.

⏱️ Dynamics History

Front-channel RMS and peak history.

⚡ Level Change

Per-band frame-to-frame level change.

🚦 Threshold Monitor

Band levels around a monitoring threshold.

⚖️ Spectral Balance

Bass / mid / high share estimate.

🎯 Advanced Spectral Balance

Seven FFT-measured bands in dBFS.

🪄 Visual Styles

Style model: the visualization mode owns the geometry; the selected style adds a compatible presentation effect on top of that mode.

Choose a style from the Style selector to overlay an effect without changing the selected mode’s geometry. None is the default and is always safe. Every style is derived from the current display frame or captured display-frame history; no style generates autonomous motion. Pulse and Glow are used only on continuous or meter-oriented renderers, while Trail, Scanline, and Precision are exposed only for renderers that implement them. Unsupported combinations show None rather than implying that an effect is active. Random rotation selects a valid complete Mode × Style × Theme combination.

Style	Effect
None (default)	No overlay
Pulse	Brightens in proportion to the current signal level
Glow	Adds a soft level-driven halo
Trail	Shows recent captured signal peaks or contours
Scanline	Marks the current aggregate signal level
Precision	Adds static analytical reference guides

🎨 Colour Themes

Theme model: themes affect the signal palette and the surrounding application/control/grid colours while keeping application chrome visually subordinate to the signal.

Choose a palette from the Theme selector in the title bar to change bar colours immediately. Themes apply semantic application, control, grid, and visualization colors in addition to their signal palette. Application chrome remains neutral and subordinate to active signal data.

Theme	Palette	Best For
ClassicSmooth (default)	Green → yellow → orange, red peak	Traditional VU/spectrum look
Ice	Blue → cyan → soft ice peak	Cool, calm analysis
Sunset	Amber → coral → pale gold peak	Warm, restrained analysis
MonoCyan	Blue-cyan lightness ladder	Clean technical display
Synthwave	Violet → magenta → softened cyan peak	Restrained retro character
Aurora	Emerald → cyan → pale lavender peak	Calm luminous analysis
Obsidian Gold	Warm gold → pale gold peak	Premium warm display
Midnight Prism	Violet → cyan → soft ice peak	Controlled nocturnal contrast
Emerald Noir	Emerald → jade → mint peak	Refined green-on-neutral display
Crimson Velvet	Crimson → rose → blush peak	Rich, controlled warm contrast
Studio	Teal → blue on graphite/slate chrome	Professional reference theme
Platinum Light	Contrasting signal palette on light instrument surfaces	Bright workspaces and readable light controls
High Contrast	High-contrast instrument colors and focus states	Accessible monitoring and clear control boundaries

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⚙️ Configuration

[!IMPORTANT] Saved per-user selections take precedence over App.config on later launches.

Spectrum\App.config supplies the initial mode, style, and theme at build time and is copied to Spectrum.exe.config beside the executable. For an already-built distribution, edit that deployed configuration before starting Spectrum:

Runtime selections apply immediately for the current session and do not modify App.config. The selected mode, style, and theme, Fixed/Random choice, and random interval are saved in the current Windows user’s application settings; saved choices take precedence over App.config on later launches. Legacy Mode=Pulse migrates to Bricks with None, Mode=Glow migrates to Spectrum plus Glow, and retired Center, Mirror, Note Map, and Ambient Particles values migrate safely to retained modes.

<appSettings>
  <add key="Mode" value="Bricks"/>
  <add key="Style" value="None"/>
  <add key="Theme" value="ClassicSmooth"/>
</appSettings>

📋 Requirements

[!IMPORTANT] The application targets Windows and .NET Framework 4.8 and depends on the included native BASS libraries.

• To run: Windows, .NET Framework 4.8, and the complete Release output folder, including the native x86 bass.dll and basswasapi.dll libraries.
• To build: Visual Studio 2022 with the .NET desktop development workload and .NET Framework 4.8 Developer/Targeting Pack, or equivalent full-framework MSBuild tools. The native references are included in Spectrum\Ref_Files\; restore the solution’s NuGet dependencies before building.

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🏗️ Build

Open Spectrum.sln in Visual Studio, select Release, restore NuGet packages and build (Ctrl+Shift+B), or run from a Visual Studio Developer PowerShell with MSBuild available:

msbuild .\Spectrum.sln -restore -p:RestorePackagesConfig=true -p:Configuration=Release
msbuild .\Spectrum.sln -t:Clean,Build -p:Configuration=Release

The output is placed in Spectrum\bin\Release\.

The Release application folder contains 12 essential root files and no subfolders: the executable, configuration, nine managed/native runtime DLLs, and one THIRD_PARTY_NOTICES.md. Release builds omit development XML documentation and combine all five bundled package notice payloads verbatim into that single notice. Unused WindowsMediaFormat and NuGet ConfigurationManager DLLs are no longer deployed; the application retains the framework’s System.Configuration. Required runtime dependencies are not embedded or deleted. Debug/test outputs remain separate. See dependency terms and provenance before redistribution; build success does not certify a publisher’s private licensing agreements.

🧪 Tests

[!NOTE] The test suite is signal-driven and deterministic, covering analysis correctness as well as timing, concurrency, stereo behavior, and per-frame cost.

Spectrum.Tests (xUnit, .NET Framework 4.8) validates the analysis with deterministic synthetic signals: FFT correctness, band-plan geometry, a tone at every bar’s centre, amplitude accuracy, band-boundary and sweep behaviour, multi-tone independence, white/pink noise, stereo semantics (including anti-phase), numerical safety, lock-free sample-history consistency under a concurrent producer, frame-rate independent ballistics and end-to-end onset/release timing, instrument-like signals, and per-frame cost.

# After building Release, use a Visual Studio developer shell with VSTest available.
# Match the application's 32-bit runtime and bundled native libraries:
vstest.console.exe .\Spectrum.Tests\bin\Release\net48\Spectrum.Tests.dll /Platform:x86

# Alternative with the .NET SDK installed; the default test-host architecture may differ:
dotnet test .\Spectrum.Tests\bin\Release\net48\Spectrum.Tests.dll

Additional regressions cover full-scale packed capture levels, elapsed-time peak hold, invalid sample-history writes, FFT window validation, mode sorting and vector icons, settings persistence, accessible chrome, and capture recovery. The historical results below apply only to their stated artifacts and do not certify unexecuted environments.

The previously verified 2026-10-14 1200 x 480 / 12-file Release passed 751/751 x86 cases, zero failed/skipped, retaining all 729 preceding names and adding 22 default-window, responsive-layout, working-area and packaging cases. For that artifact, clean, seeded legacy-output migration and repeated already-clean builds passed; all twelve distribution hashes remained identical. This retained result is artifact-specific, separate from earlier releases, and is not a claim that the latest source has been retested.

The preceding fixed-window release passed 729 x86 cases, with none failed or skipped, retaining all 705 preceding test names and adding 24 exact-window/layout cases. Mode switching preserves the user’s window bounds, client size and minimum size; compact Stereo Spectrum uses side-by-side panels instead of enlarging the window. Coverage includes genuinely shown native selector/accessibility checks at 100/125/150/200% equivalent control/font scaling, radial geometry at 96/144/192 DPI, exact-pixel cached-meter comparisons, timestamp/gap-preserving Dynamics History batching, rapid peak/drop/silence behavior, populated Trail expiry at 30/60/144 Hz and conditional-paint nonzero idle convergence. All 19 modes met the unchanged 16.667ms mean direct-drawing target at 1920×1080; this is a mean direct-drawing result, not an every-frame deadline or compositor 60FPS guarantee.

▶️ Running

[!TIP] No input-device selection is required for normal use: capture starts from the Windows default audio output through WASAPI loopback.

Run Spectrum.exe from the build output directory. The application automatically selects the Windows default audio output device (WASAPI loopback) and begins capturing.

The default client area is 1200 x 480 at the existing 96-DPI baseline. Startup and display-work-area changes shrink oversized windows to the available working area without enlarging smaller user-selected windows; mode changes never resize the frame. The existing 900 x 250 technical minimum remains. If a work area is smaller than that minimum, the top-left corner stays accessible, but full containment is physically impossible. Windows retains the application’s existing scaling behavior; no new per-monitor-DPI contract or restart-size persistence is implied.

📦 Dependencies

Library	Version	Source
Bass.Net	2.4.11.1	Included in Spectrum\Ref_Files\
NAudio	1.7.3	Included in Spectrum\Ref_Files\
bass.dll	—	Native BASS audio library
basswasapi.dll	—	Native BassWASAPI extension

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🗂️ Project Structure

The repository keeps capture/analysis, DSP, presentation ballistics, rendering, configuration, and native references clearly separated:

Spectrum/
├── Spectrum.sln
├── Spectrum/
│   ├── Analyzer.cs                  # Device handling, WASAPI capture, analysis scheduling, publication
│   ├── CaptureGate.cs               # Per-tick decision: analyze, publish silence, wait, or reset a hung stream
│   ├── Dsp/                         # Measurement: FFT (RadixTwoFft), band plan, band-power analyzer, dB scale, sample history
│   ├── BarBallistics.cs             # Time-based attack / release / peak-hold math used by the bars
│   ├── FormAudioSpectrum.cs         # Main form — renders bars, handles events
│   ├── FormAudioSpectrum.Designer.cs
│   ├── VerticalProgressBar.cs       # Custom control — one animated bar
│   ├── AdvancedVisualizationControl.cs, WaveSpectrumControl.cs, AmbientParticleFieldControl.cs
│   │                                # Renderers for the non-bar visualization modes
│   ├── VisualStyle.cs, VisualTheme.cs, BarColorThemes.cs
│   │                                # Styles, themes, and colour palettes
│   ├── VisualizerPreferences.cs     # Saved per-user mode/style/theme preferences
│   ├── RotationSettingsForm.cs      # Fixed/Random rotation settings dialog (Ctrl+R)
│   ├── Ambiance Theme.cs            # Visual theme applied to the form
│   ├── Device.cs                    # WASAPI device descriptor
│   ├── Taskbar.cs                   # Windows taskbar progress state helper
│   ├── Program.cs                   # Entry point with single-instance mutex
│   ├── App.config                   # Mode configuration
│   ├── Ref_Files/                   # Bass.Net.dll, NAudio.dll, bass.dll, basswasapi.dll
│   └── Spectrum.csproj
└── Spectrum.Tests/                  # xUnit tests: FFT, band plan, stereo, timing, themes, performance

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📐 Measurement

Signal pipeline

flowchart LR
    A[Windows audio output] --> B[WASAPI loopback]
    B --> C[Lock-free sample history]
    C --> D[DC removal + Hann window]
    D --> E[FFT]
    E --> F[One-sided bin power]
    F --> G[Stereo power average]
    G --> H[83 logarithmic bands]
    H --> I[dBFS mapping]
    I --> J[Time-based ballistics]
    J --> K[Visualization renderer]

[!NOTE] The visual presentation does not hide the physical time/frequency trade-off described below; low-frequency bands intentionally use longer analysis windows for resolution.

What a bar shows. Bar i is the power of the captured signal inside a fixed frequency band, in dB relative to a full-scale sine (dBFS): a full-scale sine whose energy lies inside one band reads 0 dBFS. The 83 bands are contiguous and logarithmically spaced (constant ratio ≈ 1/8.3 octave); band i is centred at 20·1000^(i/82) Hz and its edges are the geometric midpoints to its neighbours, so every frequency between 19.2 Hz and 20.9 kHz belongs to exactly one bar at a sufficiently high sample rate. The spectrum viewport clips the first/last band geometry to 20 Hz–20 kHz; it does not change the integrated band powers or add a frequency filter. At lower sample rates, band geometry follows the actual band plan and frequencies above Nyquist remain unmeasured rather than stretching the data to 20 kHz. No frequency weighting, bass/treble boost or per-frame normalization is applied, so pink noise reads flat and white noise rises 3 dB per octave.

Pipeline. WASAPI loopback (32-bit float) → lock-free sample history (written by the capture callback) → each analysis tick (25 ms one-shot delay plus processing and scheduling): latest frames per channel → window-weighted DC removal → periodic Hann window → FFT → one-sided bin power 2|X|²/(N·Σw²) (Parseval-normalized, so summed bins equal signal power) → mean of left/right channel power (anti-phase content cannot cancel) → bin power integrated into each band with fractional weights for bins that straddle a band edge → 10·log10 → fixed display range −72…0 dBFS mapped linearly to bar height (levels below about −71.6 dBFS, the two lowest byte steps, are gated to an empty bar) → time-based presentation ballistics.

Resolution. Each band uses the shortest window that places at least 4 bins (the Hann main lobe) inside it: ≈85 ms above ~0.5 kHz, ≈171 ms around 0.3–0.5 kHz, ≈341 ms below (window lengths scale with the sample rate). Short windows cut latency (a 1 kHz onset reaches 90 % in ~50 ms instead of ~150 ms with a single 341 ms window); the long window keeps bass resolution. Below ~140 Hz the bars are narrower than the window’s main lobe (≈11.7 Hz at 48 kHz): a pure bass tone lights a small cluster of neighbouring bars, with the strongest bar at the tone’s frequency. Its own-band reading can be lower than the input level because power spreads into neighbouring bands; the amount depends on frequency, sample rate, and band geometry. This is a physical time/frequency limit, not something the display hides.

Stereo. The front left/right pair is analysed separately and powers are averaged: L = R reads like mono, one channel alone reads −3 dB, and phase between channels never changes the level. On multichannel devices only the front pair is measured.

Meter conventions. The frequency spectrum uses a full-scale-sine power reference. PCM RMS and sample-peak meters instead use amplitude-relative digital full scale: a full-scale sine has approximately −3.0103 dBFS RMS and 0 dBFS sample peak. None of these displays claims calibrated LUFS, SPL, VU, standardized PPM, or oversampled true-peak measurement. Mono sources do not invent a second channel.

Timing (default Spectrum mode). Attack: full-scale rise in 45 ms. Release: exponential, time constant 380 ms. Peak marker: 300 ms hold, then a linear fall, independent of the bar. Peaks track measured targets as well as displayed levels, so a brief measured peak is retained before a slow bar attack finishes. Marker geometry stays above the actual painted bar or cell, with a minimum physical gap; a held peak naturally sits farther above a falling bar. Reserved space above full scale accommodates the marker without erasing signal pixels or changing dB calibration. Independent visual clearance falls at a controlled elapsed-time rate when old Trail marks or cells disappear; final collision constraints are resolved before invalidation, allowing stable nonzero meters to stop repainting. Bricks use ±2 px (≈0.5 dB) hysteresis so a level hovering at a brick boundary does not flicker (steady-level display error ≤ ±1.44 dB). A 60 FPS setting is a target, not a guarantee of achieved refresh on a Windows Forms timer. Other visual modes keep their own presentation presets. All modes retain the same window dimensions: layout never changes the window’s size or minimum size. Stereo Spectrum uses side-by-side panels in short viewports and stacked panels when height permits, with cached readable fonts. All thirteen 6 dB grid levels remain; labels are thinned only when space is insufficient, retaining endpoints when they fit. Full labels return when space permits. Crowded frequency labels are omitted, not moved off their logarithmic guides. Radial, time-domain, signed-change and grouped-octave views retain their own appropriate coordinates.

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❓ FAQ

Common questions about high-frequency content and low-frequency response timing.

The top bars are empty or much lower on some songs. Is something broken? Not necessarily. Lossy encoders may remove high-frequency content, so bars above a recording’s cutoff can correctly remain empty. Source sample rate and Nyquist also limit represented frequencies. Deterministic broadband-noise and tone tests validate the band mapping; music alone is not a numerical calibration reference.

Why do bass bars move later than cymbals? Resolving bass needs a longer analysis window (≈341 ms below ~280 Hz versus ≈85 ms above ~560 Hz), so bass bars trail treble bars by roughly 0.1 s. This is the time/frequency trade-off of any FFT analyzer.

🔧 Technical Notes

Implementation details for device-change recovery, stream-hang detection, and silence publication.

• Device changes (plug/unplug, default device switch) are detected via IMMNotificationClient and trigger an automatic re-initialisation on the UI thread
• A hang detector monitors consecutive identical WASAPI levels and forces a device reset if the stream appears stuck
• Silence (zero level, or no new captured frames) publishes the floor; bars then decay with their release time

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🎚️ Spectrum

Windows Audio Spectrum Visualizer · .NET Framework 4.8 · WASAPI Loopback

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Documentation links

Read all Spectrum Audio Analyzer guides online · Project overview · All developer projects

Verification and redistribution limitations

Spectrum provides professional audio visualization through measured frequency-band displays, PCM views, and real-time FFT analysis. Numerical and runtime evidence, including unsuccessful or unexecuted checks, is recorded in the reports above rather than inferred from appearance.

Use the complete Spectrum\bin\Release output folder; the included native BASS libraries are x86, and an x64-named solution configuration is not an x64-native distribution. .NET Framework 4.8 and Windows remain required. WASAPI loopback observes the selected endpoint’s combined output, not an isolated Spotify session; exclusive/protected streams may not be accessible.

Bundled third-party binaries require the owner’s redistribution/license authorization and appropriate notices before a production release. This checkout does not establish that authorization. No search-ranking outcome, universal 60 FPS performance, prolonged stability, or Spotify validation is implied by this README.