NavOS - Audio DOC

A browser-based audio file analyzer that examines metadata and spectral content to assess audio quality, identify likely sources, and provide educational context — all without uploading files to any server.

Features

• Quality Analysis: Scores audio files based on codec, bitrate, sample rate, and bit depth
• Source Estimation: Identifies likely provenance (CD rip, streaming, Hi-Res download, etc.)
• Spectral Analysis: SoX-compatible spectrograms with full frequency visualization
• Hi-Res Audio Support: Native sample rate decoding up to 192 kHz — no resampling artifacts
• Educational Content: Contextual explanations about audio formats and quality
• Export Options: PDF reports, copy summary, and technical details clipboard export
• Privacy-First: All processing happens in your browser — files never leave your device

Spectral Analysis

The spectrogram display matches Internet Archive / SoX reference output:

• Full dynamic range: 0 to -120 dBFS (120 dB)
• SoX default colormap: Dark blue → purple → magenta → red → orange → yellow → white
• Hi-Res support: Analyzes up to 96 kHz frequencies (192 kHz sample rate)
• Sample rate preservation: Creates AudioContext at the file's native sample rate to prevent browser resampling
• Stereo display: Stacked L/R channel visualization

Sample Rate Integrity

Source Sample Rate	Analysis Rate	Max Frequency
44.1 kHz	44.1 kHz	22.05 kHz
48 kHz	48 kHz	24 kHz
88.2 kHz	88.2 kHz	44.1 kHz
96 kHz	96 kHz	48 kHz
176.4 kHz	176.4 kHz	88.2 kHz
192 kHz	192 kHz	96 kHz

Supported Formats

• MP3 (all bitrates)
• FLAC (including Hi-Res 24-bit up to 192 kHz)
• WAV
• M4A / AAC
• OGG / Vorbis
• Opus
• AIFF

Usage

1. Visit the deployed site or run locally
2. Drop an audio file into the upload zone (or click to select)
3. View the analysis results including:
   • Quality score and tier
   • Likely source classification
   • Technical audio specifications
   • Spectral analysis with SoX-compatible spectrogram
   • Educational context
4. Export results as PDF or copy to clipboard

Development

Prerequisites

• Node.js 18+
• npm 9+

Install Dependencies

npm install

Run Development Server

npm run dev

Opens at http://localhost:5173

Run Tests

npm test

Build for Production

npm run build

Output goes to dist/ directory.

Preview Production Build

npm run preview

Architecture

src/
├── engine/           # Analysis logic
│   ├── analysisEngine.ts      # Main orchestrator
│   ├── qualityScorer.ts       # Quality scoring algorithm
│   ├── sourceEstimator.ts     # Source provenance detection
│   ├── spectralAnalyzer.ts    # FFT spectral analysis
│   └── educationSelector.ts   # Contextual education selection
├── workers/          # Web Workers
│   └── spectralWorker.ts      # Background spectral processing
├── components/       # React components
│   └── analysis/
│       ├── SpectrogramViewer.tsx      # SoX-compatible spectrogram
│       └── SpectralAnalysisSection.tsx # Spectral results UI
├── extractor/        # File metadata extraction
├── parser/           # FFprobe-format parser
├── normalizer/       # Metadata normalization
├── export/           # PDF and text export
├── rules/            # JSON-driven scoring rules
├── types/            # TypeScript definitions
│   └── spectral.ts            # Spectral analysis types
└── App.tsx           # Main UI component

Technical Details

Spectrogram Parameters

• FFT Size: 4096 samples
• Window: Hann
• Overlap: 75%
• Dynamic Range: 120 dB (0 to -120 dBFS)
• Colormap: SoX default palette

Browser Compatibility

Sample rate preservation requires AudioContext({ sampleRate: N }):

• Chrome 55+
• Firefox 50+
• Safari 14.1+
• Edge 79+

File Size Limits

• Maximum file size: 500 MB
• Files are processed entirely in-browser
• Large files may take longer to analyze

Privacy

NavOS Audio DOC processes files entirely in your browser:

• No files are uploaded to any server
• No analytics or tracking
• No user accounts required
• Works offline after initial page load

License

MIT License — see LICENSE for details.

Author

NavOS-OpenSource

• GitHub: https://github.com/sponsors/NavOS-OpenSource

Support

If you find this tool useful, consider supporting development:

Credits

Built with:

• React
• Vite
• music-metadata
• jsPDF