sounddiff

sounddiff is a CLI tool for audio producers and developers to compare two audio files and see exactly what changed. It reports differences in loudness, spectral balance, timing, and potential issues like clipping and silence. Output comes as colored terminal text, structured JSON, or a self-contained HTML report.

New to audio? The sounddiff wiki has plain-language guides to LUFS, spectral analysis, clipping, and everything else sounddiff measures.

Example

$ sounddiff mix-v3.wav mix-v4.wav

sounddiff: mix-v3.wav vs mix-v4.wav

Duration     3:42.108 → 3:42.108  (no change)
Sample Rate  48000 Hz → 48000 Hz  (no change)
Channels     stereo   → stereo    (no change)

Loudness (integrated)
  LUFS       -14.2    → -12.8     (+1.4 dB)
  Peak dBTP  -1.1     → -0.3      (+0.8 dB)
  LRA         8.2     →  6.4      (-1.8 LU)

Spectral
  Low  (20-250 Hz)    +0.8 dB avg
  Mid  (250-4k Hz)    +0.3 dB avg
  High (4k-20k Hz)    +1.9 dB avg

Segments
  0:00-1:12   similar (correlation: 0.97)
  1:12-1:14   ADDED (new content, 2.1s)
  1:14-3:42   similar (correlation: 0.98, shifted +2.1s)

Issues
  ⚠ Clipping detected in mix-v4.wav at 2:31.4 (3 samples)

Installation

pipx install sounddiff

Or with pip: pip install sounddiff

Requires Python 3.10 or later. Supports WAV, FLAC, OGG, and AIFF natively. For MP3, AAC, WMA, and Opus, install ffmpeg. See docs/install.md for detailed setup.

Usage

Compare two files with colored terminal output:

sounddiff old-mix.wav new-mix.wav

Get structured JSON for scripts and CI pipelines:

sounddiff old.wav new.wav --format json

Generate an HTML report:

sounddiff old.wav new.wav --format html -o report.html

See docs/usage.md for all options.

What it analyzes

Output formats

Terminal is the default. Colored, grouped by category, designed to be read top to bottom. Uses rich for formatting.

JSON outputs the same data in a structured format. Pipe it to jq, parse it in Python, or use it in CI pipelines for automated regression testing.

HTML generates a self-contained report with inline styles. No external dependencies. Open it in any browser, share it with your team, or archive it alongside your session files.

How it's built

sounddiff is written in Python with a modular architecture. Each analysis type (loudness, spectral, temporal, detection) lives in its own module with no cross-dependencies. The core orchestrator loads two audio files, runs all analyzers, and passes the results to a formatter.

See docs/architecture.md for the full module breakdown and data flow.

Documentation

• Wiki - guides to LUFS, spectral analysis, clipping, and other audio concepts
• Installation - system dependencies, shell completions, ffmpeg setup
• Usage - CLI options and examples
• API Reference - using sounddiff as a Python library
• Architecture - module layout and design decisions

Contributing

Contributions are welcome. See CONTRIBUTING.md for setup instructions and our development workflow.

The issue board has open work organized by milestone. Issues labeled good first issue are scoped for newcomers and have enough context to get started without deep DSP knowledge.

Security

Report vulnerabilities to dev@systemblue.io. See SECURITY.md for our disclosure policy.

License

MIT