audioscope

Audio inspector for waveform, spectrogram, playback, loop selection, loudness, and metadata review.

Sample-level inspection — keep zooming until individual samples appear as dots; hovering shows the sample index and per-channel amplitude values.

Follow playback — with Follow enabled, the view auto-scrolls to keep the playhead centered at any zoom level, down to sample resolution.

Loop selection — drag on the waveform to set a loop range and fine-tune it with the edge handles while playback cycles inside.

Spectrogram inspection — hover to read the exact time and frequency under the cursor; the spectrogram stays in sync with the waveform zoom.

Analysis type and settings — switch the analysis type (here, to mel-spectrogram) and tune FFT size, overlap, window function, and frequency scale from the settings panel.

Loudness view — momentary and short-term LUFS curves plotted against a reference level, with hover readouts for M/S loudness and sample peak.

Quick Start

audioscope is a read-only custom editor for audio files inside VS Code.

1. Install the extension.
2. Open a supported audio file.
3. If needed, right-click the file and choose Open in audioscope, or run audioscope: Open in audioscope.

[!NOTE] VS Code Media Preview can still take precedence for some extensions on first open, especially .mp3, .wav, and .ogg files.

Supported Formats

.wav, .wave, .mp3, .ogg, .oga, .flac, .m4a, .aac, .opus, .aif, .aiff

Features

Waveform and transport

• Synchronized waveform viewer
• Timeline scrubber and overview strip
• Play / pause controls
• Seek backward and forward by 5 seconds
• Playback speed control
• Follow playback mode
• Loop selection and loop handles
• Waveform zoom controls

Spectrogram and analysis

• Spectrogram visualization
• Audio analysis uses WebGPU when available, with WASM fallback for unsupported environments
• Spectrogram, mel-spectrogram, MFCC, scalogram, and chroma analysis are computed from a mono downmix of the source audio
• FFT size controls
• Overlap ratio controls
• Window function selection
• Frequency scale controls
• Colormap distribution controls
• Decibel range controls
• Mel band count controls
• MFCC coefficient controls
• Scalogram omega0 control

Metadata and loudness

• Audio metadata summary
• Codec name and long name
• Container / format information
• Duration, size, bitrate, sample rate, and channel layout
• Tags and chapter data
• Loudness analysis with LUFS, LRA, Peak, and True Peak
• FFmpeg / ffprobe tool status and fallback guidance

Settings

• audioscope.spectrogramQuality: balanced | high | max
• audioscope.spectrogramDefaults: persisted defaults for analysis controls, including advanced scalogram defaults when edited in settings JSON
• audioscope.openSampleOnStartupInDevelopment: open the bundled sample on startup in development mode

Keywords

audio inspector, waveform, spectrogram, mel, mfcc, scalogram, chroma, playback, loop, metadata, loudness, LUFS, integrated LUFS, EBU R 128, LRA, mp3, wav, flac, m4a, ogg, aac, opus, aiff, aif

Development

Build prerequisites:

• bun
• zig 0.15+
• Emscripten toolchain
• FFmpeg submodule checkout

Build from source:

bun install
git submodule update --init --recursive
bun run compile

The full build compiles:

• embedded FFmpeg / ffprobe WASM tools
• analysis WASM binaries
• webview bundles
• extension host output

Third-Party And Vendor Code

This repository includes vendored and third-party source.

• src-wasm/third_party/ffmpeg The FFmpeg source tree vendored as a submodule and used to build the embedded FFmpeg / ffprobe WebAssembly binaries. Upstream repository: https://github.com/FFmpeg/FFmpeg
• src-wasm/third_party/pffft PFFFT and FFTPACK-based FFT code used by the analysis WASM runtime. Original PFFFT repository: https://bitbucket.org/jpommier/pffft/
• src-webview/vendor/SignalsmithStretch.mjs Vendored Signalsmith Stretch Web module used for time-stretch playback in the webview transport path. Official upstream: https://signalsmith-audio.co.uk/code/stretch.git GitHub mirror: https://github.com/Signalsmith-Audio/signalsmith-stretch

Licensing and attribution details for bundled third-party code are documented in THIRD_PARTY_NOTICES.md. FFmpeg rebuild notes and revision details are documented in FFMPEG_SOURCE.md.

License

MIT