ulaw_8000 and alaw Audio Player
Play raw G.711 μ-law and A-law telephone audio — plus raw 16-bit PCM — directly in VS Code, with a waveform, click-to-seek, and keyboard play/pause.
Raw G.711 files (.ulaw_8000, .ulaw, .mulaw, .alaw, .alaw_8000) are headerless: they're just 8-bit companded samples at 8000 Hz, mono — the format telephony systems (e.g. Twilio media streams) speak natively. μ-law is the North American / Japanese variant, A-law the European one. .pcm_8000 files are the uncompressed cousin: headerless signed 16-bit little-endian PCM at 8000 Hz, mono. Nothing on a normal desktop opens any of these, and even ffplay needs the format spelled out. This extension makes them click-to-play.
Features
- Opens
*.ulaw_8000, *.ulaw, *.mulaw, *.alaw, *.alaw_8000, and *.pcm_8000 files in an audio player (as the default editor)
- Waveform rendering with played/unplayed coloring, using your editor theme's colors
- Click the waveform to seek, drag to scrub, digits 0–9 to jump to tenths, Space to play/pause
- Zero dependencies, no build step — the G.711 decoding happens in ~25 lines of JavaScript
How it works
The file's bytes are decoded with the standard ITU-T G.711 expansion (μ-law or A-law, chosen by file extension) into PCM — or, for .pcm_8000, read directly as signed 16-bit little-endian samples — loaded into a Web Audio AudioBuffer at 8000 Hz, and played in the editor webview. Since the format is fixed by convention, no header is needed — the file extension is the format declaration.
Development
No install step. Open this folder in VS Code and press F5 — a development host window opens on the samples/ folder; click tone-440hz.ulaw_8000 or tone-440hz.alaw.
To regenerate the sample files: python3 scripts/make_test_tone.py.
Packaging & publishing
Requires Node.js:
npx @vscode/vsce package # produces ulaw-8000-audio-player-x.y.z.vsix
npx @vscode/vsce publish # after `npx @vscode/vsce login <publisher>`
Before first publish, set publisher and repository in package.json.
License
MIT
