jupyterlab_voice_capture_extension

Capture microphone audio in the JupyterLab browser tab and stream it to a server-side FIFO, so terminal applications running inside the container - notably Claude Code voice mode - can record from a microphone the container itself has no access to.

The container has no capture device; the browser does. This extension bridges that gap: the browser captures the mic, ships the audio over an authenticated websocket to a Jupyter server handler, and the handler writes raw PCM to a named pipe. A separate, out-of-scope plumbing layer (PulseAudio module-pipe-source + SoX) turns that pipe into the system default audio source.

How it works

• Capture - a microphone toggle in the status bar calls getUserMedia; an AudioWorklet resamples to 16 kHz mono and encodes signed 16-bit little-endian PCM off the UI thread
• Transport - 20 ms PCM frames (640 bytes) are sent as binary websocket messages to …/jupyterlab-voice-capture-extension/stream, which lives under the Jupyter base URL and inherits Jupyter token auth - no new port is opened
• Sink - the server handler writes each frame, in order, to a FIFO (default /run/voice/pulseaudio.fifo); the PulseAudio reader creates the pipe (module-pipe-source refuses a pre-existing one), so the handler attaches as writer, waits for the pipe to appear, and tolerates a not-yet-attached reader without blocking the server

Chain: browser mic → AudioWorklet (16 kHz mono s16le) → websocket → server handler → FIFO → (PulseAudio + SoX, out of scope) → terminal app.

[!IMPORTANT] Out of scope - the extension does not manage PulseAudio, invoke SoX or any recorder, or perform speech-to-text; its responsibility ends at delivering correct PCM to the FIFO.

Requirements

• JupyterLab >= 4.0.0
• A secure context (https or localhost) - browsers only expose the microphone over a secure origin

Install

pip install jupyterlab-voice-capture-extension

Dependencies

• Python: jupyter_server and traitlets, installed automatically with the package
• System (only for the full voice chain into a terminal app): PulseAudio + SoX. Provision and verify them with the bundled CLI:

jupyterlab_voice_capture install    # apt packages + /run/voice dir + client.conf + Jupyter config line (does NOT start the daemon)
jupyterlab_voice_capture start -d   # start the PulseAudio daemon + pipe-source (run after install and each restart)
jupyterlab_voice_capture validate   # check every component, print what to fix (--json for machine output)
jupyterlab_voice_capture stop       # kill the PulseAudio daemon

See docs/jupyterlab-enable-claude-voice.md for the full setup and troubleshooting.

Usage

• Click the microphone icon in the status bar (or run Toggle Voice Capture from the command palette) to start capture
• On the first start the browser asks for microphone permission; the status label moves Disconnected → Connecting → Connected, the icon glows green while streaming, and the browser shows its active-microphone indicator
• Click again to stop - capture tracks are released and the browser indicator clears
• Only one tab streams at a time: starting capture in a second tab takes over and stops the first

Configuration

The sink FIFO path defaults to /run/voice/pulseaudio.fifo and is overridable via Jupyter server config:

c.VoiceCapture.sink_path = "/run/voice/pulseaudio.fifo"

Settings → Voice Capture has one option, Auto-connect on startup (autoConnect, default off): when enabled, capture starts automatically as JupyterLab loads instead of waiting for a click.

Uninstall

pip uninstall jupyterlab-voice-capture-extension

Troubleshoot

If you see the frontend extension but it is not working, check that the server extension is enabled:

jupyter server extension list

If the server extension is installed and enabled but you do not see the frontend extension, check the frontend extension is installed:

jupyter labextension list

Contributing

If you would like to contribute to this extension, please refer to the Contributing Guide.