Local Live Captions od Eric

Local Live Captions puts a caption panel over whatever is playing in a tab, the way Chrome's Live
Caption does — except the speech recognition runs on your own machine, inside Firefox,
using a Whisper model compiled to WebAssembly.

• Captions appear on their own as soon as a tab starts playing audio
• Everything is local: after the one-time model download the add-on works offline,
and your audio is never uploaded
• Works with ordinary <video>/<audio> players, with sites that play through the Web
Audio API, and with a microphone source for calls or anything Firefox cannot tap
• Drag the panel anywhere, resize it, change the text size, pick dark or light
• Choose your accuracy/speed trade-off: whisper-tiny.en for the fastest captions,
base or small when you want more accuracy; WebGPU if your build supports it
• Can translate other languages into English with a multilingual model
• Optionally point it at your own transcription server instead (OpenAI-compatible)

Keyboard shortcut: Ctrl+Shift+L (Cmd+Shift+L on macOS) toggles captions for the tab.

First run downloads the speech model (about 40 MB for the default). Firefox asks you
to grant site access before the add-on can read a page's audio.

Known limits: media served cross-origin without CORS headers cannot be tapped (use
microphone mode there), DRM video cannot be captured at all, and captions lag by about
the length of the phrase being spoken.