How to Add Subtitles to Any Video on macOS (Live, in Real Time)

The short answer: AddSub adds live, translated subtitles to any video playing on your Mac — streaming sites, local files, meetings, or full-screen apps — in real time, 100% on-device, with no upload. Set it up once in 4 steps and captions appear on everything you watch.

Why you might need subtitles on everything

You watch foreign films without localized subs. You follow global news or live streams in another language. You study with lecture videos where the audio is hard to follow. Or you run international meetings and want a live transcript. In every case, the problem is the same: the captions you need either don’t exist or aren’t in your language. AddSub solves it by generating subtitles live, from whatever audio your Mac is playing — and translating them into the language you read.

The 4 steps to subtitles on any video

1. Download AddSub — it’s a ~39 MB native macOS app for Apple Silicon (download page). The 7-day trial is free and starts automatically.
2. Install the audio driver — first launch asks to install the loopback driver. This is what lets AddSub read any app’s audio output (one admin password).
3. Pick your language pair — in Settings → Languages, choose the spoken language (or Auto-Detect) and your target, e.g. Japanese → English. The overlay shows both.
4. Play anything — start any video, stream, or call. Live translated subtitles float above the content with speaker labels (S1, S2, S3…) as people talk.

What works — and how well

• Streaming (Netflix, YouTube, Disney+, Crunchyroll): excellent — browser audio is captured cleanly.
• Local files (IINA, VLC, QuickTime): excellent.
• Live streams & webinars: very good — subtitles appear within a second.
• Meetings (Zoom, Teams, Meet): very good — includes speaker labels.
• Full-screen apps: the overlay floats above everything, across all spaces.

Privacy: your video never leaves your Mac

AddSub is a single native binary. Speech recognition, translation, and diarization all run on your Mac’s Neural Engine — nothing is uploaded, there’s no account, and there are no per-minute fees. It’s the private choice and the cost-free one.

Troubleshooting

• No captions appear? Check the driver is installed (Settings → Audio & System) and routing is active; confirm Microphone permission in System Settings → Privacy & Security.
• Captions lag? Use a faster model (Tiny/Small) — typical latency is under a second.
• Translation looks odd? Some pairs translate better one direction — try reversing, or Auto-Detect for the source.

Try it on any video — free for 7 days

No payment needed to start. No accounts. Download for macOS.