Dub and subtitle a video file from your computer

• The desktop app, version 1.0.7 or later, on Windows 11 or macOS 14.2 or later. Quick start with the desktop app covers installing it.
• A file it can play: MP4, MOV, MKV or WebM with AAC, MP3, Opus or FLAC sound, or an audio file such as MP3. If a file won't open has the way around everything else.
• An internet connection while it prepares. DubTab sends the sound of the part it is preparing to be transcribed and translated. The file itself stays on your computer — it is never copied or uploaded, and the picture is never sent.

1. 1
   Drop it in

   Drag a video or audio file onto the DubTab window — anywhere works. You can also choose Video file as the source on Home and press Choose a file…, or use Open file… on the Local files page.

2. 2
   Pick the language to hear

   Choose the target language. The source is always Automatic Detection for video files: DubTab works out the spoken language line by line, so a lecture that switches language part-way still gets dubbed. Check the Voice beside it too — you can switch later, but the video pauses for a moment while the new voice catches up.

3. 3
   Press Start playing

   The first lines take a few seconds to prepare. If you'd rather not wait, press Play now with the original sound — the dubbing joins in as soon as it is ready.

The dubbing is prepared a little ahead of where you are watching, so the voice keeps pace with the picture instead of trailing a few seconds behind it, as live dubbing does. Jumping ahead is fine: DubTab prepares from wherever you land.

• Bilingual and Translation at the top switch between both lines and the translation alone.
• Drag the subtitles anywhere on the picture, and double-click them to put them back. A long sentence shows in two short parts instead of one tall block over the picture.
• Audio Mixer balances the Original Audio against the Translated Voice — Choose a voice and adjust audio explains the two sliders.
• Voice switches the dubbing voice at any time. The video pauses for a moment while the line you are in catches up in the new voice, then plays on.

The Transcript tab beside the player fills in as the video is prepared, original and translation together, and follows the line being spoken. Click any line to jump the video there.

Each video keeps a single session in Sessions, however many times you watch it, so its whole transcript stays in one place — ready to search, export or summarise. From there, Play from here reopens the file at any line.

Ask AI sits next to the transcript. Ask anything about what you have watched: each point in the answer links to the moment it comes from, and clicking one jumps the video there. You can also start a question from any line in the transcript.

Drop a whole course folder instead of a single file, and DubTab opens the lecture you were on — or the next one you haven't seen.

• The Folder tab lists every lecture in the folder in order, with the one playing highlighted. Click any of them to switch.
• When a lecture ends, DubTab offers the next file in the folder. After the last one, it offers the first lecture of the next chapter — when the chapters are numbered folders, such as 03 and 04.

Playback speed, at the bottom right of the player, offers 0.75×, 1.25× and 1.5×. The dubbing speeds up or slows down with the video and keeps its normal pitch. The < and > keys step through the speeds.

Every file you have played is on the Local files page, grouped by folder, with how far you got. Resume from its card, or from Continue watching on Home.

• A course folder shows how many lectures you have watched and lists the ones not opened yet, with the next one marked Up next.
• Moved a file, or unplugged the drive it is on? Its card says so. Use Locate… to point DubTab at it again — your progress and its session stay attached.
• Remove from this list hides a file from this page and from Continue watching. Nothing is deleted: open the file again and it comes back with your progress.

• You are charged for the part of the video that gets prepared — never more than about 2½ minutes ahead of where you are, and nothing while it is paused.
• You pay for each part once. Watching a prepared part again on the same computer, in the same language, uses no minutes — even with a different voice. Watching in another language prepares it again.
• If a video turns out to be in your language already, DubTab stops preparing so you aren't charged for it, and offers Keep preparing in case it switches language later on.
• Prepared subtitles and dubbing are kept on your computer, up to 2 GB. Past that, the oldest videos are cleared first, and watching one of those again is charged again. See and clear them in Settings → Prepared videos.
• When you close a video, DubTab shows the minutes it used and how many you have left.

Understand translation hours and AI credits explains your balance.

Live dubbing has to hear a sentence before it can translate and speak it, so the voice always runs a little behind — Manage dubbing delay explains why. A file is different: DubTab can read ahead, so each line is translated, voiced and fitted to the original timing before you reach it.

So for a video you already have on your computer, open it here rather than playing it in another player with Computer audio capture.

DubTab tells you when it can't play a file, and why — usually the format, or a sound track it can't play, such as Dolby Digital or DTS on a film.

1. 1
   Play it in your own video player

   Any player that can open the file will do.

2. 2
   Choose One specific app as the source

   On Home, pick that player as the app DubTab listens to and start a session. DubTab then dubs whatever the player plays — live, with the usual small delay. Choose what DubTab listens to walks through it.