The rythmo band, the tool that makes dubbing possible
If you have ever seen a photo of a dubbing booth, you have seen it: an actor at a microphone, the screen above, and a strip of text sliding horizontally at the bottom of the picture. That strip is the rythmo band. It is the central tool of the craft, and it explains how actors land on the exact frame.
The principle, in one sentence
The text scrolls right to left at exactly picture speed. A fixed vertical marker sits in the centre. When a word crosses that marker, that is when you say it.
That is the whole idea. The actor does not read a script and guess the timing. The text itself carries the timing. All that remains is to act.
Why a script is not enough
| Script | Rythmo band | |
|---|---|---|
| Tells you the words | Yes | Yes |
| Tells you when to start | No | Yes |
| Tells you how fast to speak | No | Yes |
| Lets you keep your eyes on the picture | No | Yes |
A line that starts three tenths of a second early is visible immediately: the character's mouth is still closed. And a translated line that runs longer than the original must be spoken faster, or rewritten. On the band that constraint is visible, because the text is packed tighter.
Where it comes from
The technique was born in France in the 1950s. Back then the band was a real strip of transparent celluloid, hand lettered by a detector who stretched or squeezed the letters to match the actor's delivery. It scrolled mechanically under the screen, driven in sync with the projector.
Everything is digital now, but the vocabulary and the conventions survived, and the job of detector still exists.
What else is written on it
A professional band carries more than words. Conventions mark what cannot be spelled:
- Breaths and reactions that are not words: a gasp, a laugh, a shout, an effort
- Moments where the mouth is not visible, off screen or from behind, where sync can be looser
- Character changes, usually by separate lines or colours
- Elisions, when two words must be run together to fit the available time
The rythmo band in Dubba
Dubba generates the band automatically from the transcription. Each line is placed at the exact moment it is spoken, and each detected character gets its own line and colour, so you see at a glance when it is your turn.
The tip that changes everything on your first try. Do not read the word arriving at the marker. Read the one after it. Your voice always lags your eye. Experienced actors stay one step ahead of the marker, which is exactly why they land on time without sounding like they are reading.
Frequently asked
What is a rythmo band for?
To tell you exactly when to speak each word without looking away from the picture.
Why not just read a script?
A script gives words, not rhythm, and forces your eyes off the screen.
Is it used everywhere?
No. It is largely a French practice. Most countries dub from a script with audio cues.
Do I need to read fast?
Not really. The challenge is acting within a time constraint, and it clicks after a few takes.
What if my line is too long for the available time?
Shorten it. That is exactly what an adaptor does professionally: find a phrasing that says the same thing in the time the mouth allows.
Read next
Sources
On the history of the technique: rythmo band and dubbing.
Written by the Dubba team · Published 5 August 2026