Dubbing means replacing a video's sound with a new recording. People do it to swap a noisy original for a clean voice, to narrate a silent clip, or to put the video in another language. The steps are the same in each case.

Decide what you are replacing

There are two different jobs:

  • Narrating over the original. The original sound stays, quietly, under your voice. Good for a clip with natural ambience.
  • Replacing it. The original is muted and only the new audio plays. Good for wind noise, a bad mic or a translation.

Know which one you want before you record, because it decides the volume setting later.

An audio waveform shown before and after silences are closed up, the take shorter.

Apple's Final Cut Pro user guide is the shortest useful explanation of levels and headroom - including why a technically correct peak can still sound bad.

The iOS side of screen capture is ReplayKit, Apple's framework for recording and broadcasting the display.

Step by step

  1. Open the clip and set the playhead where the new audio should begin, not at the top of the timeline.
  2. Put headphones in. Without them the microphone picks up the video's own sound and your take comes out hollow and doubled.
  3. Turn the original down. In the Audio tool, drop the clip's volume to zero to replace it, or low to keep a bed of ambience.
  4. Record while the picture plays. In Zella this is Audio, then Record voiceover. The video plays in the recording sheet, so you speak to the cut and not to a stopwatch.
  5. Record in short passes. One or two sentences at a time. A mistake then costs seconds, and each pass is easy to nudge into place.
  6. Leave a beat of silence before and after each pass. It gives you room to trim and helps music dip cleanly around your voice.

The full method, including how to hold the phone and cut room echo, is in how to record a voiceover on iPhone while the video plays.

Dubbing into another language

Translate the script first, and read it aloud once before recording. A line that runs long in the new language will overrun its shot, so shorten it rather than speeding up your delivery. Then record in passes against the picture, as above. If the original had on-screen captions, add captions in the new language so viewers who watch without sound still follow.

Fixing a weak take

A thin, boomy or noisy recording is common on a phone. Moving closer to the microphone, facing a soft surface and switching off a fan fix most of it before you press record, which is far easier than repairing it afterwards. See how to make your voice sound better in a video for the cleanup options.

Check the result

Play the finished video once with headphones and once through the phone speaker. If the new voice drowns in the music or the old sound leaks through, adjust the volumes in the Audio tool, then export.

Frequently asked questions

How do I remove the original audio from a video on iPhone? Set that clip's volume to zero in the editor's audio controls. The picture stays and the sound is silent.

Can I record a voiceover while watching the video? Yes. Zella plays the video inside the recording sheet while you speak.

Why does my voiceover sound echoey? Usually the microphone is recording the video's sound back. Wear headphones, and record in front of a soft surface such as a curtain.

Can I dub a video into another language? Yes. Translate the script, record it in short passes against the picture, and add captions in the new language.