How Do You Add an AI Voiceover to Any Video?

There are three ways to put an AI voice on a video. Generate a voice-over in a text-to-speech tool and place it on the clip, let a talking-avatar or spokesperson tool generate the face and voice together, or use a video model that produces native audio. The first works with any footage you already have. Generate the voice in VdoBloom Text to Speech, upload it to the Timeline Editor and set the levels against your clip; the voice track and the video live on the same timeline.

Updated October 2026.

Three ways to get a voice on a video

Separate voice-over. Write a script, generate speech, then place the audio under existing footage. Most flexible: you can re-record one line without touching the video.
Avatar or spokesperson. Supply a photo and a script, and the tool generates a talking person with lip-sync. Best when the viewer needs to see a face.
Native audio in a video model. Some models generate sound with the picture. Seedance 2 includes native audio, and Veo 3.1 generates audio as part of the clip. Useful when the sound has to match the physics on screen.

Most projects use the first route. It separates the two jobs, so a change to the narration does not force a re-render of the footage.

Write a script that fits the clip length

Spoken words per second is the number that decides whether a voice-over fits. A comfortable narration pace is roughly two to two and a half words per second, so:

15 seconds: about 30 to 38 words.
30 seconds: about 60 to 75 words.
60 seconds: about 120 to 150 words.

Those are working ranges, not rules. Read your script out loud with a stopwatch and you will get a better number for your own pace. If the draft runs long, cut a sentence rather than speeding up the voice.

Write for the ear. One idea per sentence, no nested clauses, and numbers spelled the way they are said. “Fourteen ninety-nine” is easier to voice than a string of digits. If the script has to be read by a synthetic voice, punctuation does the pacing work, so use full stops where you want a pause.

Generate the voice in Text to Speech and pick a voice

Open Text to Speech, paste the script and choose a voice. The tool offers ElevenLabs Multilingual V2 and Turbo 2.5, Google Gemini Flash TTS with 30 voices across more than 70 languages, and xAI TTS. MP3 download is available when you buy a credit pack.

Audition two or three voices on the first sentence, not the whole script. The right voice is the one that makes your opening line sound natural. A warm voice suits a personal explainer; a clipped, neutral voice suits a product demo. Match the voice to the footage rather than to your personal taste.

Generate the full script in one pass if the tool supports it, so the delivery stays consistent. If you generate sentence by sentence, the tone can shift between clips. Keep the raw file as well as the finished one; you may need a word or two re-cut later.

Our AI text to speech guide covers voice selection and the quirks of synthetic delivery in more detail.

Put the audio on your clip in the Timeline Editor

Open the Timeline Editor and add your video. The media library has separate tabs for video, image and audio, and it lists audio from your creations as well as files you upload. Audio uploads are capped at 25 MB, which is several minutes of compressed speech.

Drop the voice track onto an audio track, move it to the point where the speaker should start, and trim the ends. If the video has its own sound, keep it on a separate track and lower it under the voice. The timeline is where you fix the small mismatches: a line that arrives a beat early, a pause that runs too long, a shot that needs two more seconds to let a sentence land.

If you would rather generate the face and the voice together, the Spokesperson tool builds a reusable presenter and turns a script into a talking video. That route skips the manual sync step, at the cost of control over the edit.

When to use native-audio models instead

Native audio is the better choice when the sound has to match something physical: a glass breaking, footsteps on gravel, a car passing, a door closing. Generating the picture and the sound together tends to keep them aligned in a way that a separate sound-effects pass does not.

Seedance 2 includes native audio and runs 4 to 15 seconds. Veo 3.1 also generates audio. For a talking presenter, an avatar or spokesperson tool is usually more reliable than a general video model, because lip-sync is the specific job. The trade-off is control: native audio gives you a performance you have to direct through the prompt, while a separate voice-over gives you a script you can edit word by word. Our comparison of AI video generators with sound covers the model side.

Sync, pacing and music levels

Good sync is mostly about leaving room. Start the voice a fraction after the picture, not exactly on the cut, so the first word is not clipped. End the clip after the last word rather than cutting on it.

Pace the picture to the voice. If a sentence needs four seconds, give the shot four seconds. Cutting away mid-sentence makes a clean read feel rushed.
Keep music well under speech. A background bed should be audible but not competing. If you cannot hear every consonant, the music is too loud.
Use silence deliberately. A half-second pause before the call to action does more than a sound effect.
Check on phone speakers. Laptop speakers hide problems that a phone reveals, especially sibilance and boomy music.
Normalise the final mix once. Set the voice as the loudest element and bring everything else under it.

If the video needs a face speaking the words rather than a narration over it, the lip-sync route is covered in our AI voice and lip-sync guide.

Frequently asked questions

Can I add a voice-over to a video I already made?

Yes. Generate the voice in Text to Speech, then add both the video and the audio to the Timeline Editor and line them up on separate tracks.

How many words fit in 30 seconds?

About 60 to 75 words at a comfortable pace. Read the script aloud with a stopwatch for a more accurate figure.

Which voices are available?

ElevenLabs Multilingual V2 and Turbo 2.5, Google Gemini Flash TTS with 30 voices across more than 70 languages, and xAI TTS.

Can I upload my own audio to the timeline?

Yes. The media library accepts audio uploads up to 25 MB and also lists audio from your creations.

Should I use native audio or a separate voice-over?

Use native audio when the sound must match physical action. Use a separate voice-over when you need control over every word and an easy re-record.

Generate the voice in Text to Speech, then place it on your clip in the Timeline Editor. If you want a presenter on camera, build one in the Spokesperson tool. No subscription is required, and one-time credit packs never expire. New accounts start with 10 free credits and no card, failed generations are refunded, and pack prices are on pricing.