Text to video with sound: how AI video audio works

For a long time AI video meant silent clips. You generated a picture, then spent as long again finding music, adding effects and lining everything up. Newer systems generate the sound in the same pass as the picture, which changes how you work. This guide explains what that audio is, how to ask for it, and where you will still want to add your own.

Why sound generated with the picture is different

When picture and sound come from one render, the sound can follow the action. A door closing, a footstep on gravel or a pour of coffee lands on the frame where it happens, because the system produced both together. Adding sound afterwards means placing each effect by hand against the picture.

It also saves a lot of time on short clips, where sound carries much of the feeling: a quiet street with distant traffic, a kitchen with a sizzling pan, a forest with wind in the leaves.

The four kinds of generated sound

• Ambience: the background of a place, such as rain, a market, waves or wind.
• Effects: sounds tied to something you can see, such as footsteps, a closing door or glass clinking.
• Music: a bed that fits the mood of the scene.
• Short spoken lines: a few words of speech or a voiceover tone.

How to write a prompt that gets good sound

Write the picture first, in the usual structure of subject, action, setting, light, lens and camera move. Then add one sentence about what the viewer should hear. Compare the two versions:

• *A fisherman coiling rope on a wooden pier at dawn, soft mist, 35mm, slow push-in.*
• *A fisherman coiling rope on a wooden pier at dawn, soft mist, 35mm, slow push-in. Gentle waves against the posts, a distant gull, rope creaking.*

The second names three sounds that belong to the scene. A few well-chosen sounds work better than a long list, and sounds that cannot plausibly happen in the shot tend to confuse the result.

Tips that help

• Name sounds you can imagine hearing in that exact place.
• Prefer one or two sounds to ten.
• Describe music by mood and instrument, for example gentle acoustic guitar or a slow piano.
• For speech, keep the line short and describe the tone, for example a calm voiceover tone.

What it will not do well

Generated audio is good for atmosphere and short moments. It is not a replacement for a recorded voice when you need a particular person, a long narration or exact wording. It is also not a finished mix. If your project needs a brand jingle, a studio voiceover or a mix to a broadcast standard, download the clip and add or replace the audio in any editor.

One rule matters more than the others: do not generate audio that imitates a real person's voice. It is a misuse, and the content policy and the law in many places do not allow it.

Keep it, replace it or mix it

• Keep the generated sound for social clips, teasers and atmospheric scenes.
• Replace it when you have recorded narration or music you own: mute the track in your editor and add yours.
• Mix it when you want both: lower the generated track and place your voice over it.

Checking the result

Always listen before you publish. Results vary between attempts, so if the timing or the sound is off, change the wording slightly and generate again. Draft at the lowest resolution, since a 5-second draft costs 30 credits at 480p against 100 at 1080p, and sound is part of the render, not an extra.

Where to go next

The AI video generator with audio page shows how it fits into a first project, and the prompt examples give you pictures to start from. When you are ready, a new account includes 500 free credits.