FastH3

Guide · Video with sound

Directing sound in FastH3

FastH3 results include native audio generated with the picture. The trick is to write sound into the same prompt as the action, in the order things happen, so timing and visuals line up.

Create a clip with sound

In short

  • Each FastH3 result includes an audio track.
  • Describe dialogue, ambience, music and effects in the same prompt as the visible action.
  • Put spoken lines in quotes and keep them short.
  • Clips run 5, 10 or 15 seconds at 480p (13 credits/s) or 768p (20 credits/s).

Write sound in time order

Describe the picture and sound together, beat by beat, so the model knows what should be heard when.

Example · motion with sound
A vintage red scooter descends a winding coastal road, low tracking camera beside the front wheel, engine rising through each corner, wind and tire noise in sync.

Dialogue

Keep lines short enough to be spoken in the clip length, name who says them, and describe the voice.

Example · one line to camera
A chef looks into camera in a bright open kitchen and says, "The secret is you never crowd the pan." Gentle handheld motion, close voice, quiet sizzle.

Music and effects

Name the instrument or style and one or two concrete effects rather than "epic music".

Example · playful stop-motion
Stop-motion clay frog carries pancakes across a tiny felt kitchen, warm practical lamps, visible fingerprints, playful pizzicato strings and a plate clink.

Fixing audio that does not fit

  • Sound out of sync: describe it next to the action that causes it.
  • Too busy: limit to one ambience plus one or two effects.
  • Dialogue cut off: shorten the line or choose a longer clip.

Frequently asked questions

Can I turn the audio off?

Results include native audio; mute it in your editor if you only need the picture.

Can a character speak a specific line?

Yes. Put the line in quotes and keep it short enough for the clip length.

Is FastH3 an official MiniMax product?

No. FastH3.video is an independent creative service.

Updated 2026-10-04. FastH3.video is an independent video creation service. Example clips are demonstrations, not promises of an identical result. Model names and third-party trademarks belong to their owners.