Silent Clip,
Now It Has Sound
Yes, you can start free. Inflyu's AI Add Sound to Video takes a silent clip you already have, from any AI video maker or a camera, and generates matching effects and ambience from a text prompt. Create a free account with 20 sign-up credits and no card; a run costs 1 credit, and a free account can run it once on a clip of up to 6 seconds (credit packs start at $2.99). Clips up to 30 seconds are accepted on a pack.
For UGC and product clips shot without audio
Sound design without a foley pass
1 credit per clip, up to 30 seconds of source.
Prompt to sound
Describe the sound in plain text: the model generates effects and ambience to match.
30 second cap
Source clips up to 30 seconds are accepted; longer clips are refused, not silently trimmed.
Flat 1 credit
1 credit per clip regardless of length, on any credit pack.
Picture stays untouched
Only the audio track is generated: the video itself is not re-rendered.
Keeps the original
Output is a new file in your gallery. The silent source stays intact.
Register to run
No anonymous add-sound. Credits and R2 storage need a user.
How do I add sound to a silent AI generated video?
Follow these steps in the app.
Upload the silent clip
It can be up to 30 seconds; a longer clip is refused up front, not silently trimmed.
Describe the sound
Type what you want to hear in plain words, such as ocean waves, footsteps or room tone.
Generate
A run costs 1 credit, whatever the clip length; only the audio track is generated.
Download the new file
The result is a new video in your gallery and your silent source stays intact.
Is there a free AI tool to add sound to a silent AI generated video I already have?
Yes, you can start free. Create a free account with 20 sign-up credits and no card, upload a silent clip and describe the sound you want. A run costs 1 credit; a free account can run it once, on a clip of up to 6 seconds, and credit packs start at $2.99 with no subscription for longer clips and more runs.
What is the best AI tool to add sound to a silent AI generated video?
It depends on whether you want effects, music or dialogue. In this comparison Magic Hour is free to try with no sign-up and covers dialogue, effects and music; SoundMelt handles silent clips up to 10 s; MMAudio.net lists a 50 MB limit; ZSky AI makes video with audio from scratch and does not state that it takes your own video. Inflyu generates effects and ambience from a prompt for 1 credit a run.
| Tool | Free to try | Works on your own clip | Needs a card | Output limit | Entry price | Bad at |
|---|---|---|---|---|---|---|
| Inflyu | 20 sign-up credits with a free account; credit packs from $2.99 | Yes, you upload your own clip | No card to sign up. Packs are paid at checkout. | Clips up to 30 seconds; the picture is not re-rendered, only the audio is generated | Credit packs from $2.99, no subscription | A free account can run it once, on a clip of up to 6 seconds |
| Magic Hour | Free to try online, no sign up needed | Yes (upload a clip, get synced dialogue, effects and music) | No (selected tools usable without account or card) | Not stated | Creator $12/month billed yearly ($19 monthly) | Not stated |
| ZSky AI | Ongoing free tier, no credit card; makes video with audio | No (page shows image upload for video generation; uploading your own video is not stated) | No | 1080p on Pro; free output carries a small zsky.ai wordmark plate | Pro $19/month | Free output carries a wordmark plate and it does not take your own video per its page |
| MMAudio.net | Not stated | Yes (upload MP4) | Not stated | Max file size 50 MB | Not stated | Not stated |
| SoundMelt | Free plan: 1 generation a month (2 videos), no credit card | Yes (upload a silent MP4/MOV) | No | Videos up to 10 s | Starter $4/month (20 generations) | Free plan is 1 generation a month |
Competitor facts come from each tool's own page, checked 1 Nov 2026.
Magic Hour alternative for adding sound to a silent AI generated video
Magic Hour and Inflyu both take a clip you already have and add sound to it. Magic Hour's page says you can try it online without signing up or a card, and describes synced dialogue, effects and music; it lists Creator at $12 a month billed yearly ($19 monthly) and does not state a clip length. Inflyu's AI Add Sound to Video is narrower: you describe the sound in a prompt, and it generates effects and ambience for a clip of up to 30 seconds at 1 credit. Choose Magic Hour for dialogue and music in the same step. Choose Inflyu for a quick, low-priced sound pass on a short AI clip.
Compare with Magic Hour on its own page.
How good is AI sound on my silent video, and what are the limits?
Inflyu generates effects and ambience that follow your prompt and attaches them as a new audio track, leaving the picture untouched. Limits: clips up to 30 seconds, no dialogue, and a free account runs it once on a clip of up to 6 seconds. Clips with clear sources of sound work best.
Limits today
- Length: clips up to 30 seconds; a longer clip is refused before anything is charged.
- Free accounts: one run, on a clip of up to 6 seconds; any pack lifts that.
- Picture: only the audio track is generated. The video itself is not re-rendered.
- Kind of sound: effects and ambience from your prompt. It does not write dialogue or a song.
- Account: video jobs need an account for credits and storage; registration itself is free.
What works best
- A silent clip with obvious sources of sound (water, footsteps, traffic, wind) is easiest to score.
- Name the sounds in the prompt and the room or place they happen in.
- Keep the clip short; the shorter the clip, the closer the match you can check by ear.
- Add a separate music bed afterwards if you also need music.
AI Add Sound to Video FAQ
Can I process many videos at once?+
Yes. Process up to 10 videos at once. Each video costs the same as a single run; a free account can add 1.
How much does add-sound cost?+
A flat 1 credit per clip, regardless of length, on any credit pack.
How long can my source clip be?+
Up to 30 seconds. Longer clips are refused before any credit is charged, not silently trimmed.
Does it change the picture?+
No. Only the audio track is generated: the video itself is untouched.
Do I get a free run without signup?+
No. Video jobs need an account for credits and storage. Registration itself is free.
Is there a free AI tool to add sound to a silent AI generated video I already have?+
Yes, you can start free. Create a free account with 20 sign-up credits and no card, upload a silent clip and describe the sound you want. A run costs 1 credit; a free account can run it once, on a clip of up to 6 seconds, and credit packs start at $2.99 with no subscription for longer clips and more runs.
How do I add sound to a silent AI generated video?+
Upload the silent clip (up to 30 seconds), describe the sound in plain words, and generate. Inflyu creates matching effects and ambience, adds them as a new audio track and saves a new file; your silent source stays as it was.
What is the best AI tool to add sound to a silent AI generated video?+
It depends on whether you want effects, music or dialogue. In this comparison Magic Hour is free to try with no sign-up and covers dialogue, effects and music; SoundMelt handles silent clips up to 10 s; MMAudio.net lists a 50 MB limit; ZSky AI makes video with audio from scratch and does not state that it takes your own video. Inflyu generates effects and ambience from a prompt for 1 credit a run.
Magic Hour alternative for adding sound to a silent AI generated video+
Magic Hour says you can try it without signing up and adds dialogue, effects and music; it lists Creator at $12 a month billed yearly. Inflyu's AI Add Sound to Video generates effects and ambience from a prompt for 1 credit a run, on clips up to 30 seconds. Choose Magic Hour for fuller soundtracks, Inflyu for a quick sound pass on 20 sign-up credits.
How good is AI sound on my silent video, and what are the limits?+
Inflyu generates effects and ambience that follow your prompt and attaches them as a new audio track, leaving the picture untouched. Limits: clips up to 30 seconds, no dialogue, and a free account runs it once on a clip of up to 6 seconds. Clips with clear sources of sound work best.
Do I need a subscription?+
No. You can pay as you go: credit packs are one-time purchases and their credits never expire. If you would rather have a steady supply, the monthly Starter ($9.99), Creator ($19.99), Pro ($49.99) and Brand ($99.99) plans refill your credits each month, and you can cancel anytime. Unused monthly credits do not roll over.
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