# Video SFX

> Generate sound effects, foley and ambience that follow the action in a video, from an optional prompt. The new sound replaces the video's own audio track.

Source: https://nodaro.ai/docs/nodes/video/video-sfx

The **Video SFX** node generates sound for a video: sound effects, foley and ambience that follow what happens on screen. It watches the clip, reads your optional prompt, and returns an MP4 with the generated sound. The node runs the MMAudio model.

- Found in: Video › Sound for Video
- Output: video
- API type: `video-sfx`

**The new sound replaces the audio track:** 
Video SFX drops the video's original sound. To keep the original sound as well, wire the result and the original audio, for example from [Extract Audio](https://nodaro.ai/docs/nodes/video/extract-audio), into [Merge Video & Audio](https://nodaro.ai/docs/nodes/video/merge-video-audio).

## When to use it
- Add foley or ambience to a silent generated video.
- Generate room tone, weather or other environmental sound for a short cinematic clip.
- Produce several alternate takes of the sound in one run, and keep the best one.
- Build a soundtrack in layers, with the effects from this node and the dialogue or music from other nodes.

To create a sound effect from a text description alone, without a video, use [Text to Audio](https://nodaro.ai/docs/nodes/audio/text-to-audio).

## Quick start
### Add the node

Press Tab on the canvas and choose **Video › Sound for Video › Video SFX**.

### Connect the video

Wire the clip into the **Video** input. MP4, MOV and WebM clips of up to 300 seconds work.

### Describe the sound

Type the sound in the prompt, for example `rain on a metal roof`. Leave the prompt blank for foley driven by the video alone.

### Run it

Click **Run** on the node. The video with its new sound appears on the node.

Workflow: Video SFX adds the sound of rain to a silent clip, and Merge Video & Audio lays a music track under it.

- Generate Video → Video SFX (video)
- Text → Video SFX (prompt)
- Video SFX → Merge Video & Audio (media)
- Generate Music → Merge Video & Audio (media)

## Inputs
| Input | Accepts | What it does |
| --- | --- | --- |
| **Video** | Video nodes, such as Generate Video and Upload Video | The clip that needs sound. Required. MP4 (H.264), MOV or WebM, up to 300 seconds. |
| **Prompt** | Text nodes, such as Text and Prompt | The sound to generate. A wired prompt replaces the prompt typed in the settings panel. |
| **Negative** | Text nodes | Sounds to exclude. |

The output, **Video**, is an MP4 with the generated sound. The original sound is dropped.

## Settings
| Setting | What it does |
| --- | --- |
| **Prompt** | The sound you want, for example `footsteps on dry leaves`, `rain on a metal roof` or `engine revving`. Leave it blank for foley driven by the video alone. |
| **Negative prompt** | Sounds to exclude. The default is `music`, which keeps the result free of music. Clear the field if you want music as the sound. |
| **Versions** | How many takes to generate in one run, from 1 to 4. Each version uses a different seed, and the cost grows with each version. |
| **CFG strength** | Under **Advanced**. How strictly the model follows the prompt, from 1 (loose) to 10 (strict). The default is 4.5. |
| **Inference steps** | Under **Advanced**. From 10 (fast) to 50 (clean). The default is 25. |
| **Seed** | Under **Advanced**. Leave it blank, or enter -1, for a random seed. The same seed and the same inputs give the same result. With several versions, each version adds its number to the seed, so every take is repeatable and different. |
| **Pre & post text** | Text that is always added before and after the prompt. It is hidden from people who use your workflow as an app. See [Prompt pre and post text](https://nodaro.ai/docs/concepts/prompt-pre-post-text). |

## Credits
The price depends on the length of the input video, rounded up to a bucket, and on the number of versions. Nodaro measures the video automatically. If it cannot be measured, the price of the shortest bucket is used.

| Video length | Credits per version |
| --- | --- |
| Up to 8 seconds | 10 |
| Up to 15 seconds | 10 |
| Up to 30 seconds | 20 |
| Up to 60 seconds | 30 |
| Up to 120 seconds | 50 |
| Up to 300 seconds | 110 |

The total is the price per version times the number of versions. For example, a 12-second clip with 1 version costs 10 credits, a 31-second clip costs 30 credits, and a 60-second clip with 4 versions costs 120 credits.

## Limits
- **Formats:** MP4 (H.264), MOV and WebM.
- **Length:** up to 300 seconds. A longer video is refused with the error `video_duration_exceeds_limit`.
- **Versions:** up to 4 per run.
- **Resolution:** up to 1080p is recommended. Larger videos are untested and take longer to process.

## Tips
- **Describe the sound, not the scene.** `crackling fire` works better than `campfire scene`.
- **Test on short clips.** A clip of up to 15 seconds costs the same as a clip of 8 seconds, so iterate on short clips.
- **Layer the sound.** For effects over music, generate the effects here, then mix in the music with [Merge Video & Audio](https://nodaro.ai/docs/nodes/video/merge-video-audio) or [Mix Audio](https://nodaro.ai/docs/nodes/audio/mix-audio).
- **Fix the seed to compare prompts.** With a fixed **Seed**, the only change between two runs is your prompt.

## Frequently asked questions

### Does Video SFX keep the original sound of my video?

No. The generated sound replaces the video's audio track. To keep both, wire the result and the original audio, for example from Extract Audio, into Merge Video & Audio.

### Do I need to write a prompt?

No. Leave the prompt blank, and the model makes foley driven by the video alone. A prompt such as "rain on a metal roof" steers it toward a specific sound.

### Can Video SFX generate music?

Only if you clear the Negative prompt, which is "music" by default. The default keeps the result free of music, so the node produces sound effects only.

### How long can the video be?

Up to 300 seconds, which is 5 minutes. A longer video is refused before the run. The recommended resolution is up to 1080p.

### How much does Video SFX cost?

The price depends on the length of the video and the number of versions. One version costs 10 credits for a clip of up to 15 seconds and 110 credits for a clip of up to 300 seconds.