---
name: fal-ai/kling-video/video-to-audio
display_name: Kling Video-to-Audio
category: video-to-video
creator: Kuaishou Technology (Kling AI)
fal_docs: https://fal.ai/models/fal-ai/kling-video/video-to-audio
original_source: https://klingai.com/
summary: Generates context-aware, synchronized audio soundtracks and sound effects for existing silent videos.
---

# Kling Video-to-Audio

## Overview
- **Slug:** `fal-ai/kling-video/video-to-audio`
- **Category:** Video-to-Audio / Audio Generation
- **Creator:** [Kuaishou Technology (Kling AI)](https://klingai.com/)
- **Best for:** Adding high-fidelity sound effects and background music to silent AI-generated or uploaded videos.
- **FAL docs:** [fal.ai/models/fal-ai/kling-video/video-to-audio](https://fal.ai/models/fal-ai/kling-video/video-to-audio)
- **Original source:** [klingai.com](https://klingai.com/)

## What it does
The Kling Video-to-Audio model is a specialized generative tool that analyzes the visual content of a video and produces a synchronized audio track. Unlike simple "dubbing," it uses semantic understanding to generate sound effects (Foley) and background music that match the action, rhythm, and mood of the footage. It outputs both the standalone audio file and a merged video file with the new audio applied.

## When to use this model
- **Use when:** 
    - You have a silent video generated by models like Kling, Luma, or Runway and need realistic sound effects.
    - You want to add specific environmental sounds (e.g., "crunching leaves," "city traffic") that are contextually synced to movement.
    - You need an "ASMR" style audio experience for close-up or highly detailed visual content.
- **Don't use when:** 
    - You require precise lip-syncing for dialogue (use a dedicated Lip-Sync model instead).
    - You need to strip existing audio from a video without adding new generative elements (standard FFmpeg tools are better for this).
- **Alternatives:** 
    - **[Kling V2.6 Pro Text-to-Video](https://fal.ai/models/fal-ai/kling-video/v2.6/pro/text-to-video):** Best if you are generating the video from scratch and want native audio generated simultaneously.
    - **[Stable Audio](https://fal.ai/models/fal-ai/stable-audio):** If you only need a background track and don't require pixel-perfect temporal synchronization with video actions.

## API — via FAL.ai
**Endpoint:** `https://fal.run/fal-ai/kling-video/video-to-audio` (sync) / `https://queue.fal.run/fal-ai/kling-video/video-to-audio` (queue)

### Input parameters
| Parameter | Type | Default | Range/Values | Description |
|---|---|---|---|---|
| `video_url` | string | (Required) | URL | The URL of the video to extract/generate audio for. Supports `.mp4`, `.mov`, `.webm`, `.m4v`, `.gif`. Max 100MB. Duration: 3.0s to 20.0s. |
| `sound_effect_prompt` | string | "Car tires screech..." | Max 200 chars | Describes the specific sound effects to generate. Focus on physical actions seen in the video. |
| `background_music_prompt` | string | "" | Max 200 chars | Describes the musical style, mood, or genre of the background track. |
| `asmr_mode` | boolean | `false` | `true`, `false` | Enhances detailed, intimate sound effects. Ideal for "satisfying" videos or close-ups. |

### Output
The output is a JSON object containing:
- **`video`**: A [File object](https://fal.ai/models/fal-ai/kling-video/video-to-audio/api#type-File) containing the original video with the generated audio dubbed in.
- **`audio`**: A [File object](https://fal.ai/models/fal-ai/kling-video/video-to-audio/api#type-File) containing the standalone generated audio in MP3 format.

### Example request
```json
{
  "video_url": "https://example.com/silent_video.mp4",
  "sound_effect_prompt": "Heavy footsteps on a wooden floor, creaking door",
  "background_music_prompt": "Tense cinematic orchestral music",
  "asmr_mode": false
}
```

### Pricing
- **Cost:** ~$0.035 per video request on FAL.ai.
- Note: Pricing may vary based on video duration or specific partner rates.

## API — via Original Source (BYO-key direct)
Kling AI offers a native developer API via their platform at [klingai.com](https://klingai.com/). While FAL.ai provides a simplified "Video-to-Audio" endpoint, the native Kling 3.0 API generally handles audio through the `motion_has_audio` parameter in their text-to-video and image-to-video endpoints. 
- **Native Endpoint:** Typically `https://api.klingai.com/v1/videos/text2video` or similar (requires an API Key from the Kling AI Developer Portal).
- **Extra Features:** The native API supports advanced "Element Binding" to maintain character voice consistency and "Multi-Shot" narratives up to 15 seconds.

## Prompting best practices
- **Be Action-Oriented:** For `sound_effect_prompt`, describe verbs and materials. *Good:* "Metal clanging on concrete, echoing." *Bad:* "A factory setting."
- **Describe Mood for Music:** Use emotive adjectives for `background_music_prompt`. *Example:* "Melancholic piano with a lo-fi beat."
- **Coordinate Prompts:** Ensure your prompts match the visual speed. If the video is a slow-motion shot, ask for "stretched, deep bass thuds" rather than fast-paced sounds.
- **Avoid Vague Terms:** Words like "good sound" or "high quality" waste character space. Focus on specific audio textures.

## Parameter tuning guide
- **`asmr_mode`:** Toggle this on only for videos featuring textures (sand, slime, cooking, soft fabric). It increases the gain on high-frequency "crisp" sounds but can sound unnatural for wide-angle city shots.
- **Prompt Length:** Keep prompts under 200 characters. If you over-describe, the model may prioritize the earlier parts of the prompt and ignore the later ones.

## Node inputs/outputs
- **Inputs:**
    - `Video URL` (File/Link)
    - `SFX Prompt` (String)
    - `BGM Prompt` (String)
    - `ASMR Toggle` (Boolean)
- **Outputs:**
    - `Dubbed Video` (Video File)
    - `Audio Only` (Audio File)
- **Chain-friendly with:**
    - **[Kling V1.5/2.6/3.0](https://fal.ai/models/fal-ai/kling-video):** Generate the visual first, then pass the result to this node.
    - **[MiniMax Video-01](https://fal.ai/models/fal-ai/minimax-video):** Excellent for generating high-quality cinematic visuals that need sound enhancement.

## Notes & gotchas
- **Duration Limits:** The video must be between 3 and 20 seconds. Shorter or longer videos will cause a validation error.
- **File Types:** While it accepts GIFs, the output will always be a video format (MP4) to support the audio track.
- **Sync Accuracy:** The synchronization is "semantic," meaning it understands *what* is happening, but for extremely fast micro-actions, it may occasionally have a slight temporal offset.

## Sources
- [FAL.ai Kling Video-to-Audio Documentation](https://fal.ai/models/fal-ai/kling-video/video-to-audio/api)
- [Kling AI Official Model Guide](https://klingai.com/quickstart/klingai-video-3-model-user-guide)
- [Atlas Cloud Developer Guide to Kling API](https://www.atlascloud.ai/blog/guides/integrating-kling-3-0-api-the-developers-guide-to-mass-ai-video-production)
