ffmpeg-noise-reduction

## CRITICAL GUIDELINES

### Windows File Path Requirements

**MANDATORY: Always Use Backslashes on Windows for File Paths**

When using Edit or Write tools on Windows, you MUST use backslashes (`\`) in file paths, NOT forward slashes (`/`).

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## Quick Reference

| Task | Filter | Command Pattern |
|------|--------|-----------------|
| Video denoising (best) | `nlmeans` | `-vf nlmeans=s=3:p=7:r=15` |
| Video denoising (fast) | `hqdn3d` | `-vf hqdn3d=4:3:6:4.5` |
| GPU video denoising | `nlmeans_vulkan` | `-vf nlmeans_vulkan` |
| Audio denoising | `afftdn` | `-af afftdn=nf=-25` |
| Adaptive temporal | `atadenoise` | `-vf atadenoise` |

## When to Use This Skill

Use for **noise reduction workflows**:
- Cleaning low-light or high-ISO footage
- Removing film grain
- Reducing compression artifacts
- Cleaning audio recordings
- Broadcast signal cleanup
- Pre-processing before encoding

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# FFmpeg Noise Reduction (2025)

Comprehensive guide to video and audio denoising filters.

## Video Denoising

### nlmeans - Non-Local Means (Best Quality)

The highest quality software denoiser, using non-local means algorithm.

```bash
# Basic denoising
ffmpeg -i noisy.mp4 -vf "nlmeans" output.mp4

# Medium denoising (good default)
ffmpeg -i noisy.mp4 -vf "nlmeans=s=3.0:p=7:r=15" output.mp4

# Strong denoising (very noisy footage)
ffmpeg -i noisy.mp4 -vf "nlmeans=s=5.0:p=7:r=15" output.mp4

# Light denoising (preserve detail)
ffmpeg -i noisy.mp4 -vf "nlmeans=s=1.5:p=5:r=9" output.mp4

# Denoise only chroma (preserve luma detail)
ffmpeg -i noisy.mp4 -vf "nlmeans=s=3.0:sc=5.0:p=7:r=15" output.mp4
```

**Parameters:**
| Parameter | Description | Default | Range |
|-----------|-------------|---------|-------|
| `s` | Denoising strength (sigma) | 1.0 | 0-30 |
| `p` | Patch size | 7 | 1-99 (odd) |
| `pc` | Patch size for chroma | 0 (same as p) | 1-99 |
| `r` | Research window size | 15 | 1-99 (odd) |
| `rc` | Research window for chroma | 0 (same as r) | 1-99 |

**Strength guidelines:*