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 (/).

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

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:

s value	Use case
1.0-2.0	Light noise, preserve detail
2.0-4.0	Moderate noise (typical)
4.0-6.0	Heavy noise, low light
6.0+	Extreme noise (quality loss)

nlmeans_opencl - GPU-Accelerated NLMeans

OpenCL accelerated version, much faster.

bash

# OpenCL denoising
ffmpeg -i noisy.mp4 \
  -vf "hwupload,nlmeans_opencl=s=3:p=7:r=15,hwdownload,format=yuv420p" \
  output.mp4

# Strong denoising with OpenCL
ffmpeg -i noisy.mp4 \
  -vf "hwupload,nlmeans_opencl=s=5:p=7:r=21,hwdownload,format=yuv420p" \
  output.mp4

nlmeans_vulkan - Vulkan-Accelerated NLMeans (FFmpeg 8.0+)

Cross-platform GPU acceleration using Vulkan.

bash

# Vulkan denoising
ffmpeg -init_hw_device vulkan \
  -i noisy.mp4 \
  -vf "hwupload,nlmeans_vulkan=s=3:p=7:r=15,hwdownload,format=yuv420p" \
  output.mp4

# Full Vulkan pipeline
ffmpeg -init_hw_device vulkan=vk \
  -filter_hw_device vk \
  -hwaccel vulkan -hwaccel_output_format vulkan \
  -i noisy.mp4 \
  -vf "nlmeans_vulkan=s=3" \
  -c:v h264_vulkan output.mp4

hqdn3d - High Quality 3D Denoiser (Fast)

Faster than nlmeans with good results for moderate noise.

bash

# Default settings
ffmpeg -i noisy.mp4 -vf "hqdn3d" output.mp4

# Custom settings (luma_spatial:chroma_spatial:luma_tmp:chroma_tmp)
ffmpeg -i noisy.mp4 -vf "hqdn3d=4:3:6:4.5" output.mp4

# Strong spatial denoising
ffmpeg -i noisy.mp4 -vf "hqdn3d=8:6:6:4" output.mp4

# Strong temporal denoising (for static scenes)
ffmpeg -i noisy.mp4 -vf "hqdn3d=4:3:12:9" output.mp4

# Light denoising
ffmpeg -i noisy.mp4 -vf "hqdn3d=2:1.5:3:2" output.mp4

Parameters:

Parameter	Description	Default	Range
`luma_spatial`	Luma spatial strength	4.0	0-255
`chroma_spatial`	Chroma spatial strength	3.0	0-255
`luma_tmp`	Luma temporal strength	6.0	0-255
`chroma_tmp`	Chroma temporal strength	4.5	0-255

atadenoise - Adaptive Temporal Averaging

Temporal denoiser that preserves motion.

bash

# Basic temporal denoising
ffmpeg -i noisy.mp4 -vf "atadenoise" output.mp4

# Stronger denoising
ffmpeg -i noisy.mp4 -vf "atadenoise=0a=0.1:0b=0.2:1a=0.1:1b=0.2:2a=0.1:2b=0.2" output.mp4

# Adjust threshold and planes
ffmpeg -i noisy.mp4 -vf "atadenoise=s=9:p=5" output.mp4

Parameters:

Parameter	Description	Default
`0a`, `1a`, `2a`	Threshold A for planes 0,1,2	0.02
`0b`, `1b`, `2b`	Threshold B for planes 0,1,2	0.04
`s`	Number of frames to average	9
`p`	Planes to process	7 (all)

vaguedenoiser - Wavelet Denoiser

Uses wavelet transform for denoising.

bash

# Basic wavelet denoising
ffmpeg -i noisy.mp4 -vf "vaguedenoiser" output.mp4

# Adjust threshold
ffmpeg -i noisy.mp4 -vf "vaguedenoiser=threshold=3:method=soft" output.mp4

# Stronger denoising
ffmpeg -i noisy.mp4 -vf "vaguedenoiser=threshold=6:nsteps=6" output.mp4

Parameters:

Parameter	Description	Default	Values
`threshold`	Denoising threshold	2	0-inf
`method`	Thresholding method	hard	hard, soft, garrote
`nsteps`	Decomposition steps	6	1-32
`percent`	Percent of full denoising	85	0-100

fftdnoiz - FFT-Based Denoising

Frequency domain denoising.

bash

# Basic FFT denoising
ffmpeg -i noisy.mp4 -vf "fftdnoiz" output.mp4

# Adjust sigma
ffmpeg -i noisy.mp4 -vf "fftdnoiz=sigma=8" output.mp4

# Strong denoising
ffmpeg -i noisy.mp4 -vf "fftdnoiz=sigma=15:block=32:overlap=0.8" output.mp4

owdenoise - Overcomplete Wavelet Denoiser

Another wavelet-based option.

bash

# Basic wavelet denoising
ffmpeg -i noisy.mp4 -vf "owdenoise" output.mp4

# Adjust depth and strength
ffmpeg -i noisy.mp4 -vf "owdenoise=depth=10:ls=3:cs=3" output.mp4

removegrain - RemoveGrain

Classic grain/noise removal (from AviSynth).

bash

# Mode 1 (basic)
ffmpeg -i noisy.mp4 -vf "removegrain=m0=1" output.mp4

# Different modes for different noise types
ffmpeg -i noisy.mp4 -vf "removegrain=m0=17:m1=17:m2=17" output.mp4

Audio Denoising

afftdn - FFT Denoiser (Recommended)

Powerful audio noise reduction using FFT.

bash

# Basic audio denoising
ffmpeg -i noisy_audio.mp4 -af "afftdn" output.mp4

# Specify noise floor
ffmpeg -i noisy_audio.mp4 -af "afftdn=nf=-25" output.mp4

# Stronger noise reduction
ffmpeg -i noisy_audio.mp4 -af "afftdn=nf=-20:nt=w" output.mp4

# With noise profile (sample noise-only section first)
ffmpeg -i noisy_audio.mp4 -af "afftdn=nr=10:nf=-30:nt=w:om=o" output.mp4

# Adaptive noise floor
ffmpeg -i noisy_audio.mp4 -af "afftdn=nt=c:om=o:bn=9" output.mp4

Parameters:

Parameter	Description	Default	Range
`nr`	Noise reduction (dB)	12	0.01-97
`nf`	Noise floor (dB)	-50	-80 to -20
`nt`	Noise type	w	w=white, v=vinyl, s=shellac, c=custom
`bn`	Number of noise bands	15	3-33
`rf`	Residual floor (dB)	-38	-80 to -20
`om`	Output mode	o	i=input, o=output, n=noise

anlmdn - Non-Local Means Audio Denoiser

Audio equivalent of video nlmeans.

bash

# Basic NLM audio denoising
ffmpeg -i noisy_audio.mp4 -af "anlmdn" output.mp4

# Adjust strength
ffmpeg -i noisy_audio.mp4 -af "anlmdn=s=0.0001" output.mp4

# Stronger denoising
ffmpeg -i noisy_audio.mp4 -af "anlmdn=s=0.001:p=0.01" output.mp4

Parameters:

Parameter	Description	Default
`s`	Denoising strength	0.00001
`p`	Patch radius	0.002
`r`	Research radius	0.006
`m`	Output mode	o (output)

adeclick - Remove Clicks/Pops

Removes impulsive noise from audio.

bash

# Remove clicks
ffmpeg -i clicked_audio.mp4 -af "adeclick" output.mp4

# Adjust parameters
ffmpeg -i clicked_audio.mp4 -af "adeclick=w=55:o=75" output.mp4

adeclip - Remove Clipping

Repairs clipped audio.

bash

# Fix clipping
ffmpeg -i clipped_audio.mp4 -af "adeclip" output.mp4

Combined Workflows

Low-Light Video Enhancement

bash

# Denoise + brighten + contrast
ffmpeg -i dark_noisy.mp4 \
  -vf "nlmeans=s=4:p=7:r=15,eq=brightness=0.1:contrast=1.2:saturation=1.1" \
  -c:v libx264 -crf 18 \
  enhanced.mp4

Interview Cleanup (Video + Audio)

bash

# Clean both video and audio noise
ffmpeg -i interview.mp4 \
  -vf "hqdn3d=3:2:4:3" \
  -af "afftdn=nf=-30:nr=10,loudnorm" \
  -c:v libx264 -crf 20 \
  -c:a aac -b:a 192k \
  interview_clean.mp4

Film Grain Removal

bash

# Strong nlmeans for film grain
ffmpeg -i grainy_film.mp4 \
  -vf "nlmeans=s=5:p=7:r=21" \
  -c:v libx264 -crf 18 -preset slow \
  degrained.mp4

# Preserve some grain (artistic choice)
ffmpeg -i grainy_film.mp4 \
  -vf "nlmeans=s=2.5:p=5:r=11" \
  -c:v libx264 -crf 18 \
  light_degrain.mp4

Compression Artifact Removal

bash

# Remove blocking artifacts from highly compressed video
ffmpeg -i compressed.mp4 \
  -vf "hqdn3d=2:1.5:3:2,unsharp=5:5:0.3:5:5:0" \
  -c:v libx264 -crf 18 \
  cleaner.mp4

GPU-Accelerated Batch Processing

bash

#!/bin/bash
# Process multiple noisy videos with GPU

for video in noisy_*.mp4; do
  output="clean_${video}"
  ffmpeg -init_hw_device vulkan \
    -i "$video" \
    -vf "hwupload,nlmeans_vulkan=s=3,hwdownload,format=yuv420p" \
    -c:v libx264 -crf 18 \
    "$output"
done

Filter Comparison

Video Denoising Speed vs Quality

Filter	Quality	Speed	GPU Option	Best For
`nlmeans`	Excellent	Slow	Yes (OpenCL/Vulkan)	Final output
`hqdn3d`	Good	Fast	No	Real-time, previews
`atadenoise`	Good	Medium	No	Static scenes
`vaguedenoiser`	Good	Medium	No	Mixed content
`fftdnoiz`	Good	Medium	No	Periodic noise

Audio Denoising Comparison

Filter	Quality	Speed	Best For
`afftdn`	Excellent	Fast	All-purpose
`anlmdn`	Good	Medium	Speech
`adeclick`	Specialized	Fast	Clicks/pops

Parameter Tuning Tips

Video Denoising

Start conservative - Begin with s=2-3, increase if needed
Preserve edges - Lower patch size (p=5) preserves more detail
Test on samples - Process 10-second clips first
Consider GPU - nlmeans_opencl/vulkan are 5-10x faster
Match content - Static scenes tolerate stronger temporal denoising

Audio Denoising

Find noise floor - Listen to quiet sections
Use appropriate type - White noise vs vinyl vs custom
Don't over-process - Artifacts can be worse than noise
Check residual - Use om=n to hear what's being removed

Best Practices

Denoise before encoding - Noise compresses poorly
Preserve some texture - Over-denoising looks artificial
Match source quality - Don't denoise clean footage
Use GPU when available - Massive speed improvement
Combine filters carefully - Multiple denoisers can cause artifacts
Test different filters - Content-dependent results

This guide covers noise reduction for 2025. For video analysis and detection, see ffmpeg-video-analysis. For hardware acceleration, see ffmpeg-hardware-acceleration.

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ffmpeg-noise-reduction

Install this agent skill to your Project

SKILL.md

CRITICAL GUIDELINES

Windows File Path Requirements

Quick Reference

When to Use This Skill

FFmpeg Noise Reduction (2025)

Video Denoising

nlmeans - Non-Local Means (Best Quality)

nlmeans_opencl - GPU-Accelerated NLMeans

nlmeans_vulkan - Vulkan-Accelerated NLMeans (FFmpeg 8.0+)

hqdn3d - High Quality 3D Denoiser (Fast)

atadenoise - Adaptive Temporal Averaging

vaguedenoiser - Wavelet Denoiser

fftdnoiz - FFT-Based Denoising

owdenoise - Overcomplete Wavelet Denoiser

removegrain - RemoveGrain

Audio Denoising

afftdn - FFT Denoiser (Recommended)

anlmdn - Non-Local Means Audio Denoiser

adeclick - Remove Clicks/Pops

adeclip - Remove Clipping

Combined Workflows

Low-Light Video Enhancement

Interview Cleanup (Video + Audio)

Film Grain Removal

Compression Artifact Removal

GPU-Accelerated Batch Processing

Filter Comparison

Video Denoising Speed vs Quality

Audio Denoising Comparison

Parameter Tuning Tips

Video Denoising

Audio Denoising

Best Practices