josiahsiegel 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 | Command Pattern |
|---|---|
| Basic filter_complex | -filter_complex "[0:v][1:v]overlay" |
| Named labels | [input]filter[output] |
| Chain filters | filter1,filter2,filter3 |
| Separate chains | chain1;chain2 |
| Map output | -map "[label]" |
When to Use This Skill
Use for complex filtergraph operations:
- Multi-input compositions (PiP, grids, overlays)
- Video transitions and effects
- Audio mixing and routing
- Stream splitting for multiple outputs
- GPU + CPU hybrid processing
For basic filters: use ffmpeg-fundamentals-2025
For hardware acceleration: use ffmpeg-hardware-acceleration
FFmpeg filter_complex Reference (2025)
Comprehensive guide to complex filtergraphs, multi-input compositions, and advanced filter chains.
filter_complex Syntax
Basic Structure
-filter_complex "filterchain1;filterchain2;..."
Each filterchain consists of:
- Input labels:
[input_label] - Filter(s):
filter1,filter2,...(comma-separated) - Output labels:
[output_label]
Complete Syntax
[input_label1][input_label2]filter=param1=value1:param2=value2[output_label]
Syntax Components
| Component | Description | Example |
|---|---|---|
[0:v] |
Video stream from input 0 | First input video |
[0:a] |
Audio stream from input 0 | First input audio |
[1:v] |
Video stream from input 1 | Second input video |
[label] |
Custom named label | User-defined |
, |
Chain filters sequentially | scale,fps |
; |
Separate independent chains | chain1;chain2 |
= |
Parameter assignment | scale=1280:720 |
: |
Parameter separator | w=1280:h=720 |
Stream References
| Reference | Meaning |
|---|---|
[0] |
First input (all streams) |
[0:v] |
First input, video stream |
[0:a] |
First input, audio stream |
[0:s] |
First input, subtitle stream |
[0:v:0] |
First input, first video stream |
[1:a:1] |
Second input, second audio stream |
Default Labels
- Unlabeled first filter input uses
in - Unlabeled last filter output uses
out - Unlabeled pads connect sequentially
Escaping Rules
# Wrap filtergraph in double quotes
ffmpeg -i input.mp4 \
-filter_complex "[0:v]drawtext=text='Hello World':fontsize=24[out]" \
-map "[out]" output.mp4
# Using shell variables
text="Dynamic Text"
ffmpeg -i input.mp4 \
-filter_complex "[0:v]drawtext=text='$text':fontsize=24[out]" \
-map "[out]" output.mp4
# Escaping special characters (colons in timestamps)
ffmpeg -i input.mp4 \
-filter_complex "[0:v]drawtext=text='Time\: %{pts\:hms}':fontsize=24[out]" \
-map "[out]" output.mp4
Common Composition Patterns
1. Picture-in-Picture (PiP)
# Basic PiP - small video in bottom-right corner
ffmpeg -i main.mp4 -i pip.mp4 \
-filter_complex "\
[1:v]scale=320:240[pip];\
[0:v][pip]overlay=W-w-10:H-h-10" \
-c:v libx264 -c:a copy output.mp4
# PiP with border
ffmpeg -i main.mp4 -i pip.mp4 \
-filter_complex "\
[1:v]scale=320:240,drawbox=x=0:y=0:w=iw:h=ih:c=white:t=3[pip];\
[0:v][pip]overlay=W-w-10:H-h-10" \
output.mp4
# Animated PiP (moving)
ffmpeg -i main.mp4 -i pip.mp4 \
-filter_complex "\
[1:v]scale=320:240[pip];\
[0:v][pip]overlay='W-w-10-sin(t)*20':'H-h-10-cos(t)*20'" \
output.mp4
# PiP with fade-in
ffmpeg -i main.mp4 -i pip.mp4 \
-filter_complex "\
[1:v]scale=320:240,fade=in:st=2:d=1[pip];\
[0:v][pip]overlay=W-w-10:H-h-10:enable='gte(t,2)'" \
output.mp4
2. Video Grid Layouts
Using hstack/vstack (fast, simple):
# 2x2 Grid
ffmpeg -i 1.mp4 -i 2.mp4 -i 3.mp4 -i 4.mp4 \
-filter_complex "\
[0:v]scale=640:360[v0];\
[1:v]scale=640:360[v1];\
[2:v]scale=640:360[v2];\
[3:v]scale=640:360[v3];\
[v0][v1]hstack=inputs=2[top];\
[v2][v3]hstack=inputs=2[bottom];\
[top][bottom]vstack=inputs=2[out]" \
-map "[out]" output.mp4
# 3x2 Grid
ffmpeg -i 1.mp4 -i 2.mp4 -i 3.mp4 -i 4.mp4 -i 5.mp4 -i 6.mp4 \
-filter_complex "\
[0:v]scale=426:240[v0];\
[1:v]scale=426:240[v1];\
[2:v]scale=426:240[v2];\
[3:v]scale=426:240[v3];\
[4:v]scale=426:240[v4];\
[5:v]scale=426:240[v5];\
[v0][v1][v2]hstack=inputs=3[top];\
[v3][v4][v5]hstack=inputs=3[bottom];\
[top][bottom]vstack=inputs=2[out]" \
-map "[out]" output.mp4
Using xstack (more flexible positioning):
# 2x2 Grid with xstack
ffmpeg -i 1.mp4 -i 2.mp4 -i 3.mp4 -i 4.mp4 \
-filter_complex "\
[0:v]scale=640:360[v0];\
[1:v]scale=640:360[v1];\
[2:v]scale=640:360[v2];\
[3:v]scale=640:360[v3];\
[v0][v1][v2][v3]xstack=inputs=4:layout=0_0|640_0|0_360|640_360[out]" \
-map "[out]" output.mp4
# L-shaped layout
ffmpeg -i main.mp4 -i side1.mp4 -i side2.mp4 \
-filter_complex "\
[0:v]scale=960:720[main];\
[1:v]scale=320:360[s1];\
[2:v]scale=320:360[s2];\
[main][s1][s2]xstack=inputs=3:layout=0_0|960_0|960_360[out]" \
-map "[out]" output.mp4
3. Video Transitions (xfade)
# Simple fade transition
ffmpeg -i first.mp4 -i second.mp4 \
-filter_complex "\
[0:v][1:v]xfade=transition=fade:duration=1:offset=4[v];\
[0:a][1:a]acrossfade=d=1[a]" \
-map "[v]" -map "[a]" output.mp4
# Dissolve transition
ffmpeg -i first.mp4 -i second.mp4 \
-filter_complex "\
[0:v][1:v]xfade=transition=dissolve:duration=2:offset=3[v]" \
-map "[v]" output.mp4
# Wipe transitions
ffmpeg -i first.mp4 -i second.mp4 \
-filter_complex "[0:v][1:v]xfade=transition=wipeleft:duration=1:offset=4[v]" \
-map "[v]" output.mp4
# Multiple transitions (3+ clips)
ffmpeg -i 1.mp4 -i 2.mp4 -i 3.mp4 \
-filter_complex "\
[0:v]settb=AVTB,fps=30[v0];\
[1:v]settb=AVTB,fps=30[v1];\
[2:v]settb=AVTB,fps=30[v2];\
[v0][v1]xfade=transition=fade:duration=1:offset=4[xf1];\
[xf1][v2]xfade=transition=dissolve:duration=1:offset=8[out]" \
-map "[out]" output.mp4
Available xfade transitions:
fade,fadeblack,fadewhitewipeleft,wiperight,wipeup,wipedownslideleft,slideright,slideup,slidedowncirclecrop,rectcrop,distanceradial,smoothleft,smoothrightdissolve,pixelize,diagtl,diagtr,diagbl,diagbrhlslice,hrslice,vuslice,vdslicehblur,fadegrays,squeezev,squeezeh
4. Audio Mixing
# Mix two audio tracks
ffmpeg -i video.mp4 -i music.mp3 \
-filter_complex "\
[0:a][1:a]amix=inputs=2:duration=first:dropout_transition=2[aout]" \
-map 0:v -map "[aout]" output.mp4
# Mix with volume control
ffmpeg -i vocals.mp4 -i music.mp3 \
-filter_complex "\
[0:a]volume=1.0[v0];\
[1:a]volume=0.3[v1];\
[v0][v1]amix=inputs=2:duration=first[aout]" \
-map 0:v -map "[aout]" output.mp4
# Audio with delay (ducking)
ffmpeg -i main.mp4 -i effect.mp3 \
-filter_complex "\
[1:a]adelay=2000|2000[delayed];\
[0:a][delayed]amix=inputs=2:duration=first[aout]" \
-map 0:v -map "[aout]" output.mp4
# Merge channels (stereo from two mono)
ffmpeg -i left.wav -i right.wav \
-filter_complex "[0:a][1:a]amerge=inputs=2[aout]" \
-map "[aout]" stereo.wav
# Audio crossfade between tracks
ffmpeg -i track1.mp3 -i track2.mp3 \
-filter_complex "[0:a][1:a]acrossfade=d=3:c1=tri:c2=tri[out]" \
-map "[out]" mixed.mp3
5. Text and Watermark Overlays
# Static text overlay
ffmpeg -i input.mp4 \
-filter_complex "\
[0:v]drawtext=text='Watermark':\
fontsize=48:fontcolor=white@0.8:\
x=10:y=H-th-10[out]" \
-map "[out]" output.mp4
# Fade-in text
ffmpeg -i input.mp4 \
-filter_complex "\
[0:v]drawtext=text='Hello':\
fontsize=64:fontcolor=white:\
x=(w-text_w)/2:y=(h-text_h)/2:\
alpha='if(lt(t,1),t,1)'[out]" \
-map "[out]" output.mp4
# Scrolling credits
ffmpeg -i input.mp4 \
-filter_complex "\
[0:v]drawtext=textfile=credits.txt:\
fontsize=32:fontcolor=white:\
x=(w-text_w)/2:y=h-t*50[out]" \
-map "[out]" output.mp4
# Timed text (appear/disappear)
ffmpeg -i input.mp4 \
-filter_complex "\
[0:v]drawtext=text='Show at 2s':\
fontsize=48:fontcolor=yellow:\
x=100:y=100:\
enable='between(t,2,5)'[out]" \
-map "[out]" output.mp4
# Logo/image watermark
ffmpeg -i video.mp4 -i logo.png \
-filter_complex "\
[1:v]scale=150:-1[logo];\
[0:v][logo]overlay=W-w-20:20[out]" \
-map "[out]" -map 0:a output.mp4
6. Stream Splitting and Multiple Outputs
# Split for multiple resolutions
ffmpeg -i input.mp4 \
-filter_complex "\
[0:v]split=3[v1][v2][v3];\
[v1]scale=1920:1080[hd];\
[v2]scale=1280:720[sd];\
[v3]scale=640:360[mobile]" \
-map "[hd]" hd.mp4 \
-map "[sd]" sd.mp4 \
-map "[mobile]" mobile.mp4
# Split video and audio separately
ffmpeg -i input.mp4 \
-filter_complex "\
[0:v]split=2[v1][v2];\
[0:a]asplit=2[a1][a2];\
[v1]scale=1280:720[vout1];\
[v2]scale=640:360[vout2]" \
-map "[vout1]" -map "[a1]" output1.mp4 \
-map "[vout2]" -map "[a2]" output2.mp4
7. Video Concatenation with Filters
# Concatenate with format normalization
ffmpeg -i 1.mp4 -i 2.mp4 -i 3.mp4 \
-filter_complex "\
[0:v]scale=1920:1080,fps=30,setpts=PTS-STARTPTS[v0];\
[1:v]scale=1920:1080,fps=30,setpts=PTS-STARTPTS[v1];\
[2:v]scale=1920:1080,fps=30,setpts=PTS-STARTPTS[v2];\
[0:a]aformat=sample_rates=48000:channel_layouts=stereo[a0];\
[1:a]aformat=sample_rates=48000:channel_layouts=stereo[a1];\
[2:a]aformat=sample_rates=48000:channel_layouts=stereo[a2];\
[v0][a0][v1][a1][v2][a2]concat=n=3:v=1:a=1[outv][outa]" \
-map "[outv]" -map "[outa]" output.mp4
GPU-Accelerated Filtergraphs
Full CUDA Pipeline
# GPU decode -> GPU filter -> GPU encode
ffmpeg -hwaccel cuda -hwaccel_output_format cuda -i main.mp4 \
-hwaccel cuda -hwaccel_output_format cuda -i overlay.mp4 \
-filter_complex "\
[0:v]scale_cuda=1920:1080[main];\
[1:v]scale_cuda=320:180[pip];\
[main][pip]overlay_cuda=W-w-10:H-h-10[out]" \
-map "[out]" -map 0:a \
-c:v h264_nvenc -preset p4 output.mp4
Hybrid GPU + CPU Pipeline
When you need CPU-only filters (drawtext, subtitles), use hwdownload/hwupload:
# GPU scale -> CPU text -> GPU encode
ffmpeg -hwaccel cuda -hwaccel_output_format cuda -i input.mp4 \
-filter_complex "\
[0:v]scale_cuda=1920:1080[scaled];\
[scaled]hwdownload,format=nv12[cpu];\
[cpu]drawtext=text='Watermark':fontsize=48:x=10:y=10[text];\
[text]hwupload_cuda[out]" \
-map "[out]" \
-c:v h264_nvenc output.mp4
ABR Ladder with GPU
# Generate multiple resolutions on GPU
ffmpeg -y -vsync 0 \
-hwaccel cuda \
-hwaccel_output_format cuda \
-i input.mp4 \
-filter_complex "[0:v]split=3[v1][v2][v3];\
[v1]scale_cuda=1920:1080[hd];\
[v2]scale_cuda=1280:720[sd];\
[v3]scale_cuda=640:360[mobile]" \
-map "[hd]" -c:v h264_nvenc -b:v 5M output_1080p.mp4 \
-map "[sd]" -c:v h264_nvenc -b:v 2M output_720p.mp4 \
-map "[mobile]" -c:v h264_nvenc -b:v 500k output_360p.mp4
Advanced Patterns
Multi-Layer Composition
# Video with lower third, logo, and timecode
ffmpeg -i main.mp4 -i logo.png -i lower_third.png \
-filter_complex "\
[1:v]scale=150:-1[logo];\
[2:v]scale=400:-1[third];\
[0:v][logo]overlay=W-w-20:20[step1];\
[step1][third]overlay=50:H-h-80:enable='between(t,5,55)'[step2];\
[step2]drawtext=text='%{pts\\:hms}':\
fontsize=32:fontcolor=white:\
x=W-tw-20:y=H-th-20[out]" \
-map "[out]" -map 0:a output.mp4
Audio Visualization Overlay
# Waveform overlay on video
ffmpeg -i video.mp4 -i audio.mp3 \
-filter_complex "\
[1:a]showwaves=s=1920x200:mode=cline:colors=white@0.8[wave];\
[0:v][wave]overlay=0:H-h-50[out]" \
-map "[out]" -map 1:a output.mp4
# Spectrum analyzer
ffmpeg -i video.mp4 \
-filter_complex "\
[0:a]showspectrum=s=1920x200:legend=0:color=rainbow[spec];\
[0:v][spec]overlay=0:H-h[out]" \
-map "[out]" -map 0:a output.mp4
Time-Based Effects
# Different effects at different times
ffmpeg -i input.mp4 \
-filter_complex "\
[0:v]split=3[v1][v2][v3];\
[v1]trim=0:5,setpts=PTS-STARTPTS[part1];\
[v2]trim=5:10,setpts=PTS-STARTPTS,eq=brightness=0.2:saturation=2.0[part2];\
[v3]trim=10,setpts=PTS-STARTPTS[part3];\
[part1][part2][part3]concat=n=3:v=1:a=0[out]" \
-map "[out]" -map 0:a output.mp4
Debugging Filtergraphs
Verbose Logging
# Enable debug logging
ffmpeg -loglevel debug -i input.mp4 -filter_complex "..." output.mp4
# Show filter graph info
ffmpeg -filter_complex_script script.txt -lavfi "..." 2>&1 | grep -i filter
Validate Filtergraph
# Test filtergraph without encoding (null output)
ffmpeg -i input.mp4 -filter_complex "..." -f null -
# Check specific filter options
ffmpeg -h filter=overlay
ffmpeg -h filter=xfade
ffmpeg -h filter=amix
Common Errors
| Error | Cause | Solution |
|---|---|---|
| "Input pad not connected" | Missing input label | Add [0:v] or correct label |
| "Output pad not connected" | Unused filter output | Add -map or connect to next filter |
| "Stream specifier not found" | Invalid stream reference | Check input has that stream type |
| "Filter not found" | Missing filter in FFmpeg build | Check ffmpeg -filters |
| "Discarding frame" | Timestamp discontinuity | Add setpts=PTS-STARTPTS |
Performance Tips
- Order matters - Put expensive filters later in the chain
- Use GPU filters when available (scale_cuda, overlay_cuda)
- Avoid unnecessary format conversions - Keep same pixel format
- Split before filters if creating multiple outputs
- Use
-threads 0to auto-detect optimal thread count
Best Practices
- Use meaningful labels -
[scaled]not[v1]for clarity - Test on short clips - Use
-t 5to test first 5 seconds - Check all streams - Verify audio mapping with
-map - Normalize inputs - Match fps, resolution before concat/transitions
- Quote the filtergraph - Use double quotes around entire -filter_complex
- Handle audio separately - Video and audio often need different processing
This guide covers filter_complex patterns for 2025. For hardware acceleration details, see ffmpeg-hardware-acceleration. For basic filter syntax, see ffmpeg-fundamentals-2025.