ffmpeg

$2a

# To 1920x1080 (maintain aspect ratio, add black bars)

ffmpeg -i input.mp4 -vf "scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:(ow-iw)/2:(oh-ih)/2" output.mp4

# To 1920x1080 (crop to fill)

ffmpeg -i input.mp4 -vf "scale=1920:1080:force_original_aspect_ratio=increase,crop=1920:1080" output.mp4

# Scale to width, auto height

ffmpeg -i input.mp4 -vf "scale=1280:-2" output.mp4

Compress Video

# Good quality, smaller file (CRF 23 is default, lower = better quality)

ffmpeg -i input.mp4 -c:v libx264 -crf 23 -preset medium -c:a aac -b:a 128k output.mp4

# Aggressive compression for web preview

ffmpeg -i input.mp4 -c:v libx264 -crf 28 -preset fast -c:a aac -b:a 96k output.mp4

# Target file size (e.g., ~10MB for 60s video = ~1.3Mbps)

ffmpeg -i input.mp4 -c:v libx264 -b:v 1300k -c:a aac -b:a 128k output.mp4

Extract Audio

# Extract to MP3

ffmpeg -i input.mp4 -vn -acodec libmp3lame -q:a 2 output.mp3

# Extract to AAC

ffmpeg -i input.mp4 -vn -acodec aac -b:a 192k output.m4a

# Extract to WAV (uncompressed)

ffmpeg -i input.mp4 -vn output.wav

Convert Audio Formats

# M4A to MP3 (for ElevenLabs voice samples)

ffmpeg -i input.m4a -codec:a libmp3lame -qscale:a 2 output.mp3

# WAV to MP3

ffmpeg -i input.wav -codec:a libmp3lame -b:a 192k output.mp3

# Adjust volume

ffmpeg -i input.mp3 -filter:a "volume=1.5" output.mp3

Trim/Cut Video

# Cut from timestamp to duration (recommended - reliable)

ffmpeg -i input.mp4 -ss 00:00:30 -t 00:00:15 -c:v libx264 -c:a aac output.mp4

# Cut from timestamp to timestamp

ffmpeg -i input.mp4 -ss 00:00:30 -to 00:00:45 -c:v libx264 -c:a aac output.mp4

# Stream copy (faster but may lose frames at cut points)

# Only use when source has frequent keyframes

ffmpeg -i input.mp4 -ss 00:00:30 -t 00:00:15 -c copy output.mp4

Note: Re-encoding is recommended for trimming. Stream copy (-c copy) can silently drop video if the seek point doesn't align with a keyframe.

Speed Up / Slow Down

# 2x speed (video and audio)

ffmpeg -i input.mp4 -filter_complex "[0:v]setpts=0.5*PTS[v];[0:a]atempo=2.0[a]" -map "[v]" -map "[a]" output.mp4

# 0.5x speed (slow motion)

ffmpeg -i input.mp4 -filter_complex "[0:v]setpts=2.0*PTS[v];[0:a]atempo=0.5[a]" -map "[v]" -map "[a]" output.mp4

# Video only (no audio)

ffmpeg -i input.mp4 -filter:v "setpts=0.5*PTS" -an output.mp4

Concatenate Videos

# Create file list

echo "file 'clip1.mp4'" > list.txt

echo "file 'clip2.mp4'" >> list.txt

echo "file 'clip3.mp4'" >> list.txt

# Concatenate (same codec/resolution)

ffmpeg -f concat -safe 0 -i list.txt -c copy output.mp4

# Concatenate with re-encoding (different sources)

ffmpeg -f concat -safe 0 -i list.txt -c:v libx264 -c:a aac output.mp4

Add Fade In/Out

# Fade in first 1 second, fade out last 1 second (30fps video)

ffmpeg -i input.mp4 -vf "fade=t=in:st=0:d=1,fade=t=out:st=9:d=1" -c:a copy output.mp4

# Audio fade

ffmpeg -i input.mp4 -af "afade=t=in:st=0:d=1,afade=t=out:st=9:d=1" -c:v copy output.mp4

Get Video Info

# Duration, resolution, codec info

ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 input.mp4

# Full info

ffprobe -v quiet -print_format json -show_format -show_streams input.mp4

Remotion-Specific Patterns

Video Speed Adjustment for Remotion

**When to use FFmpeg vs Remotion playbackRate:**

Scenario

Use FFmpeg

Use Remotion

Constant speed (1.5x, 2x)

Either works

✅ Simpler

Extreme speeds (>4x or <0.25x)

✅ More reliable

May have issues

Variable speed (accelerate over time)

✅ Pre-process

Complex workaround needed

Need perfect audio sync

✅ Guaranteed

Usually fine

Demo needs to fit voiceover timing

✅ Pre-calculate

Runtime adjustment

Remotion limitation: playbackRate must be constant. Dynamic interpolation like playbackRate={interpolate(frame, [0, 100], [1, 5])} won't work correctly because Remotion evaluates frames independently.

# Speed up demo to fit a scene (e.g., 60s demo into 20s = 3x speed)

ffmpeg -i demo-raw.mp4 \

  -filter_complex "[0:v]setpts=0.333*PTS[v];[0:a]atempo=3.0[a]" \

  -map "[v]" -map "[a]" \

  public/demos/demo-fast.mp4

# Slow motion for emphasis (0.5x speed)

ffmpeg -i action.mp4 \

  -filter_complex "[0:v]setpts=2.0*PTS[v];[0:a]atempo=0.5[a]" \

  -map "[v]" -map "[a]" \

  public/demos/action-slow.mp4

# Speed up without audio (common for screen recordings)

ffmpeg -i demo.mp4 -filter:v "setpts=0.5*PTS" -an public/demos/demo-2x.mp4

# Timelapse effect (10x speed, drop audio)

ffmpeg -i long-demo.mp4 -filter:v "setpts=0.1*PTS" -an public/demos/timelapse.mp4

Calculate speed factor:

• To fit X seconds of video into Y seconds of scene: speed = X / Y

• setpts multiplier = 1 / speed (e.g., 3x speed = setpts=0.333*PTS)

• atempo value = speed (e.g., 3x speed = atempo=3.0)

Extreme speed (>2x audio): Chain atempo filters (each limited to 0.5-2.0 range):

# 4x speed audio

-filter_complex "[0:a]atempo=2.0,atempo=2.0[a]"

# 8x speed audio

-filter_complex "[0:a]atempo=2.0,atempo=2.0,atempo=2.0[a]"

Prepare Demo Recording for Remotion

# Standard 1080p, 30fps, Remotion-ready

ffmpeg -i raw-recording.mp4 \

  -vf "scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:(ow-iw)/2:(oh-ih)/2,fps=30" \

  -c:v libx264 -crf 18 -preset slow \

  -c:a aac -b:a 192k \

  -movflags faststart \

  public/demos/demo.mp4

Screen Recording to Remotion Asset

# From iPhone/iPad recording (usually 60fps, variable resolution)

ffmpeg -i iphone-recording.mov \

  -vf "scale=1920:-2,fps=30" \

  -c:v libx264 -crf 20 \

  -an \

  public/demos/mobile-demo.mp4

Batch Convert GIFs

for f in assets/*.gif; do

  ffmpeg -i "$f" -movflags faststart -pix_fmt yuv420p \

    -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" \

    "public/demos/$(basename "$f" .gif).mp4"

done

Common Issues

"Height not divisible by 2"

Add scale filter: -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2"

Video won't play in browser

Use: -movflags faststart -pix_fmt yuv420p -c:v libx264

Audio out of sync after speed change

Use filter_complex with atempo: -filter_complex "[0:v]setpts=0.5*PTS[v];[0:a]atempo=2.0[a]"

File too large

Increase CRF (23→28) or reduce resolution

Quality Guidelines

Use Case

CRF

Preset

Notes

Archive/Master

18

slow

Best quality, large files

Production

20-22

medium

Good balance

Web/Preview

23-25

fast

Smaller files

Draft/Quick

28+

veryfast

Fast encoding

Platform-Specific Output Optimization

After Remotion renders your video (typically to out/video.mp4), use FFmpeg to optimize for each distribution platform.

Workflow Integration

Remotion render (master)     FFmpeg optimization      Platform upload

       ↓                            ↓                       ↓

   out/video.mp4  ────────→  out/video-youtube.mp4  ───→  YouTube

                  ────────→  out/video-twitter.mp4  ───→  Twitter/X

                  ────────→  out/video-linkedin.mp4 ───→  LinkedIn

                  ────────→  out/video-web.mp4      ───→  Website embed

YouTube (Recommended Settings)

YouTube re-encodes everything, so upload high quality:

# YouTube optimized (1080p)

ffmpeg -i out/video.mp4 \

  -c:v libx264 -preset slow -crf 18 \

  -profile:v high -level 4.0 \

  -bf 2 -g 30 \

  -c:a aac -b:a 192k -ar 48000 \

  -movflags +faststart \

  out/video-youtube.mp4

# YouTube Shorts (vertical 1080x1920)

ffmpeg -i out/video.mp4 \

  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2" \

  -c:v libx264 -crf 18 -c:a aac -b:a 192k \

  out/video-shorts.mp4

Twitter/X

Twitter has strict limits: max 140s, 512MB, 1920x1200:

# Twitter optimized (under 15MB target for fast upload)

ffmpeg -i out/video.mp4 \

  -c:v libx264 -preset medium -crf 24 \

  -profile:v main -level 3.1 \

  -vf "scale='min(1280,iw)':'min(720,ih)':force_original_aspect_ratio=decrease" \

  -c:a aac -b:a 128k -ar 44100 \

  -movflags +faststart \

  -fs 15M \

  out/video-twitter.mp4

# Check file size and duration

ffprobe -v error -show_entries format=duration,size -of csv=p=0 out/video-twitter.mp4

LinkedIn

LinkedIn prefers MP4 with AAC audio, max 10 minutes:

# LinkedIn optimized

ffmpeg -i out/video.mp4 \

  -c:v libx264 -preset medium -crf 22 \

  -profile:v main \

  -vf "scale='min(1920,iw)':'min(1080,ih)':force_original_aspect_ratio=decrease" \

  -c:a aac -b:a 192k -ar 48000 \

  -movflags +faststart \

  out/video-linkedin.mp4

Website/Embed (Optimized for Fast Loading)

# Web-optimized MP4 (small file, progressive loading)

ffmpeg -i out/video.mp4 \

  -c:v libx264 -preset medium -crf 26 \

  -profile:v baseline -level 3.0 \

  -vf "scale=1280:720" \

  -c:a aac -b:a 128k \

  -movflags +faststart \

  out/video-web.mp4

# WebM alternative (better compression, wider browser support)

ffmpeg -i out/video.mp4 \

  -c:v libvpx-vp9 -crf 30 -b:v 0 \

  -vf "scale=1280:720" \

  -c:a libopus -b:a 128k \

  -deadline good \

  out/video-web.webm

GIF (for Previews/Thumbnails)

# High-quality GIF (first 5 seconds)

ffmpeg -i out/video.mp4 -t 5 \

  -vf "fps=15,scale=480:-1:flags=lanczos,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse" \

  out/preview.gif

# Smaller file GIF

ffmpeg -i out/video.mp4 -t 3 \

  -vf "fps=10,scale=320:-1:flags=lanczos,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse" \

  out/preview-small.gif

Platform Requirements Quick Reference

Platform

Max Resolution

Max Size

Max Duration

Audio

YouTube

8K

256GB

12 hours

AAC 48kHz

Twitter/X

1920x1200

512MB

140s

AAC 44.1kHz

LinkedIn

4096x2304

5GB

10 min

AAC 48kHz

Instagram Feed

1080x1350

4GB

60s

AAC 48kHz

Instagram Reels

1080x1920

4GB

90s

AAC 48kHz

TikTok

1080x1920

287MB

10 min

AAC

Batch Export for All Platforms

#!/bin/bash

# save as: export-all-platforms.sh

INPUT="out/video.mp4"

# YouTube (high quality)

ffmpeg -i "$INPUT" -c:v libx264 -preset slow -crf 18 \

  -c:a aac -b:a 192k -movflags +faststart \

  out/video-youtube.mp4

# Twitter (compressed)

ffmpeg -i "$INPUT" -c:v libx264 -crf 24 \

  -vf "scale='min(1280,iw)':'-2'" \

  -c:a aac -b:a 128k -movflags +faststart \

  out/video-twitter.mp4

# LinkedIn

ffmpeg -i "$INPUT" -c:v libx264 -crf 22 \

  -c:a aac -b:a 192k -movflags +faststart \

  out/video-linkedin.mp4

# Web embed (small)

ffmpeg -i "$INPUT" -c:v libx264 -crf 26 \

  -vf "scale=1280:720" \

  -c:a aac -b:a 128k -movflags +faststart \

  out/video-web.mp4

echo "Exported:"

ls -lh out/video-*.mp4

Error Handling

Common errors and fixes when processing video:

# Check if FFmpeg succeeded

ffmpeg -i input.mp4 -c:v libx264 output.mp4 && echo "Success" || echo "Failed: check input file"

# Validate output file is playable

ffprobe -v error -select_streams v:0 -show_entries stream=codec_name -of csv=p=0 output.mp4

# Get detailed error info

ffmpeg -v error -i input.mp4 -f null - 2>&1 | head -20

Handling Common Failures

Error

Cause

Fix

"No such file"

Input path wrong

Check path, use quotes for spaces

"Invalid data"

Corrupted input

Re-download or re-record source

"height not divisible by 2"

Odd dimensions

Add scale filter with trunc

"encoder not found"

Missing codec

Install FFmpeg with full codecs

Output 0 bytes

Silent failure

Check full ffmpeg output for errors

Feedback &#x26; Contributions

If this skill is missing information or could be improved:

• Missing a command? Describe what you needed

• Found an error? Let me know what's wrong

• Want to contribute? I can help you:

• Update this skill with improvements

• Create a PR to github.com/digitalsamba/claude-code-video-toolkit

Just say "improve this skill" and I'll guide you through updating .claude/skills/ffmpeg/SKILL.md.