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Video and audio processing with FFmpeg for format conversion, resizing, compression, audio extraction, and preparing assets for Remotion.
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| name | ffmpeg-video-processing |
| description | Video and audio processing with FFmpeg for format conversion, resizing, compression, audio extraction, and preparing assets for Remotion. |
| version | 1.0.0 |
| author | digitalsamba/claude-code-video-toolkit |
| tools | ["exec","filesystem"] |
| commands | [] |
| icon | 🎬 |
FFmpeg is the essential tool for video/audio processing. This skill covers common operations for Remotion video projects.
Use exec to run:
ffmpeg -i input.gif -movflags faststart -pix_fmt yuv420p \
-vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" output.mp4
Why these flags:
-movflags faststart - Moves metadata to start for web streaming-pix_fmt yuv420p - Ensures compatibility with most playersscale=trunc(...) - Forces even dimensions (required by most codecs)Use exec to run:
# 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
Use exec to run:
# 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
Use exec to run:
# 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
Use exec to run:
# 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
Use exec to run:
# 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.
Use exec to run:
# 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
Use exec to run:
# 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
Use exec to run:
# 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
Use exec to run:
# 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
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.
Use exec to run:
# 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:
speed = X / Y1 / speed (e.g., 3x speed = setpts=0.333*PTS)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]"
Use exec to run:
# 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
Use exec to run:
# 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
Use exec to run:
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
Add scale filter: -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2"
Use: -movflags faststart -pix_fmt yuv420p -c:v libx264
Use filter_complex with atempo: -filter_complex "[0:v]setpts=0.5*PTS[v];[0:a]atempo=2.0[a]"
Increase CRF (23 to 28) or reduce resolution
| 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 |
After Remotion renders your video (typically to out/video.mp4), use FFmpeg to optimize for each distribution platform.
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 re-encodes everything, so upload high quality.
Use exec to run:
# 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 has strict limits: max 140s, 512MB, 1920x1200.
Use exec to run:
# 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 prefers MP4 with AAC audio, max 10 minutes.
Use exec to run:
# 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
Use exec to run:
# 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
Use exec to run:
# 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 | Max Resolution | Max Size | Max Duration | Audio |
|---|---|---|---|---|
| YouTube | 8K | 256GB | 12 hours | AAC 48kHz |
| Twitter/X | 1920x1200 | 512MB | 140s | AAC 44.1kHz |
| 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 |
Use filesystem to create the script, then exec to run it:
#!/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
Common errors and fixes when processing video:
Use exec to run:
# 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
| 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 |