FFmpeg for Video Production
FFmpeg is the essential tool for video/audio processing. This skill covers common operations for Remotion video projects.
Quick Reference
GIF to MP4 (Remotion-compatible)
bashffmpeg -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)
Resize Video
bash# 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
bash# 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
bash# 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
bash# 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
bash# 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
bash# 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
bash# 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
bash# 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
bash# 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.
bash# 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):
bash# 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
bash# 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
bash# 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
bashfor 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:
bash# 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:
bash# 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:
bash# 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)
bash# 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)
bash# 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 |
| 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
bash#!/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:
bash# 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 & Contributions
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