メニュー
Video and audio processing with FFmpeg for format conversion, resizing, compression, audio extraction, and preparing assets for Remotion.
Codex または Claude でインストール この Prompt をコピーして Codex、Claude、または他のアシスタントに貼り付けると、Skill ページを確認してインストールできます。
Read a business card image, extract contact details (name, phone, email, company, etc.), append them to a Google Sheet, then send a welcome email and WhatsApp message to the contact.
>-
Fetch and summarize YouTube video transcripts using a residential IP proxy to bypass cloud IP blocks.
Create, inspect, and edit Microsoft PowerPoint presentations and PPTX decks with reliable layouts, templates, placeholders, notes, charts, and visual QA.
Perform JIRA operations using the MCP server as primary, with automatic fallback to REST API for operations that don't work via MCP (e.g., story points via Agile estimation endpoint, epic linking via parent field). Includes sprint workflow helpers.
Produce thoughtful design artifacts (slide decks, prototypes, mockups, landing pages, dashboards) using HTML/CSS/JS/SVG as the medium.
SOC 職業分類に基づく
| 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 |