How to use
- Copy the installation command and review the source package before installing it in your own agent environment.
- Check the source document for required tools, credentials and supported hosts.
- Describe your input and desired deliverable; review the output against the source material.
npx skills add https://github.com/guyronnen/openmontage --skill video-editBefore you start
- Installation does not include a model subscription, API allowance or permission to access your files.
- Repository stars and installation counts describe activity, not an independent quality or security test.
Original skill document
Rendered from the source repository. Headings, examples, code, tables, links, and referenced images are preserved.
Video Edit
Edit videos locally by running ffmpeg/ffprobe directly. No wrapper scripts needed.
Prerequisites
Install ffmpeg (includes ffprobe):
bash
# macOS
brew install ffmpeg
# Ubuntu/Debian
sudo apt update && sudo apt install -y ffmpeg
# Verify
ffmpeg -version && ffprobe -versionQuick Reference
Get video info
bash
ffprobe -v quiet -print_format json -show_format -show_streams video.mp4Trim
bash
ffmpeg -y -ss 00:00:30 -to 00:01:45 -i video.mp4 -c copy trimmed.mp4Concatenate clips
bash
# 1. Create a file list
printf "file '%s'\n" clip1.mp4 clip2.mp4 clip3.mp4 > list.txt
# 2. Concat with stream copy
ffmpeg -y -f concat -safe 0 -i list.txt -c copy joined.mp4Resize for platform
bash
ffmpeg -y -i video.mp4 \
-vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black" \
-c:a copy tiktok.mp4Change speed
bash
# 2x faster
ffmpeg -y -i video.mp4 -filter:v "setpts=0.5*PTS" -filter:a "atempo=2.0" fast.mp4
# 0.5x (slow motion)
ffmpeg -y -i video.mp4 -filter:v "setpts=2.0*PTS" -filter:a "atempo=0.5" slow.mp4Extract audio
bash
ffmpeg -y -i video.mp4 -vn -acodec libmp3lame audio.mp3Replace audio
bash
ffmpeg -y -i video.mp4 -i audio.mp3 -c:v copy -map 0:v:0 -map 1:a:0 -shortest output.mp4Compress
bash
ffmpeg -y -i video.mp4 -crf 23 -preset medium -c:a copy compressed.mp4Convert format
bash
ffmpeg -y -i video.mov output.mp4Add image overlay
bash
# Logo in top-right corner
ffmpeg -y -i video.mp4 -i logo.png \
-filter_complex "overlay=W-w-10:10" -c:a copy watermarked.mp4Platform Presets
| Platform | Resolution | Scale + pad filter |
|---|---|---|
| TikTok | 1080 x 1920 | scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black |
| YouTube | 1920 x 1080 | scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:(ow-iw)/2:(oh-ih)/2:black |
| 1080 x 1350 | scale=1080:1350:force_original_aspect_ratio=decrease,pad=1080:1350:(ow-iw)/2:(oh-ih)/2:black | |
| Square | 1080 x 1080 | scale=1080:1080:force_original_aspect_ratio=decrease,pad=1080:1080:(ow-iw)/2:(oh-ih)/2:black |
| Twitter/X | 1920 x 1080 | scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:(ow-iw)/2:(oh-ih)/2:black |
Use the filter with: ffmpeg -y -i input.mp4 -vf "<filter>" -c:a copy output.mp4
Tips
- Always use
-yto overwrite output without prompting. - Use
-c copywhen you only need to cut/join (no re-encoding, very fast). - Lower CRF = better quality, larger file. Range 18-28 is typical; 23 is the default.
- For detailed recipes and flag explanations, see
references/operations.md.
