Specification
- Skill ID
- calesthio/openmontage/video-edit
- Publisher
- calesthio
- Repository
- openmontage
- Installs
- 0
- Files
- 2
- Synced
- Sep 23, 2026
How to use it
Open any RiverX project, open the Skills panel in the chat, and search for this identifier. The files are fetched from the source repository at install time.
calesthio/openmontage/video-editInstalls these files- SKILL.md
- references/operations.md
What this skill tells the agent
Video Edit
Edit videos locally by running ffmpeg/ffprobe directly. No wrapper scripts needed.
Prerequisites
Install ffmpeg (includes ffprobe):
# macOS
brew install ffmpeg
# Ubuntu/Debian
sudo apt update && sudo apt install -y ffmpeg
# Verify
ffmpeg -version && ffprobe -versionQuick Reference
Get video info
ffprobe -v quiet -print_format json -show_format -show_streams video.mp4Trim
ffmpeg -y -ss 00:00:30 -to 00:01:45 -i video.mp4 -c copy trimmed.mp4Concatenate clips
# 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
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
# 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
ffmpeg -y -i video.mp4 -vn -acodec libmp3lame audio.mp3Replace audio
ffmpeg -y -i video.mp4 -i audio.mp3 -c:v copy -map 0:v:0 -map 1:a:0 -shortest output.mp4Compress
ffmpeg -y -i video.mp4 -crf 23 -preset medium -c:a copy compressed.mp4Convert format
ffmpeg -y -i video.mov output.mp4Add image overlay
# 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.
More from calesthio
Use this skill in a project
Open any RiverX project, search the Skills panel for calesthio/openmontage/video-edit, and install it in one click.
