FFmpeg CLI

Process video and audio using FFmpeg CLI for transcoding, cutting, merging, audio extraction, thumbnails, GIFs, speed, filters, subtitles, and watermarks.

Security Scan

The skill's scripts and runtime instructions match the stated purpose (local FFmpeg helper scripts); it does not request secrets or download remote code, but it assumes ffmpeg (and a few common CLI tools) are present and will execute shell scripts on local files.

Purpose & Capability

Name/description (FFmpeg CLI operations) align with the provided scripts. All eight scripts perform expected video/audio tasks (convert, cut, merge, extract audio, gif, thumbnail, speed, watermark). No unrelated credentials, hosts, or binaries are requested.

Instruction Scope

SKILL.md instructs the agent to run the included shell scripts against local files. The scripts only perform local file I/O and call ffmpeg; they do not call external network endpoints or read environment secrets. Minor operational notes: speed.sh uses bc (not declared in the metadata) and one echo line in speed.sh references an undefined variable (RATEx). Filenames are written into a temporary concat file without sanitization, which could behave unexpectedly with specially crafted filenames.

Install Mechanism

No remote download/install spec in the registry; SKILL.md metadata suggests installing ffmpeg via a brew formula (a well-known package source). There are no arbitrary URL downloads or archive extracts in the skill.

Credentials

The skill declares no required environment variables or credentials. It only needs local ffmpeg (and implicitly common CLI tools like mktemp and bc). There are no requests for unrelated secrets or config paths.

Persistence & Privilege

always is false and the skill is user-invocable. disable-model-invocation is false (normal platform default) — the skill could be invoked autonomously, but that is expected behavior and not combined with other privilege or credential requests.

Assessment

This skill is internally consistent: it provides local ffmpeg wrapper scripts and doesn't request secrets or download code. Before installing, ensure you have ffmpeg (brew install ffmpeg is suggested) and common utilities (bc, mktemp) on your system. Review the scripts if you will run them on untrusted files — they execute ffmpeg and write temporary files (merge.sh creates /tmp/ffmpeg_merge_*.txt) and do minimal filename sanitization. If you want to limit risk, run the scripts in a sandbox or only use trusted input files. If you need the skill to never run autonomously, disable model invocation when enabling the skill on your agent.

Quick Reference

Task	Command
Cut video	{baseDir}/scripts/cut.sh -i <input> -s <start> -e <end> -o <output>
Merge clips	{baseDir}/scripts/merge.sh -o <output> <file1> <file2> ...
Extract audio	{baseDir}/scripts/extract-audio.sh -i <video> -o <output.mp3>
Generate thumbnail	{baseDir}/scripts/thumb.sh -i <video> -t <timestamp> -o <out.jpg>
Create GIF	{baseDir}/scripts/gif.sh -i <video> -s <start> -e <end> -o <out.gif>
Convert format	{baseDir}/scripts/convert.sh -i <input> -o <output.mp4>
Change speed	{baseDir}/scripts/speed.sh -i <input> -r <0.5-2.0> -o <output>
Add watermark	{baseDir}/scripts/watermark.sh -i <video> -w <image> -o <output>

Scripts

cut.sh - Cut video segment

{baseDir}/scripts/cut.sh -i video.mp4 -s 00:01:30 -e 00:02:45 -o clip.mp4

merge.sh - Concatenate videos

{baseDir}/scripts/merge.sh -o merged.mp4 part1.mp4 part2.mp4 part3.mp4

extract-audio.sh - Pull audio track

{baseDir}/scripts/extract-audio.sh -i video.mp4 -o audio.mp3

thumb.sh - Extract frame as image

{baseDir}/scripts/thumb.sh -i video.mp4 -t 00:00:15 -o frame.jpg

gif.sh - Convert clip to GIF

{baseDir}/scripts/gif.sh -i video.mp4 -s 00:00:10 -e 00:00:15 -o clip.gif

convert.sh - Transcode to new format

{baseDir}/scripts/convert.sh -i input.avi -o output.mp4

speed.sh - Adjust playback speed

{baseDir}/scripts/speed.sh -i video.mp4 -r 2.0 -o fast.mp4  # 2x speed
{baseDir}/scripts/speed.sh -i video.mp4 -r 0.5 -o slow.mp4  # 0.5x speed

watermark.sh - Overlay image watermark

{baseDir}/scripts/watermark.sh -i video.mp4 -w logo.png -o output.mp4

Notes

• All scripts support common video formats (mp4, avi, mov, mkv, webm, etc.)
• Output quality is optimized for balanced file size and clarity
• Use -h or no args to see script usage