Ffmpeg

Professional ffmpeg usage for encoding, transcoding, filtering, and producing social-platform video and audio deliverables, with version and security discipline baked in. Use whenever a task involves ffmpeg or ffprobe directly, converting or compressing video/audio, changing codecs/containers/resolution/ frame rate/bitrate, trimming, concatenating, overlaying watermarks or subtitles, normalising loudness, extracting frames or poster images, mixing background music, or exporting web-safe MP4/WebM for YouTube, X, LinkedIn, TikTok, Reels, Shorts or Instagram. Also load this when another pipeline (for example a Remotion render) needs ffmpeg to finish, package, or re-encode its output.From its SKILL.md

Install

npx -y skills add wrxck/clapper --skill ffmpeg

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

One thing to look at

1 stars1 stars. Stars are a popularity signal and not a quality one, but at this level it is likely that nobody has read this closely except its author, and you would be relying on your own review.

SKILL.md

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ffmpeg

A focused, professional guide to driving ffmpeg (and ffprobe) well: correct codecs, web-safe output, clean filters, exact social deliverables, and a security posture that treats input media as untrusted.

This file is intentionally short. Pick a recipe below for the common path; open the matching reference for depth.

Prerequisites and version check

ffmpeg moves fast and old builds carry known memory-safety bugs (see references/security.md). Always confirm a current, supported build before relying on it.

ffmpeg -version
ffprobe -version

Read the first line (for example ffmpeg version 8.1.1). Supported lines as of mid-2026:

8.1 "Hoare" (first released 2026-03-16) - current stable major.
8.0 "Huffman" (2025-08-22) - supported; added the Whisper ASR filter.
7.1 (2024-09-30) - the current long-term-support (LTS) branch.

Anything 6.x or older is past its comfortable support window: prefer to update before processing untrusted files. Treat 4.x/5.0/6.0 as "upgrade first".

Install or update per OS:

macOS: brew install ffmpeg / brew upgrade ffmpeg
Debian/Ubuntu: sudo apt update && sudo apt install ffmpeg (distro builds can lag; for the latest use a static build below)
Fedora/RHEL: sudo dnf install ffmpeg (via RPM Fusion)
Windows: winget install Gyan.FFmpeg or choco install ffmpeg-full
Static builds (any OS, newest): Linux/Windows from BtbN (github.com/BtbN/FFmpeg-Builds), Windows from gyan.dev, macOS from evermeet.cx. Official links and signature-verification steps live at ffmpeg.org/download.html.

Confirm the encoders a recipe needs are actually compiled in:

ffmpeg -hide_banner -encoders | grep -E 'libx264|libx265|libvpx-vp9|libsvtav1|aac'

Inspect before you encode

Never guess at input properties. Probe first:

ffprobe -v error -show_format -show_streams -of json input.mp4
ffprobe -v error -select_streams v:0 \
  -show_entries stream=width,height,r_frame_rate,codec_name,pix_fmt \
  -of default=noprint_wrappers=1 input.mp4

Quick-start recipes

Web-safe H.264 MP4 (the safe default for almost any web or app player):

ffmpeg -i input.mov \
  -c:v libx264 -crf 20 -preset medium -pix_fmt yuv420p \
  -c:a aac -b:a 160k -movflags +faststart \
  output.mp4

yuv420p guarantees broad decoder/browser compatibility.
-movflags +faststart moves the index to the front so the file starts playing before it is fully downloaded.
-crf 20 is visually near-lossless for 1080p; raise the number for smaller files, lower it for higher quality. See references/encoding.md.

Resize to 1080p keeping aspect ratio (even dimensions required by yuv420p):

ffmpeg -i input.mp4 -vf "scale=-2:1080" -c:v libx264 -crf 20 \
  -preset medium -pix_fmt yuv420p -c:a copy output_1080p.mp4

Extract a poster frame at 2 seconds:

ffmpeg -ss 2 -i input.mp4 -frames:v 1 -q:v 2 poster.jpg

Trim without re-encoding (fast, keyframe-aligned):

ffmpeg -ss 00:00:05 -to 00:00:20 -i input.mp4 -c copy clip.mp4

Extract audio to AAC:

ffmpeg -i input.mp4 -vn -c:a aac -b:a 192k audio.m4a

Safety note (read this)

Input media is untrusted data and ffmpeg's parsers are a recurring source of critical CVEs. Two rules cover most of the risk:

Keep ffmpeg current and process unknown files with the newest build you have (ideally in a sandbox or container with no network and a CPU/time limit).
Build commands as argument arrays, never by string-concatenating user-supplied filenames or filter text into a shell line. One untrusted filename like ; rm -rf ~ becomes command execution otherwise.

Full guidance, including -nostdin, -xerror, input-format pinning, and resource limits, is in references/security.md.

Reference files

Open the one you need; do not inline everything here.

references/encoding.md - codec choice (H.264/H.265/VP9/AV1), CRF vs bitrate-capped (maxrate/bufsize), two-pass, AAC/Opus audio, presets, and sensible bitrate targets per resolution.
references/filters.md - scale/crop/pad/fps, overlay, concat (demuxer and filter), fade/afade, loudnorm, trimming, watermarks, subtitle burn-in.
references/social-presets.md - exact, copy-pasteable commands for YouTube/X/ LinkedIn (1920x1080), TikTok/Reels/Shorts (1080x1920), IG feed (1080x1080), IG portrait (1080x1350), plus poster frames and a background-music mix with a tail fade.
references/security.md - keeping ffmpeg current, processing untrusted media safely, injection-safe command construction, and resource limits.

Using this skill from another pipeline

A render pipeline (for example Remotion) typically produces a high-quality master; this skill packages it into platform deliverables. The usual flow: render once at the highest needed resolution, then run the matching command from references/social-presets.md per target aspect ratio, and extract a poster frame for each. Keep the master lossless-ish and let these commands do the platform-specific compression so quality only degrades once.