ffmpeg

A command-line tool for converting and inspecting audio and video files. It can change formats, trim clips, extract audio, resize video, and create GIFs.

In plain words
What is it for?
Use it to convert media, cut sections, extract sound, resize videos, make GIFs, or inspect media files. It writes transformed media to a new file, leaving the original unchanged.
Why use it?
It handles common media changes without requiring a video-editing application. It also lets you check details such as a file’s codec, duration, and resolution.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/atomicbot-ai/atomic-agent/ffmpeg
Any agent
npx skills add AtomicBot-ai/atomic-agent --skill ffmpeg
Clone the repo
git clone --depth 1 https://github.com/AtomicBot-ai/atomic-agent

Made for: Claude Code, Codex.

Per session 47 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 924 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00047 $0.00924
Opus 5 $0.00023 $0.00462
Sonnet 5 $0.00009 $0.00185
Haiku 4.5 $0.00005 $0.00092

Measured 2d ago against content hash 6d86ab7e2433, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

ffmpeg scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

starter-skills/ffmpeg/SKILL.md · 81 lines

How it starts

The opening of the file, as written. The whole thing — 81 lines — stays where its author put it; the contents beside it link to each section on GitHub.

ffmpeg

Transform audio and video files with ffmpeg and inspect them with ffprobe. Operations are non-destructive: always write to a new output file. Re-encoding can be slow on long media — set realistic expectations.

Setup health check (run first, every session)

Verify with one solo step:

[{ "tool": "os.shell.run", "args": { "cmd": "ffmpeg", "args": ["-version"] } }]

Outcome map:

  • exit 0 + version → ready, proceed.
  • command not found: ffmpeg → enter Setup playbook → "ffmpeg missing".

Setup playbook (when prerequisites are missing)

ffmpeg missing

Reply (solo reply step):

"ffmpeg is not installed. I can install it: brew install ffmpeg. Install it?"

On yes:

[{ "tool": "os.shell.run", "args": { "cmd": "brew", "args": ["install", "ffmpeg"] } }]

On Linux: apt-get install ffmpeg.

When to use

  • "Convert this video/audio to ", "extract the audio from this mp4".
  • "Trim from 0:30 to 1:00", "resize to 720p", "make a GIF from this clip".
  • "What codec / duration / resolution is this file?" (use ffprobe).

When NOT to use

  • Downloading media from URLs — that's yt-dlp territory (separate skill).
  • Still-image editing — use the imagemagick skill.
  • Lossless container-only edits where a remux suffices — still fine here, just use -c copy to avoid re-encoding.

Common operations

All examples invoke os.shell.run. Inspect first with ffprobe; the approval gate surfaces each write. Use -c copy to remux without re-encoding when only the container changes.

Goal cmd / args
Inspect media ffprobe ["-hide_banner", "in.mp4"]
Convert MOV → MP4 ffmpeg ["-i", "in.mov", "-c:v", "libx264", "-c:a", "aac", "out.mp4"]
Extract audio (MP3) ffmpeg ["-i", "in.mp4", "-vn", "-q:a", "2", "out.mp3"]
Trim (start 30s, 30s long) ffmpeg ["-ss", "00:00:30", "-i", "in.mp4", "-t", "30", "-c", "copy", "clip.mp4"]
Resize to 720p ffmpeg ["-i", "in.mp4", "-vf", "scale=-2:720", "out_720p.mp4"]
Video → GIF ffmpeg ["-i", "in.mp4", "-vf", "fps=12,scale=480:-1", "out.gif"]
Extract one frame ffmpeg ["-ss", "00:00:05", "-i", "in.mp4", "-frames:v", "1", "frame.png"]
Remux only (fast) ffmpeg ["-i", "in.mkv", "-c", "copy", "out.mp4"]

Read the full file on GitHub · 81 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 81 lines · 47 tokens per session scan A 6d86ab7e2433

Subscribe to this mod's changes

ffmpeg is a skill published in the GitHub repository AtomicBot-ai/atomic-agent (2,438 stars, last pushed today), licensed MIT. It adds 47 tokens to every session and 924 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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