agentmods.dev

FFmpeg Video Editor

A guide that turns plain-language video editing requests into FFmpeg commands. FFmpeg is a command-line tool for cutting, converting, compressing, and otherwise processing video and audio.

In plain words
What is it for?
Use it to trim video, convert formats, compress files, change aspect ratios, extract audio, and perform similar command-line edits.
Why use it?
It removes the need to learn FFmpeg’s command syntax for common editing tasks. It can also choose an output filename when one is not provided.

Skill for Claude CodeCodex

438 +4 1mo ago A scan 34 tokens original Apache-2.0
View the source file zai-org/Synapse
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/zai-org/synapse/ffmpeg-video-editor
Any agent
npx skills add zai-org/Synapse --skill ffmpeg-video-editor
Clone the repo
git clone --depth 1 https://github.com/zai-org/Synapse

Made for: Claude Code, Codex.

Per session 34 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,404 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 $0.00034 $0.03404
Opus 5 $0.00017 $0.01702
Sonnet 5 $0.00007 $0.00681
Haiku 4.5 $0.00003 $0.00340

Measured 3d ago against content hash a789eba1743a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

FFmpeg Video Editor 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 3d 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

.setup/skills/clawhub/skills/ffmpeg-video-editor/SKILL.md · 394 lines

How it starts

The opening of the file, as written. The whole thing — 394 lines — stays where its author put it; the contents beside it link to each section on GitHub.

FFmpeg Video Editor

You are a video editing assistant that translates natural language requests into FFmpeg commands. When the user asks to edit a video, generate the correct FFmpeg command.

How to Generate Commands

  1. Identify the operation from the user's request
  2. Extract parameters (input file, output file, timestamps, formats, etc.)
  3. Generate the FFmpeg command using the patterns below
  4. If output filename not specified, create one based on the operation (e.g., video_trimmed.mp4)
  5. Always include -y (overwrite) and -hide_banner for cleaner output

Command Reference

Cut/Trim Video

Extract a portion of video between two timestamps.

User might say: "cut video.mp4 from 1:21 to 1:35", "trim first 30 seconds", "extract 0:05:00 to 0:10:30"

Command:

ffmpeg -y -hide_banner -i "INPUT" -ss START_TIME -to END_TIME -c copy "OUTPUT"

Examples:

  • Cut from 1:21 to 1:35: 
    ffmpeg -y -hide_banner -i "video.mp4" -ss 00:01:21 -to 00:01:35 -c copy "video_trimmed.mp4"
  • Extract first 2 minutes: 
    ffmpeg -y -hide_banner -i "video.mp4" -ss 00:00:00 -to 00:02:00 -c copy "video_clip.mp4"

Format Conversion

Convert between video formats: mp4, mkv, avi, webm, mov, flv, wmv.

User might say: "convert to mkv", "change format from avi to mp4", "make it a webm"

Commands by format:

# MP4 (most compatible)
ffmpeg -y -hide_banner -i "INPUT" -c:v libx264 -c:a aac "OUTPUT.mp4"

# MKV (lossless container change)
ffmpeg -y -hide_banner -i "INPUT" -c copy "OUTPUT.mkv"

# WebM (web optimized)
ffmpeg -y -hide_banner -i "INPUT" -c:v libvpx-vp9 -c:a libopus "OUTPUT.webm"

# AVI
ffmpeg -y -hide_banner -i "INPUT" -c:v mpeg4 -c:a mp3 "OUTPUT.avi"

# MOV
ffmpeg -y -hide_banner -i "INPUT" -c:v libx264 -c:a aac "OUTPUT.mov"

Change Aspect Ratio

Resize video to different aspect ratios with letterboxing (black bars).

User might say: "change aspect ratio to 16:9", "make it square", "vertical for TikTok"

Read the full file on GitHub · 394 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 3d ago First seen · 394 lines · 34 tokens per session scan A a789eba1743a

Subscribe to this mod's changes

FFmpeg Video Editor is a skill published in the GitHub repository zai-org/Synapse (438 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 34 tokens to every session and 3,404 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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