How do I install the Ffmpeg skill?

Run npx skillmds@latest add sakydev/ffmpeg in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Ffmpeg safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Ffmpeg?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Ffmpeg free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Ffmpeg?

sakydev (@sakydev) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Ffmpeg by sakydev — Agent Skill

Name: Ffmpeg
Author: sakydev

Ffmpeg

Use this skill whenever the user asks to process, convert, compress, trim, merge, extract, or otherwise manipulate video or audio files using ffmpeg. Covers format conversion, compression, clipping, filtering, and any other ffmpeg operation.

sakydev 14f4247 2.9 KB Updated Sep 17, 2026

File contents

FFmpeg Skill

Hard rules

Never overwrite the original. Write to a new file. Derive the name if none given: video.mp4 becomes video_compressed.mp4. Never use -y on the same path as the input.
Never destroy quality. Minimum floors:

Codec Flag Floor Good default

H.264 (libx264) -crf 28 max 18-23

H.265 (libx265) -crf 32 max 24-28

VP9 (libvpx-vp9) -crf 40 max 31-36

AAC -b:a 128k min 192k

MP3 -q:a 4 max 2

If the target size requires going below these floors, say so. Offer the best size achievable at the floor instead.
File over 1 GB? Stop. Say: "This file is [size]. Processing will take a while and produce large intermediates. Continue?" Only proceed with confirmation.

Codec	Flag	Floor	Good default
H.264 (libx264)	`-crf`	28 max	18-23
H.265 (libx265)	`-crf`	32 max	24-28
VP9 (libvpx-vp9)	`-crf`	40 max	31-36
AAC	`-b:a`	128k min	192k
MP3	`-q:a`	4 max	2

Step 1 — Inspect first

Always run this before building any command:

ffprobe -v quiet -print_format json -show_format -show_streams "<input>"

Read the size, codec, resolution, bitrate, duration. Check the 1 GB rule here.

Step 2 — Pick the right approach

Compression: libx264 -crf 23 -preset slow. Copy audio unless asked otherwise: -c:a copy.

Format conversion: If only the container changes, use -c copy. No re-encode. No quality loss. Instant.

Trimming: -ss before -i for fast seek. -c copy when possible.

Audio extraction: -vn -c:a copy to extract without re-encoding.

Scaling: -vf scale=1280:-2 to preserve aspect ratio. Always pair with a re-encode.

Step 3 — Show the command before running

ffmpeg -i "input.mp4" -c:v libx264 -crf 23 -preset slow -c:a copy "input_compressed.mp4"
# -crf 23     : quality (lower = better)
# -preset slow : smaller file, same quality
# -c:a copy   : audio untouched

Show it. Explain non-obvious flags. Ask before running on large files or long operations.

Step 4 — Report after

Original size vs output size.
Any quality warnings from stderr.
Output file path.

Output larger than input? Flag it. Suggest -c copy if applicable.

Concerns

Situation	Say
Target size needs CRF above floor	"Hitting [size] needs CRF [N]. Below acceptable quality. Best I can do at the floor is [size]."
User says "compress as much as possible"	"How small do you need it? Below CRF [N] it degrades noticeably."
Input already matches target format	"Already [format]. I can remux without re-encoding. Lossless and instant."
User asks to overwrite original	"Not overwriting the original. Saving as [derived name] instead."
File over 1 GB	Stop. Confirm before proceeding.

---name: ffmpegdescription: Use this skill whenever the user asks to process, convert, compress, trim, merge, extract, or otherwise manipulate video or audio files using ffmpeg. Covers format conversion, compression, clipping, filtering, and any other ffmpeg operation.---# FFmpeg Skill## Hard rules1. **Never overwrite the original.** Write to a new file. Derive the name if none given: `video.mp4` becomes `video_compressed.mp4`. Never use `-y` on the same path as the input.2. **Never destroy quality.** Minimum floors: | Codec | Flag | Floor | Good default | |---|---|---|---| | H.264 (libx264) | `-crf` | 28 max | 18-23 | | H.265 (libx265) | `-crf` | 32 max | 24-28 | | VP9 (libvpx-vp9) | `-crf` | 40 max | 31-36 | | AAC | `-b:a` | 128k min | 192k | | MP3 | `-q:a` | 4 max | 2 | If the target size requires going below these floors, say so. Offer the best size achievable at the floor instead.3. **File over 1 GB? Stop.** Say: "This file is [size]. Processing will take a while and produce large intermediates. Continue?" Only proceed with confirmation.## Step 1 — Inspect firstAlways run this before building any command:```bashffprobe -v quiet -print_format json -show_format -show_streams "<input>"```Read the size, codec, resolution, bitrate, duration. Check the 1 GB rule here.## Step 2 — Pick the right approach**Compression:** `libx264 -crf 23 -preset slow`. Copy audio unless asked otherwise: `-c:a copy`.**Format conversion:** If only the container changes, use `-c copy`. No re-encode. No quality loss. Instant.**Trimming:** `-ss` before `-i` for fast seek. `-c copy` when possible.**Audio extraction:** `-vn -c:a copy` to extract without re-encoding.**Scaling:** `-vf scale=1280:-2` to preserve aspect ratio. Always pair with a re-encode.## Step 3 — Show the command before running```bashffmpeg -i "input.mp4" -c:v libx264 -crf 23 -preset slow -c:a copy "input_compressed.mp4"# -crf 23 : quality (lower = better)# -preset slow : smaller file, same quality# -c:a copy : audio untouched```Show it. Explain non-obvious flags. Ask before running on large files or long operations.## Step 4 — Report after- Original size vs output size.- Any quality warnings from stderr.- Output file path.Output larger than input? Flag it. Suggest `-c copy` if applicable.## Concerns| Situation | Say ||---|---|| Target size needs CRF above floor | "Hitting [size] needs CRF [N]. Below acceptable quality. Best I can do at the floor is [size]." || User says "compress as much as possible" | "How small do you need it? Below CRF [N] it degrades noticeably." || Input already matches target format | "Already [format]. I can remux without re-encoding. Lossless and instant." || User asks to overwrite original | "Not overwriting the original. Saving as [derived name] instead." || File over 1 GB | Stop. Confirm before proceeding. |

Frequently asked questions