# Ffmpeg

> Extract audio and transcode MP4 to WebM using ffmpeg.

- Skill: `th0rgal/ffmpeg` (Agent Skill)
- Install (CLI): `npx skillmds@latest add th0rgal/ffmpeg`
- Raw SKILL.md: https://api.skillmd.com/api/skills/th0rgal/ffmpeg/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: Th0rgal (https://skillmd.com/u/th0rgal)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/th0rgal/ffmpeg

---


# ffmpeg

## Use when
- Extract audio from a video file.
- Transcode an MP4 video to WebM.

## Don't use when
- A higher-level video-editing skill or tool is already in use for complex edits.
- The task is purely file transfer or metadata inspection (no transcoding needed).

## Outputs
- Output files should be written to `artifacts/` when possible (e.g., `artifacts/output.webm`).

## Templates or Examples
- Use the command blocks below as templates, swapping inputs/outputs and codecs as needed.

## Requirements
- Prefer safe defaults and explicit codecs.
- Keep commands minimal and reproducible.
- Use ASCII-only output unless file already uses Unicode.

## Commands

### Extract audio (MP4 → MP3)
```
ffmpeg -y -i input.mp4 -vn -c:a libmp3lame -q:a 2 output.mp3
```

### Extract audio (MP4 → WAV, lossless)
```
ffmpeg -y -i input.mp4 -vn -c:a pcm_s16le -ar 44100 -ac 2 output.wav
```

### Transcode MP4 → WebM (VP9 + Opus)
```
ffmpeg -y -i input.mp4 -c:v libvpx-vp9 -crf 32 -b:v 0 -row-mt 1 -c:a libopus -b:a 128k output.webm
```

### Transcode MP4 → WebM (VP8 + Vorbis)
```
ffmpeg -y -i input.mp4 -c:v libvpx -crf 10 -b:v 1M -c:a libvorbis -b:a 128k output.webm
```

## Notes
- `-y` overwrites output files. Remove if you want interactive prompts.
- Lower `-crf` means higher quality (and larger files).
- If audio-only extraction is desired, use `-vn` to drop video.