# FFmpeg Media Processing

Converts, resizes, compresses and extracts audio from media files with FFmpeg.

- Repository: https://github.com/calesthio/OpenMontage (74341 stars)
- Category: Media
- License: AGPL-3.0
- Last updated: 2026-10-28
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add calesthio/OpenMontage --skill ffmpeg -g -a claude-code -y`
Codex: `npx skills add calesthio/OpenMontage --skill ffmpeg -g -a codex -y`
Cursor: `npx skills add calesthio/OpenMontage --skill ffmpeg -g -a cursor -y`
Gemini CLI: `npx skills add calesthio/OpenMontage --skill ffmpeg -g -a gemini-cli -y`

## Description

Video and audio processing with FFmpeg. Use for format conversion, resizing, compression, audio extraction, and preparing assets for Remotion. Triggers include converting GIF to MP4, resizing video, extracting audio, compressing files, or any media transformation task.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# FFmpeg for Video Production

FFmpeg is the essential tool for video/audio processing. This skill covers common operations for Remotion video projects.

## Quick Reference

### GIF to MP4 (Remotion-compatible)

```bash
ffmpeg -i input.gif -movflags faststart -pix_fmt yuv420p \
  -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" output.mp4
```

**Why these flags:**
- `-movflags faststart` - Moves metadata to start for web streaming
- `-pix_fmt yuv420p` - Ensures compatibility with most players
- `scale=trunc(...)` - Forces even dimensions (required by most codecs)

### Resize Video

```bash
# To 1920x1080 (maintain aspect ratio, add black bars)
ffmpeg -i input.mp4 -vf "scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:(ow-iw)/2:(oh-ih)/2" output.mp4

# To 1920x1080 (crop to fill)
ffmpeg -i input.mp4 -vf "scale=1920:1080:force_original_aspect_ratio=increase,crop=1920:1080" output.mp4

# Scale to width, auto height
ffmpeg -i input.mp4 -vf "scale=1280:-2" output.mp4
```

### Compress Video

```bash
# Good quality, smaller file (CRF 23 is default, lower = better quality)
ffmpeg -i input.mp4 -c:v libx264 -crf 23 -preset medium -c:a aac -b:a 128k output.mp4

# Aggressive compression for web preview
ffmpeg -i input.mp4 -c:v libx264 -crf 28 -preset fast -c:a aac -b:a 96k output.mp4

# Target file size (e.g., ~10MB for 60s video = ~1.3Mbps)
ffmpeg -i input.mp4 -c:v libx264 -b:v 1300k -c:a aac -b:a 128k output.mp4
```

### Extract Audio

```bash
# Extract to MP3
ffmpeg -i input.mp4 -vn -acodec libmp3lame -q:a 2 output.mp3

# Extract to AAC
ffmpeg -i input.mp4 -vn -acodec aac -b:a 192k output.m4a

# Extract to WAV (uncompressed)
ffmpeg -i input.mp4 -vn output.wav
```

### Convert Audio Formats

```bash
# M4A to MP3 (for ElevenLabs voice samples)
ffmpeg -i input.m4a -codec:a libmp3lame -qscale:a 2 output.mp3

# WAV to MP3
ffmpeg -i input.wav -codec:a libmp3lame -b:a 192k output.mp3

# Adjust volume
ffmpeg -i input.mp3 -filter:a "volume=1.5" output.mp3
```

The rest: https://github.com/calesthio/OpenMontage/blob/HEAD/.agents/skills/ffmpeg/SKILL.md