FFmpeg Media Processing Skill
FFmpeg is a universal media converter that reads from multiple inputs, applies filters/transformations, and writes to multiple outputs.
When to Use This Skill
Invoke this skill when the user wants to:
- Convert video/audio formats (MP4, MKV, WebM, MP3, etc.)
- Compress or resize videos
- Trim, cut, or merge media files
- Extract audio from video
- Add subtitles or text overlays
- Create GIFs from video
- Adjust speed, rotate, crop, or apply effects
- Stream media (HLS, DASH, RTMP)
Example Inputs/Outputs
| User Says |
Claude Does |
| "Convert video.mkv to mp4" |
ffmpeg -i video.mkv output.mp4 |
| "Extract audio from movie.mp4" |
ffmpeg -i movie.mp4 -vn audio.mp3 |
| "Compress this video" |
ffmpeg -i input.mp4 -crf 23 output.mp4 |
| "Make a GIF from the first 5 seconds" |
ffmpeg -t 5 -i input.mp4 -vf "fps=10,scale=320:-1" output.gif |
| "Add subtitles to my video" |
ffmpeg -i input.mp4 -vf subtitles=subs.srt output.mp4 |
Additional Resources
- CONCEPTS.md - Core concepts: video, audio, codecs, containers, processing pipeline
- REFERENCE.md - Complete command reference for all operations
- ADVANCED.md - Streaming (HLS/DASH/RTMP), complex filters, batch processing
Synopsis
ffmpeg [global_options] {[input_file_options] -i input_url} ... {[output_file_options] output_url} ...
IMPORTANT: Order matters! Options apply to the next specified file and reset between files.
Quick Reference - Main Options
| Option |
Purpose |
-i url |
Specify input file |
-c copy |
Stream copy (no re-encode, fast) |
-c:v codec |
Set video codec (libx264, libx265, libvpx-vp9) |
-c:a codec |
Set audio codec (aac, libmp3lame, libopus) |
-vf filter |
Apply video filter |
-af filter |
Apply audio filter |
-ss time |
Seek to position |
-t duration |
Limit duration |
-y |
Overwrite output |
-vn |
No video |
-an |
No audio |
Most Common Commands
Convert Format
ffmpeg -i input.mkv output.mp4
ffmpeg -i input.mp4 -c:v libvpx-vp9 -c:a libopus output.webm
Extract Audio
ffmpeg -i video.mp4 -vn -c:a copy audio.aac
ffmpeg -i video.mp4 -vn -c:a libmp3lame -b:a 192k audio.mp3
Compress Video
ffmpeg -i input.mp4 -c:v libx264 -crf 23 -c:a copy output.mp4
Trim/Cut
ffmpeg -ss 00:01:00 -i input.mp4 -t 00:00:30 -c copy output.mp4
Resize
ffmpeg -i input.mp4 -vf scale=1280:720 output.mp4
ffmpeg -i input.mp4 -vf scale=640:-1 output.mp4
Create GIF
ffmpeg -i input.mp4 -vf "fps=10,scale=320:-1" output.gif
Add Text
ffmpeg -i input.mp4 -vf "drawtext=text='Hello':fontsize=36:fontcolor=white:x=(w-text_w)/2:y=(h-text_h)/2" output.mp4
Burn Subtitles
ffmpeg -i input.mp4 -vf "subtitles=subs.srt" output.mp4
Extract Frames
ffmpeg -i input.mp4 -vf fps=1 frame_%04d.png
Speed Up/Slow Down
# 2x speed
ffmpeg -i input.mp4 -filter_complex "[0:v]setpts=0.5*PTS[v];[0:a]atempo=2.0[a]" -map "[v]" -map "[a]" output.mp4
Merge Files
# Create filelist.txt with: file 'part1.mp4' (one per line)
ffmpeg -f concat -safe 0 -i filelist.txt -c copy output.mp4
Video Options
| Option |
Purpose |
-r fps |
Set frame rate |
-s WxH |
Set resolution |
-crf N |
Quality (0-51, lower=better, default 23) |
-b:v bitrate |
Set video bitrate |
-preset name |
Encoding speed (ultrafast to veryslow) |
Audio Options
| Option |
Purpose |
-ar freq |
Sample rate (44100, 48000) |
-ac N |
Channels (1=mono, 2=stereo) |
-b:a bitrate |
Audio bitrate |
Common Filters
| Filter |
Example |
Purpose |
| scale |
scale=1280:720 |
Resize |
| crop |
crop=640:480:100:50 |
Crop (w:h:x:y) |
| transpose |
transpose=1 |
Rotate 90° CW |
| hflip/vflip |
hflip |
Mirror |
| fade |
fade=t=in:d=2 |
Fade in/out |
| drawtext |
drawtext=text='Hi' |
Text overlay |
| subtitles |
subtitles=subs.srt |
Burn subtitles |
| overlay |
overlay=10:10 |
Image overlay |
File Info
ffprobe input.mp4
ffprobe -v quiet -print_format json -show_format -show_streams input.mp4
Best Practices
- Use
-c copy when possible (fast, no quality loss)
- Place
-ss before -i for fast seeking
- Use
-y to overwrite without prompts
- Use
-crf 18-28 for quality control
- Check file info with
ffprobe first
For complete reference, see REFERENCE.md, CONCEPTS.md, and ADVANCED.md.
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