AgentSkillsCN

FFmpeg Media Processing

当用户要求转换、压缩、裁剪、调整大小、提取音频、添加字幕、创建GIF或处理视频/音频文件时使用。

SKILL.md
--- frontmatter
name: FFmpeg Media Processing
description: Use when user asks to convert, compress, trim, resize, extract audio, add subtitles, create GIFs, or process video/audio files
dependencies: ffmpeg

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 SaysClaude 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

code
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

OptionPurpose
-i urlSpecify input file
-c copyStream copy (no re-encode, fast)
-c:v codecSet video codec (libx264, libx265, libvpx-vp9)
-c:a codecSet audio codec (aac, libmp3lame, libopus)
-vf filterApply video filter
-af filterApply audio filter
-ss timeSeek to position
-t durationLimit duration
-yOverwrite output
-vnNo video
-anNo audio

Most Common Commands

Convert Format

bash
ffmpeg -i input.mkv output.mp4
ffmpeg -i input.mp4 -c:v libvpx-vp9 -c:a libopus output.webm

Extract Audio

bash
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

bash
ffmpeg -i input.mp4 -c:v libx264 -crf 23 -c:a copy output.mp4

Trim/Cut

bash
ffmpeg -ss 00:01:00 -i input.mp4 -t 00:00:30 -c copy output.mp4

Resize

bash
ffmpeg -i input.mp4 -vf scale=1280:720 output.mp4
ffmpeg -i input.mp4 -vf scale=640:-1 output.mp4

Create GIF

bash
ffmpeg -i input.mp4 -vf "fps=10,scale=320:-1" output.gif

Add Text

bash
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

bash
ffmpeg -i input.mp4 -vf "subtitles=subs.srt" output.mp4

Extract Frames

bash
ffmpeg -i input.mp4 -vf fps=1 frame_%04d.png

Speed Up/Slow Down

bash
# 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

bash
# Create filelist.txt with: file 'part1.mp4' (one per line)
ffmpeg -f concat -safe 0 -i filelist.txt -c copy output.mp4

Video Options

OptionPurpose
-r fpsSet frame rate
-s WxHSet resolution
-crf NQuality (0-51, lower=better, default 23)
-b:v bitrateSet video bitrate
-preset nameEncoding speed (ultrafast to veryslow)

Audio Options

OptionPurpose
-ar freqSample rate (44100, 48000)
-ac NChannels (1=mono, 2=stereo)
-b:a bitrateAudio bitrate

Common Filters

FilterExamplePurpose
scalescale=1280:720Resize
cropcrop=640:480:100:50Crop (w:h:x:y)
transposetranspose=1Rotate 90° CW
hflip/vfliphflipMirror
fadefade=t=in:d=2Fade in/out
drawtextdrawtext=text='Hi'Text overlay
subtitlessubtitles=subs.srtBurn subtitles
overlayoverlay=10:10Image overlay

File Info

bash
ffprobe input.mp4
ffprobe -v quiet -print_format json -show_format -show_streams input.mp4

Best Practices

  1. •Use -c copy when possible (fast, no quality loss)
  2. •Place -ss before -i for fast seeking
  3. •Use -y to overwrite without prompts
  4. •Use -crf 18-28 for quality control
  5. •Check file info with ffprobe first

For complete reference, see REFERENCE.md, CONCEPTS.md, and ADVANCED.md.