video-edit（视频编辑）

Video Edit

Edit videos locally by running ffmpeg/ffprobe directly. No wrapper scripts needed.

Prerequisites

Install ffmpeg (includes ffprobe):

# macOS
brew install ffmpeg

# Ubuntu/Debian
sudo apt update && sudo apt install -y ffmpeg

# Verify
ffmpeg -version && ffprobe -version

Quick Reference

Get video info

ffprobe -v quiet -print_format json -show_format -show_streams video.mp4

Trim

ffmpeg -y -ss 00:00:30 -to 00:01:45 -i video.mp4 -c copy trimmed.mp4

Concatenate clips

# 1. Create a file list
printf "file '%s'\n" clip1.mp4 clip2.mp4 clip3.mp4 > list.txt

# 2. Concat with stream copy
ffmpeg -y -f concat -safe 0 -i list.txt -c copy joined.mp4

Resize for platform

ffmpeg -y -i video.mp4 \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black" \
  -c:a copy tiktok.mp4

Change speed

# 2x faster
ffmpeg -y -i video.mp4 -filter:v "setpts=0.5*PTS" -filter:a "atempo=2.0" fast.mp4

# 0.5x (slow motion)
ffmpeg -y -i video.mp4 -filter:v "setpts=2.0*PTS" -filter:a "atempo=0.5" slow.mp4

Extract audio

ffmpeg -y -i video.mp4 -vn -acodec libmp3lame audio.mp3

Replace audio

ffmpeg -y -i video.mp4 -i audio.mp3 -c:v copy -map 0:v:0 -map 1:a:0 -shortest output.mp4

Compress

ffmpeg -y -i video.mp4 -crf 23 -preset medium -c:a copy compressed.mp4

Convert format

ffmpeg -y -i video.mov output.mp4

Add image overlay

# Logo in top-right corner
ffmpeg -y -i video.mp4 -i logo.png \
  -filter_complex "overlay=W-w-10:10" -c:a copy watermarked.mp4

Platform Presets

Use the filter with: ffmpeg -y -i input.mp4 -vf "<filter>" -c:a copy output.mp4

Tips

• Always use -y to overwrite output without prompting.
• Use -c copy when you only need to cut/join (no re-encoding, very fast).
• Lower CRF = better quality, larger file. Range 18-28 is typical; 23 is the default.
• For detailed recipes and flag explanations, see references/operations.md.