ffmpeg-cli

FFmpeg

The universal multimedia framework. Convert, process, and stream video and audio.

• Official site: https://ffmpeg.org
• Docs: https://ffmpeg.org/documentation.html

Common Commands

Format Conversion

ffmpeg -i input.mp4 output.webm                    # Convert MP4 to WebM
ffmpeg -i input.mov output.mp4                      # Convert MOV to MP4
ffmpeg -i input.wav output.mp3                      # Convert WAV to MP3
ffmpeg -i input.mp4 -c:v libx264 -crf 23 output.mp4  # Re-encode with H.264

Extract Audio

ffmpeg -i video.mp4 -vn -acodec mp3 audio.mp3      # Extract audio as MP3
ffmpeg -i video.mp4 -vn -acodec pcm_s16le audio.wav # Extract as WAV
ffmpeg -i video.mp4 -vn -c:a copy audio.aac         # Extract without re-encoding

Trim and Cut

ffmpeg -i input.mp4 -ss 00:01:00 -to 00:02:00 -c copy clip.mp4  # Cut 1:00-2:00
ffmpeg -i input.mp4 -ss 30 -t 10 -c copy clip.mp4               # 10 seconds starting at 30s

Thumbnails and Screenshots

ffmpeg -i input.mp4 -ss 00:00:05 -frames:v 1 thumb.png          # Screenshot at 5s
ffmpeg -i input.mp4 -vf "fps=1/10" thumb_%04d.png               # One frame every 10s
ffmpeg -i input.mp4 -vf "thumbnail" -frames:v 1 best_thumb.png  # Best thumbnail

Resize and Scale

ffmpeg -i input.mp4 -vf "scale=1280:720" output.mp4             # Resize to 720p
ffmpeg -i input.mp4 -vf "scale=-1:480" output.mp4               # Scale height, keep ratio

GIF Creation

ffmpeg -i input.mp4 -ss 0 -t 5 -vf "fps=10,scale=320:-1" output.gif

Concatenation

# Create file list: file 'clip1.mp4'\nfile 'clip2.mp4'
ffmpeg -f concat -safe 0 -i filelist.txt -c copy output.mp4

Audio Processing

ffmpeg -i input.mp3 -af "volume=1.5" louder.mp3                 # Increase volume
ffmpeg -i input.mp3 -af "atempo=1.5" faster.mp3                 # Speed up audio
ffmpeg -i input.mp4 -an output_silent.mp4                       # Remove audio

Probe (inspect file)

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

Agent Best Practices

• Use -c copy when possible to avoid re-encoding (much faster)
• Use ffprobe to inspect files before processing
• Use -y flag to overwrite output without prompting
• Use -hide_banner to reduce noisy output
• CRF (Constant Rate Factor) controls quality: 18 = high, 23 = default, 28 = low
• Use -preset ultrafast for quick encodes, -preset slow for quality
• Pipe output to /dev/null and use -progress pipe:1 for parseable progress

Example Workflows

Convert video for web

ffmpeg -y -hide_banner -i input.mov -c:v libx264 -crf 23 -preset medium -c:a aac -b:a 128k output.mp4

Get video duration

ffprobe -v quiet -show_entries format=duration -of csv=p=0 input.mp4