FFmpeg Commands Cheat Sheet: Convert, Compress, Trim, and Merge Video

Overview

FFmpeg is one of the most powerful open-source tools for audio and video processing. It powers many video platforms and conversion services. This cheat sheet collects the most useful FFmpeg commands for common tasks.

Install FFmpeg

Platform	Install method
Windows	Download from the FFmpeg official download page, extract, and add `bin` to PATH
macOS	`brew install ffmpeg`
Ubuntu / Debian	`sudo apt update && sudo apt install ffmpeg`
CentOS / RHEL	`sudo yum install ffmpeg` after enabling EPEL

Check Media Information

ffprobe -v error -show_format -show_streams input.mp4

This shows codec, resolution, frame rate, bitrate, audio codec, sample rate, and more.

Convert Formats

Conversion	Command
MOV to MP4	`ffmpeg -i input.mov -c:v libx264 -crf 23 output.mp4`
MKV to MP4 without re-encoding	`ffmpeg -i input.mkv -c copy output.mp4`
MP4 to GIF	`ffmpeg -i input.mp4 -vf "fps=10,scale=480:-1" output.gif`
Extract audio to MP3	`ffmpeg -i input.mp4 -vn -c:a libmp3lame -q:a 2 output.mp3`

Compress Video

Use CRF for Quality Control

ffmpeg -i input.mp4 -c:v libx264 -crf 28 -preset medium -c:a aac -b:a 96k output.mp4

CRF ranges from 0 to 51. Lower values mean higher quality and larger files.

CRF 18–23: Visually lossless, good for archiving
CRF 24–28: Balanced quality and size, good for web sharing
CRF 29–35: High compression, good for mobile previews

Use Target Bitrate

ffmpeg -i input.mp4 -b:v 1500k -b:a 128k output.mp4

Trim Video

Lossless Trim

ffmpeg -ss 00:00:10 -to 00:01:00 -i input.mp4 -c copy output.mp4

This cuts from 10 seconds to 1 minute without re-encoding.

Resize Video

ffmpeg -i input.mp4 -vf "scale=1280:-1" output.mp4

-1 keeps the aspect ratio automatically.

Audio Commands

# Extract audio as MP3
ffmpeg -i input.mp4 -vn -c:a libmp3lame output.mp3

# Increase volume to 1.5x
ffmpeg -i input.mp3 -af "volume=1.5" output.mp3

# Merge two audio files
ffmpeg -i a.mp3 -i b.mp3 -filter_complex "amix=inputs=2:duration=longest" output.mp3

Merge Videos

echo "file 'part1.mp4'" > list.txt
echo "file 'part2.mp4'" >> list.txt
ffmpeg -f concat -safe 0 -i list.txt -c copy output.mp4

Add a Watermark

ffmpeg -i input.mp4 -i logo.png -filter_complex "overlay=10:10" output.mp4

Use overlay=W-w-10:H-h-10 for the bottom-right corner.

Troubleshooting

Problem	Cause	Solution
Slow encoding	CPU software encoding	Add `-c:v h264_nvenc` for NVIDIA hardware encoding
No audio in output	Audio stream dropped	Add `-c:a aac`
Audio and video out of sync after trimming	`-ss` placed after `-i`	Place `-ss` before `-i`
Merge fails	Different codecs or parameters	Re-encode all clips with the same settings first