Here you will find a cheat sheet of some useful commands for ffmpeg.
ffmpeg is a powerful CLI tool able to edit and convert countless video/audio/image formats, but at times its commands are hard to remember.
To help myself and others, I will collect and explain here the commands that I use most often to create animations and change file formats.
Please note that these are for Windows, but you can easly change paths and formats for Unix systems.
Open your terminal of choice and let's begin!

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# Extract frames from a video.

R:\ffmpeg.exe -i input.mp4 -filter:v fps=fps=15/1 R:\frames\frame%04d.png

•  Insert framerate of the input video. 15fps in this example.
•  Recursively increment name.

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# Extract Color Palette from a video. This is needed for GIF creation and must be used before the next command.

R:\ffmpeg.exe -i input.mp4 -vf fps=15,scale=-1:-1:flags=lanczos,palettegen palette.png

•  Insert framerate of the input video. 15fps in this example.

# Generate GIF from a video and its Color Palette.

R:\ffmpeg.exe -i input.mp4 -i R:\palette.png -filter_complex "fps=15,scale=-1:-1:flags=lanczos[x];[x][1:v]paletteuse" output.gif

•  Insert framerate of the input video. 15fps in this example.
•  Resolution in px, -1 is same as source. scale=320:-1 is 320px.

# How to use Dither control to change quality and size of the output GIF.

R:\ffmpeg.exe -i input.mp4 -i R:\palette.png -filter_complex "fps=15,scale=-1:-1:flags=lanczos[x];[x][1:v]paletteuse=dither=bayer:bayer_scale=2:diff_mode=rectangle" output.gif

•  Bayer algorithm.
•  Intensity and mode.

R:\ffmpeg.exe -i input.mp4 -i R:\palette.png -filter_complex "fps=15,scale=-1:-1:flags=lanczos[x];[x][1:v]paletteuse=dither=sierra2_4a:diff_mode=rectangle" output.gif

•  Sierra algorithm.
•  Mode.

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# Change Container. This conversion change the container of the file, leaving the codecs untouched. This has a lot of limitations because every container supports only a limited quantity of codecs. Choose the output container accordingly. This kind of conversion should be almost instantaneous, limited by memory copy speed.

R:\ffmpeg -i input.mkv -vcodec copy -acodec copy output.mp4

•  The output container is automatically detected from the file extension.

R:\ffmpeg -i input.mkv -vcodec copy -acodec aac output.mp4

•  If your source has and audio codec unsupported by the output, specify a compatible codec. This will need more time.

# Codec Conversion - Quality Target. This is an actual codec change. I will cover only the most basic instructions since this is the most vaste and versatile part of FFMPEG.

R:\ffmpeg.exe -i input.mp4 -c:v libx264 -crf 22 -preset fast -c:a aac -b:a 194k output.mp4

•  Video codec. Common choices are libx264 libx265 libvpx-vp9 libaom-av1 (h264, h265/HEVEC, VP9, AV1).
•  Quality control. The range of the CRF scale is 0–51, where 0 is lossless (for 8 bit only, for 10 bit use -qp 0), 23 is the default, and 51 is worst quality possible. A lower value generally leads to higher quality, and a subjectively sane range is 17–28 for h264. 28 is default for h265.
•  Compression control. The preset determines compression efficiency and therefore affects encoding speed. Valid presets are ultrafast, superfast, veryfast, faster, fast, medium, slow, slower, veryslow, and placebo. Use the slowest preset you have patience for.
•  Audio Bitrate.

# Codec Conversion - Bitrate Target. You often need to target a specific file size, since bitrate(kbps) = file size(kb) / duration(seconds).

R:\ffmpeg.exe -i input.mp4 -c:v libx264 -b:v 2600k -preset fast -c:a aac -b:a 194k output.mp4

•  Video Bitrate in kbps.

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# Compare two video files. You can use this to highlight the differences between the source file and the compressed output.

R:\ffmpeg.exe -i source.mp4 -i encoded.mkv -filter_complex "blend=all_mode=difference,format=yuv420p" -c:v libx264 -crf 20 -c:a copy output.mp4

# Quick Tips about the terminal usage.
Remember that you can drag and drop ffmpeg.exe from its folder to the terminal. You can do the same with the input files so you don't have to write the path.
You can press TAB to auto-complete path and file names.
You can change the work folder with the command cd C:\work\path
You can press ↑ (up) to recall the previous command and edit it, so you don't have to rewrite it from start.
You can paste text in Windows Terminal with Right Mouse Click inside the window.
You can stop the current conversion with CTRL+C

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