ten-second guide to video compression

modified January 10, 2021.

compression generally requires sacrificing quality, since most video codecs are plenty good at compressing.

this is my default:

ffmpeg -i in.mp4 -map_metadata -1 -vf scale=800:-1 -crf 28 -c:a copy out.mp4

more details

you generally want to set a higher crf (bitrate). default is 23, below 17 is visually non-lossy, every +6 is half the bitrate. the -c:a copy copies audio stream.

ffmpeg -i in.mp4 -crf 28 -c:a copy out.mp4

also consider removing all metadata

ffmpeg -i in.mp4 -map_metadata -1 -c:v copy -c:a copy out.mp4

also consider scaling down the video (-1 means “whatever value keeps it proportional”)

ffmpeg -i in.mp4 -vf scale=800:-1 -c:a copy out.mp4

also consider changing the encoding speed to compression ratio. from low compression to high compression, you have: ultrafast, superfast, veryfast, faster, fast, medium (default), slow, slower, veryslow

ffmpeg -i in.mp4 -preset slow -c:a copy out.mp4

also consider changing to a newer codec, though this sacrifices compatability with many players (default is -c:v libx264)

ffmpeg -i in.mp4 -c:v libx265 -c:a copy out.mp4

and here’s the do-everything command:

ffmpeg -i in.mp4 -crf 28 -map_metadata -1 -vf scale=800:-1 -preset slow -c:v libx265 -c:a copy out.mp4

ten-second guide to video compression (permalink) (tweet)
the no-JavaScript necronomicon

---