Reduce file size of a video with ffmpeg

Question

So i'm tried to reduce video filesize by scale down video -vf 640:-2, but nothing changes. Scale down or up doesnt affect video filesize

I've read ffmpeg wiki about Scaling but it dont have any information about scale and filesize.

When i'm scale down images, filesize have big drop but for video, nothing changes

Answer 1

You can use -crf option to reduce final video size.

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.

-crf 23 (for default)

You have to use H.264 encoder. this will help almost all type of video. works batter in mp4 videos.