ffmpegHow to upscale video to 4k

ffmpeg -i in.mp4 -vf scale=-1:2160:flags=lanczos -c:v libx264 -crf 21 out.mp4ctrl + cyoutubegithub

`-i in.mp4` input video file	`-vf` apply specific video filters
`scale=` scale video	`-1` width will be automatically calculated based on aspect ratio
`2160` set scaling height to 2160 pixels (4k resolution)	`flags=lanczos` use `lanczos` scaling algorithm
`-c:v libx264` use H.264 codec	`-crf 21` use good quality for encoding
`out.mp4` resulting video file