Cut video from 29 minutes to the end and save in out file
ffmpeg -ss 00:29:50 -i video.webm -c copy out.webm
ffmpeg -hide_banner -framerate 20 -video_size $(xrandr | awk '/\*/{printf$1}') -f x11grab -i $DISPLAY.0 screenRecording.mp4
ffmpeg -i input.mp4 -i input.mp3 -c copy -map 0:v:0 -map 1:a:0 output.mp4