James58899 says to Ow< [MSFW]
ffmpeg.exe -i input.mkv -map_metadata:s:a:v -1 -c:v libx264 -crf 18 -preset veryfast -level 5.2 -c:a copy -vf ass=ass/01.ass -movflags +faststart output1.mp4 ffmpeg -i "D:\動漫\[VCB-Studio] Sound! Euphonium [Hi10p_1080p]\[VCB-Studio] Sound! Euphonium [06][Hi10p_1080p][x264_flac].mkv" -map_metadata:s:a:v -1 -c:v libx264 -crf 18 -preset veryfast -level 5.2 -c:a copy -vf ass=ass/06.ass -movflags +faststart 06.mkv