ffmpeg -i VTS_01_1.VOB -vf yadif -c:v libx264 -crf 23 -preset medium -c:a aac -strict -2 -b:a 128k -ar 44100 -ac 2 01.mp4
to concat prepare a list.txt file as follow:
file <path of video 1>
file <path of video 2>
file <path of video 3>
file <path of video 4>
after start concat with
ffmpeg -f concat -safe 0 -i list.txt -c copy video_output.mp4