commands:
ffmpeg -threads 2 -f v4l2 -i /dev/video1 -f alsa -i hw:2 -aq 1 -vcodec mjpeg -qscale:v 1 -pix_fmt yuvj420p -r 29.97 -s 768x480 -aspect 4:3 -filter:v yadif=0:0:0 drawbox=x=0:y=ih-h:w=iw:h5:color=black ./Videos/test_box.avi

output:
Unable to find a suitable output format for 'drawbox=x=0:y=ih-h:w=iw:h5:color=black'
drawbox=x=0:y=ih-h:w=iw:h5:color=black: Invalid argument