ffmpeg -y \
-f x11grab -video_size 1280x720 -framerate 30 -show_region 1 -i :0.0+0,49 \
-f video4linux2 -input_format mjpeg -r 30 -i /dev/video0 \
-filter_complex overlay=main_w-overlay_w:main_h-overlay_h \
-vcodec libx264 -preset veryfast -maxrate 1400k -bufsize 1400k -g 60 \
-threads 0 \
-f flv test.flv