usage:
-hwaccel qsv -c:v h264_qsv -i in -c:v mjpeg_qsv -global_quality 80 -f
mjpeg out

Signed-off-by: ChaoX A Liu <chaox.a.liu@gmail.com>
Signed-off-by: Zhengxu Huang <zhengxu.maxwell@gmail.com>
Signed-off-by: Andrew Zhang <huazh407@gmail.com>
Signed-off-by: Maxym Dmytrychenko <maxim.d33@gmail.com>