@M0YNG Here are some ffmpeg commands from my DVB-S2X days, perhaps you'll find them useful:

Transmit side:

ffmpeg -s 640x480 -f video4linux2 -i /dev/video0 -f pulse -i default -vcodec libx265 -slices 4 -thread_type +slice+frame -x265-params "keyint=10:repeat-headers=1" -preset ultrafast -tune zerolatency -bufsize:v 1k -b:v 700k -maxrate:v 700k -r 20 -f s16le -ar 48000 -ac 1 -acodec libopus -async 1 -bufsize:a 1k -b:a 10k -f mpegts -muxrate 889000.0 udp://127.0.0.1:48550