OBS to nginx stream audio but not webcam

[NonLinear]

I have implement the recommended steps as described in several sites (https://www.digitalocean.com/commun...aming-server-using-nginx-rtmp-on-ubuntu-20-04) to have live streaming from nginx web server but at the end I listen only the audio but not webcam. The instructions are too simple to make a mistake. I set up an Ubundu 20.04, install nginx with rtmp module, no ufw (firewall), configure the nginx.conf file as it needs etc... I use OBS to capture my audio and webcam and send it as RTMP streaming to nginx. No error in the nginx log. As player to play the RTMP stream I use the VLC. I tested the OBS to send RTMP to YouTube and everything ok. Also when I change the device capture in OBS from webcam to desktop then it works!!! Why only the webcam doesn't show when I use nginx? Thanks