I use shell script to display IPCAMS. for one set of cams I use successfully
cvlc -vvv --network-caching $cache rtsp://192.168.3.$port:554 --zoom $zoom
$zoom are script parameters.
But, for the 2 commands below, streaming works only when using GUI and not command line.
In both cases, I contacted IPCAM's manufucturer to get the correct syntax. I tried to alter to syntax of set one - with/without cvlc/vlc , zoom, cache, without any success.