https://forum.videolan.org/viewtopic.php?t=138120 mederi's answer may help for you. About input-slave, I have tested some other cases that work well. 1. subtitle from http vlc http://127.0.0.1:8080/video/demo.mkv :input-slave=http/subtitle://127.0.0.1:8080/video/demo.ass :sub-track=0 2. audio from ...