[SR-Users] Disabling video rtp proxing

Hi, I'm using rtpengine for RTP proxying with kamailio. I use it just for audio. But eventually some terminal reinvites offering video. I don't want to refuse the request but just disable RTP proxying for video as my employer has limited bandwidth and want to reserve it only for audio. So I checked the rtpengine module documentation but it seems there is no way to restrict RTP proxying to be performed only for m=audio. I tried some things like replace_body("^m=video [0-9]+", "m=video 0"); and subst_body('/^m=video [0-9]+ /m=video 0 /'); and msg_apply_changes(); but still the RTP proxying for video is set up. Any hints on how to solve this?