A small script to set the dissector to RTP to an entire port range

port_range_rtp.lua

-- Sets the dissector RTP to the specified port range in Wireshark
-- Effectively equivalent to set "Decode as..." RTP for all ports in range
--
-- I apply it like this:
-- Menu "Tools" -> "Lua console"
-- paste the code and click "Evaluate", then click "Close"
-- the capture will reload and all the UDP port range will be decoded as RTP.

local udp_port = DissectorTable.get("udp.port")
local rtp = Dissector.get("rtp")
udp_port:add("30000-60000", rtp)
reload_lua_plugins()
print("Done")