What is RTSP?
RTSP (Real Time Streaming Protocol) is a network protocol created to control streaming media servers. It is used to establish and maintain streaming sessions between a stream source or playback client and a media server. RTSP uses RTP and RTCP for the delivery of the media.
RTSP maintains session state by using control sequences. These are commands that are sent over RTCP with session identifiers used to track concurrent sessions. Most RTSP control messages are sent by the client to the server, but some RTSP commands are initiated by the server and sent to the client. The default RTSP transport layer port number is 554.