RTP and RTSP are among the oldest streaming protocols. But they are still actively used because of such protocol features as low latency (in regard of RTP) and support of so-called publishing (in regard of RTSP) when a live media stream is pushed by a client to a server for further distribution. Many modern protocols lack this publishing feature, because already created ones work well enough covering all needs for video streaming software development.
RTSP found wide adoption in security while RTP is actively used in VoIP. Even the relatively fresh WebRTC utilizes RTP as a media transport. So, there is no lack of applications for both RTSP and RTP protocols. Their wide popularity guarantees wide compatibility for new software products using them.
VASTreaming RTSP library for iOS provides the ability to publish a live stream to RTSP server, pull and watch a stream from RTSP server as well as run a tiny RTSP server with the ability to ingest published streams and re-distribute streams to connected clients. See RTSP library page for more details about the protocol itself as well as our implementation details and specifics.
