RTP
RTP (Real-time Transport Protocol) is a network protocol that carries audio and video packets in real time, adding timestamps and sequence numbers so the receiver can play them in order. It usually runs over UDP for speed. RTP is the delivery layer underneath WebRTC, RTSP and many VoIP systems, while a companion protocol called RTCP reports on quality.
Why it matters
RTP is the plumbing under most real-time video, from browser calls to telehealth visits. How well it is tuned decides whether calls feel natural or choppy. Because it favors speed over guaranteed delivery, products built on it must handle lost packets gracefully rather than pausing to wait for them.
How it works
- The sender breaks compressed audio and video into small packets.
- Each packet gets a sequence number and a timestamp so the receiver can rebuild order and timing.
- Packets travel over UDP, which is fast but does not guarantee delivery.
- The receiver uses a small jitter buffer to smooth out arrival times, then plays the media.
- A companion protocol, RTCP, reports packet loss and delay back to the sender.
What is the difference between RTP and RTSP?
RTP carries the actual audio and video packets, while RTSP sends control commands such as play and pause. Think of RTSP as the remote control and RTP as the delivery truck. An IP camera session often uses RTSP to start the stream and RTP to send the media itself.
Does RTP use TCP or UDP?
RTP usually runs over UDP. UDP does not stop to resend lost packets, which keeps delay low for live calls and streams. A late packet is often useless in real-time video anyway. RTP can run over TCP when firewalls block UDP, but that tends to add delay when the network loses packets.
Where it's used
Video call apps and telehealth platforms built on WebRTC send every call over RTP, so audio and video arrive in order with very little delay even when some data gets lost.
By the numbers
- The current RTP specification, RFC 3550, was published in July 2003 as an Internet Standard (STD 64), replacing RFC 1889. (RFC 3550: RTP, A Transport Protocol for Real-Time Applications)
