RTMP

Real-Time Messaging Protocol (RTMP) is a TCP-based protocol developed by Macromedia for streaming audio, video, and data over the Internet. It provides a persistent connection between a client and a streaming server to support low-latency live communication, primarily in professional streaming workflows.

RTMP was developed by Macromedia, which was acquired by Adobe in 2005. It became widely used for ingest from encoders and for distribution to servers that repackage streams for delivery to clients, particularly in the era of Flash-based playback. With the decline of Flash, RTMP remains common as an ingest protocol and within internal streaming pipelines, even as playback increasingly relies on alternative formats.

Technically, RTMP uses a handshake, a chunk-based framing system, and AMF (Advanced Message Format) encoding for control messages such as connect, publish, and play. It runs over TCP and normally uses port 1935. Variants include RTMPS, which runs RTMP over TLS/SSL for encrypted transmission. There is also support for RTMP over HTTP tunneling, but this is not widely used for standard streaming scenarios.

In typical architectures, a live encoder publishes a stream to a media server via RTMP. The server may perform transcoding or redistribution and then deliver the stream to viewers or repackage it into HTTP-based formats such as HLS or DASH for broader browser compatibility. RTMP remains popular as an ingest and internal distribution protocol due to its low apparent latency and compatibility with many encoders and servers.

Today, RTMP is still widely used in professional workflows, but browsers do not support RTMP natively. Accordingly, RTMP streams are commonly converted to HTTP-based protocols for playback, while alternative low-latency options such as WebRTC or low-latency HLS/DASH are used for browser-based delivery.