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RTMP - Real-Time Messaging Protocol

Published Date: 5 November 2022

What is RTMP?

RTMP—or Real-Time Messaging Protocol is a communication standard for transporting audio and video content over the internet. It was launched by Macromedia as a proprietary specification for streaming high-performance audio and video data between the Flash Player and the Flash Communication Server. However, it also has other applications today, for instance, Adobe LiveCycle Data Services ES.

Different RTMP Variations

The different RTMP protocol variations include:

  • RTMP, the standard communication protocol that acts on top of Transmission Control Protocol (TCP) and has a default port number of 1935.
  • RTMPS, which works on top of Transport Layer Security (TLS/SSL).
  • RTMPE, a proprietary RTMP which leverages Adobe's security mechanism i.e.  industry standard cryptographic primitives for encryption.
  • RTMPT, which works under HTTP requests to bypass firewalls and corporate traffic filtering. RTMPT's encapsulated sessions often carry RTMP, RTMPS, and RTMP packets.
  • RTMFP, a secure Real-Time Media Flow Protocol suite, which works over User Datagram Protocol (UDP). It is designed by Adobe Systems wherein end users can directly communicate with one another (P2P).

How does RTMP work?

RTMP holds a stable connection between the client and server, ensuring there is rapid transfer of video data from the server to the viewer.

Since RTMP is positioned above the Transmission Control Protocol (TCP), it employs a three-way process when transmitting data. It begins with the client or initiator requesting the acceptor or server to resume a connection. The accepter complies with a response, which the initiator acknowledges and ensures a connection is maintained at either end. This makes RTMP rather reliable.

Advantages of RTMP

  • It is quick and simple to set up a low-cost encoder, whether software based or hardware solutions.
  • RTMP delivers video as a single file, simplifying management and processing, as opposed to streaming protocols like HLS which delivers in numerous chunks.
  • RTMP has been an industry standard for quite some time, which makes it compatible with a host of tools and devices out there.
  • RTMP is still among the fastest video streaming protocols out there.

Disadvantages of RTMP

  • Newer standards such as HLS support both HTML5 streaming and adaptive bitrate (ABR) video delivery.
  • RTMP is limited by firewalls.
  • RTMP is linked with unavoidable security issues wrt Flash.
  • A host of major browsers aren't compatible with RTMP.
  • RTMP is not compatible with mobile devices.
  • It doesn't provide quality at par with newer streaming protocols.

Related Terms

Video Quality

In simple terms, video quality is the characteristic of a video that determines how clear, crisp, and detailed the video transmitted to the viewer is.

Video Watermark

A video watermark is a digital copyright tool used to identify the video's copyright owner or prevent illegal distribution.


1:1 is a commonly used aspect ratio in videography. It produces videos that are a perfect square; the width and height of the video image are the same.

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