real time messaging protocol (Adobe, streaming) (RTMP)

The Real Time Messaging Protocol (RTMP) is a proprietary streaming protocol from Adobe. The Real Time Messaging Protocol supports streaming audio, video, and data between streaming servers and Flash players over the Internet.

The RTMP protocol comes in several flavors. One variant of RTMP uses the TCP protocol as its transport protocol and can transmit streaming data unencrypted in real time over persistent connections. To ensure even transmission of audio and video data, the different data are fragmented differently. Video and data are transmitted in 128- byte fragments, audio in 64-byte fragments. The fragments of the different data are interleaved with each other and transmitted multiplexed over one connection. RTMP can also transmit encapsulated MP3 data and Flash video streams at higher levels. There is also an encrypted transmission using the SSL protocol, Secure Socket Layer (SSL).

In a second variant, the streaming data is transmitted in a tunneling technique to avoid blocking by firewalls. This RTMP variant (RTMPT) encapsulates the RTMP data in an HTTP header with a request. Corresponding tunneling is also used in the third variant with RTMPS (secure).