Real Data Transport (RDT) is a proprietary transport protocol for the actual audio-video data, developed by

RealNetworks RealNetworks LLC is an American technology company and provider of Internet streaming media delivery software and services based in Seattle, Washington. The company also provides subscription-based online entertainment services and mobile enter ...

in the 1990s. It is commonly used in companion with a control protocol for

streaming media Streaming media refers to multimedia delivered through a Computer network, network for playback using a Media player (disambiguation), media player. Media is transferred in a ''stream'' of Network packet, packets from a Server (computing), ...

like the

IETF The Internet Engineering Task Force (IETF) is a standards organization for the Internet standard, Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster ...

Real Time Streaming Protocol The Real-Time Streaming Protocol (RTSP) is an application-level network protocol designed for multiplexing and packetizing multimedia transport streams (such as interactive media, video and audio) over a suitable transport protocol. RTSP ...

(RTSP). A non-proprietary alternative for RDT is IETF's

Real-time Transport Protocol The Real-time Transport Protocol (RTP) is a network protocol for delivering audio and video over IP networks. RTP is used in communication and entertainment systems that involve streaming media, such as telephony, video teleconference applic ...

(RTP), which is also implemented in RealNetworks players. As reported in a 2002 book about firewalls, RDT used two unidirectional UDP connections, one for the data sent from the server to the client and another in the opposite direction for retransmission requests. The same book reported that RealNetworks' G2 server used RDT in this configuration by default. Another 2003 book reported that RDT was also seen carried over

Transmission Control Protocol The Transmission Control Protocol (TCP) is one of the main communications protocol, protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, th ...

(TCP), as a fall-back mechanism. RDT is now included as part of the Helix Community project.

References

External links

Helix Community RDT implementation
C++ source code repository.
RDT v2
protocol specs from Helix Community
RDT v3
protocol specs from Helix Community {{compu-network-stub Streaming Application layer protocols Data Transport