Secure Reliable Transport
SRT (Secure Reliable Transport) is an open source Internet transmission protocol based on UDT protocol. Haivision and Wowza have cooperated to establish SRT alliance to manage and support open source applications of SRT protocol. This organization is committed to promoting the interoperability of video streaming solutions and realizing low latency network video transmission.
SRT is improved from UDT (UDP based Data Transfer) protocol. SRT protocol retains most of the core concepts and mechanisms of UDT protocol, and introduces some improved and enhanced functions, including flow control for real-time audio and video, enhanced congestion control, modification of control data, and improvement of encryption mechanism.
SRT protocol features:
Three features: safety, reliability and low latency.
In terms of security, SRT supports AES encryption to ensure end-to-end video transmission security.
In terms of reliability, SRT ensures the stability of transmission through forward correction technology (FEC).
In terms of low latency, SRT is based on UDP protocol, which solves the problem of high transmission latency of TCP protocol.
SRT solves the complex transmission timing problem, and can support real-time transmission of high-throughput files and high-definition videos.
Advantages of SRT protocol:
Reliability: It is suitable for any network environment and can efficiently handle network packet loss, jitter, bandwidth fluctuation and other disturbances;
Low latency: Due to the UDP transmission mode and ARQ packet loss recovery mechanism, the transmission delay level based on the public network can generally be controlled within 1s;
High quality: SRT's transmission and error correction mechanism can maximize the use of available bandwidth and eliminate network errors and interference, so it can transmit higher bit rate video streams in the same network environment, and cooperate with H Efficient encoding formats such as 264 and HEVC can ensure high video quality under poor network conditions;
High bandwidth utilization: The multi rate adaptive distribution technology, which is different from ABR, requires additional bandwidth for redundant rate. SRT monitors the network link status in real time and can adjust the rate in real time (NAE, network adaptive coding). In addition, ARQ's packet loss recovery mechanism also greatly saves bandwidth and reduces network congestion compared with TCP's packet loss recovery mechanism;
Security: SRT uses AES-128 or 256 encryption to protect content security;
Free and open source: SRT is completely free and open source.
Shortcomings of SRT:
SRT is based on bidirectional UDP point-to-point connection, which is suitable for high-quality, low latency and reliable transmission of point-to-point, but not suitable for content distribution to mass users.