SRT (Secure Reliable Transport) Latency (End-to-End)

2 min read · av1 video ffmpeg  ·
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"Secure Reliable Transport (SRT) is an open source video transport protocol that utilises the UDP transport protocol" (wiki)

Feature

  • UDP is faster TCP
  • Lost packet? SRT can retransmit lost packets quickly
  • AES encryption
  • Transport protocol, so you can use any video format, high compression codec like HEVC, AV1 (Also LCEVC, AV2, VVC in the future)
  • Low latency ~1000ms

SRT test on local network I install OBS, ffmpeg and srt-live-transmit on localhost. latency results around 300ms.

SRT End-to-End testing Now, I use OBS to stream video to the SRT server at Singapore (RTT from Thailand around ~30ms) then playback from Thailand. The latency is around ~400ms which is not bad. However I have not optimized much, so may be a better result if I optimize all factors.

SRT (Secure Reliable Transport) Latency (End-to-End) #1

  1. OBS for Video Encoder (Thailand)
  2. SRT Server (Singapore)
  3. Playback (Thailand)

Latency ~532ms

SRT (Secure Reliable Transport) Latency (End-to-End) #2

  1. OBS for Video Encoder (Thailand)
  2. SRT Server (Singapore)
  3. Playback (Thailand)

Latency ~365ms

SRT (Secure Reliable Transport) Latency (End-to-End) #3

  1. OBS for Video Encoder (Thailand)
  2. SRT Server (Singapore)
  3. Playback (Thailand)

Latency ~400ms

What I Config

Please note that I test on my low spec desktop (AMD 3200g). I believe that the video encoder process is a key factor of the result. Better computer performance should better result.