TRaX Docs
reference

SRT: the streamid contract

SRT is the recommended contribution protocol for TRaX: encrypted, loss-tolerant, low-latency. All routing and authentication for an SRT connection rides in the streamid field.

Format

<action>:<path>[:<user>:<pass>]
Field Values
action publish (send a feed) or read (pull a feed)
path The stream path you were provisioned (see path grammar)
user / pass Credentials. JWT form: user is the literal string trax, pass is the session JWT. Stream-key form: the key in both fields

Complete publish URL with a session JWT:

srt://<trax-media-host>:8890?streamid=publish:<path>:trax:<jwt>

With a stream key:

srt://<trax-media-host>:8890?streamid=publish:<path>:<stream-key>:<stream-key>

Reading is identical with action = read.

Hard rules

  1. Do not URL-encode the streamid. The SRT library and the TRaX edge parse the raw string with literal : delimiters. Encoders that percent-encode the streamid will fail authentication.
  2. 512-byte cap. libsrt hard-caps the streamid at 512 bytes. A session JWT consumes most of that budget — never wrap a JWT inside another JWT, and never append extra fields to the streamid. Overflow does not fail cleanly: the sender typically dies within the first second with an unhelpful Bad parameters / rejected-handshake error.
  3. One token, one path, one action. The JWT's claims must match the action and path in the streamid exactly; mismatches are rejected at handshake.

Failure modes

Symptom Likely cause
Immediate disconnect (<1s), Bad parameters streamid over 512 bytes (usually a doubled/wrapped JWT)
Handshake rejected Expired token, action/path mismatch with the JWT claims, or URL-encoded streamid
Connects, no media routed Wrong path — the connection authenticated but the path isn't provisioned

Encoder quick reference

ffmpeg:

ffmpeg -re -i input.mp4 -c copy -f mpegts \
  "srt://<trax-media-host>:8890?streamid=publish:<path>:trax:<jwt>"

OBS: Settings → Stream → Service Custom, server srt://<trax-media-host>:8890?streamid=publish:<path>:trax:<jwt>, stream key empty. See the OBS / ffmpeg quickstart.