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 (see path grammar); inputs/generic-input-<id> for an input created over /v1
user / pass The credential. For publishing to an input, the input's stream key in both positions

Complete publish URL:

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

You do not assemble this yourself. The complete field of the ingest endpoint (or the studio's Connection Information panel) hands you the whole URL; the studio may also append &latency= and &oheadbw= tuning to it, which the sender applies.

Reading uses the same grammar with action = read and a read credential the platform issues for that path.

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 fail authentication.
  2. 512-byte cap. libsrt hard-caps the streamid at 512 bytes. A stream-key streamid is well under that; never append extra fields to it or wrap it in anything. Overflow does not fail cleanly: the sender typically dies within the first second with an unhelpful Bad parameters / rejected-handshake error.
  3. One key, one path, one action. The key authenticates publishing to the path it was issued for, and nothing else. A key from one input does not open another.

Failure modes

Symptom Likely cause
Immediate disconnect (<1s), Bad parameters streamid over 512 bytes, or edited
Handshake rejected URL-encoded streamid, a mangled or revoked key, or a key used against a different path
Connects, no media routed Wrong path: the connection authenticated but the path isn't the input you expect

Encoder quick reference

ffmpeg:

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

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