RTPRelay - Routr

RTPRelay is a middleware that drives RTPEngine over the ng protocol. It rewrites the SDP of calls so RTPEngine relays the media, which bridges WebRTC clients and SIP clients and helps clients that cannot exchange media directly. It has no configuration file.

Docker image

fonoster/routr-rtprelay

Ports

Port	Protocol	Purpose
`51903` (set by `BIND_ADDR`)	gRPC	`Processor` service, used as a middleware by the Dispatcher

Environment variables

Name	Default	Description
`RTPENGINE_HOST`		RTPEngine host or IP. Required
`RTPENGINE_PORT`	`22222`	RTPEngine ng control port
`RTPENGINE_TIMEOUT`	`5000`	Timeout for RTPEngine requests, in milliseconds
`BIND_ADDR`	`0.0.0.0:51903`	Address to listen on
`LOGS_LEVEL`		Log level, for example `verbose` or `info`
`OTEL_EXPORTER_OTLP_ENDPOINT`		OTLP/HTTP endpoint. Setting it turns on tracing
`OTEL_EXPORTER_OTLP_TRACES_ENDPOINT`		OTLP/HTTP traces endpoint. Takes precedence over `OTEL_EXPORTER_OTLP_ENDPOINT`
`OTEL_SERVICE_NAME`	`rtprelay`	Service name reported in traces
`OTEL_SDK_DISABLED`		`true` turns tracing off

gRPC contract

Service	Method	Request	Response
`fonoster.routr.processor.v2beta1.Processor`	`ProcessMessage`	`MessageRequest`	`MessageResponse`

RTPRelay acts on INVITE and ACK with SDP, 180 Ringing, 200 OK with SDP, and BYE. It passes every other message through unchanged. See processor.proto.

Minimal example

This command runs RTPRelay against an RTPEngine instance.

docker run -it \
  -e RTPENGINE_HOST=rtpengine \
  -p 51903:51903 \
  fonoster/routr-rtprelay

This Dispatcher fragment registers RTPRelay as a post-processor middleware.

spec:
  middlewares:
    - ref: rtprelay-middleware
      addr: rtprelay:51903
      postProcessor: true

Notes

RTPRelay does nothing until you add it to the Dispatcher’s spec.middlewares.
In routr-one, setting RTPENGINE_HOST starts RTPRelay and adds it as a post-processor middleware automatically.
RTPRelay controls media relaying only. Routr is not a media server, and RTPEngine is a separate service you run.