Apparently, that can be set in the mqtt url
= Output format option =
[-F log|kv|json|csv|mqtt|influx|syslog|trigger|null] Produce decoded output in given format.
Without this option the default is LOG and KV output. Use "-F null" to remove the default.
Append output to file with :<filename> (e.g. -F csv:log.csv), defaults to stdout.
Specify MQTT server with e.g. -F mqtt://localhost:1883
Add MQTT options with e.g. -F "mqtt://host:1883,opt=arg"
MQTT options are: user=foo, pass=bar, retain[=0|1], <format>[=topic]
Default user and password are read from MQTT_USERNAME and MQTT_PASSWORD env vars.
A base topic can be set with base=<topic>, default is "rtl_433/HOSTNAME".
Supported MQTT formats: (default is all)
events: posts JSON event data
states: posts JSON state data
devices: posts device and sensor info in nested topics
Any topic string overrides the base topic and will expand keys like [/model]
E.g. -F "mqtt://localhost:1883,user=USERNAME,pass=PASSWORD,retain=0,devices=rtl_433[/id]"
With MQTT each rtl_433 instance needs a distinct driver selection. The MQTT Client-ID is computed from the driver string.
If you use multiple RTL-SDR, perhaps set a serial and select by that (helps not to get the wrong antenna).
Specify InfluxDB 2.0 server with e.g. -F "influx://localhost:9999/api/v2/write?org=<org>&bucket=<bucket>,token=<authtoken>"
Specify InfluxDB 1.x server with e.g. -F "influx://localhost:8086/write?db=<db>&p=<password>&u=<user>"
Additional parameter -M time:unix:usec:utc for correct timestamps in InfluxDB recommended
Specify host/port for syslog with e.g. -F syslog:127.0.0.1:1514