Can't decode byte from rtl_tcp subprocess?

[contagon]

When trying to start my docker container, I'm getting this as my output:

rtlamr2mqtt  | [2022-08-24 19:03:13] RTLAMR2MQTT Starting...
rtlamr2mqtt  | [2022-08-24 19:03:13] Using "/etc/rtlamr2mqtt.yaml" config file
rtlamr2mqtt  | [2022-08-24 19:03:13] RTL SDR Device 0bda:2838 found on USB port 001:003 - Index: 0
rtlamr2mqtt  | [2022-08-24 19:03:13] Configured MQTT sender:
rtlamr2mqtt  | [2022-08-24 19:03:13]  > hostname => MY_IP
rtlamr2mqtt  | [2022-08-24 19:03:13]  > port => 1883
rtlamr2mqtt  | [2022-08-24 19:03:13]  > username => MY_USERNAME
rtlamr2mqtt  | [2022-08-24 19:03:13]  > client_id => rtlamr2mqtt
rtlamr2mqtt  | [2022-08-24 19:03:13]  > base_topic => rtlamr
rtlamr2mqtt  | [2022-08-24 19:03:13]  > availability_topic => rtlamr/status
rtlamr2mqtt  | [2022-08-24 19:03:13]  > tls => None
rtlamr2mqtt  | [2022-08-24 19:03:13] Sending message to MQTT:
rtlamr2mqtt  | [2022-08-24 19:03:13]  > topic => rtlamr/status
rtlamr2mqtt  | [2022-08-24 19:03:13]  > payload => online
rtlamr2mqtt  | [2022-08-24 19:03:13]  > retain => True
rtlamr2mqtt  | [2022-08-24 19:03:13] Trying to start RTL_TCP: /usr/bin/rtl_tcp -d 0 -s 2048000
rtlamr2mqtt  | [2022-08-24 19:03:13] RTL_TCP started with PID 9
rtlamr2mqtt  | Traceback (most recent call last):
rtlamr2mqtt  |   File "/usr/bin/rtlamr2mqtt.py", line 507, in <module>
rtlamr2mqtt  |     outs, errs = rtltcp.communicate(timeout=5)
rtlamr2mqtt  |   File "/usr/local/lib/python3.10/subprocess.py", line 1152, in communicate
rtlamr2mqtt  |     stdout, stderr = self._communicate(input, endtime, timeout)
rtlamr2mqtt  |   File "/usr/local/lib/python3.10/subprocess.py", line 2041, in _communicate
rtlamr2mqtt  |     stdout = self._translate_newlines(stdout,
rtlamr2mqtt  |   File "/usr/local/lib/python3.10/subprocess.py", line 1029, in _translate_newlines
rtlamr2mqtt  |     data = data.decode(encoding, errors)
rtlamr2mqtt  | UnicodeDecodeError: 'utf-8' codec can't decode byte 0xff in position 25: invalid start byte
rtlamr2mqtt exited with code 1

This is running on a headless machine running Ubuntu 20. It appears rtl_tcp outputs something that utf-8 doesn't know how to decode... Any ideas on how to fix this? Happy to provide more info and open an issue if this belongs there.

[contagon]

Figured this out myself, for some reason my rtl-sdr dongle wasn't getting mapped into the docker container properly -> caused rcl_tcp to fail -> caused the above failure when the subprocess couldn't handle some byte in the error log.

Was able to figure it out by removing "universal_newlines=True" from the subprocess command.