It's just an old HP Proliant home server with a USB sound dongle, and VLC transcoding from ALSA PCM to Opus and serving HTTP. VLC does it all!
My radio has a WiFi interface, but it's weird and unreliable (only supports RTSP, 401s if the requested host isn't its internal IP, crashes after 12 hours, etc). So I just use a short analog audio cable instead.
--no-alsa-stereo because my input source is mono. --sout-keep probably isn't necessary now, but it was when I was streaming from the radio's crashy RTSP service.
The #transcode block sets up a simple pipeline: first transcode to Opus at the specified output bitrate (24 Kbps is plenty for recorded voice), then mux it up and serve it via HTTP. I added a low-pass filter at ~6 KHz because there's some of high frequency noise from either my radio's analog output stage or the cabling. I had to look through the VLC source code[1] to find the preset frequency bands since I couldn't find them in VLC docs.
My radio has a WiFi interface, but it's weird and unreliable (only supports RTSP, 401s if the requested host isn't its internal IP, crashes after 12 hours, etc). So I just use a short analog audio cable instead.