Doesn't seem to be working under Winamp 5.666 and a file encoded using oggenc:
code:
ffprobe test.ogg
[ogg @ 0x98047c0] 550 bytes of comment header remain
Input #0, ogg, from 'test.ogg':
Duration: 04:33:21.47, start: 0.000000, bitrate: 41 kb/s
Stream #0:0: Audio: opus, 48000 Hz, mono, fltp
Metadata:
ENCODER : opusenc from opus-tools 0.1.10-71-32d4b475 AVX1 [Jun 3 2018]
ENCODER_OPTIONS : --bitrate 48