On Wed, Jul 05, 2017 at 09:52:21 +0200, Moritz Barsnick wrote:
It is being set, but according to lame/libmp3lame's documentation, the lowest constant bitrate it can encode at 48 kHz sample rate is 32 kbits/s.
Actually, that's a limitation of the MP3 codec, not of the libmp3lame encoder.
I believe MP3 just isn't suitable. Opus is basically quite efficient. MP3 can't match that. If you need those recordings in MP3, they'll be larger. If it's an option, you may want to try the codec HE-AAC v2 instead. (You'll need libfdk_aac to encode to that variant, I believe.) I understand that codec is also great with low bitrates (and I have heard quite "good" sounding music in 48 kbits/s stereo.)
So this remains the recommendation: Live with it or choose a suitable codec. How about Opus? ;-) Moritz