Im happy to report smplayer 21.8.0 with mpv 0.33.0-349-g5304e9fe31 no longer exhibits this issue. This can be closed.
mpv 0.32 performance degradation
Audio -> stereo mode -> reverse broken on Mono input
I looked some more in the source code and found a hacky workaround that almost works for me. I can use sed.exe to edit smplayer.ini: mplayer_additional_options="" every single time before starting smplayer.exe :o) Sadly this only works once, smplayer doesnt reread smplayer.ini every time, even if timestamp updated. Edit: hmm, I could manually kill smplayer.exe every time, yes that would work :P As you can tell Im trying all the lazy solutions first :)
I looked some more in the source code and found a hacky workaround that almost works for me. I can use sed.exe to edit smplayer.ini: mplayer_additional_options="" every single time before starting smplayer.exe :o) Sadly this only works once, smplayer doesnt reread smplayer.ini every time, even if timestamp updated. As you can tell Im trying all the lazy solutions first :)
command line --help -help -h -? displays empty line
actually https://www.smplayer.info/forum/viewtopic.php?f=2&t=8105 sounds even better, because cmplayer is also missing ability to pass separate audio stream URL. Being able to pass arbitrary parameters to underlying player would solve that.