-ac ffvorbis is broken in r38407
Playing video file with vorbis audio produces no sound. Playing audio only ogg vorbis file ends immediately, without playing anything. No error is shown in both cases.
both of -corei7 and -k8-sse3 mplayer r38407 builds failed in the same way. mplayer builds up to r38363 (including) work normal.
Meanwhile -ac libvorbis works, so adding -ac -ffvorbis, workarounds the issue.
Correction: the working one is -afm libvorbis -ac vorbis, not in -afm ffmpeg. Setting driver ffmpeg dll libvorbis in codecs.conf doesn't seem to work.
I can confirm this on Gentoo Linux using the package media-video/mplayer-1.5_p20230618::gentoo with media-video/ffmpeg-6.0-r6:0/58.60.60::gentoo.
As a workaround you can edit ~/.mplayer/config with this:
[extension.ogg]
ac=vorbis