Makefile diff 89,90d88 < --cc=${CC} \ < --disable-altivec \ 129a128,138 > > FLAVORS=altivec > FLAVOR?= > > .if !${FLAVOR:Maltivec} > CONFIGURE_ARGS+=--cc=${CC} > CONFIGURE_ARGS+=--disable-altivec > .else > CONFIGURE_ARGS+=--cc=gcc > CONFIGURE_ARGS+=--enable-altivec > .endif Due to some buggy AltiVec code present in FFmpeg 4.2.2, base clang can not successfully build. Base gcc however has no issues in doing so.
I have tried patches linked at this URL https://trac.ffmpeg.org/ticket/7861 . This allows base clang to build a broken FFmpeg that gives a floating point exception error when converting a file. For these reasons, I believe using base gcc is the best solution. Only tested on OpenBSD 6.7 macppc.