It gets built in /usr/games/lib/daphne/libvldp2.so and it's in the source code in src/vldp2/libmpeg2.
Created attachment 214553 [details, diff] tries to remove the use of internal libmpeg2 copy Noticed too late that daphne requires "extra hardware". Still, attaching what I gobbled together, maybe someone else has these laserdiscs, players and thingies, and can proceed. The patch tries to drop the mpeg2dec originating subdirs from compilation and adds -lmpeg2, and ends up slicing libvldp2.so down from ~105k to ~31k with a reference to a Shared library libmpeg2.so. So I'd imagine it might work, but without the ROMs and hardware I cannot test it beyond the screen that says "couldn't find ROMs". (Also, ebuild should be amended accordingly, e.g., the dependency to media-libs/libmpeg2 added.)
seems like it works so I went ahead and added the patch. Heavy users of daphne might report subtle issues that might make me hide the patch behind a system-libs use flag but until then it seems ok. thanks for the patch.