OK I had both libvpx0 AND libvpx1 installed, but not libvpx-utils. So I marked them both for reinstall, and libvpx-utils for install. Afterward, Digikam crashed on trying to open it the first time but succeeded the second time. I have not yet tried to process any photos.
I hope this gives some hints to those in the know about what's going on.
Thanks